Materials

18 pages, 8052 KiB

Open AccessArticle

Steel Catenary Riser Fatigue Assessment: Fracture Mechanics Approach Versus S–N Curve Method

by Niantao Zhang, Caiyan Deng, Wenqiang Zhang, Siyuan Li and Baoming Gong

Materials 2024, 17(22), 5677; https://doi.org/10.3390/ma17225677 - 20 Nov 2024

Viewed by 341

In this paper, the fatigue resistance of a full-scale Steel Catenary Riser (SCR) girth weld is investigated using the Strength–Number of cycles (S–N) curve method based on weld formation quality and fracture mechanics approaches. The test results, presented in [...] Read more.

In this paper, the fatigue resistance of a full-scale Steel Catenary Riser (SCR) girth weld is investigated using the Strength–Number of cycles (S–N) curve method based on weld formation quality and fracture mechanics approaches. The test results, presented in the form of S–N curves, are superior to the design curve E in BS 7608. Compared with the S–N curve determined by a resonant bending rig, the analytical fracture mechanics, i.e., engineering critical assessment (ECA) based on BS 7910, can provide a rational estimation of full-scale girth welds. For the numerical methods, the short crack growth phase is crucial to improving the accuracy and reliability of the assessment. For the girth weld with a concave root, the geometries of the weld cap are the predominant factors for fatigue life. Although the crack initiation site is always located at the outer surface regardless of the flushed or welded caps, the weld grinding treatment is still effective in promoting fatigue life. Full article

(This article belongs to the Special Issue Corrosion Behavior and Mechanical Properties of Metallic Materials)

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19 pages, 3162 KiB

Open AccessArticle

Challenges and Performance of Filter Dusts as a Supplementary Cementitious Material

by Johannes Berger, Anabella Mocciaro, Gisela Cordoba, Cecilia Martinefsky, Edgardo F. Irassar, Nancy Beuntner, Sebastian Scherb, Karl-Christian Thienel and Alejandra Tironi

Materials 2024, 17(22), 5676; https://doi.org/10.3390/ma17225676 - 20 Nov 2024

Viewed by 235

Abstract

Global industry relies on a linear approach for economic growth. One step towards transformation is the implementation of a circular economy and the reclamation of anthropogenic deposits. This study examines two filter dusts, one German and one Argentinian, from the production of calcined [...] Read more.

Global industry relies on a linear approach for economic growth. One step towards transformation is the implementation of a circular economy and the reclamation of anthropogenic deposits. This study examines two filter dusts, one German and one Argentinian, from the production of calcined clays, representing such deposits. Investigations and comparisons of untreated and calcined filter dust and the industrial base product pave the way for using waste product filter dust as supplementary cementitious material (SCM). In the future, some twenty thousand tons of contemporary waste could potentially be used annually as SCM. The results confirm the suitability of one material as a full-fledged SCM without further treatment and a measured pozzolanic reactivity on par with fly ash. Sample materials were classified into two groups: one was found to be a reactive pozzolanic material; the other was characterized as filler material with minor pozzolanic reactivity. Additionally, important insights into the physical properties of oven dust and heat-treated oven dust were obtained. For both material groups, an inversely proportional relationship with rising calcination temperatures was found for the specific surface area and water demand. The impact of the calcination temperature on both the particle size distribution and the potential to optimize the reactivity performance is presented. Full article

(This article belongs to the Special Issue Advances in Natural Building and Construction Materials)

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31 pages, 13872 KiB

Open AccessArticle

Hyperelastic and Stacked Ensemble-Driven Predictive Modeling of PEMFC Gaskets Under Thermal and Chemical Aging

by Su-Yeon Park, Akeem Bayo Kareem, Toyyeebah Ajibola Mustapha, Woo-Jeong Joo and Jang-Wook Hur

Materials 2024, 17(22), 5675; https://doi.org/10.3390/ma17225675 - 20 Nov 2024

Viewed by 284

Abstract

This study comprehensively investigates the stress distribution and aging effects in Ethylene Propylene Diene Monomer (EPDM) and Liquid Silicone Rubber (LSR) gasket materials through a novel integration of hyperelastic modeling and advanced machine learning techniques. By employing the Mooney–Rivlin, Ogden, and Yeoh hyperelastic [...] Read more.

This study comprehensively investigates the stress distribution and aging effects in Ethylene Propylene Diene Monomer (EPDM) and Liquid Silicone Rubber (LSR) gasket materials through a novel integration of hyperelastic modeling and advanced machine learning techniques. By employing the Mooney–Rivlin, Ogden, and Yeoh hyperelastic models, we evaluated the mechanical behavior of EPDM and LSR under conditions of no aging, heat aging, and combined heat- and sulfuric-acid exposure. Each model revealed distinct sensitivities to stress distribution and material deformation, with peak von Mises stress values indicating that LSR experiences higher internal stress than EPDM across all conditions. For instance, without aging, LSR shows a von Mises stress of 24.17 MPa compared to 14.96 MPa for EPDM, while under heat and sulfuric acid exposure, LSR still exhibits higher stress values, showcasing its resilience under extreme conditions. Additionally, the ensemble learning approach achieved a classification accuracy of 98% for LSR and 84% for EPDM in predicting aging effects, underscoring the robustness of our predictive framework. These findings offer practical implications for selecting suitable gasket materials and developing predictive maintenance strategies in industrial applications, such as fuel cells, where material integrity under stress and aging is paramount. Full article

(This article belongs to the Special Issue Advanced Materials: Process, Properties, and Applications)

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17 pages, 352 KiB

Open AccessReview

Role of Metalloproteinases in Adhesion to Radicular Dentin: A Literature Review

by Marihana Valdez-Montoya, Mariana Melisa Avendaño-Félix, Julio César Basurto-Flores, Maricela Ramírez-Álvarez, María del Rosario Cázarez-Camacho, Miguel Ángel Casillas-Santana, Norma Verónica Zavala-Alonso, Seyla Nayjaá Sarmiento-Hernández, Erika de Lourdes Silva-Benítez and Jesús Eduardo Soto-Sainz

Materials 2024, 17(22), 5674; https://doi.org/10.3390/ma17225674 - 20 Nov 2024

Viewed by 286

Abstract

Introduction: Root dentin is a porous and complex dental surface that may have irregularities and deposits of organic material. To achieve an effective bond between restorative materials and root dentin, it is necessary that the restorative materials adhere intimately to the dentin surface. [...] Read more.

Introduction: Root dentin is a porous and complex dental surface that may have irregularities and deposits of organic material. To achieve an effective bond between restorative materials and root dentin, it is necessary that the restorative materials adhere intimately to the dentin surface. Metalloproteinases (MMPs) are a group of proteolytic enzymes that perform an important role in degrading the extracellular matrix and remodeling connective tissue. The aim of this research was to determine the scientific evidence available on the role played by MMPs in adhesion to root dentin and their putative inhibitors. Materials and Methods: Several techniques have been used to evaluate the presence of MMPs in the root dentin of human and bovine teeth, such as Western blot, immunohistochemistry, immunofluorescence, and zymography, the latter also being used together with the EnzCheck assay to evaluate the inhibitory effect of adhesion protocols on the activity of root MMPs in vitro. Results: When analyzing the databases, 236 articles were found, 12 of which met the selection criteria. The variables analyzed were articles that evaluated different MMP inhibitors in root dentin. Conclusions: In the adhesion to radicular dentin, MMPs have a crucial role in the degradation of the extracellular matrix of dentin and the remodeling of the dentin surface because excessive MMP activity can be harmful to dental health, since excessive degradation of the extracellular matrix of dentin can weaken the tooth structure and decrease fracture resistance. Therefore, it is important to monitor MMP activity during root dentin bonding procedures. Full article

(This article belongs to the Special Issue Research Progress in Functional Dental Materials)

18 pages, 4738 KiB

Open AccessArticle

Unveiling the Significance of Graphene Nanoplatelet (GNP) Localization in Tuning the Performance of PP/HDPE Blends

by Reza Salehiyan, Ali A. El-Samak, Milad Kamkar, Elnaz Erfanian, Stephen A. Hodge, Uttandaraman Sundararaj and Tony McNally

Materials 2024, 17(22), 5673; https://doi.org/10.3390/ma17225673 - 20 Nov 2024

Viewed by 232

Abstract

High-density polyethylene (HDPE) and polypropylene (PP) blends are widely used in industries requiring mechanically durable materials, yet the impact of processing parameters on blend performance remains underexplored. This study investigates the influence of blending sequence and screw speed on the properties of blends [...] Read more.

High-density polyethylene (HDPE) and polypropylene (PP) blends are widely used in industries requiring mechanically durable materials, yet the impact of processing parameters on blend performance remains underexplored. This study investigates the influence of blending sequence and screw speed on the properties of blends of HDPE and PP filled with 1.25 wt.% graphene nanoplatelets (GNPs). Changes in crystallization behaviour, tensile strength, and viscoelastic responses with blending sequence are studied. The addition of GNP increases the crystallization temperature (T_c) of PP in the PE/PP blend by 4 °C when GNP is pre-mixed with PE to form (PE+GNP)/PP blends. In contrast, when GNP is pre-mixed with PP to create (PP+GNP)/PE blends, the T_c of PP rises by approximately 11 °C, from 124 °C for the neat PE/PP blend to 135 °C. On the other hand, the T_c of PE remains unchanged regardless of the blending sequence. XRD patterns reveal the impact of blending regime on crystallinity, with GNP alignment affecting peak intensities confirming the more efficient interaction of GNPs with PP when premixed before blending with PE, (PP+GNP)/PE. Tensile moduli are less sensitive to the changes in processing, e.g., screw speed and blending sequence. In contrast, elongation at break and tensile toughness show distinct variations. The elongation at the break of the (PP+GNP)/PE blend decreases by 30% on increasing screw speed from 50 to 200 rpm. Moreover, the elongation at the break of (PE+GNP)/PP prepared at 100 rpm is ~40% higher than that of the (PP+GNP)/PE. (PE+GNP)/PP displays a ‘quasi-co-continuous’ morphology linked to its higher elastic modulus G′ compared to that of the (PP+GNP)/PE blend. This study highlights the importance and correlation between processing and blend properties, offering insights into fine-tuning polymer composite formulation for optimal performance. Full article

(This article belongs to the Special Issue Advances in Functional Polymers and Nanocomposites)

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10 pages, 2063 KiB

Open AccessArticle

Size Dependence of the Tetragonal to Orthorhombic Phase Transition of Ammonia Borane in Nanoconfinement

by Shah Najiba, Jiuhua Chen, Mohammad S. Islam, Yongzhou Sun, Andriy Durygin and Vadym Drozd

Materials 2024, 17(22), 5672; https://doi.org/10.3390/ma17225672 - 20 Nov 2024

Viewed by 215

Abstract

We have investigated the thermodynamic property modification of ammonia borane via nanoconfinement. Two different mesoporous silica scaffolds, SBA-15 and MCM-41, were used to confine ammonia borane. Using in situ Raman spectroscopy, we examined how pore size influences the phase transition temperature from tetragonal [...] Read more.

We have investigated the thermodynamic property modification of ammonia borane via nanoconfinement. Two different mesoporous silica scaffolds, SBA-15 and MCM-41, were used to confine ammonia borane. Using in situ Raman spectroscopy, we examined how pore size influences the phase transition temperature from tetragonal (I4mm) to orthorhombic (Pmn21) for ammonia borane. In bulk ammonia borane, the phase transition occurs at around 217 K; however, confinement in SBA-15 (with ~8 nm pore sizes) reduces this temperature to approximately 195 K, while confinement in MCM-41 (with pore sizes of 2.1–2.7 nm) further lowers it to below 90 K. This suppression of the phase transition as a function of pore size has not been previously studied using Raman spectroscopy. The stability of the I4mm phase at a much lower temperature can be interpreted by incorporating the surface energy terms to the overall free energy of the system in a simple thermodynamic model, which leads to a significant increase in the surface energy when transitioning from the tetragonal phase to the orthorhombic phase. Full article

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18 pages, 6646 KiB

Open AccessArticle

Hydrogen Trapping at Fe/Cu Interfaces

by Philipp Hammer, Matthias Militzer and Vsevolod I. Razumovskiy

Materials 2024, 17(22), 5671; https://doi.org/10.3390/ma17225671 - 20 Nov 2024

Viewed by 186

Abstract

Copper (Cu) in steel production can be a residual element, causing challenges during steel processing, as well as an alloying element, improving corrosion resistance and providing hardenability by nanosized precipitates. For the transition toward a green economy, increased recycling rates in steel production [...] Read more.

Copper (Cu) in steel production can be a residual element, causing challenges during steel processing, as well as an alloying element, improving corrosion resistance and providing hardenability by nanosized precipitates. For the transition toward a green economy, increased recycling rates in steel production and alternative energy carriers, such as hydrogen, are of vital importance. As hydrogen is known for its embrittling effect on high-strength steels, this work sought to explore possible mitigation strategies for hydrogen embrittlement (HE) with the help of Cu precipitates. Hydrogen trapping at Cu/Fe interfaces following the complex phase transformations in the Cu precipitation sequence from body-centered cubic (bcc) to the so-called 9R structure to face-centered cubic (fcc) was addressed by a series of systematic density functional theory calculations. In combination with thermodynamic calculations, the pressing question regarding which of the precipitate structures was most desirable for the tackling of HE was alluded to. We found that hydrogen trapping at the Cu/Fe interfaces increased from −0.05 to −0.18 eV following the precipitation sequence. Despite this relatively weak hydrogen trapping, which was in the range of dislocations, we showed through thermodynamic calculations that fcc Cu precipitates could still contribute to lowering the risk of triggering the hydrogen-enhanced localized plasticity (HELP) mechanism of HE. Full article

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12 pages, 3264 KiB

Open AccessArticle

Effect of Waste Concrete Powder Content and Microwave Heating Parameters on the Properties of Porous Alkali-Activated Materials from Coal Gangue

by Vasilii Mischinenko, Andrey Vasilchenko and Georgy Lazorenko

Materials 2024, 17(22), 5670; https://doi.org/10.3390/ma17225670 - 20 Nov 2024

Viewed by 308

Abstract

The objective of this research is to fabricate waste-based alkali-activated foams with better properties in a quick time by using energy-efficient techniques such as microwave irradiation. The present study reports the effect of microwave heating parameters, including heating time and output power, on [...] Read more.

The objective of this research is to fabricate waste-based alkali-activated foams with better properties in a quick time by using energy-efficient techniques such as microwave irradiation. The present study reports the effect of microwave heating parameters, including heating time and output power, on the properties of porous alkali-activated materials (AAMs) that use coal gangue (CG) as a precursor. The effects of concrete waste (CW) content (0–20 wt %) on the performance and microstructure of CG-based AAMs were investigated. Mechanical, thermal, and microstructural investigations were conducted to characterize the obtained materials. The experimental results indicate that the best characteristics of CG-based alkali-activated foams were achieved when microwave power and microwave heating time were 800 W and 10 min, respectively. The foams prepared by adding the waste concrete powder increased stability and showed lower bulk density and thermal conductivity. When the waste concrete powder content was 10 wt %, the CG-based alkali-activated foams showed the best overall performance. At the same time, the mechanical properties of the alkali-activated foams declined only slightly (~9%). The findings of this work provide a basis for further studies on improving the characteristics of CG-based alkali-activated foams due to the physical effect of a microwave field on fresh mortar without the use of a chemical foaming agent while reducing energy consumption in the production process. Full article

(This article belongs to the Special Issue Geopolymers and Alkali-Activated Materials: Preparation and Properties)

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11 pages, 2838 KiB

Open AccessArticle

The Synthesis of a Large Stokes-Shift Dye and Intercalation into the Nanochannels of Zeolite L

by Fabian Walther, Achim Ecker, Dominik Brühwiler and Marc Bornand

Materials 2024, 17(22), 5669; https://doi.org/10.3390/ma17225669 - 20 Nov 2024

Viewed by 272

Abstract

A host–guest-based fluorescent composite with a large Stokes shift was synthesized by intercalating 2,2′-(thiophene-2,5-diyl)bis(benzo[d]oxazol-6-amine) (BBTA) into the nanochannels of zeolite L (ZL) and sealing the pores with (3-aminopropyl)triethoxysilane (APTES). To confirm the orientation of the amino groups in BBTA, a single crystal of [...] Read more.

A host–guest-based fluorescent composite with a large Stokes shift was synthesized by intercalating 2,2′-(thiophene-2,5-diyl)bis(benzo[d]oxazol-6-amine) (BBTA) into the nanochannels of zeolite L (ZL) and sealing the pores with (3-aminopropyl)triethoxysilane (APTES). To confirm the orientation of the amino groups in BBTA, a single crystal of 2,5-bis(6-nitrobenzo[d]oxazol-2-yl)thiophene (BBTN) was grown and examined by X-ray crystallography. The evidence of successful intercalation of BBTA into the nanochannels of ZL was provided by fluorescence spectrometry, gas sorption and fluorescence microscopy. BBTA showed a Stokes shift of 6641 cm⁻¹ (157 nm) in ethanol and 4611 cm⁻¹ (93 nm) in toluene. The BBTA-ZL composite (BBTA-ZL-s) showed a Stokes shift of 5677 cm⁻¹ (123 nm) in toluene, and 5450 cm⁻¹ (124 nm) in ethanol. In addition, the degree of loading was determined and stability against leaching was confirmed. We report the synthesis of this novel composite dye material with potential applications where free dyes are not applicable and which retains a large Stokes shift, independent of its chemical environment. Full article

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20 pages, 16954 KiB

Open AccessArticle

Study on the Properties of High Fly Ash Content Alkali-Activated Fly Ash Slag Pastes and Fiber-Reinforced Mortar Under Normal Temperature Curing

by Zhu Yuan, Yanmin Jia, Jinyu Sun, Xiaobo Zhang, Yaojie Hu and Xuhua Han

Materials 2024, 17(22), 5668; https://doi.org/10.3390/ma17225668 - 20 Nov 2024

Viewed by 350

Abstract

In order to efficiently utilize industrial solid waste while minimizing the preparation cost of engineering materials and the technical difficulty of construction, this paper prepared a high fly ash content alkali-activated fly ash slag composite system at normal temperatures and conducted an in-depth [...] Read more.

In order to efficiently utilize industrial solid waste while minimizing the preparation cost of engineering materials and the technical difficulty of construction, this paper prepared a high fly ash content alkali-activated fly ash slag composite system at normal temperatures and conducted an in-depth investigation on it. A systematic study was conducted on the workability, mechanical properties, and microstructures of the alkali-activated fly ash slag pastes, including setting times, strength, phase, and molecular structures. We then designed and prepared fiber-reinforced alkali-activated fly ash slag mortar and studied the effects of the alkali activator modulus, glass fiber (GF), and polypropylene fiber (PPF) on the workability, mechanical properties, and frost resistance of the mortar. The following main conclusions were drawn: By adjusting the modulus of alkali activator for alkali-activated fly ash slag pastes, characteristics that meet engineering requirements could be obtained. The compressive strength of the pastes decreased with increasing proportions of fly ash, and it first increased and then decreased with increases in the activator modulus. The flexural strength decreased to varying degrees as the modulus of the activator increased. Through SEM, fly ash particles with different reaction degrees could be observed, indicating that the reaction was still ongoing. The addition of GF and PPF reduced the fluidity of mortar and significantly improved its strength and frost resistance. Fiber had the most significant effect on improving the strength of the mortar, as an activator modulus of 1.0. 0.45% PPF increased the flexural and compressive strength of the mortar by 14.33% and 29.1%, respectively, while 0.90% GF increased the flexural and compressive strength of the mortar by 3.12% and 19.21%, respectively. The frost resistance of the mortar with an activator modulus of 1.0 was significantly better than that of the mortar with an activator modulus of 1.4. 0.45% PPF and reduced the quality loss rate of the mortar by 49.30%, effectively delaying the deterioration of its freeze-thaw performance. Full article

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19 pages, 21170 KiB

Open AccessArticle

Multiple Preheating Processes for Suppressing Liquefaction Cracks in IN738LC Superalloy Fabricated by Electron Beam Powder Bed Fusion (EB-PBF)

by Yang Li, Hongyu Long, Bo Wei, Jun Zhou and Feng Lin

Materials 2024, 17(22), 5667; https://doi.org/10.3390/ma17225667 - 20 Nov 2024

Viewed by 296

Abstract

In additive manufacturing, controlling hot cracking in non-weldable nickel-based superalloys poses a significant challenge for forming complex components. This study introduces a multiple preheating process for the forming surface in electron beam powder bed fusion (EB-PBF), employing a dual-band infrared surface temperature measurement [...] Read more.

In additive manufacturing, controlling hot cracking in non-weldable nickel-based superalloys poses a significant challenge for forming complex components. This study introduces a multiple preheating process for the forming surface in electron beam powder bed fusion (EB-PBF), employing a dual-band infrared surface temperature measurement technique instead of the conventional base plate thermocouple method. This new approach reduces the temperature drop during forming, decreasing surface cooling by 28.6% compared to traditional methods. Additionally, the precipitation of carbides and borides is reduced by 38.5% and 80.1%, respectively, lowering the sensitivity to liquefaction cracking. This technique enables crack-free forming at a lower powder bed preheating temperature (1000 °C), thereby improving the powder recycling rate by minimizing powder sintering. Microstructural analysis confirms that this method reduces low-melting eutectic formation and alleviates liquefaction cracking at high-angle grain boundaries caused by thermal cycling. Consequently, crack-free IN738 specimens with high-temperature durability were successfully achieved, providing a promising approach for the EB-PBF fabrication of crack-resistant IN738 components. Full article

(This article belongs to the Special Issue Fabrication of Advanced Materials)

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14 pages, 2556 KiB

Open AccessArticle

Electrical Conductivity as an Informative Factor of the Properties of Liposomal Systems with Naproxen Sodium for Transdermal Application

by Witold Musiał, Carla Caddeo, Alina Jankowska-Konsur, Giorgio Passiu, Tomasz Urbaniak, Maria Twarda and Adam Zalewski

Materials 2024, 17(22), 5666; https://doi.org/10.3390/ma17225666 - 20 Nov 2024

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Abstract

Liposomal preparations play an important role as formulations for transdermal drug delivery; however, the electrical conductivity of these systems is sparingly evaluated. The aim of the study was to outline the range of the values of electrical conductivity values that may be recorded [...] Read more.

Liposomal preparations play an important role as formulations for transdermal drug delivery; however, the electrical conductivity of these systems is sparingly evaluated. The aim of the study was to outline the range of the values of electrical conductivity values that may be recorded in the future pharmaceutical systems in the context of their viscosity. The electrical conductivity, measured by a conductivity probe of k = 1.0 cm⁻¹, and the dynamic viscosity of liposomal and non-liposomal systems with naproxen sodium, embedded into a methylcellulose hydrophilic gel (0.25%), were compared with data from preparations without naproxen sodium in a range reflecting the naproxen sodium concentrations 0.1·10⁻²–9.5·10⁻² mol/L. The specific conductivity covered a 1.5 μS·cm⁻¹–5616.0 μS·cm⁻¹ range, whereas the viscosity ranged from 0.9 to 9.4 mPa·s. The naproxen sodium highly influenced the electrical conductivity, whereas the dynamic viscosity was a moderate factor. The observed phenomena may be ascribed to the high mobility of sodium ions recruited from naproxen sodium and the relatively low concentrations of applied methylcellulose. The assembly of lecithin in liposomes may have lowered the specific conductivity of the systems with naproxen sodium. These measurements will be further developed for implementation as simple assays of the concentrations of active pharmaceutical ingredient in release experiments of preparations proposed for dermatological applications. Full article

(This article belongs to the Special Issue Functional Hydrogels: Design, Properties and Applications)

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15 pages, 8875 KiB

Open AccessArticle

The Customized Heat Treatment for Enhancing the High-Temperature Durability of Laser-Directed Energy Deposition-Repaired Single-Crystal Superalloys

by Yimo Guo, Nannan Lu, Pengfei Yang, Jingjing Liang, Guangrui Zhang, Chuanyong Cui, Ting-An Zhang, Yizhou Zhou, Xiaofeng Sun and Jinguo Li

Materials 2024, 17(22), 5665; https://doi.org/10.3390/ma17225665 - 20 Nov 2024

Viewed by 260

Abstract

The high-temperature durability performance plays a crucial role in the applications of single-crystal (SX) superalloys repaired by laser-directed energy deposition (L-DED). A specialized heat treatment process for L-DED-repaired SX superalloys was developed in this study. The effect of the newly customized heat treatment [...] Read more.

The high-temperature durability performance plays a crucial role in the applications of single-crystal (SX) superalloys repaired by laser-directed energy deposition (L-DED). A specialized heat treatment process for L-DED-repaired SX superalloys was developed in this study. The effect of the newly customized heat treatment on the microstructure and high-temperature mechanical properties of DD32 SX superalloy repaired by L-DED was investigated. Results indicate that the repaired area of the newly customized heat treatment specimen still maintained a SX structure, the average size of the γ′ phase was 236 nm, and the volume fraction was 69%. Obviously recrystallized grains were formed in the repair area of the standard heat treatment specimens, and carbide precipitated along the grain boundary. The size of the γ′ phase was about 535 nm. The high-temperature durable life of the newly custom heat treatment specimen was about 19.09 h at 1000 °C/280 MPa, the fracture mode was microporous aggregation fracture, and the fracture location was in the repair area. The durable life of the standard heat treatment specimen was about 8.70 h, the fracture mode was cleavage fracture, and the fracture location was in the matrix area. The crack source of both specimens was interdendrite carbide. Full article

(This article belongs to the Special Issue Laser Processing of Metals and Alloys: Structures, Properties, and Applications)

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22 pages, 12709 KiB

Open AccessArticle

Synergistic Reduction in Asphalt VOC Emissions by Hydrochloric Acid-Modified Zeolite and LDHs

by Haowei Zhao, Anqi Chen, Shaopeng Wu, Haiqin Xu, Huan Wang and Yang Lv

Materials 2024, 17(22), 5664; https://doi.org/10.3390/ma17225664 - 20 Nov 2024

Viewed by 220

Abstract

Asphalt releases a large number of irritating fumes during construction and use, which is a serious emission pollution that not only damages the atmospheric environment but also produces highly toxic and carcinogenic volatile organic compounds (VOCs), posing a health risk to human beings. [...] Read more.

Asphalt releases a large number of irritating fumes during construction and use, which is a serious emission pollution that not only damages the atmospheric environment but also produces highly toxic and carcinogenic volatile organic compounds (VOCs), posing a health risk to human beings. In this study, a compound-doped modified bitumen for reducing VOC emission was prepared by using zeolite as the main adsorbent material, modified by hydrochloric acid, and LDHs as a synergistic adsorbent material. By determining its basic and rheological properties, the results show that the compounding of LDHs and HCL-modified zeolite added to asphalt can improve the high-temperature performance of asphalt binder, but at the same time, the anti-fatigue property will be decreased. By GC-MS experimental analysis, a total of 72.2% fewer volatile organic compounds (VOCs) were released by the compound modified asphalt compound than by virgin asphalt, which resulted in a significant reduction in asphalt fume emissions. It shows that the asphalt VOC molecules are well adsorbed by the porous adsorption of LDHs and zeolite materials, and it is also found experimentally that they inhibit the emission of VOCs through the blocking and adsorption effects. This study provides a scientific basis for inhibiting the emission of VOCs during asphalt pavement construction. Full article

(This article belongs to the Special Issue Green and Sustainable Infrastructure Construction Materials (2nd Edition))

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18 pages, 14512 KiB

Open AccessArticle

Mechanical Behavior of Thin Ceramic Laminates on Central Incisors

by Stephanie Soares Favero, Kelli Nunes Monteiro, Aline Rodrigues, Ketuly Marques Cestari, Carlos Alberto Jurado, Abdulaziz Alhotan and Paulo Francisco Cesar

Materials 2024, 17(22), 5663; https://doi.org/10.3390/ma17225663 - 20 Nov 2024

Viewed by 157

Abstract

Restorative dentistry often uses ceramic laminate veneers for aesthetic anterior teeth restorations due to their natural appearance and minimal invasiveness. However, the understanding of their clinical performance and how ceramic microstructure and processing affect longevity is limited. Objective: This study aimed to address [...] Read more.

Restorative dentistry often uses ceramic laminate veneers for aesthetic anterior teeth restorations due to their natural appearance and minimal invasiveness. However, the understanding of their clinical performance and how ceramic microstructure and processing affect longevity is limited. Objective: This study aimed to address this gap by determining the mechanical behavior, fracture load, and failure modes of CAD-CAM processed laminate veneers made of either lithium-disilicate-based glass ceramic (IPS e.max CAD) or feldspathic porcelain (Vita Mark II). It also aimed to develop a mechanical cycling methodology capable of determining the lifetime and failure modes of thin ceramic laminate veneers. Materials and Methods: Eighteen human maxillary central incisors were used to create the specimens. Minimal enamel preparation was required to ensure the proper adaptation of the thin ceramic laminates. Ceramic laminates made from lithium disilicate and feldspathic porcelain (Vita Mark II) were produced via CAD-CAM, with the final thicknesses less than 0.5 mm, then cemented with resin cement. Results: The mean fracture load for the glass ceramic was 431.8 ± 217.9 N, while for the porcelain, it was 454.4 ± 72.1 N. Failure modes differed considerably: porcelain showed more chipping, while lithium disilicate was associated with tooth structure failure. Conclusion: The material used did not significantly affect the fracture load of thin ceramic laminates in static tests. However, failure modes differed considerably. It was not possible to determine a set of mechanical cycling parameters that could establish the fatigue properties of thin ceramic laminates, as the maximum number of cycles reached was 536,818. Full article

(This article belongs to the Special Issue Recent Advancements in Technology and Applications for Dental Ceramics (Second Edition))

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15 pages, 8053 KiB

Open AccessArticle

In Situ Monitoring of Anodic Acidification Process Using 3D μ-XCT Method

by Chaoqun Zeng, Shanshan Qin, Zhijun Deng and Miaochang Zhu

Materials 2024, 17(22), 5662; https://doi.org/10.3390/ma17225662 - 20 Nov 2024

Viewed by 206

Abstract

Debonding of the primary anode caused by anodic acidification is one of the major failure modes of the impressed current cathodic protection (ICCP) system in reinforced concrete structures. This study used 3D micro X-ray computed tomography (μ-XCT) to monitor the in situ evolution [...] Read more.

Debonding of the primary anode caused by anodic acidification is one of the major failure modes of the impressed current cathodic protection (ICCP) system in reinforced concrete structures. This study used 3D micro X-ray computed tomography (μ-XCT) to monitor the in situ evolution of the anodic acidification-affected zone. Samples were scanned after 0 to 40 days of the accelerated anodic acidification test. The anodic acidification-affected zone was identified in μ-XCT images using the gray level segmentation method. The total volume of this zone was measured using the 3D reconstruction method. It was found that detailed 3D information can be extracted using the 3D reconstruction method. The spatial heterogeneity was analyzed using this reconstructed volume information. The Faraday efficiency was calculated and found to increase after 20 days of operation. It was also found that the affected zone was proportional to the input electrical energy. The proposed model is useful for estimating the durability of an ICCP system. Full article

(This article belongs to the Section Construction and Building Materials)

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26 pages, 7129 KiB

Open AccessArticle

Multiscale Modeling of Nanoparticle Precipitation in Oxide Dispersion-Strengthened Steels Produced by Laser Powder Bed Fusion

by Zhengming Wang, Seongun Yang, Stephanie B. Lawson, Cheng-Hsiao Tsai, V. Vinay K. Doddapaneni, Marc Albert, Benjamin Sutton, Chih-Hung Chang, Somayeh Pasebani and Donghua Xu

Materials 2024, 17(22), 5661; https://doi.org/10.3390/ma17225661 - 20 Nov 2024

Viewed by 367

Abstract

Laser Powder Bed Fusion (LPBF) enables the efficient production of near-net-shape oxide dispersion-strengthened (ODS) alloys, which possess superior mechanical properties due to oxide nanoparticles (e.g., yttrium oxide, Y-O, and yttrium-titanium oxide, Y-Ti-O) embedded in the alloy matrix. To better understand the precipitation mechanisms [...] Read more.

Laser Powder Bed Fusion (LPBF) enables the efficient production of near-net-shape oxide dispersion-strengthened (ODS) alloys, which possess superior mechanical properties due to oxide nanoparticles (e.g., yttrium oxide, Y-O, and yttrium-titanium oxide, Y-Ti-O) embedded in the alloy matrix. To better understand the precipitation mechanisms of the oxide nanoparticles and predict their size distribution under LPBF conditions, we developed an innovative physics-based multiscale modeling strategy that incorporates multiple computational approaches. These include a finite volume method model (Flow3D) to analyze the temperature field and cooling rate of the melt pool during the LPBF process, a density functional theory model to calculate the binding energy of Y-O particles and the temperature-dependent diffusivities of Y and O in molten 316L stainless steel (SS), and a cluster dynamics model to evaluate the kinetic evolution and size distribution of Y-O nanoparticles in as-fabricated 316L SS ODS alloys. The model-predicted particle sizes exhibit good agreement with experimental measurements across various LPBF process parameters, i.e., laser power (110–220 W) and scanning speed (150–900 mm/s), demonstrating the reliability and predictive power of the modeling approach. The multiscale approach can be used to guide the future design of experimental process parameters to control oxide nanoparticle characteristics in LPBF-manufactured ODS alloys. Additionally, our approach introduces a novel strategy for understanding and modeling the thermodynamics and kinetics of precipitation in high-temperature systems, particularly molten alloys. Full article

(This article belongs to the Special Issue High-Performance Alloys and Steels)

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23 pages, 6167 KiB

Open AccessReview

The Development of Processing Methods and Materials Used for Non-Pneumatic Tires: A Review

by Meng Sun, Haolong Zhong, Kangpei Qin, Ting Xu, Wengang Yang, Yu Zhang and Lei Lu

Materials 2024, 17(22), 5660; https://doi.org/10.3390/ma17225660 - 20 Nov 2024

Viewed by 375

Abstract

Non-pneumatic tires (NPTs) have garnered significant attention due to their advantages, such as energy efficiency, safety, versatile applications, and superior performance, compared to traditional rubber-based pneumatic tires (PTs). This mini review provides a concise overview of NPTs, beginning with their definition, structural design, [...] Read more.

Non-pneumatic tires (NPTs) have garnered significant attention due to their advantages, such as energy efficiency, safety, versatile applications, and superior performance, compared to traditional rubber-based pneumatic tires (PTs). This mini review provides a concise overview of NPTs, beginning with their definition, structural design, and classification based on structural variations. The review then examines recent advancements in the materials used for NPTs, including those for the tread, elastic support structure, skeleton, and adhesives, with a focus on their specific properties. Furthermore, it summarizes various manufacturing techniques such as compression molding, centrifugal casting, injection molding, 3D printing, and mechanical assembly. Lastly, the review outlines the general manufacturing procedures of NPTs, discusses the challenges currently faced by the technology, and offers insights into future development directions. This mini review aims to support NPT researchers and practitioners, particularly in the fields of process and materials engineering, in advancing their work on NPTs. Full article

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14 pages, 8709 KiB

Open AccessArticle

Effect of Flax By-Products on the Mechanical and Cracking Behaviors of Expansive Soil

by Georgy Lazorenko, Anton Kasprzhitskii, Vasilii Mischinenko, Alexandr Fedotov and Ekaterina Kravchenko

Materials 2024, 17(22), 5659; https://doi.org/10.3390/ma17225659 - 20 Nov 2024

Viewed by 244

Abstract

Expansive soils, prone to significant volume changes with moisture fluctuations, challenge engineering infrastructure due to their swelling and shrinking. Traditional stabilization methods, including mechanical and chemical treatments, often have high material and environmental costs. This study explores fibrous by-products of flax processing, a [...] Read more.

Expansive soils, prone to significant volume changes with moisture fluctuations, challenge engineering infrastructure due to their swelling and shrinking. Traditional stabilization methods, including mechanical and chemical treatments, often have high material and environmental costs. This study explores fibrous by-products of flax processing, a sustainable alternative, for reinforcing expansive clay soil. Derived from the Linum usitatissimum plant, flax fibers offer favorable mechanical properties and environmental benefits. The research evaluates the impact of flax tow (FT) reinforcement on enhancing soil strength and reducing cracking. The results reveal that incorporating up to 0.6% randomly distributed FTs, consisting of technical flax fibers and shives, significantly improves soil properties. The unconfined compressive strength (UCS) increased by 29%, with 0.6% FT content, reaching 525 kPa, compared to unreinforced soil and further flax tow additions, which led to a decrease in UCS. This reduction is attributed to diminished soil–fiber interactions and increased fiber clustering. Additionally, flax tows effectively reduce soil cracking. The crack length density (CLD) decreased by 6% with 0.4% FTs, and higher concentrations led to increased cracking. The crack index factor (CIF) decreased by 71% with 0.4% flax tows but increased with higher FT concentrations. Flax tows enhance soil strength and reduce cracking while maintaining economic and environmental efficiency, offering a viable solution for stabilizing expansive clays in geotechnical applications. Full article

(This article belongs to the Section Green Materials)

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11 pages, 4915 KiB

Open AccessArticle

Accelerating Discontinuous Precipitation to Increase Strength by Pre-Deformation in Cu-Ni-Si Alloys

by Yicheng Cao, Wei Luo, Wenjing Zhang, Haofeng Xie, Zhen Yang, Zengde Li, Lijun Peng and Yunqing Zhu

Materials 2024, 17(22), 5658; https://doi.org/10.3390/ma17225658 - 20 Nov 2024

Viewed by 256

Abstract

Discontinuous precipitation-strengthened Cu-Ni-Si alloys are highly regarded for their combination of high strength and excellent electrical conductivity. However, the slow process of discontinuous precipitation, typically requiring up to 24 h for complete formation, significantly increases the alloy’s production costs and limits potential improvements [...] Read more.

Discontinuous precipitation-strengthened Cu-Ni-Si alloys are highly regarded for their combination of high strength and excellent electrical conductivity. However, the slow process of discontinuous precipitation, typically requiring up to 24 h for complete formation, significantly increases the alloy’s production costs and limits potential improvements in its properties. This study addresses this issue by applying pre-deformation to Cu-6Ni-1.42Si alloys, which accelerated the discontinuous precipitation (DP) of Ni₂Si by approximately 48 times, resulting in the formation of fast DP and full DP alloys. The fast DP alloy exhibited a smaller DP size and inter-distance than the full DP alloy, achieving a tensile strength of 1070 MPa and a conductivity of 38.5% IACS. In contrast, the full DP alloy had a slightly lower tensile strength (approximately 930 MPa) but a higher conductivity of 46% IACS. Both alloys outperform traditional Cu-Ni-Si alloys in strength while maintaining comparable conductivity. The accelerated DP technique improves mechanical properties without significantly sacrificing conductivity, offering a new approach for high-performance conductive materials. Full article

(This article belongs to the Special Issue Microstructure, Mechanical Properties, and Deformation Characteristics of Metals and Alloys)

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22 pages, 6474 KiB

Open AccessArticle

Effect of Dehydrogenation and Heat Treatments on the Microstructure and Tribological Behavior of Electroless Ni-P Nanocomposite Coatings

by Giulia Pedrizzetti, Enrico Baroni, Michele Gragnanini, Rita Bottacchiari, Mattia Merlin, Giovanni Pulci and Francesco Marra

Materials 2024, 17(22), 5657; https://doi.org/10.3390/ma17225657 - 20 Nov 2024

Viewed by 235

Abstract

High phosphorus Ni-P coatings, both unreinforced and modified by the addition of alumina (Al₂O₃) and zirconia (ZrO₂) nanoparticles, were manufactured by electroless deposition technique and heat-treated with different temperature and duration schedules. The effect of dehydrogenation (200 [...] Read more.

High phosphorus Ni-P coatings, both unreinforced and modified by the addition of alumina (Al₂O₃) and zirconia (ZrO₂) nanoparticles, were manufactured by electroless deposition technique and heat-treated with different temperature and duration schedules. The effect of dehydrogenation (200 °C for 2 h) and its combination with crystallization heat treatment was studied in terms of microstructural changes and wear resistance. The amorphous structure of the coatings was not altered by the introduction of both Al₂O₃ and ZrO₂ nanoparticles, and the addition of 1.5 g/L of ZrO₂ yielded the highest microhardness due to better particles dispersion. Dehydrogenation improved hardness because of the early stages of grain growth; however, the greatest improvement in hardness (+120% compared to unreinforced Ni-P) was obtained after annealing at 400 °C for 1 h, because of the microprecipitation of the Ni₃P crystalline phase induced by thermal treatment. No detectable differences in hardness and microstructure were detected when annealing at 400 °C for 1 h with or without prior dehydrogenation; however, the dehydrogenated coatings exhibited a lower Young’s modulus. ZrO₂-reinforced coatings demonstrated improved wear resistance, and wear tests revealed that dehydrogenation is fundamental for lowering the coefficient of friction (−14%) and wear rate (−97%) when performed before annealing at 400 °C for 1 h. The analysis of the wear tracks showed that the non-dehydrogenated samples failed by complete coating delamination from the substrate, with abrasion identified as the predominant wear mechanism. Conversely, the dehydrogenated samples demonstrated better resistance due to the formation of a protective oxide layer, leading to an overall increase in the coating wear resistance. Full article

(This article belongs to the Special Issue Design and Electrochemical Synthesis of Multifunctional Surfaces)

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25 pages, 12906 KiB

Open AccessArticle

Surface Nanocrystallization and Improvement of the Mechanical and Tribological Properties of AISI 304 Steel Using Multi-Pass Nanostructuring Burnishing

by Viktor Kuznetsov, Igor Tatarintsev, Vladimir Voropaev and Andrey Skorobogatov

Materials 2024, 17(22), 5656; https://doi.org/10.3390/ma17225656 - 20 Nov 2024

Viewed by 252

Abstract

Owing to their high producibility and resistance to corrosion, austenitic chromium–nickel steels are widely used in the chemical, petroleum, and food industries. However, their significant disadvantage lies in their poor structural performance, which cannot be improved by heat treatment. This significantly limits the [...] Read more.

Owing to their high producibility and resistance to corrosion, austenitic chromium–nickel steels are widely used in the chemical, petroleum, and food industries. However, their significant disadvantage lies in their poor structural performance, which cannot be improved by heat treatment. This significantly limits the usability of these steels in parts of machines that operate under friction loads. Hardening can be achieved by decreasing the size of grains and applying deformation-induced martensitic transformation. Nanostructuring burnishing (NSB) may be one of the technologies suited for producing parts of tribological assemblies with enhanced operating characteristics. Nanostructuring burnishing using a sliding indenter is being developed as a method of industrial surface nanocrystallization through severe plastic deformation used in the mechanical machining of various types of parts. This article investigates the possibility of enhancing the mechanical and tribological properties of nanocrystallized surfaces of austenitic steels, which are formed through nanostructuring burnishing using a tool with a natural diamond spherical indenter and a change in sliding speed from 40 to 280 m/min with one, three, and five passes. Increasing the tool sliding speed makes surface nanostructuring machining of big parts highly effective. This paper aims to establish the influence exerted by the sliding speed and number of indenter passes on the formation of a nanocrystalline structure, as well as on the modification of microhardness and residual stresses, texture, and tribological properties of the surface layer in the nanostructuring burnishing of AISI 304 steel. Transmission microscopy and microdurometry, 3D-profilometry, and tribological tests of surfaces nanocrystallized with the “ball-on-disk” scheme with dry and lubricated friction established the optimal values of speed and number of passes for a spherical indenter in nanostructuring burnishing. Full article

(This article belongs to the Special Issue Metal Coatings for Wear and Corrosion Applications (Second Edition))

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14 pages, 23867 KiB

Open AccessArticle

Solid-State Synthesis for High-Tetragonality, Small-Particle Barium Titanate

by Tianyu Hao, Jing Shen, Qiaochu Peng, Jie Liu, Wenbin Hu and Cheng Zhong

Materials 2024, 17(22), 5655; https://doi.org/10.3390/ma17225655 - 20 Nov 2024

Viewed by 210

Abstract

This study successfully synthesized high-tetragonality barium titanate (BaTiO₃) particles with a small particle size by implementing ball milling in the solid-state synthesis of BaTiO₃ and utilizing nanoscale raw materials. This study also addressed the issues of impurities and uneven particle [...] Read more.

This study successfully synthesized high-tetragonality barium titanate (BaTiO₃) particles with a small particle size by implementing ball milling in the solid-state synthesis of BaTiO₃ and utilizing nanoscale raw materials. This study also addressed the issues of impurities and uneven particle size distribution that could exist in the synthesized BaTiO₃ particles. The crystal structure, morphology, and particle size of the synthesized BaTiO₃ particles have been meticulously analyzed and discussed through the use of techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and the laser particle size analyzer. BaTiO₃ has been successfully synthesized, exhibiting a uniform particle size with an average diameter of 170 nm and a high tetragonality value of 1.01022. This new solid-state synthesis method provided insights to avoid the impact of “size effects” during the process of electronic device miniaturization. Full article

(This article belongs to the Special Issue Feature Papers in Refractories and Ceramics: Microstructure, Properties and Applications (3rd Edition))

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25 pages, 8992 KiB

Open AccessArticle

Combination of In Situ Diffraction Experiments and Acoustic Emission Testing to Understand Compression Behavior of Mg-Gd Alloys

by Gerardo Garces, Bryan W. Chavez, Pablo Pérez, Judit Medina, Kristian Mathis, Rafael Barea, Andreas Stark, Norbert Schell and Paloma Adeva

Materials 2024, 17(22), 5654; https://doi.org/10.3390/ma17225654 - 20 Nov 2024

Viewed by 298

Abstract

The compressive deformation of the extruded binary Mg-Gd with gadolinium in solid solution has been studied in situ by combining synchrotron diffraction and acoustic emission techniques during compression tests. These two techniques are useful in investigating the evolution of twinning in all its [...] Read more.

The compressive deformation of the extruded binary Mg-Gd with gadolinium in solid solution has been studied in situ by combining synchrotron diffraction and acoustic emission techniques during compression tests. These two techniques are useful in investigating the evolution of twinning in all its stages. The extruded bars develop a fiber texture with the basal plane parallel to the extrusion direction. Moreover, the quenching of the magnesium bars immediately after the extrusion process ensured the production of the solid solution of gadolinium in the magnesium matrix. The solid solution of gadolinium solute atoms is the main strengthening mechanism of alloys and has a strong influence in plastic deformation. Tensile twinning controls the macroscopic yielding under compressive modes, although the activation of basal and non-basal dislocation systems has been also detected by in situ techniques. The presence of gadolinium atoms in solid solution tends to inhibit tensile twinning and, therefore, the twin volume fraction decreases with the increase in the gadolinium content. The compressive work hardening curve shows a maximum peak at intermediate plastic strain which is related to the interaction of dislocations within twins. The maximum value and the position of the peak decreases with the increase in the gadolinium content. Full article

(This article belongs to the Section Metals and Alloys)

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13 pages, 3313 KiB

Open AccessArticle

A Deep Learning Model for Estimating the Quality of Bimetallic Tracks Obtained by Laser Powder-Directed Energy Deposition

by Vincent Wong, Alberta Aversa and Alessandro Roger Rodrigues

Materials 2024, 17(22), 5653; https://doi.org/10.3390/ma17225653 - 19 Nov 2024

Viewed by 332

Abstract

During the fabrication of Inconel 718–AISI 316L bimetallic components via laser powder-directed energy deposition, understanding the relationships between processes, microstructures, and material properties is crucial to obtaining high-quality parts. Physical–chemical properties, cooling rates, and thermal expansion coefficients of each material may affect the [...] Read more.

During the fabrication of Inconel 718–AISI 316L bimetallic components via laser powder-directed energy deposition, understanding the relationships between processes, microstructures, and material properties is crucial to obtaining high-quality parts. Physical–chemical properties, cooling rates, and thermal expansion coefficients of each material may affect the microstructure of parts, generating segregations and cracks. This paper analyzes how the process parameters affect the dimensions, chemical composition, and microhardness of bimetallic tracks. We created a dataset that included laser power, powder feed rate, material, skeletal density, dimensional features, chemical composition, and microhardness. Then, a deep learning methodology using a multilayer perceptron was used to estimate the relationship between these factors. The architecture comprised four inputs in the input layer and five hidden layers with 20, 40, 30, 30, and 30 neurons, respectively. This architecture was used to estimate the dimensional features, chemical composition, and microhardness. The model precision was evaluated using the determination coefficient (R²) and the mean absolute error (MAE) function. Lastly, we used a random forest classifier to select the bead quality from the optimal process parameters. The results showed a significant decrease in training loss and validation loss between 50 and 100 epochs. This decreasing trend continued until 350 epochs. This paper contributes to understanding the relationships between process–structure properties in the bimetallic tracks of Inconel 718 and AISI 316L. Full article

(This article belongs to the Special Issue Advanced Materials Joining and Manufacturing Techniques)

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17 pages, 5937 KiB

Open AccessArticle

Topology Optimization of Periodic Structures Subject to Self-Weight Loading Using a Heuristic Method

by Katarzyna Tajs-Zielińska

Materials 2024, 17(22), 5652; https://doi.org/10.3390/ma17225652 - 19 Nov 2024

Viewed by 319

Abstract

This paper deals with the actual and challenging process of the optimal design of topologies of periodic structures taking into account the design-dependent loads. The topology formulation used in this paper minimizes the compliance value of the structure and is subject to a [...] Read more.

This paper deals with the actual and challenging process of the optimal design of topologies of periodic structures taking into account the design-dependent loads. The topology formulation used in this paper minimizes the compliance value of the structure and is subject to a total volume constraint while maintaining a periodic pattern and self-weight load. This combination represents a promising and original contribution to the field of ongoing research, although it is not yet widely recognized. This paper aims to fill this gap by presenting the first results of numerical optimization tests. The redistribution of material within a design domain is governed by the rules of Cellular Automata, a locally oriented optimization tool that can be applied to all types of structural optimization, including topology optimization. The technique has been demonstrated by numerical tests on two- and three-dimensional examples. The calculations were performed for different types of periodic schemes. The optimized structures did not show the checkerboard effect or the presence of residual gray elements in the final topologies. The strategy used in this paper ensures connectivity between periodic subdomains without imposing additional conditions on the algorithm. Full article

(This article belongs to the Section Materials Simulation and Design)

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16 pages, 6128 KiB

Open AccessArticle

Wear Resistance Design of Laser Cladding Ni-Based Self-Fluxing Alloy Coating Using Machine Learning

by Jiabo Fu, Quanling Yang, Oleg Devojno, Marharyta Kardapolava, Iryna Kasiakova and Chenchong Wang

Materials 2024, 17(22), 5651; https://doi.org/10.3390/ma17225651 - 19 Nov 2024

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Abstract

To improve the collaborative design of laser cladding Ni-based self-fluxing alloy (SFA) wear-resistant coatings, machine learning methods were applied. A comprehensive database was constructed from the literature, linking alloy composition, processing parameters, testing conditions, and the wear properties of Ni-based SFA coatings. Feature [...] Read more.

To improve the collaborative design of laser cladding Ni-based self-fluxing alloy (SFA) wear-resistant coatings, machine learning methods were applied. A comprehensive database was constructed from the literature, linking alloy composition, processing parameters, testing conditions, and the wear properties of Ni-based SFA coatings. Feature correlation analysis using Pearson’s correlation coefficient and feature importance assessment via the random forest (RF) model highlighted the significant impact of C and B elements. The predictive performance of five classical machine learning algorithms was evaluated using metrics such as the squared correlation coefficient (R²) and mean absolute error (MAE). The RF model, which exhibited the best overall performance, was further combined with a genetic algorithm (GA) to optimize both composition and processing parameters collaboratively. This integrated RF-GA optimization system significantly enhanced efficiency and successfully designed multiple composition and process plans. The optimized alloy demonstrated superior wear resistance with an average friction coefficient of only 0.34, attributed to an enhanced solid solution strengthening effect (110 MPa) and increased hard phase content (52%), such as Ni₃Si, CrB, and NbC. These results provide valuable methodological insights and theoretical support for the preparation of laser cladding coatings and enable efficient process optimization for other laser processing applications. Full article

(This article belongs to the Special Issue Advances in Friction, Wear-Resistant and Solid-Lubricating Properties of Materials)

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25 pages, 20805 KiB

Open AccessArticle

Analysis of Influence of Coating Type on Friction Behaviour and Surface Topography of DC04/1.0338 Steel Sheet in Bending Under Tension Friction Test

by Tomasz Trzepieciński, Krzysztof Szwajka, Marek Szewczyk, Joanna Zielińska-Szwajka, Marek Barlak, Katarzyna Nowakowska-Langier and Sebastian Okrasa

Materials 2024, 17(22), 5650; https://doi.org/10.3390/ma17225650 - 19 Nov 2024

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Abstract

The working conditions of tools during plastic working operations are determined by, among other things, temperature, loads, loading method, and processing speed. In sheet metal forming processes, additionally, lubricant and tool surface roughness play a key role in changing the surface topography of [...] Read more.

The working conditions of tools during plastic working operations are determined by, among other things, temperature, loads, loading method, and processing speed. In sheet metal forming processes, additionally, lubricant and tool surface roughness play a key role in changing the surface topography of the drawpieces. This article presents the results of friction analysis on the edge of the punch in a deep drawing process using the bending under tension test. A DC04 steel sheet was used as the test material. The influence of various types of titanium nitride and titanium coatings applied on the surface of countersamples made of 145Cr6 cold-work tool steel was tested by means of high-intensity plasma pulses, magnetron sputtering, and electron pulse irradiation. The influence of the type of tool coating on the evolution of the coefficient of friction, the change in the sheet surface topography, and the temperature in the contact zone is presented in this paper. An increase in the coefficient of friction with sample elongation was observed. Countersamples modified with protective coatings provided a more stable coefficient value during the entire friction test compared to dry friction conditions. The electron pulse irradiated countersample provided the highest stability of the coefficient of friction in the entire range of sample elongation until fracture. The skewness Ssk of the sheet metal tested against the coated countersamples was characterized by negative value, which indicates a plateau-like shape of their surface. The highest temperature in the contact zone during friction with all types of countersamples was observed for the uncoated countersample. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Thermal Sprayed Coatings)

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13 pages, 2107 KiB

Open AccessArticle

The Effect of the Pyrolysis Temperature of a Leather–Textile Mixture from Post-Consumer Footwear on the Composition and Structure of Carbonised Materials

by Anna Kowalik-Klimczak, Monika Łożyńska, Maciej Życki and Bogusław Woźniak

Materials 2024, 17(22), 5649; https://doi.org/10.3390/ma17225649 - 19 Nov 2024

Viewed by 575

Abstract

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a [...] Read more.

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a low ash content and a high net calorific value, which translates into the high gross calorific value of the material. In addition, it contains relatively little S and Cl, which is promising for its use in the process of pyrolysis. The effect of the pyrolysis temperature on the efficiency of carbonising leather and textile mixtures, their physico-chemical parameters, elemental composition, and structure, as well as the development of a specific surface, is investigated. The research results imply that as the pyrolysis temperature grows, the carbonisation efficiency declines. The produced materials consist primarily of C, O, N, and H, whose contents depend on the pyrolysis temperature. Moreover, all the carbonised materials display the presence of two G and D bands, which is typical for carbon materials. Based on the peak intensities of the bands, I_D/I_G coefficients are calculated to assess the organisation of the materials’ structures. As the pyrolysis temperature rises, the structural organisation declines, contributing to an increased material porosity and, thus, a greater specific surface of the carbonised materials. This study contributes data on the thermal management and pyrolysis of leather and textile waste into useful carbonised materials. Investigating the applicability of carbonised materials is projected as the next stage of research work. Full article

(This article belongs to the Section Carbon Materials)

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19 pages, 3453 KiB

Open AccessReview

Opportunities and Challenges for Predicting the Service Status of SLM Metal Parts Under Big Data and Artificial Intelligence

by Xiaoling Yan and Huiwen Fu

Materials 2024, 17(22), 5648; https://doi.org/10.3390/ma17225648 - 19 Nov 2024

Viewed by 381

Abstract

Selective laser melting (SLM) technology is a high-end dual-use technology that is implemented in aerospace and medical equipment, as well as the automotive industry and other military and civilian industries, and is urgently needed for major equipment manufacturing and national defense industries. This [...] Read more.

Selective laser melting (SLM) technology is a high-end dual-use technology that is implemented in aerospace and medical equipment, as well as the automotive industry and other military and civilian industries, and is urgently needed for major equipment manufacturing and national defense industries. This paper examines the challenges of uncontrollable service states and the inability to ensure service safety of SLM metal parts under nonlinear and complex operating conditions. An overview of the prediction of the service status of SLM metal parts was introduced, and an effective approach solving the problem was provided in this paper. In this approach, the cross-scale coupling mechanism between mesoscopic damage evolution and macroscopic service state evolution is clarified by tracking the mesoscopic damage evolution process of SLM metal parts based on ultrasonic nonlinear responses. The failure mechanism is organically integrated with hidden information from monitoring big data, and a “chimeric” model to accurately evaluate the service status of SLM metal parts is constructed. Combining nonlinear ultrasound technology with big data and artificial intelligence to construct a “chimeric” model and consummate the corresponding methods and theories for evaluating the service status of SLM metal parts is an effective way to reveal the mesoscopic damage evolution and service status evolution mechanisms of SLM metal parts under complex factor coupling, and to accurately describe and characterize the service status of parts under complex operating conditions. The proposed approach will provide a theoretical basis and technical guarantee for the precise management of SLM parts’ service safety in key equipment fields such as aerospace, medical equipment, and the automotive industry. Full article

(This article belongs to the Section Advanced Materials Characterization)

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