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Materials, Volume 15, Issue 10 (May-2 2022) – 326 articles

Cover Story (view full-size image):

Silicon and graphene are among the most important areas of research. Silicon is still the king of the semiconductor industry! On the other hand, graphene is the first two-dimensional material and has many unprecedented physical and chemical properties. The combination of silicon and carbon—or SiC—is yet another amazing material with a very bright future. Owing to its excellent thermal, mechanical, and semiconductive properties, SiC is a leading material for many strategic applications.

This article researches a very important question: is SiC the only possible composition of Si/C? Or could we play with the composition or dimensions of SixCy materials? View this paper

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14 pages, 3753 KiB  
Article
Electrochemical Corrosion Behavior of MIG-Welded 7N01-T4 Aluminum Alloy by ER5356 and ER5087 Welding Wires
by Ping Wei, Mingfang Wu, Dashuang Liu, Ziqiang Zhao, Yun Liang and Zhihui Dong
Materials 2022, 15(10), 3737; https://doi.org/10.3390/ma15103737 - 23 May 2022
Cited by 4 | Viewed by 2122
Abstract
7N01-T4 aluminum alloy plates were welded by the metal inert gas (MIG) welding method, with ER5087 and ER5356 welding wires, respectively. The electrochemical corrosion behavior of the weld zones in the two kinds of welded joints using 3.5 wt.% and 5 wt.% NaCl [...] Read more.
7N01-T4 aluminum alloy plates were welded by the metal inert gas (MIG) welding method, with ER5087 and ER5356 welding wires, respectively. The electrochemical corrosion behavior of the weld zones in the two kinds of welded joints using 3.5 wt.% and 5 wt.% NaCl solutions were investigated by polarization curve, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and laser confocal scanning microscope (LCSM). The results indicated the better corrosion resistance of the weld zone in the ER5356 welded joint than that in the ER5087 welded joint, which was related to the different contents of Mn and Zn elements and the distribution of precipitates for the weld zones in the two kinds of welded joints. Based on the LSCM of the weld zones, the maximum depth (dmax) of corrosion pits for the weld zone in the ER5356 welded joint was lower than that in the ER5087 welded joint when immersed in the same NaCl concentrations. The dmax of the corrosion pit of the weld zone in the ER5356 welded joint using the 5 wt.% NaCl solution was 78.5 ± 0.96 μm, which was much bigger than that using the 3.5 wt.% NaCl solution. For the weld zone in the ER5087 welded joint with 5 wt.% NaCl solution, more Cl- was adsorbed onto the active surface of weld zones, which accelerated the corrosion, resulting in the corrosion mechanism from pitting to intergranular corrosion. Full article
(This article belongs to the Topic Advanced Forming Technology of Metallic Materials)
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10 pages, 2710 KiB  
Article
Application of Laser-Induced Breakdown Spectroscopy in the Quantitative Analysis of Elements—K, Na, Ca, and Mg in Liquid Solutions
by Wojciech Skrzeczanowski and Maria Długaszek
Materials 2022, 15(10), 3736; https://doi.org/10.3390/ma15103736 - 23 May 2022
Cited by 3 | Viewed by 1586
Abstract
Results of laser-induced breakdown spectroscopy measurements of K, Na, Ca, and Mg content in liquid media are discussed in the paper. Calibration results show correct parameters—linearity and R2 coefficients of determination at the levels of 0.94–0.99. Obtained regression equations have been used [...] Read more.
Results of laser-induced breakdown spectroscopy measurements of K, Na, Ca, and Mg content in liquid media are discussed in the paper. Calibration results show correct parameters—linearity and R2 coefficients of determination at the levels of 0.94–0.99. Obtained regression equations have been used to determine K, Na, Ca, and Mg concentrations in biological samples with known element content. Measurement results showed acceptable, within the expanded standard uncertainty, conformity with their content in the certified materials. Results have been supported by multivariate factorial analysis, which was especially effective for Ca and Mg samples. For these elements, factorial analysis allows the application of the whole spectra to obtain quantitative data on the tested samples, in contrast to a common method based on the selection of a particular spectral line for the calibration. Full article
(This article belongs to the Section Optical and Photonic Materials)
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18 pages, 2461 KiB  
Article
Silk Vascular Grafts with Optimized Mechanical Properties for the Repair and Regeneration of Small Caliber Blood Vessels
by Elisa Valsecchi, Marco Biagiotti, Antonio Alessandrino, Dario Gastaldi, Pasquale Vena and Giuliano Freddi
Materials 2022, 15(10), 3735; https://doi.org/10.3390/ma15103735 - 23 May 2022
Cited by 5 | Viewed by 2510
Abstract
As the incidence of cardiovascular diseases has been growing in recent years, the need for small-diameter vascular grafts is increasing. Considering the limited success of synthetic grafts, vascular tissue engineering/repair/regeneration aim to find novel solutions. Silk fibroin (SF) has been widely investigated for [...] Read more.
As the incidence of cardiovascular diseases has been growing in recent years, the need for small-diameter vascular grafts is increasing. Considering the limited success of synthetic grafts, vascular tissue engineering/repair/regeneration aim to find novel solutions. Silk fibroin (SF) has been widely investigated for the development of vascular grafts, due to its good biocompatibility, tailorable biodegradability, excellent mechanical properties, and minimal inflammatory reactions. In this study, a new generation of three-layered SF vascular scaffolds has been produced and optimized. Four designs of the SILKGraft vascular prosthesis have been developed with the aim of improving kink resistance and mechanical strength, without compromising the compliance with native vessels and the proven biocompatibility. A more compact arrangement of the textile layer allowed for the increase in the mechanical properties along the longitudinal and circumferential directions and the improvement of the compliance value, which approached that reported for the saphenous and umbilical veins. The higher braid density slightly affected the grafts’ morphology, increasing surface roughness, but the novel design mimicked the corrugation approach used for synthetic grafts, causing significant improvements in kink resistance. Full article
(This article belongs to the Special Issue Development and Application of Silk-Proteins Based Biomaterials)
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19 pages, 5804 KiB  
Article
Concrete Elastic Modulus Experimental Research Based on Theory of Capillary Tension
by Fengbin Zhou, Changwang Su, Daifeng Wu, Jianmin Hua, Lepeng Huang, Qiming Luo, Maoyi Liu, Mi Nie and Chunyao Tang
Materials 2022, 15(10), 3734; https://doi.org/10.3390/ma15103734 - 23 May 2022
Cited by 1 | Viewed by 2706
Abstract
The risk of cracking in the early stage is a critical indicator of the performance of concrete structures. Concrete cracked when the tensile stresses caused by deformation under restraint conditions exceeded its tensile strength. This research aims at an accurate prediction of shrinkage [...] Read more.
The risk of cracking in the early stage is a critical indicator of the performance of concrete structures. Concrete cracked when the tensile stresses caused by deformation under restraint conditions exceeded its tensile strength. This research aims at an accurate prediction of shrinkage cracking of concrete under constraints. Based on the theory of capillary tension under the concrete shrinkage mechanism, the method to test and compute the elastic modulus of a micro-matrix around the capillary, Et, was derived. Shrinkage and porosity determination tests were conducted to obtain the shrinkage values and confining stresses of concrete at different strength grades, different ages and under different restraint conditions, accordingly. Meanwhile, the proposed method of this research was used to obtain Et. The restraint stress given by Et was compared with the experimental result under the corresponding time. The results suggested a positive correlation between the elastic modulus of a micro-matrix around the capillary, Et, precomputed by the theory, and the static elastic modulus, Ec, and that the ratio between the two gradually decreased with the passage of time, which ranged from 2.8 to 3.1. Full article
(This article belongs to the Topic Modern Material Technologies Intended for Industrial Applications)
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16 pages, 6918 KiB  
Article
Polarization Independent Metamaterial Absorber with Anti-Reflection Coating Nanoarchitectonics for Visible and Infrared Window Applications
by Ahmad Musa, Mohammad Lutful Hakim, Touhidul Alam, Mohammad Tariqul Islam, Ahmed S. Alshammari, Kamarulzaman Mat, M. Salaheldeen M., Sami H. A. Almalki and Md. Shabiul Islam
Materials 2022, 15(10), 3733; https://doi.org/10.3390/ma15103733 - 23 May 2022
Cited by 28 | Viewed by 2851
Abstract
The visible and infrared wavelengths are the most frequently used electromagnetic (EM) waves in the frequency spectrum; able to penetrate the atmosphere and reach Earth’s surface. These wavelengths have attracted much attention in solar energy harvesting; thermography; and infrared imaging applications for the [...] Read more.
The visible and infrared wavelengths are the most frequently used electromagnetic (EM) waves in the frequency spectrum; able to penetrate the atmosphere and reach Earth’s surface. These wavelengths have attracted much attention in solar energy harvesting; thermography; and infrared imaging applications for the detection of electrical failures; faults; or thermal leakage hot spots and inspection of tapped live energized components. This paper presents a numerical analysis of a compact cubic cross-shaped four-layer metamaterial absorber (MA) structure by using a simple metal-dielectric-metal-dielectric configuration for wideband visible and infrared applications. The proposed MA achieved above 80% absorption in both visible and near-infrared regions of the spectrum from 350 to 1250 nm wavelength with an overall unit cell size of 0.57λ × 0.57λ × 0.59λ. The SiO2 based anti-reflection coating of sandwiched tungsten facilitates to achieve the wide high absorption bandwidth. The perceptible novelty of the proposed metamaterial is to achieve an average absorptivity of 95.3% for both visible and infrared wavelengths with a maximum absorptivity of 98% from 400 nm to 900 nm. Furthermore, the proposed structure provides polarization insensitivity with a higher oblique incidence angle tolerance up to 45°. Full article
(This article belongs to the Topic Nanoarchitectonics with Molecular and Materials Science: Functional Materials for Energy, Environment, Bio and Others)
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9 pages, 5086 KiB  
Article
Strength and Microstructure of Geopolymer Based on Fly Ash and Metakaolin
by Salim Barbhuiya and Edmund Pang
Materials 2022, 15(10), 3732; https://doi.org/10.3390/ma15103732 - 23 May 2022
Cited by 14 | Viewed by 2693
Abstract
The production of Portland cement is widely regarded as a major source of greenhouse gas emissions. This contributes to 6–7% of total CO2 emissions, according to the International Energy Agency. As a result, several efforts have been made in recent decades to [...] Read more.
The production of Portland cement is widely regarded as a major source of greenhouse gas emissions. This contributes to 6–7% of total CO2 emissions, according to the International Energy Agency. As a result, several efforts have been made in recent decades to limit or eliminate the usage of Portland cement in concrete. Geopolymer has garnered a lot of attention among the numerous alternatives due to its early compressive strength, low permeability, high chemical resistance, and great fire-resistant behaviour. This study looks at the strength and microstructure of geopolymer based on fly ash and a combination of metakaolin and fly ash. Compressive strengths were measured at 7, 14, and 28 days, and microstructure was examined using SEM and XRD. Full article
(This article belongs to the Topic Innovative Construction and Building Materials)
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19 pages, 5777 KiB  
Article
Fluidized ZnO@BCFPs Particle Electrodes for Efficient Degradation and Detoxification of Metronidazole in 3D Electro-Peroxone Process
by Dan Yuan, Shungang Wan, Rurong Liu, Mengmeng Wang and Lei Sun
Materials 2022, 15(10), 3731; https://doi.org/10.3390/ma15103731 - 23 May 2022
Cited by 5 | Viewed by 2249
Abstract
A novel material of self-shaped ZnO-embedded biomass carbon foam pellets (ZnO@BCFPs) was successfully synthesized and used as fluidized particle electrodes in three-dimensional (3D) electro-peroxone systems for metronidazole degradation. Compared with 3D and 2D + O3 systems, the energy consumption was greatly reduced [...] Read more.
A novel material of self-shaped ZnO-embedded biomass carbon foam pellets (ZnO@BCFPs) was successfully synthesized and used as fluidized particle electrodes in three-dimensional (3D) electro-peroxone systems for metronidazole degradation. Compared with 3D and 2D + O3 systems, the energy consumption was greatly reduced and the removal efficiencies of metronidazole were improved in the 3D + O3 system. The degradation rate constants increased from 0.0369 min−1 and 0.0337 min−1 to 0.0553 min−1, respectively. The removal efficiencies of metronidazole and total organic carbon reached 100% and 50.5% within 60 min under optimal conditions. It indicated that adding ZnO@BCFPs particle electrodes was beneficial to simultaneous adsorption and degradation of metronidazole due to improving mass transfer of metronidazole and forming numerous tiny electrolytic cells. In addition, the process of metronidazole degradation in 3D electro-peroxone systems involved hydroxyethyl cleavage, hydroxylation, nitro-reduction, N-denitrification and ring-opening. The active species of ·OH and ·O2− played an important role. Furthermore, the acute toxicity LD50 and the bioconcentration factor of intermediate products decreased with the increasing reaction time. Full article
(This article belongs to the Special Issue Preparation and Application of Environmental Functional Materials)
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13 pages, 4660 KiB  
Article
Computational Design and Characterisation of Gyroid Structures with Different Gradient Functions for Porosity Adjustment
by Leonie Wallat, Patrick Altschuh, Martin Reder, Britta Nestler and Frank Poehler
Materials 2022, 15(10), 3730; https://doi.org/10.3390/ma15103730 - 23 May 2022
Cited by 14 | Viewed by 4018
Abstract
Triply periodic minimal surface (TPMS) structures have a very good lightweight potential, due to their surface-to-volume ratio, and thus are contents of various applications and research areas, such as tissue engineering, crash structures, or heat exchangers. While TPMS structures with a uniform porosity [...] Read more.
Triply periodic minimal surface (TPMS) structures have a very good lightweight potential, due to their surface-to-volume ratio, and thus are contents of various applications and research areas, such as tissue engineering, crash structures, or heat exchangers. While TPMS structures with a uniform porosity or a linear gradient have been considered in the literature, this paper focuses on the investigation of the mechanical properties of gyroid structures with non-linear porosity gradients. For the realisation of the different porosity gradients, an algorithm is introduced that allows the porosity to be adjusted by definable functions. A parametric study is performed on the resulting gyroid structures by performing mechanical simulations in the linear deformation regime. The transformation into dimensionless parameters enables material-independent statements, which is possible due to linearity. Thus, the effective elastic behaviour depends only on the structure geometry. As a result, by introducing non-linear gradient functions and varying the density of the structure over the entire volume, specific strengths can be generated in certain areas of interest. A computational design of porosity enables an accelerated application-specific structure development in the field of engineering. Full article
(This article belongs to the Topic Numerical Modeling on Metallic Materials)
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15 pages, 3038 KiB  
Article
Marginal Bone Loss in Internal Conical Connection Implants Placed at the Crestal and Subcrestal Levels before Prosthetic Loading: A Randomized Clinical Study
by Natalia Palacios-Garzón, Elisabeth Mauri-Obradors, Raúl Ayuso-Montero, Eugenio Velasco-Ortega, José María Anglada-Cantarell and José López-López
Materials 2022, 15(10), 3729; https://doi.org/10.3390/ma15103729 - 23 May 2022
Cited by 6 | Viewed by 2127
Abstract
The vertical position concerning the bone in which the implants are placed has been related as one of the factors causing marginal bone loss. The objective of this study was to evaluate the bone loss that occurs before prosthetic loading around tapered internal [...] Read more.
The vertical position concerning the bone in which the implants are placed has been related as one of the factors causing marginal bone loss. The objective of this study was to evaluate the bone loss that occurs before prosthetic loading around tapered internal connection (CIC) implants placed at the crestal (C) and subcrestal (S) levels. Method: A randomized clinical trial (RCT) was carried out, with a sample size of 62 implants placed in 27 patients who underwent radiological controls on the day of placement, at one month, and at 4 months, and stability was measured by resonance frequency analysis (RFA) on three occasions. Results: Bone loss in implants C and S from the time of placement (T0) and the month after (T1) was not significant (p = 0.54) (C = 0.19 mm and S = 0.15 mm). The difference between one month (T1) and four months (T2) (C = 0.17 mm and S = 0.22 mm) was not significant either (p = 0.26). The difference between the day of placement (T0) and the third and last measurement (T2) was almost null (p = 0.94) (C = 0.35 mm and S = 0.36). The overall success rate of the implants was 97.8%. The stability of the implants measured with RFA went from 70.60 (T0) to 73.16 (T1) and 74.52 (T2). Conclusions: No significant differences were found in the bone loss for implants placed at the C and S levels. The millimeters of bone loss detected in both vertical positions did not have a significant impact on the stability of the implants. Full article
(This article belongs to the Special Issue Dental Implants: Materials and Design)
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10 pages, 1602 KiB  
Review
Uncemented Cups and Impaction Bone Grafting for Acetabular Bone Loss in Revision Hip Arthroplasty: A Review of Rationale, Indications, and Outcomes
by Rocco D’Apolito and Luigi Zagra
Materials 2022, 15(10), 3728; https://doi.org/10.3390/ma15103728 - 23 May 2022
Cited by 6 | Viewed by 3076 | Correction
Abstract
Total hip arthroplasty (THA) is increasingly performed in young patients and the number of revisions is estimated to rise over time. Acetabular osteolysis and bone loss are frequently encountered during revision and may be classified and treated in different ways. Impaction bone grafting [...] Read more.
Total hip arthroplasty (THA) is increasingly performed in young patients and the number of revisions is estimated to rise over time. Acetabular osteolysis and bone loss are frequently encountered during revision and may be classified and treated in different ways. Impaction bone grafting (IBG) with morselized allograft offers a viable option. IBG was introduced over 40 years ago in combination with cemented cups, and is also used with uncemented cups. The impacted bone chips act as a void filler to restore bone stock; once incorporated they are substituted by host bone. Surgery entails assessment of the defect, acetabular preparation, preparation of the morselized graft, impaction of the graft, and cup implantation. Satisfactory medium- and long-term results have now been reported in most studies. With the advent of high-porosity cups, indications have been extended, enhancing the potential of IBG, in which primary stability of the cup to the host bone is essential for a successful procedure. Synthetic bone substitutes have also been used in combination with allogenic grafts and may extend the original technique for which long-term studies are warranted. Full article
(This article belongs to the Special Issue Synthetic and Biologic Materials for Prosthetic and Reconstructive Applications for Musculoskeletal Tissue)
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22 pages, 8857 KiB  
Article
An Evaluation of 3D-Printed Materials’ Structural Properties Using Active Infrared Thermography and Deep Neural Networks Trained on the Numerical Data
by Barbara Szymanik
Materials 2022, 15(10), 3727; https://doi.org/10.3390/ma15103727 - 23 May 2022
Cited by 4 | Viewed by 2080
Abstract
This article describes an approach to evaluating the structural properties of samples manufactured through 3D printing via active infrared thermography. The mentioned technique was used to test the PETG sample, using halogen lamps as an excitation source. First, a simplified, general numerical model [...] Read more.
This article describes an approach to evaluating the structural properties of samples manufactured through 3D printing via active infrared thermography. The mentioned technique was used to test the PETG sample, using halogen lamps as an excitation source. First, a simplified, general numerical model of the phenomenon was prepared; then, the obtained data were used in a process of the deep neural network training. Finally, the network trained in this manner was used for the material evaluation on the basis of the original experimental data. The described methodology allows for the automated assessment of the structural state of 3D−printed materials. The usage of a generalized model is an innovative method that allows for greater product assessment flexibility. Full article
(This article belongs to the Special Issue Advances in Electromagnetic Properties of Materials and Related Nondestructive Testing)
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23 pages, 6956 KiB  
Article
Experimental Study on the Characterization of Orientation of Polyester Short Fibers in Rubber Composites by an X-ray Three-Dimensional Microscope
by Benhui Yu, Jianbin Ren, Kongshuo Wang, Chuansheng Wang and Huiguang Bian
Materials 2022, 15(10), 3726; https://doi.org/10.3390/ma15103726 - 23 May 2022
Viewed by 2528
Abstract
Polyester-short-fiber-reinforced rubber composites have been detected by an X-ray three-dimensional microscope, and then the three-dimensional reconstruction of the image has been carried out to characterize the orientation of polyester short fibers in the composites for the first time. Based on the summary of [...] Read more.
Polyester-short-fiber-reinforced rubber composites have been detected by an X-ray three-dimensional microscope, and then the three-dimensional reconstruction of the image has been carried out to characterize the orientation of polyester short fibers in the composites for the first time. Based on the summary of three traditional methods and mechanisms of characterizing the orientation of polyester short fibers by the numerical parameter method, the direct test method, and the indirect test method, the method and mechanism of the X-ray three-dimensional microscope applied to the orientation characterization of polyester short fibers have been studied. The combination of the center point and threshold segmentation methods has been used to distinguish which fiber section belongs to the same fiber, and the identification of the whole short fiber in different slice images has been realized for the first time. Moreover, Avizo software has been used to realize the three-dimensional reconstruction of a polyester short fiber scanning image. The obtained data have been integrated and the orientation angle and orientation degree have been quantitatively characterized for the first time. This has filled the key technical problem of quantitative characterization of the orientation angle and orientation degree of polyester fibers. The image has been verified by 3Dmed software, and furthermore, the accuracy of the three-dimensional reconstruction results has been verified. Full article
(This article belongs to the Topic Rubbers and Elastomers Materials)
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39 pages, 5911 KiB  
Article
Potential of Rapid Tooling in Rapid Heat Cycle Molding: A Review
by Nurul Hidayah Mohamad Huzaim, Shayfull Zamree Abd Rahim, Luqman Musa, Abdellah El-hadj Abdellah, Mohd Mustafa Al Bakri Abdullah, Allan Rennie, Rozyanti Rahman, Sebastian Garus, Katarzyna Błoch, Andrei Victor Sandu, Petrica Vizureanu and Marcin Nabiałek
Materials 2022, 15(10), 3725; https://doi.org/10.3390/ma15103725 - 23 May 2022
Cited by 18 | Viewed by 4305
Abstract
Rapid tooling (RT) and additive manufacturing (AM) are currently being used in several parts of industry, particularly in the development of new products. The demand for timely deliveries of low-cost products in a variety of geometrical patterns is continuing to increase year by [...] Read more.
Rapid tooling (RT) and additive manufacturing (AM) are currently being used in several parts of industry, particularly in the development of new products. The demand for timely deliveries of low-cost products in a variety of geometrical patterns is continuing to increase year by year. Increased demand for low-cost materials and tooling, including RT, is driving the demand for plastic and rubber products, along with engineering and product manufacturers. The development of AM and RT technologies has led to significant improvements in the technologies, especially in testing performance for newly developed products prior to the fabrication of hard tooling and low-volume production. On the other hand, the rapid heating cycle molding (RHCM) injection method can be implemented to overcome product surface defects generated by conventional injection molding (CIM), since the surface gloss of the parts is significantly improved, and surface marks such as flow marks and weld marks are eliminated. The most important RHCM technique is rapid heating and cooling of the cavity surface, which somewhat improves part quality while also maximizing production efficiencies. RT is not just about making molds quickly; it also improves molding productivity. Therefore, as RT can also be used to produce products with low-volume production, there is a good potential to explore RHCM in RT. This paper reviews the implementation of RHCM in the molding industry, which has been well established and undergone improvement on the basis of different heating technologies. Lastly, this review also introduces future research opportunities regarding the potential of RT in the RHCM technique. Full article
(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)
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13 pages, 5426 KiB  
Article
Electrochemical Behavior of SiC-Coated AA2014 Alloy through Plasma Electrolytic Oxidation
by Talal A. Aljohani, Majed O. Alawad, Sally Elkatatny, Abdulrahman I. Alateyah, Meteb T. Bin Rubayan, Mohammed A. Alhajji, Muntathir I. AlBeladi, Fuad Khoshnaw and Waleed H. El-Garaihy
Materials 2022, 15(10), 3724; https://doi.org/10.3390/ma15103724 - 23 May 2022
Cited by 4 | Viewed by 2396
Abstract
In this study, the corrosion performance of AA2014 aluminum alloy was enhanced by coating the alloy with a layer containing silica (SiC) that was formed by the plasma electrolytic oxidation (PEO) process. The PEO process was performed with different electrical parameters (frequency, current [...] Read more.
In this study, the corrosion performance of AA2014 aluminum alloy was enhanced by coating the alloy with a layer containing silica (SiC) that was formed by the plasma electrolytic oxidation (PEO) process. The PEO process was performed with different electrical parameters (frequency, current mode, and duty ratio) and both with and without SiC to investigate the microstructural and electrochemical differences in the coated samples produced from the process. The microstructure and composition of the PEO coatings were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). A potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behavior of the AA2014-PEO-coated samples. The potentiodynamic polarization showed that the SiC-PEO-coated samples had a significantly decreased corrosion rate (99.8%) compared with the uncoated AA2014 Al alloy. Our results showed that the coats containing SiC possessed a much higher corrosion resistance than both the uncoated AA2014 Al alloy (8,344,673%) and the SiC-free coatings, which possess low corrosion resistance, because of their higher chemical stability and more compact microstructure. Full article
(This article belongs to the Special Issue Microstructure, Tribological and Corrosion Behaviors of Coatings)
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9 pages, 13590 KiB  
Article
Direct Wafer-Scale CVD Graphene Growth under Platinum Thin-Films
by Yelena Hagendoorn, Gregory Pandraud, Sten Vollebregt, Bruno Morana, Pasqualina M. Sarro and Peter G. Steeneken
Materials 2022, 15(10), 3723; https://doi.org/10.3390/ma15103723 - 23 May 2022
Cited by 4 | Viewed by 3075
Abstract
Since the transfer process of graphene from a dedicated growth substrate to another substrate is prone to induce defects and contamination and can increase costs, there is a large interest in methods for growing graphene directly on silicon wafers. Here, we demonstrate the [...] Read more.
Since the transfer process of graphene from a dedicated growth substrate to another substrate is prone to induce defects and contamination and can increase costs, there is a large interest in methods for growing graphene directly on silicon wafers. Here, we demonstrate the direct CVD growth of graphene on a SiO2 layer on a silicon wafer by employing a Pt thin film as catalyst. We pattern the platinum film, after which a CVD graphene layer is grown at the interface between the SiO2 and the Pt. After removing the Pt, Raman spectroscopy demonstrates the local growth of monolayer graphene on SiO2. By tuning the CVD process, we were able to fully cover 4-inch oxidized silicon wafers with transfer-free monolayer graphene, a result that is not easily obtained using other methods. By adding Ta structures, local graphene growth on SiO2 is selectively blocked, allowing the controlled graphene growth on areas selected by mask design. Full article
(This article belongs to the Special Issue Carbon-Based Electronic Materials)
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24 pages, 3358 KiB  
Article
Compressive Strength Estimation of Fly Ash/Slag Based Green Concrete by Deploying Artificial Intelligence Models
by Kaffayatullah Khan, Babatunde Abiodun Salami, Mudassir Iqbal, Muhammad Nasir Amin, Fahim Ahmed and Fazal E. Jalal
Materials 2022, 15(10), 3722; https://doi.org/10.3390/ma15103722 - 23 May 2022
Cited by 21 | Viewed by 3297
Abstract
Cement production is one of the major sources of decomposition of carbonates leading to the emission of carbon dioxide. Researchers have proven that incorporating industrial wastes is of paramount significance for producing green concrete due to the benefits of reducing cement production. The [...] Read more.
Cement production is one of the major sources of decomposition of carbonates leading to the emission of carbon dioxide. Researchers have proven that incorporating industrial wastes is of paramount significance for producing green concrete due to the benefits of reducing cement production. The compressive strength of concrete is an imperative parameter to consider when designing concrete structures. Considering high prediction capabilities, artificial intelligence models are widely used to estimate the compressive strength of concrete mixtures. A variety of artificial intelligence models have been developed in the literature; however, evaluation of the modeling procedure and accuracy of the existing models suggests developing such models that manifest the detailed evaluation of setting parameters on the performance of models and enhance the accuracy compared to the existing models. In this study, the computational capabilities of the adaptive neurofuzzy inference system (ANFIS), gene expression programming (GEP), and gradient boosting tree (GBT) were employed to investigate the optimum ratio of ground-granulated blast furnace slag (GGBFS) and fly ash (FA) to the binder content. The training process of GEP modeling revealed 200 chromosomes, 5 genes, and 12 head sizes as the best hyperparameters. Similarly, ANFIS hybrid subclustering modeling with aspect ratios of 0.5, 0.1, 7, and 150; learning rate; maximal depth; and number of trees yielded the best performance in the GBT model. The accuracy of the developed models suggests that the GBT model is superior to the GEP, ANFIS, and other models that exist in the literature. The trained models were validated using 40% of the experimental data along with parametric and sensitivity analysis as second level validation. The GBT model yielded correlation coefficient (R), mean absolute error (MAE), and root mean square error (RMSE), equaling 0.95, 3.07 MPa, and 4.80 MPa for training, whereas, for validation, these values were recorded as 0.95, 3.16 MPa, and 4.85 MPa, respectively. The sensitivity analysis revealed that the aging of the concrete was the most influential parameter, followed by the addition of GGBFS. The effect of the contributing parameters was observed, as corroborated in the literature. Full article
(This article belongs to the Special Issue Artificial Intelligence for Cementitious Materials)
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13 pages, 5678 KiB  
Article
Influence of Elbow Angle on Erosion-Corrosion of 1018 Steel for Gas–Liquid–Solid Three Phase Flow
by Rehan Khan, Hamdan H. Ya, Imran Shah, Usama Muhammad Niazi, Bilal Anjum Ahmed, Muhammad Irfan, Adam Glowacz, Zbigniew Pilch, Frantisek Brumercik, Mohammad Azeem, Mohammad Azad Alam and Tauseef Ahmed
Materials 2022, 15(10), 3721; https://doi.org/10.3390/ma15103721 - 23 May 2022
Cited by 11 | Viewed by 3132
Abstract
Erosive wear due to the fact of sand severely affects hydrocarbon production industries and, consequently, various sectors of the mineral processing industry. In this study, the effect of the elbow geometrical configuration on the erosive wear of carbon steel for silt–water–air flow conditions [...] Read more.
Erosive wear due to the fact of sand severely affects hydrocarbon production industries and, consequently, various sectors of the mineral processing industry. In this study, the effect of the elbow geometrical configuration on the erosive wear of carbon steel for silt–water–air flow conditions were investigated using material loss analysis, surface roughness analysis, and microscopic imaging technique. Experiments were performed under the plug flow conditions in a closed flow loop at standard atmospheric pressure. Water and air plug flow and the disperse phase was silt (silica sand) with a 2.5 wt % concentration, and a silt grain size of 70 µm was used for performing the tests. The experimental analysis showed that silt impact increases material disintegration up to 1.8 times with a change in the elbow configuration from 60° to 90° in plug flow conditions. The primary erosive wear mechanisms of the internal elbow surface were sliding, cutting, and pit propagation. The maximum silt particle impaction was located at the outer curvature in the 50° position in 60° elbows and the 80° position in 90° elbows in plug flow. The erosion rate decreased from 10.23 to 5.67 mm/year with a change in the elbow angle from 90° to 60°. Moreover, the microhardness on the Vickers scale increased from 168 to 199 in the 90° elbow and from 168 to 184 in the 60° elbow. Full article
(This article belongs to the Special Issue Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings)
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13 pages, 5239 KiB  
Review
Fabrication and Sensing Application of Phase Shifted Bragg Grating Sensors
by Xiaoyan Sun, Li Zeng, Youwang Hu and Ji’an Duan
Materials 2022, 15(10), 3720; https://doi.org/10.3390/ma15103720 - 23 May 2022
Cited by 10 | Viewed by 2739
Abstract
As a special kind of Bragg grating, phase-shifted fiber Bragg grating (PS-FBG) has attracted extensive attention because of its extremely narrow transmission window and excellent sensing performance. The main purpose of this manuscript is to discuss the PS-FBG with special sensing characteristics and [...] Read more.
As a special kind of Bragg grating, phase-shifted fiber Bragg grating (PS-FBG) has attracted extensive attention because of its extremely narrow transmission window and excellent sensing performance. The main purpose of this manuscript is to discuss the PS-FBG with special sensing characteristics and explore the influence of different inscription technologies on the sensing characteristics of PS-FBG by comparing the existing inscription methods. The sensing characteristics, advantages and disadvantages of PS-FBG with different structures are analyzed. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings and Its Applications)
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11 pages, 2233 KiB  
Article
Strengthening Performance Optimization of Single Ball Impact Treatment by Evaluating Residual Stress
by Yang Lei, Zhengwei Wang and Huan Qi
Materials 2022, 15(10), 3719; https://doi.org/10.3390/ma15103719 - 23 May 2022
Cited by 4 | Viewed by 1896
Abstract
Residual stress plays an essential role in affecting the strengthening performance by a surface treatment. Studying the impact of a single ball on a target surface is the basis of shot peening technology in order to obtain the distribution of the residual stress, [...] Read more.
Residual stress plays an essential role in affecting the strengthening performance by a surface treatment. Studying the impact of a single ball on a target surface is the basis of shot peening technology in order to obtain the distribution of the residual stress, and to optimize the processing parameters. In this paper, a numerical model has been developed to represent single ball impacts on high manganese steel by considering different processing parameters. It was found that by increasing the ball diameter and impact velocity, the depth of maximum residual compressive stress and the depth of the residual compressive stress layer became significantly enlarged due to increasing kinetic energy of the impacting ball. It was also found from simulation that with an increase in ball impact angle, the maximum residual compressive stress, the depth of maximum residual compressive stress and the depth of the residual compressive stress layer were significantly improved; an exception was the surface residual compressive stress, which showed a decreasing trend. Moreover, by employing quantitative analysis with the entropy method, it was found that within the range of processing parameters considered in the simulation, it is recommended to use a ball with a diameter of 0.6 mm to impact the target, with a velocity of 80 m/s and an angle of 90° for the best strengthening performance. Full article
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13 pages, 4224 KiB  
Article
Study on Stability of Mechanical Properties for Porous Fe-Cr-Al Alloys after Long-Term Aging
by Huibin Zhang, Junliang Ma, Zhencheng Gao, Fei Guo, Shenghang Xu, Guangya Hou and Guoqu Zheng
Materials 2022, 15(10), 3718; https://doi.org/10.3390/ma15103718 - 22 May 2022
Cited by 7 | Viewed by 2067
Abstract
Nowadays, both the ferrite phase and B2-structured intermetallic in the Fe-Cr-Al alloy system are developed as porous materials, which have been further applied as high-temperature filter materials in industry. This work presents a comparative study of the mechanical properties of porous Fe20Cr5Al, Fe10Cr10Al [...] Read more.
Nowadays, both the ferrite phase and B2-structured intermetallic in the Fe-Cr-Al alloy system are developed as porous materials, which have been further applied as high-temperature filter materials in industry. This work presents a comparative study of the mechanical properties of porous Fe20Cr5Al, Fe10Cr10Al and Fe10Cr20Al aged at 480 °C for 500 h. The changes in tensile strength, elongation and hardness were determined, and the microstructure changes as well as slight oxidation states of the aged samples were investigated. The results show that the precipitated Cr-rich phase in porous Fe20Cr5Al can increase the hardness and decrease the ductility, while intergranular oxidation can degrade the mechanical performance of the three porous Fe-Cr-Al materials. It is noted that porous Fe10Cr20Al exhibits relatively superior mechanical stability during long-term aging. Meanwhile, by introducing boron, the mechanical performance of the aged porous Fe-Cr-Al alloys can be stabilized since the possible internal oxidation of the exposed grain boundaries is inhibited. Full article
(This article belongs to the Special Issue Advances in High Entropy Materials)
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11 pages, 4826 KiB  
Article
Strengthening of 0.18 wt % C Steel by Cold Differential Speed Rolling
by Jee-Hyun Kang and Young-Gun Ko
Materials 2022, 15(10), 3717; https://doi.org/10.3390/ma15103717 - 22 May 2022
Cited by 1 | Viewed by 1800
Abstract
Steel sheets containing 0.18 wt % C were deformed by differential speed rolling (DSR) up to four passes and compared to the steel sheets processed by equal speed rolling (ESR). Not only microstructure, but also mechanical properties and rolling load, were studied, which [...] Read more.
Steel sheets containing 0.18 wt % C were deformed by differential speed rolling (DSR) up to four passes and compared to the steel sheets processed by equal speed rolling (ESR). Not only microstructure, but also mechanical properties and rolling load, were studied, which enlightens the relationship between microstructure, mechanical properties, and rolling load. Moreover, microstructure and properties resulting from ESR were systematically compared. During the rolling deformation, coarse grains were elongated first parallel to the rolling direction, and ultrafine grains were subsequently formed via continuous dynamic recrystallization. Microstructural analysis revealed that DSR was more effective than ESR in terms of achieving grain refinement and microstructure homogeneity. High-angle grain boundaries surrounding the ultrafine grains contributed to grain boundary strengthening, resulting in a dramatic increase in both hardness and strength after DSR. Although the steel was strengthened by rolling, the rolling load firstly increased and subsequently decreased as the number of passes increased, and lower force was required during DSR than during ESR. These can be explained by considering deformation volume and sticking friction. Full article
(This article belongs to the Section Metals and Alloys)
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13 pages, 5492 KiB  
Article
TiO2 Thickness-Dependent Charge Transfer in an Ordered Ag/TiO2/Ni Nanopillar Arrays Based on Surface-Enhanced Raman Scattering
by Cai Wang, Xufeng Guo and Qun Fu
Materials 2022, 15(10), 3716; https://doi.org/10.3390/ma15103716 - 22 May 2022
Cited by 5 | Viewed by 2270
Abstract
In this study, an ordered Ag/TiO2/Ni nanopillar arrays hybrid substrate was designed, and the charge transfer (CT) process at the metal–semiconductor and substrate–molecule interface was investigated based on the surface-enhanced Raman scattering (SERS) spectra of 4-Aminothiophenol (PATP) absorbed on the composite [...] Read more.
In this study, an ordered Ag/TiO2/Ni nanopillar arrays hybrid substrate was designed, and the charge transfer (CT) process at the metal–semiconductor and substrate–molecule interface was investigated based on the surface-enhanced Raman scattering (SERS) spectra of 4-Aminothiophenol (PATP) absorbed on the composite system. The surface plasmon resonance (SPR) absorption of Ag changes due to the regulation of TiO2 thickness, which leads to different degrees of CT enhancement in the system. The CT degree of SERS spectra obtained at different excitation wavelengths was calculated to study the contribution of CT enhancement to SERS, and a TiO2 thickness-dependent CT enhancement mechanism was proposed. Furthermore, Ag/TiO2/Ni nanopillar arrays possessed favorable detection ability and uniformity, which has potential as a SERS-active substrate. Full article
(This article belongs to the Special Issue Study on Advanced Metal Matrix Composites)
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18 pages, 8107 KiB  
Article
Size Effect of Hydrated Lime on the Mechanical Performance of Asphalt Concrete
by Amjad Albayati, Yu Wang and Jonathan Haynes
Materials 2022, 15(10), 3715; https://doi.org/10.3390/ma15103715 - 22 May 2022
Cited by 15 | Viewed by 2566
Abstract
Despite widespread agreement on the beneficial nature of hydrated lime (HL) addition to asphalt concrete mixes, understanding of the effect of HL particle size is still limited. Previous investigations have focused mainly on two different size comparisons, and so certain guidance for a [...] Read more.
Despite widespread agreement on the beneficial nature of hydrated lime (HL) addition to asphalt concrete mixes, understanding of the effect of HL particle size is still limited. Previous investigations have focused mainly on two different size comparisons, and so certain guidance for a practical application cannot yet be produced. This study investigates three distinct sizes of HL, in the range of regular, nano, and sub-nano scales, for their effects on the properties of modified asphalt concretes. Five different percentages of HL as a partial replacement of ordinary limestone filler in asphalt concrete mixes were studied for wearing course application purposes. Experimental tests were conducted to evaluate the mechanical properties, including resistance to plastic flow, volumetric properties, moisture susceptibility, resilient modulus, and permanent deformation. The results revealed that a positive correlation exists between the mechanical properties and the fineness of HL particle sizes. Full article
(This article belongs to the Topic Innovative Construction and Building Materials)
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14 pages, 5072 KiB  
Article
Effect of Ultrasonic-Assisted Modification Treatment on the Microstructure and Properties of A356 Alloy
by Xinyi Hu, Dongfu Song, Huiping Wang, Yiwang Jia, Haiping Zou and Mingjuan Chen
Materials 2022, 15(10), 3714; https://doi.org/10.3390/ma15103714 - 22 May 2022
Cited by 7 | Viewed by 2081
Abstract
Ultrasonic treatment was applied to an A356 aluminum melt with different modifiers, and the effects of ultrasonic treatment on the structure and properties of the A356 alloy were studied. The results showed that α-Al was effectively refined with different ultrasonic modification treatments. In [...] Read more.
Ultrasonic treatment was applied to an A356 aluminum melt with different modifiers, and the effects of ultrasonic treatment on the structure and properties of the A356 alloy were studied. The results showed that α-Al was effectively refined with different ultrasonic modification treatments. In particular, ultrasonic treatment showed the most obvious refinement with macroscopic grains of unmodified alloy and optimized the refinement of secondary dendrite arm spacings in the Sr/Ce synergistic alloys. The eutectic Si of the unmodified A356 alloy had no obvious change after the ultrasonic treatment, but the branch diameter of the eutectic Si reduced in the Sr and Sr/Ce modification alloys after the ultrasonic treatment. The ultrasonic treatment significantly improved the ultimate tensile strength and elongation of the as-cast A356 alloy with the unmodified material, which was due to refinement of the α-Al grains by the ultrasonic treatment. After the T6 heat treatment, the ultimate tensile strength values of the alloys showed no obvious change due to the ultrasonic treatment, but the plasticity of the alloy was significantly improved. Mg2Si precipitation was the dominant strengthening mechanism during the T6 heat treatment, while the plasticity was determined by the size and distribution of the eutectic Si. Acoustic cavitation caused by the ultrasound-activated impurities and the induced heterogeneous nucleation and supercooled nucleation in the groove melt was the main cause of the α-Al refinement, the eutectic Si modification and the improvement in the mechanical properties. Full article
(This article belongs to the Special Issue Advances in Crystallization Kinetics, Structure and Properties of Engineering Materials, Surface-Modified Non-ferrous Alloys)
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16 pages, 12221 KiB  
Article
Mechanical Behavior and Structural Characterization of a Cu-Al-Ni-Based Shape-Memory Alloy Subjected to Isothermal Uniaxial Megaplastic Compression
by Vladimir Pushin, Nataliya Kuranova, Alexey E. Svirid and Yurii Ustyugov
Materials 2022, 15(10), 3713; https://doi.org/10.3390/ma15103713 - 22 May 2022
Cited by 5 | Viewed by 2268
Abstract
For the first time, uniaxial megaplastic compression was successfully applied to a polycrystalline shape-memory Cu-Al-Ni-based alloy. The samples before and after uniaxial megaplastic compression were examined by methods of X-ray diffraction, optical, electron transmission, and scanning microscopy. The temperature dependences of electrical resistance [...] Read more.
For the first time, uniaxial megaplastic compression was successfully applied to a polycrystalline shape-memory Cu-Al-Ni-based alloy. The samples before and after uniaxial megaplastic compression were examined by methods of X-ray diffraction, optical, electron transmission, and scanning microscopy. The temperature dependences of electrical resistance and the mechanical properties of the alloys under uniaxial tension were also measured. The mechanical behavior under uniaxial megaplastic compression in isothermal conditions in the range of 300–1073 K was studied using the Instron 8862 electric testing machine. The microstructure, phase composition, and martensitic transformations in the eutectoid alloy (Cu-14wt.%Al–4 wt.%Ni) were studied. The radical refinement of the grain structure of the initial hardened D03 austenite was found under controlled isothermal compression, due to dynamic recrystallization in the temperature range 673–1073 K and velocities of 0.5–5 mm/min. Compression at 873–1073 K was accompanied by simultaneous partial pro-eutectoid decomposition with the precipitation of the γ2 phase. Compression at temperatures of 673 and 773 K—that is, below the eutectoid decomposition temperature (840 K)—was accompanied by the precipitation of disperse γ2 and α phases, and ultradisperse B2’ particles. Cooling of the deformed alloy to room temperature after performing each regime of compression led to thermoelastic martensitic transformation, together with the precipitation of the β′ and γ′ phases. The formation of a fine-grained structure produced an unusual combination of strength and plasticity of the initially brittle alloy both under controlled uniaxial compression, and during subsequent tensile tests at room temperature. Full article
(This article belongs to the Special Issue Materials with Shape Memory: Phase Transformations, Microstructure and Properties)
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9 pages, 849 KiB  
Article
Does Backgrounds Color Influence the Appearance of Gingiva-Colored Resin-Based Composites?
by María M. Pérez, Cristina Benavides-Reyes, Maria Tejada-Casado, Javier Ruiz-López and Cristina Lucena
Materials 2022, 15(10), 3712; https://doi.org/10.3390/ma15103712 - 22 May 2022
Cited by 6 | Viewed by 2599
Abstract
Dental materials are mainly tested in vitro, so laboratory conditions must reproduce the oral environment to ensure the validity of their results. This study aimed to evaluate the influence of backgrounds on the color of gingiva-colored resin-based composites (GCRBC). Three discs of each [...] Read more.
Dental materials are mainly tested in vitro, so laboratory conditions must reproduce the oral environment to ensure the validity of their results. This study aimed to evaluate the influence of backgrounds on the color of gingiva-colored resin-based composites (GCRBC). Three discs of each of 20 shades of GCRBCs and each thickness (1 and 2 mm) were prepared. Diffuse reflectance was measured on-air and over three natural teeth (0M3/B1, 3M3/B3, and 5M3/B4 shades of Vita 3D Master/Vita Classical guides, respectively) using a calibrated spectroradiometer, CIE D65 illuminant and the CIE 45°/0° geometry. CIEDE2000 color difference formula and its 50:50% perceptibility and acceptability thresholds have been used to calculate and interpret the results. It can be stated that the background influences the color of all GCRBCs tested, although the effect is more pronounced for 1 mm thick samples. L*, a* and b* coordinates values of GCRBCs on air were significantly different from those obtained on natural teeth backgrounds, and the total color differences were greater than the acceptability thresholds. Since GCRBCs are placed on a dental substrate in clinical conditions, it is not advisable to perform color measurements of GCRBCs on-air because of the high color differences found. This recommendation is especially relevant for thin specimens. Full article
(This article belongs to the Special Issue Research on the Properties of Dental Composites)
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20 pages, 11374 KiB  
Article
Three-Dimensional Smooth Particle Hydrodynamics Modeling and Experimental Analysis of the Ballistic Performance of Steel-Based FML Targets
by Andrzej Kubit, Tomasz Trzepieciński, Radosław Kiciński and Kamil Jurczak
Materials 2022, 15(10), 3711; https://doi.org/10.3390/ma15103711 - 22 May 2022
Cited by 9 | Viewed by 2617
Abstract
In this paper, shields made of 1.3964 stainless steel bonded to a fiber laminate were subjected to ballistic impact response of 7.62 × 51 mm ŁPS (light projectile with a lead core) projectiles. Additionally, between the steel sheet metal and the laminate, a [...] Read more.
In this paper, shields made of 1.3964 stainless steel bonded to a fiber laminate were subjected to ballistic impact response of 7.62 × 51 mm ŁPS (light projectile with a lead core) projectiles. Additionally, between the steel sheet metal and the laminate, a liquid-filled bag was placed, which was a mixture of ethylene glycol (C2H6O2) with 5 wt.% SiO2 nanopowder. Numerical modeling of the projectile penetrating the samples was carried out using the finite element method in the Abaqus program. The elasto-plastic behavior of the projectile material and the component layers of the shields was taken into account. Projectile penetration through glycol-filled bag has been performed using the smooth particle hydrodynamics technique. The morphology of the penetration channel was also analyzed using a scanning electron microscope. For the shield variant with a glycol-filled bag between the steel and laminate plates, the inlet speed of projectile was 834 m/s on average, and 366 m/s behind the sample. For the variant where there was no glycol-filled bag between the steel and laminate plates, the inlet and outlet average velocities were 836 m/s, after 481 m/s, respectively. Referring to the steel-glycol-laminate and steel-laminate variants, it can be concluded that the laminate-glycol-laminate is more effective. Full article
(This article belongs to the Special Issue Technologies for Joining and Forming Thin-Walled Structures in the Construction of Transportation Vehicles)
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13 pages, 8816 KiB  
Article
Investigation of Surface Integrity Induced by Various Finishing Processes of AISI 52100 Bearing Rings
by Nabil Jouini, Philippe Revel and Guillaume Thoquenne
Materials 2022, 15(10), 3710; https://doi.org/10.3390/ma15103710 - 22 May 2022
Cited by 7 | Viewed by 2164
Abstract
Surface integrity induced by finishing processes significantly affects the functional performance of machined components. In this work, three kinds of finishing processes, i.e., precision hard turning, conventional grinding, and sequential grinding and honing, were used for the finish machining of AISI 52100 bearing [...] Read more.
Surface integrity induced by finishing processes significantly affects the functional performance of machined components. In this work, three kinds of finishing processes, i.e., precision hard turning, conventional grinding, and sequential grinding and honing, were used for the finish machining of AISI 52100 bearing steel rings. The surface integrity induced by these finishing processes was studied via SEM investigations and residual stress measurements. To investigate rolling contact fatigue performance, contact fatigue tests were performed on a twin-disc testing machine. As the main results, the SEM observations show that precision hard turning and grinding introduce microstructural alterations. Indeed, in precision hard turning, a fine white layer (<1 μm) is observed on the top surface, followed by a thermally affected zone in the subsurface, and in grinding only, a white layer with 5 μm thickness is observed. However, no microstructural changes are found after sequential grinding and honing processes. White layers induced by precision hard turning and grinding possess compressive residual stresses. Grinding and sequential grinding and honing processes generate similar residual stress distributions, which are maximum and compressive at the machined surface and tensile at the subsurface depth of 15 μm. Precision hard turning generates a “hook”-shaped residual stress profile with maximum compressive value at the subsurface depth and thus contributes as a prenominal factor to the obtainment of the longest fatigue life with respect to other finishing processes. Due to the high quality of surface roughness (Ra = 0.05 μm), honing post grinding improves the fatigue life of bearing rings by 2.6 times in comparison with grinding. Subsurface compressive residual stresses, as well as low surface roughness, are key parameters for extending bearing fatigue life. Full article
(This article belongs to the Special Issue Finishing Operations to Enhance Surface Integrity of Parts)
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20 pages, 13698 KiB  
Article
Study of the Influence of Zirconium, Titanium and Strontium on the Properties and Microstructure of AlSi7Mg0.3Cu0.5 Alloy
by Dana Bolibruchová, Michal Kuriš, Marek Matejka and Justyna Kasińska
Materials 2022, 15(10), 3709; https://doi.org/10.3390/ma15103709 - 22 May 2022
Cited by 7 | Viewed by 2251
Abstract
The aim of the paper is to describe and specify the properties and microstructure of Al-Si alloy using Zr, a combination of Zr with elements used in the grafting of Al (Ti) alloys, and modification (Sr). Al-Si alloys with a combination of Zr [...] Read more.
The aim of the paper is to describe and specify the properties and microstructure of Al-Si alloy using Zr, a combination of Zr with elements used in the grafting of Al (Ti) alloys, and modification (Sr). Al-Si alloys with a combination of Zr and Ti and Sr elements represent an opportunity for the development of new aluminum alloys with a specific use. The experiment focused on the analysis of the synergistic effects of Zr with Ti and Zr with Sr on a AlSi7Mg0.3Cu0.5 alloy. The experimental alloys contained a constant Zr content of 0.15 wt. % and were alloyed with a gradual addition of Ti and Sr in the range of 0.1 to 0.3 wt. % for Ti, and 0.1 to 0.3 wt. % for Sr. The experimental samples were cast by meltable model casting technology. In variants with a constant addition of Zr 0.15 wt. % and a gradual addition of Ti, we observed an increase in the values of mechanical characteristics, with a significant decrease in ductility. When evaluating the structure of experimental alloys, Ti affected it by increasing the number of precipitated Zr phases. Experimental alloys with Zr and Sr addition were characterized by nucleation of Zr phases in angular morphology. It can be concluded that the investigated elements are expected to have a positive (strengthening) effect even at higher operating temperatures. Full article
(This article belongs to the Special Issue Modern Foundry Materials and Technologies)
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11 pages, 3469 KiB  
Article
Microfluidic Fabrication and Thermal Properties of Microencapsulated N-Hexadecane with a Hybrid Polymer Shell for Thermal Energy Storage
by Luxi Yang, Linchuan Dai, Lu Ye, Rui Yang and Yangcheng Lu
Materials 2022, 15(10), 3708; https://doi.org/10.3390/ma15103708 - 22 May 2022
Cited by 6 | Viewed by 1959
Abstract
In this study, a strategy based on microfluidic method is developed toward a facile fabrication of phase change material microcapsules with uniform and controllable particle size as well as high encapsulation ratio and thermal stability. N-hexadecane, as a phase change material, was successfully [...] Read more.
In this study, a strategy based on microfluidic method is developed toward a facile fabrication of phase change material microcapsules with uniform and controllable particle size as well as high encapsulation ratio and thermal stability. N-hexadecane, as a phase change material, was successfully encapsulated by a hybrid shell of poly (methyl methacrylate) and polyurea. The fabrication process includes the following three steps: (1) Formation of oil-in-water droplets with uniform micron size in the microfluidic chip; (2) formation of the first polyurea shell to encapsulate droplets by fast interfacial polymerization when the droplets pass through the coiled transport microchannel; and (3) completion of free radical polymerization of methyl methacrylate inside the microspheres by heating to form the hybrid microcapsule shell. The average size, encapsulation ratio, and phase change enthalpy of microcapsules changed by varying the flow rate of the dispersion phase and raw material composition. The highest melting enthalpy of 222.6 J g−1 and encapsulation ratio of 94.5% of the microcapsule were obtained when the flow rates of the continuous and dispersion fluids were 600 μL min−1 and 24 μL min−1, respectively. It is shown that the phase change material microcapsules were stable after 50 heating/cooling cycles. Full article
(This article belongs to the Section Polymeric Materials)
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