Materials

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3 pages, 195 KiB

Open AccessEditorial

Future Trends in Advanced Materials and Processes

by Petrica Vizureanu

Materials 2022, 15(19), 6554; https://doi.org/10.3390/ma15196554 - 21 Sep 2022

Viewed by 1302

Abstract

The main objective of this Special Issue was to publish original high-quality research papers covering the most recent advances in materials properties, as well as comprehensive reviews addressing the relevant state-of-the-art topics in the area of materials processing, with relevant practical applications [...] [...] Read more.

The main objective of this Special Issue was to publish original high-quality research papers covering the most recent advances in materials properties, as well as comprehensive reviews addressing the relevant state-of-the-art topics in the area of materials processing, with relevant practical applications [...] Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

Research

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13 pages, 8234 KiB

Open AccessArticle

Microstructure of Dolostones of Different Geological Ages and Dedolomitization Reaction

by Zhiyuan Fan, Zhongyang Mao, Xiang Liu, Lei Yi, Tao Zhang, Xiaojun Huang and Min Deng

Materials 2022, 15(12), 4109; https://doi.org/10.3390/ma15124109 - 9 Jun 2022

Cited by 1 | Viewed by 1552

Abstract

Dolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. [...] Read more.

Dolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. In this paper, rocks were selected from five different geological ages: Jixianian, Cambrian, Ordovician, Devonian, and Triassic ages. The ordering degree and the content of MgCO₃ of dolomites in rocks of different geological ages were determined by X-ray diffraction (XRD). The degree of dedolomitization reaction in rocks cured in 80 °C, 1 mol/L NaOH solution was determined by quantitative X-ray diffraction (QXRD). The morphology of dolomites in rocks was determined by a polarizing microscope. The products of the dedolomitization reaction were determined by field emission electron microscopy (FESEM-EDS). According to the test results, the following conclusions are drawn. There is a good positive correlation between ordering degree and the molar fraction of MgCO₃ of dolomites. When the MgCO₃ mole fraction of dolomites varies from 47.17% to 49.60%, the higher the MgCO₃ mole fraction, the greater the ordering degree of dolomite. By analyzing the degree of the dedolomitization reaction of different dolostone powders cured at 80 °C in 1 mol/L NaOH solution, it is found that the older the geological age of dolostone, the slower the dedolomitization reaction rate and the lower the degree of dedolomitization reaction. The lower the ordering degree of dolomite crystal in the same geological age, the faster the rate of dedolomitization reaction and the higher the degree of dedolomitization reaction. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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39 pages, 5911 KiB

Open AccessArticle

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 17 | Viewed by 4296

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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24 pages, 8893 KiB

Open AccessArticle

Development of High-Tech Self-Compacting Concrete Mixtures Based on Nano-Modifiers of Various Types

by Sergey A. Stel’makh, Evgenii M. Shcherban’, Alexey Beskopylny, Levon R. Mailyan, Besarion Meskhi, Nikita Beskopylny and Yuriy Zherebtsov

Materials 2022, 15(8), 2739; https://doi.org/10.3390/ma15082739 - 8 Apr 2022

Cited by 23 | Viewed by 2675

Abstract

Promising areas of concrete material science are maximum greening, reducing the carbon footprint, and, at the same time, solving the problems of increasing the cost of raw materials using industrial waste as modifiers for self-compacting concrete mixtures. This study aimed to review, investigate [...] Read more.

Promising areas of concrete material science are maximum greening, reducing the carbon footprint, and, at the same time, solving the problems of increasing the cost of raw materials using industrial waste as modifiers for self-compacting concrete mixtures. This study aimed to review, investigate and test from the point of view of theory and practice the possibility of using various industrial types as a nano-modifier in self-compacting concrete with improved performance. The possibility of nano-modification of self-compacting concrete with a complex modifier based on industrial waste has been proved and substantiated theoretically and experimentally. The possibility of improving the technological properties of concrete mixtures using such nanomodifiers was confirmed. The recipe and technological parameters of the process were revealed and their influence on the characteristics of concrete mixes and concretes were expressed and determined. Experimental technological and mathematical dependencies between the characteristics of the technological process and raw materials and the characteristics of concrete mixtures and concretes were determined. The optimization of these parameters was carried out, a theoretical substantiation of the obtained results was proposed, and a quantitative picture was presented, expressed in the increment of the properties of self-compacting concrete mixtures using nano-modifiers from industrial waste concretes based on them. The mobility of the concrete mixture increased by 12%, and the fluidity of the mixture increased by 83%. In relation to the control composition, the concrete strength increased by 19%, and the water resistance of concrete increased by 22%. The ultimate strains decreased by 14%, and elastic modulus increased by 11%. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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23 pages, 3695 KiB

Open AccessArticle

Mathematical Modeling and Experimental Substantiation of the Gas Release Process in the Production of Non-Autoclaved Aerated Concrete

by Evgenii M. Shcherban’, Sergey A. Stel’makh, Alexey Beskopylny, Levon R. Mailyan, Besarion Meskhi, Anatoly Shuyskiy, Nikita Beskopylny and Natal’ya Dotsenko

Materials 2022, 15(7), 2642; https://doi.org/10.3390/ma15072642 - 3 Apr 2022

Cited by 9 | Viewed by 2770

Abstract

The widespread use of aerated concrete in construction has led to the emergence of many types and compositions. However, additional research should fill theoretical gaps in the phenomenon of gas release during the formation of the structure of aerated concrete. Based on theoretical [...] Read more.

The widespread use of aerated concrete in construction has led to the emergence of many types and compositions. However, additional research should fill theoretical gaps in the phenomenon of gas release during the formation of the structure of aerated concrete. Based on theoretical analysis and experimental studies, the article proposes a mathematical model of the swelling process based on the physicochemical laws of convection and molecular diffusion of hydrogen from a mixture and the conditions of swelling, precipitation, and stabilization of the mixture. An improved method for the manufacture of aerated concrete is proposed, which consists of introducing cement pre-hydrated for 20–30 min into the composition of the aerated concrete mixture and providing improved gas-holding capacity and increased swelling of the mixture, reducing the average density of aerated concrete up to 29% and improving heat-shielding properties up to 31%. At the same time, the small dynamics of a decrease in the strength properties of aerated concrete were observed, which is confirmed by an increased structural quality factor (CSQ) of up to 13%. As a result, aerated concrete has been obtained that meets the requirements of environmental friendliness and has improved mechanical and physical characteristics. Economic efficiency is to reduce the cost of production of aerated concrete and construction in general by about 15%. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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14 pages, 39402 KiB

Open AccessArticle

A Mixing Model for Describing Electrical Conductivity of a Woven Structure

by Magdalena Tokarska

Materials 2022, 15(7), 2512; https://doi.org/10.3390/ma15072512 - 29 Mar 2022

Cited by 2 | Viewed by 1713

Abstract

The main aim of the research was to describe electro-conductive woven structures by specifying the phases’ exponents using the generalised Archie’s law. Special woven structures were designed to transfer Archie’s model to the textile object. The woven structure was treated as a complex [...] Read more.

The main aim of the research was to describe electro-conductive woven structures by specifying the phases’ exponents using the generalised Archie’s law. Special woven structures were designed to transfer Archie’s model to the textile object. The woven structure was treated as a complex multiphase mixture. The structure was composed of two conducting phases (strips and strip contacts) and one non-conducting phase (pore space). It was found that the designed structures were characterised by the phases’ exponents that exceeded the value of 2, which denoted low connectivity in the conductive phases. A qualitative and quantitative description of the woven structure was feasible, i.e., the connectedness and the connectivity, respectively. The connectedness of both of the phases was dependent on the material from which the structure was designed. The fraction of each of the phases involved in the current conductivity was important. The connectivity connected with structure density, in varying degrees, affected the electro-conductive properties of the woven structure. It was important how the phases were arranged in the whole composite. It was found that the strips’ contact phases played an important role in the structure of the composite. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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14 pages, 5430 KiB

Open AccessArticle

The Effects of Niobium and Molybdenum on the Microstructures and Corrosion Properties of CrFeCoNiNbxMoy Alloys

by Chun-Huei Tsau, Yi-Hsuan Chen and Meng-Chi Tsai

Materials 2022, 15(6), 2262; https://doi.org/10.3390/ma15062262 - 18 Mar 2022

Cited by 2 | Viewed by 2015

Abstract

The present work systematically investigated the effects of niobium and molybdenum on the microstructures and corrosion properties of high-entropy CrFeCoNiNb_xMo_x and CrFeCoNiNb_xMo_1−x alloys, the maximum content of (Nb + Mo) was 20 at.%. All of the alloys [...] Read more.

The present work systematically investigated the effects of niobium and molybdenum on the microstructures and corrosion properties of high-entropy CrFeCoNiNb_xMo_x and CrFeCoNiNb_xMo_1−x alloys, the maximum content of (Nb + Mo) was 20 at.%. All of the alloys were prepared by arc melting under an argon atmosphere. In CrFeCoNiNb_xMo_x alloys (x = 0.15, 0.3 and 0.5), increasing Nb and Mo content would change the microstructure of the alloy from a hypoeutectic structure (x ≤ 0.3) to a hypereutectic one (x = 0.5). All of the CrFeCoNiNbxMo_1−x alloys (x = 0.25, 0.5 and 0.75) had a hypereutectic microstructure. Only two phases were analyzed in these alloys, which were face-centered cubic (FCC) and hexagonal close packing (HCP). Increasing the content of Nb and Mo increases the hardness of the alloys by the effects of the solid solution strengthening and formation of the HCP phase. The potentiodynamic polarization curves of these alloys were also measured in 1 M sulfuric acid and 1 M sodium chloride solutions to evaluate the corrosion resistance of these alloys. The CrFeCoNiNb_0.3Mo_0.3 alloy had the smallest corrosion rate (0.0732 mm/yr) in 1 M deaerated H₂SO₄ solution, and the CrFeCoNiNb_0.15Mo_0.15 alloy had the smallest corrosion rate (0.0425 mm/yr) in 1 M deaerated NaCl solution. However, the CrFeCoNiNb_0.5Mo_0.5 alloy still had the best combination of corrosion resistance and hardness in the present study. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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15 pages, 6305 KiB

Open AccessArticle

A Novel Process to Recover Gypsum from Phosphogypsum

by Junhui Xiao, Tao Lu, Yuanfa Zhuang and Huang Jin

Materials 2022, 15(5), 1944; https://doi.org/10.3390/ma15051944 - 5 Mar 2022

Cited by 22 | Viewed by 3588

Abstract

In this study, we investigated a coarse phosphogypsum containing 49.63% SO₃, 41.41% CaO, 10.68%, 4.47% SiO₂, 1.28% P₂O₅, 0.11% F, CaSO₄·2H₂O purity of 80.65%, and whiteness of 27.68. Phosphogypsum contains calcium [...] Read more.

In this study, we investigated a coarse phosphogypsum containing 49.63% SO₃, 41.41% CaO, 10.68%, 4.47% SiO₂, 1.28% P₂O₅, 0.11% F, CaSO₄·2H₂O purity of 80.65%, and whiteness of 27.68. Phosphogypsum contains calcium sulfate dehydrate as the main mineral, with small amounts of brushite, quartz, muscovite, and zoisite. Harmful elements, such as silicon, phosphorus, and fluorine, are mainly concentrated in the +0.15 mm and −0.025 mm fraction, which can be pre-selected and removed by the grading method to further increase the CaSO₄·2H₂O content. Gypsum was recovered using a direct flotation method, which included one roughing, one scavenging, and two cleaning operations, from −0.15 mm to +0.025 mm. The test results show that a gypsum concentrate with a CaSO₄·2H₂O purity of 98.94%, CaSO₄·2H₂O recovery of 80.02%, and whiteness of 37.05 was achieved. The main mineral in the gypsum concentrate was gypsum, and limited amounts of muscovite and zoisite entered the gypsum concentrate because of the mechanical entrainment of the flotation process. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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17 pages, 9029 KiB

Open AccessArticle

Hazards of Radioactive Mineralization Associated with Pegmatites Used as Decorative and Building Material

by Mohamed M. El Dabe, A. M. Ismail, Mohamed Metwaly, Sherif A. Taalab, Mohamed Y. Hanfi and Antoaneta Ene

Materials 2022, 15(3), 1224; https://doi.org/10.3390/ma15031224 - 6 Feb 2022

Cited by 14 | Viewed by 2406

Abstract

The present study aimed to assess the radiological hazards associated with applying the investigated granite in the building materials and the infrastructures applications. The investigated granites are classified into four categories: El-Urf, barren, colourful and opaque. El Urf monzogranite intrudes metagabbro diorite complex [...] Read more.

The present study aimed to assess the radiological hazards associated with applying the investigated granite in the building materials and the infrastructures applications. The investigated granites are classified into four categories: El-Urf, barren, colourful and opaque. El Urf monzogranite intrudes metagabbro diorite complex with sharp contacts. Based on the activity concentrations, the environmental parameters such as absorbed dose rate (D_air), annual effective dose (AED), radium equivalent activity (Ra_eq), external (H_ex) and internal (H_in) hazard indices were measured. The mineralized pegmatite is located in the southwestern foothill of the Gabal El Urf younger granite. It displays well-defined zonation of three zones: outer, middle and inner zones represented by potash feldspar, quartz and mica, respectively. The isorad map showed that El Urf monzogranite is barren (Up to 100 cps) surrounding an excavation of the studied pegmatite that exhibits moderate colorful mineralization (phase-I = 500–1500 cps) and anomalous opaque mineralization (phase-II = 1500–3500 cps) pegmatites. The obtained results of radionuclides activity concentrations illustrated that the Opaque granites have the highest values of ²³⁸U (561 ± 127 Bq kg⁻¹), ²³²Th (4289 ± 891 Bq kg⁻¹) and ⁴⁰K (3002 ± 446 Bq kg⁻¹) in the granites, which are higher than the recommended worldwide average. Many of the radiological hazard parameters were lesser than the international limits in the younger granites and barren pegmatites. All of these parameters were higher in the colorful and opaque mineralized pegmatites. The high activity and the elevated radiological hazard parameters in the mineralized pegmatites are revised to the presence of radioactive and radioelements bearing minerals, such as thorite, meta-autunite, kasolite, phurcalite, columbite, fergusonite, Xenotime and fluorapatite. Other instances of mineralization were also recorded as cassiterite, atacamite, galena, pyrite and iron oxide minerals. Thus, the granites with high radioactivity concentration cannot be applied in the different applications of building materials and ornamental stones. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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15 pages, 6743 KiB

Open AccessArticle

EIS Characterization of Ti Alloys in Relation to Alloying Additions of Ta

by Pedro P. Socorro-Perdomo, Néstor R. Florido-Suárez, Julia C. Mirza-Rosca and Mircea Vicentiu Saceleanu

Materials 2022, 15(2), 476; https://doi.org/10.3390/ma15020476 - 8 Jan 2022

Cited by 33 | Viewed by 2880

Abstract

The increased popularity of Ti and its alloys as important biomaterials is driven by their low modulus, greater biocompatibility, and better corrosion resistance in comparison to traditional biomaterials, such as stainless steel and Co–Cr alloys. Ti alloys are successfully used in severe stress [...] Read more.

The increased popularity of Ti and its alloys as important biomaterials is driven by their low modulus, greater biocompatibility, and better corrosion resistance in comparison to traditional biomaterials, such as stainless steel and Co–Cr alloys. Ti alloys are successfully used in severe stress situations, such as Ti–6Al–4V, but this alloy is related to long-term health problems and, in response, different Ti alloys composed of non-toxic and non-allergic elements such as Nb, Zr, Mo, and Ta have been developed for biomedical applications. In this context, binary alloys of titanium and tantalum have been developed and are predicted to be potential products for medical purposes. More than this, today, novel biocompatible alloys such as high entropy alloys with Ti and Ta are considered for biomedical applications and therefore it is necessary to clarify the influence of tantalum on the behavior of the alloy. In this study, various Ti–xTa alloys (with x = 5, 15, 25, and 30) were characterized using different techniques. High-resolution maps of the materials’ surfaces were generated by scanning tunneling microscopy (STM), and atom distribution maps were obtained by energy dispersive X-ray spectroscopy (EDS). A thorough output of chemical composition, and hence the crystallographic structure of the alloys, was identified by X-ray diffraction (XRD). Additionally, the electrochemical behavior of these Ti–Ta alloys was investigated by EIS in simulated body fluid at different potentials. The passive layer resistance increases with the potential due to the formation of the passive layer of TiO₂ and Ta₂O₅ and then decreases due to the dissolution processes through the passive film. Within the Ti–xTa alloys, Ti–25Ta demonstrates excellent passive layer and corrosion resistance properties, so it seems to be a promising product for metallic medical devices. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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12 pages, 2081 KiB

Open AccessArticle

Radiological Hazard Evaluation of Some Egyptian Magmatic Rocks Used as Ornamental Stone: Petrography and Natural Radioactivity

by El Saeed R. Lasheen, Mohammed A. Rashwan, Hamid Osman, Sultan Alamri, Mayeen U. Khandaker and Mohamed Y. Hanfi

Materials 2021, 14(23), 7290; https://doi.org/10.3390/ma14237290 - 28 Nov 2021

Cited by 25 | Viewed by 2001

Abstract

Magmatic rocks represent one of the most significant rocks due to their abundance, durability and appearance; they can be used as ornamental stones in the construction of dwellings. The current study is concerned with the detailed petrography and natural radioactivity of seven magmatic [...] Read more.

Magmatic rocks represent one of the most significant rocks due to their abundance, durability and appearance; they can be used as ornamental stones in the construction of dwellings. The current study is concerned with the detailed petrography and natural radioactivity of seven magmatic rocks. All are commercial granitic rocks and are identified as black Aswan, Nero Aswan, white Halayeb, Karnak, Verdi, red Hurghada and red Aswan. Their respective mineralogical compositions are classified as porpheritic granodiorite, granodiorite, tonalite, monzogranite, syenogranite, monzogranite and syenogranite. A total of nineteen samples were prepared from these seven rock types in order to assess their suitability as ornamental stones. Concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K radionuclides were measured using NaI (Tl) scintillation gamma-ray spectrometry. Among the studied magmatic rocks, white Halayeb had the lowest average values of ²²⁶Ra (15.7 Bq/kg), ²³²Th (4.71 Bq/kg) and ⁴⁰K (~292 Bq/kg), all below the UNSCEAR reported average world values or recommended reference limits. In contrast, the other granitic rocks have higher values than the recommended limit. Except for the absorbed dose rate, other radiological hazard parameters including radium equivalent activity, annual effective dose equivalent, external, and internal hazard indices reflect that the White Halyeb rocks are favorable for use as ornamental stone in the construction of luxurious and high-demand residential buildings. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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15 pages, 1884 KiB

Open AccessArticle

New Titanium Alloys, Promising Materials for Medical Devices

by Madalina Simona Baltatu, Petrica Vizureanu, Andrei Victor Sandu, Nestor Florido-Suarez, Mircea Vicentiu Saceleanu and Julia Claudia Mirza-Rosca

Materials 2021, 14(20), 5934; https://doi.org/10.3390/ma14205934 - 9 Oct 2021

Cited by 44 | Viewed by 2966

Abstract

Titanium alloys are used in medical devices due to their mechanical properties, but also for their corrosion resistance. The natural passivation of titanium-based biomaterials, on the surface of which a dense and coherent film of nanometric thickness is formed, composed mainly of TiO [...] Read more.

Titanium alloys are used in medical devices due to their mechanical properties, but also for their corrosion resistance. The natural passivation of titanium-based biomaterials, on the surface of which a dense and coherent film of nanometric thickness is formed, composed mainly of TiO₂, determines an apparent bioactivity of them. In this paper, the method of obtaining new Ti20MoxSi alloys (x = 0.0, 0.5, 0.75, and 1.0) is presented, their microstructure is analyzed, and their electrochemical responses in Ringer´s solution were systematically investigated by linear polarization, cyclic potential dynamic polarization, and electrochemical impedance spectroscopy (EIS). The alloys corrosion resistance is high, and no evidence of localized breakdown of the passive layer was observed. There is no regularity determined by the composition of the alloys, in terms of corrosion resistance, but it seems that the most resistant is Ti20Mo1.0Si. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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15 pages, 7568 KiB

Open AccessArticle

A Study to Derive Equivalent Mechanical Properties of Porous Materials with Orthotropic Elasticity

by Changmin Pyo, Younghyun Kim, Jaewoong Kim and Sungwook Kang

Materials 2021, 14(18), 5132; https://doi.org/10.3390/ma14185132 - 7 Sep 2021

Cited by 4 | Viewed by 2124

Abstract

The need for diverse materials has emerged as industry becomes more developed, and there is a need for materials with pores in various industries, including the energy storage field. However, there is difficulty in product design and development using the finite element method [...] Read more.

The need for diverse materials has emerged as industry becomes more developed, and there is a need for materials with pores in various industries, including the energy storage field. However, there is difficulty in product design and development using the finite element method because the mechanical properties of a porous material are different from those of a base material due to the pores. Therefore, in this study, a Python program that can estimate the equivalent property of a material with pores was developed and its matching was verified through comparison with the measurement results. For high-efficiency calculation, the pores were assumed to be circular or elliptical, and they were also assumed to be equally distributed in each direction. The material with pores was assumed to be an orthotropic material, and its equivalent mechanical properties were calculated using the equivalent strain and equivalent stress by using the appropriate material property matrix. The material properties of a specimen with the simulated pores were measured using UTM, and the results were compared with the simulation results to confirm that the degree of matching achieved 6.4%. It is expected that this study will contribute to the design and development of a product in the industrial field. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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20 pages, 8127 KiB

Open AccessArticle

Thermal Shock Resistance and Thermal Insulation Capability of Laser-Glazed Functionally Graded Lanthanum Magnesium Hexaluminate/Yttria-Stabilised Zirconia Thermal Barrier Coating

by Muhammed Anaz Khan, Annakodi Vivek Anand, Muthukannan Duraiselvam, Koppula Srinivas Rao, Ramachandra Arvind Singh and Subramanian Jayalakshmi

Materials 2021, 14(14), 3865; https://doi.org/10.3390/ma14143865 - 10 Jul 2021

Cited by 12 | Viewed by 2752

Abstract

In this work, functionally graded lanthanum magnesium hexaluminate (LaMgAl₁₁O₁₉)/yttria-stabilised zirconia (YSZ) thermal barrier coating (FG-TBC), in as-sprayed and laser-glazed conditions, were investigated for their thermal shock resistance and thermal insulation properties. Results were compared with those of a dual-layered [...] Read more.

In this work, functionally graded lanthanum magnesium hexaluminate (LaMgAl₁₁O₁₉)/yttria-stabilised zirconia (YSZ) thermal barrier coating (FG-TBC), in as-sprayed and laser-glazed conditions, were investigated for their thermal shock resistance and thermal insulation properties. Results were compared with those of a dual-layered coating of LaMgAl₁₁O₁₉ and YSZ (DC-TBC). Thermal shock tests at 1100 °C revealed that the as-sprayed FG-TBC had improved thermal stability, i.e., higher cycle lifetime than the as-sprayed DC-TBC due to its gradient architecture, which minimised stress concentration across its thickness. In contrast, DC-TBC spalled at the interface due to the difference in the coefficient of thermal expansion between the LaMgAl₁₁O₁₉ and YSZ layers. Laser glazing improved cycle lifetimes of both the types of coatings. Microstructural changes, mainly the formation of segmentation cracks in the laser-glazed surfaces, provided strain tolerance during thermal cycles. Infrared rapid heating of the coatings up to 1000 °C showed that the laser-glazed FG-TBC had better thermal insulation capability, as interlamellar pores entrapped gas and constrained heat transfer across its thickness. From the investigation, it is inferred that (i) FG-TBC has better thermal shock resistance and thermal insulation capability than DC-TBC and (ii) laser glazing can significantly enhance the overall thermal performance of the coatings. Laser-glazed FG-TBC provides the best heat management, and has good potential for applications that require effective heat management, such as in gas turbines. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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15 pages, 3604 KiB

Open AccessArticle

Transmission, Reflection and Dissipation of Microwaves in Magnetic Composites with Nanocrystalline Finemet-Type Flakes

by Anatoly B. Rinkevich, Dmitry V. Perov and Yuriy I. Ryabkov

Materials 2021, 14(13), 3499; https://doi.org/10.3390/ma14133499 - 23 Jun 2021

Cited by 7 | Viewed by 1936

Abstract

The microwave properties of a composite material containing flakes of finemet-type nanocrystalline alloy placed in the epoxy matrix have been investigated. Two compositions have been studied: with 15% and 30% flakes. Frequency dependences of transmission and reflection coefficients are measured in the frequency [...] Read more.

The microwave properties of a composite material containing flakes of finemet-type nanocrystalline alloy placed in the epoxy matrix have been investigated. Two compositions have been studied: with 15% and 30% flakes. Frequency dependences of transmission and reflection coefficients are measured in the frequency range from 12 to 38 GHz. The dielectric permittivity and magnetic permeability are obtained, and the microwave losses are calculated. The dependences of transmission and reflection coefficients have been drawn as functions of wave frequency and thickness of the composite material, taking into account the frequency dependences of permittivity and permeability. The regions of maximal and minimal microwave absorption have been defined. The influence of wave interference on the frequency dependence of microwave absorption is studied. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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14 pages, 4792 KiB

Open AccessArticle

Re-Melting Behaviour and Wear Resistance of Vanadium Carbide Precipitating Cr_27.5Co₁₄Fe₂₂Mo₂₂Ni_11.65V_2.85 High Entropy Alloy

by Kai Treutler, Swenja Lorenz and Volker Wesling

Materials 2021, 14(8), 1871; https://doi.org/10.3390/ma14081871 - 9 Apr 2021

Cited by 4 | Viewed by 2071

Abstract

High entropy alloys (HEAs) are among of the most promising new metal material groups. The achievable properties can exceed those of common alloys in different ways. Due to the mixture of five or more alloying elements, the variety of high entropy alloys is [...] Read more.

High entropy alloys (HEAs) are among of the most promising new metal material groups. The achievable properties can exceed those of common alloys in different ways. Due to the mixture of five or more alloying elements, the variety of high entropy alloys is fairly huge. The presented work will focus on some first insights on the weldability and the wear behavior of vanadium carbide precipitation Cr_27.5Co₁₄Fe₂₂Mo₂₂Ni_11.65V_2.85 HEA. The weldability should always be addressed in an early stage of any alloy design to avoid welding-related problems afterwards. The cast Cr_27.5Co₁₄Fe₂₂Mo₂₂Ni_11.65V_2.85 HEA has been remelted using a TIG welding process and the resulting microstructure has been examined. The changes in the microstructure due to the remelting process showed little influence of the welding process and no welding-related problems like hot cracks have been observed. It will be shown that vanadium carbides or vanadium-rich phases precipitate after casting and remelting in a two phased HEA matrix. The hardness of the as cast alloy is 324HV0.2 and after remelting the hardness rises to 339HV0.2. The wear behavior can be considered as comparable to a Stellite 6 cobalt base alloy as determined in an ASTM G75 test. Overall, the basic HEA design is promising due to the precipitation of vanadium carbides and should be further investigated. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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21 pages, 1876 KiB

Open AccessReview

Recent Developments in Steelmaking Industry and Potential Alkali Activated Based Steel Waste: A Comprehensive Review

by Ikmal Hakem Aziz, Mohd Mustafa Al Bakri Abdullah, Mohd Arif Anuar Mohd Salleh, Liew Yun Ming, Long Yuan Li, Andrei Victor Sandu, Petrica Vizureanu, Ovidiu Nemes and Shaik Numan Mahdi

Materials 2022, 15(5), 1948; https://doi.org/10.3390/ma15051948 - 6 Mar 2022

Cited by 22 | Viewed by 3694

Abstract

The steel industry is responsible for one-third of all global industrial CO₂ emissions, putting pressure on the industry to shift forward towards more environmentally friendly production methods. The metallurgical industry is under enormous pressure to reduce CO₂ emissions as a result [...] Read more.

The steel industry is responsible for one-third of all global industrial CO₂ emissions, putting pressure on the industry to shift forward towards more environmentally friendly production methods. The metallurgical industry is under enormous pressure to reduce CO₂ emissions as a result of growing environmental concerns about global warming. The reduction in CO₂ emissions is normally fulfilled by recycling steel waste into alkali-activated cement. Numerous types of steel waste have been produced via three main production routes, including blast furnace, electric arc furnace, and basic oxygen furnace. To date, all of the steel waste has been incorporated into alkali activation system to enhance the properties. This review focuses on the current developments over the last ten years in the steelmaking industry. This work also summarizes the utilization of steel waste for improving cement properties through an alkali activation system. Finally, this work presents some future research opportunities with regard to the potential of steel waste to be utilized as an alkali-activated material. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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40 pages, 542 KiB

Open AccessReview

A State-of-the-Art Review on Innovative Geopolymer Composites Designed for Water and Wastewater Treatment

by Ismail Luhar, Salmabanu Luhar, Mohd Mustafa Al Bakri Abdullah, Rafiza Abdul Razak, Petrica Vizureanu, Andrei Victor Sandu and Petre-Daniel Matasaru

Materials 2021, 14(23), 7456; https://doi.org/10.3390/ma14237456 - 4 Dec 2021

Cited by 59 | Viewed by 5234

Abstract

There is nothing more fundamental than clean potable water for living beings next to air. On the other hand, wastewater management is cropping up as a challenging task day-by-day due to lots of new additions of novel pollutants as well as the development [...] Read more.

There is nothing more fundamental than clean potable water for living beings next to air. On the other hand, wastewater management is cropping up as a challenging task day-by-day due to lots of new additions of novel pollutants as well as the development of infrastructures and regulations that could not maintain its pace with the burgeoning escalation of populace and urbanizations. Therefore, momentous approaches must be sought-after to reclaim fresh water from wastewaters in order to address this great societal challenge. One of the routes is to clean wastewater through treatment processes using diverse adsorbents. However, most of them are unsustainable and quite costly e.g. activated carbon adsorbents, etc. Quite recently, innovative, sustainable, durable, affordable, user and eco-benevolent Geopolymer composites have been brought into play to serve the purpose as a pretty novel subject matter since they can be manufactured by a simple process of Geopolymerization at low temperature, lower energy with mitigated carbon footprints and marvellously, exhibit outstanding properties of physical and chemical stability, ion-exchange, dielectric characteristics, etc., with a porous structure and of course lucrative too because of the incorporation of wastes with them, which is in harmony with the goal to transit from linear to circular economy, i.e., “one’s waste is the treasure for another”. For these reasons, nowadays, this ground-breaking inorganic class of amorphous alumina-silicate materials are drawing the attention of the world researchers for designing them as adsorbents for water and wastewater treatment where the chemical nature and structure of the materials have a great impact on their adsorption competence. The aim of the current most recent state-of-the-art and scientometric review is to comprehend and assess thoroughly the advancements in geo-synthesis, properties and applications of geopolymer composites designed for the elimination of hazardous contaminants viz., heavy metal ions, dyes, etc. The adsorption mechanisms and effects of various environmental conditions on adsorption efficiency are also taken into account for review of the importance of Geopolymers as most recent adsorbents to get rid of the death-defying and toxic pollutants from wastewater with a view to obtaining reclaimed potable and sparkling water for reuse offering to trim down the massive crisis of scarcity of water promoting sustainable water and wastewater treatment for greener environments. The appraisal is made on the performance estimation of Geopolymers for water and wastewater treatment along with the three-dimensional printed components are characterized for mechanical, physical and chemical attributes, permeability and Ammonium (NH₄⁺) ion removal competence of Geopolymer composites as alternative adsorbents for sequestration of an assortment of contaminants during wastewater treatment. Full article

(This article belongs to the Special Issue Future Trends in Advanced Materials and Processes)

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