Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.293
Fei Ren, Xu Niu, Aiqi Wang, Yonghao Liu, Ruzhuan Wang
The dielectric constant, known as a fundamental physical parameter that describes solid material's response to an electric field, is sensitive to temperature. Therefore, it is very important to reasonably characterize the dielectric constant of the material at different temperatures. In this work, by considering the concept of the energy storage limit associating with electrons transitions and the relationship between the dielectric constant and band gap energy, a novel and simple theoretical model for determining the temperature-dependent dielectric constant of solid materials is developed. In comparison to the traditional semi-empirical and fitting models, this model does not contain any fitting parameters, and which just has the basic material parameters including the heat capacity, Debye temperature and linear expansion coefficient. The theoretical model is verified by the good agreement between the model predictions and the experimental measurements of CdTe, ZnSe, InP, GaP, GaN, Diamond, Al2O3, AlN and SiC. This work provides a convenient and effective method for predicting the dielectric constant of solid materials at different temperatures.
{"title":"A novel theoretical model for the temperature-dependent dielectric constant of solid materials","authors":"Fei Ren, Xu Niu, Aiqi Wang, Yonghao Liu, Ruzhuan Wang","doi":"10.1016/j.ceramint.2024.12.293","DOIUrl":"10.1016/j.ceramint.2024.12.293","url":null,"abstract":"<div><div>The dielectric constant, known as a fundamental physical parameter that describes solid material's response to an electric field, is sensitive to temperature. Therefore, it is very important to reasonably characterize the dielectric constant of the material at different temperatures. In this work, by considering the concept of the energy storage limit associating with electrons transitions and the relationship between the dielectric constant and band gap energy, a novel and simple theoretical model for determining the temperature-dependent dielectric constant of solid materials is developed. In comparison to the traditional semi-empirical and fitting models, this model does not contain any fitting parameters, and which just has the basic material parameters including the heat capacity, Debye temperature and linear expansion coefficient. The theoretical model is verified by the good agreement between the model predictions and the experimental measurements of CdTe, ZnSe, InP, GaP, GaN, Diamond, Al<sub>2</sub>O<sub>3</sub>, AlN and SiC. This work provides a convenient and effective method for predicting the dielectric constant of solid materials at different temperatures.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8627-8633"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.291
Onur Alev , Okan Özdemir , Alp Kılıç , Serkan Büyükköse , Eda Goldenberg
Radio frequency magnetron sputtering is an effective method for growing MoS₂ thin films with tailored optical and electrical properties for various applications. This study investigates how deposition pressure and target power impact the morphology, structural, optical, and electrical characteristics of MoS₂ thin films. Scanning electron microscopy (SEM) revealed a nanoflake surface morphology with flake widths from 24 to 32 nm, where lower target power produces more pronounced flake structures. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of MoO3 alongside the formation of MoS2. XPS analysis also indicated sulfur vacancies and molybdenum oxide formation due to ambient oxygen, with the Mo/S ratio significantly affected by deposition pressure at higher target powers. Optical analysis demonstrated that higher sputtering pressures enhance transparency, with transmission reaching 80 %, while lower pressures result 30 % transmission. High target power caused a red shift in the absorption edge, while reduced deposition pressure narrowed the optical band gap, ranging from 2.1 to 2.5 eV, due to defect formation and sulfur vacancies, as revealed by photoluminescence and Raman spectroscopy. Electrical measurements indicated a shift from Schottky to Ohmic contact behavior for thin films grown at lower pressures, resulting higher conductivity. Additionally, activation energy decreased with increasing target power but rose significantly with higher deposition pressures, indicating that thin films with Ohmic contact have lower activation energy than those with Schottky contact. These findings underscore the critical role of sputtering parameters, especially target power and plasma pressure, in defect engineering, which directly influences the optical and electrical performance of MoS₂ thin films.
{"title":"Effects of target power and deposition pressure on magnetron-sputtered molybdenum disulfide thin films: Morphological, structural, optical, and electrical characteristics","authors":"Onur Alev , Okan Özdemir , Alp Kılıç , Serkan Büyükköse , Eda Goldenberg","doi":"10.1016/j.ceramint.2024.12.291","DOIUrl":"10.1016/j.ceramint.2024.12.291","url":null,"abstract":"<div><div>Radio frequency magnetron sputtering is an effective method for growing MoS₂ thin films with tailored optical and electrical properties for various applications. This study investigates how deposition pressure and target power impact the morphology, structural, optical, and electrical characteristics of MoS₂ thin films. Scanning electron microscopy (SEM) revealed a nanoflake surface morphology with flake widths from 24 to 32 nm, where lower target power produces more pronounced flake structures. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of MoO<sub>3</sub> alongside the formation of MoS<sub>2</sub>. XPS analysis also indicated sulfur vacancies and molybdenum oxide formation due to ambient oxygen, with the Mo/S ratio significantly affected by deposition pressure at higher target powers. Optical analysis demonstrated that higher sputtering pressures enhance transparency, with transmission reaching 80 %, while lower pressures result 30 % transmission. High target power caused a red shift in the absorption edge, while reduced deposition pressure narrowed the optical band gap, ranging from 2.1 to 2.5 eV, due to defect formation and sulfur vacancies, as revealed by photoluminescence and Raman spectroscopy. Electrical measurements indicated a shift from Schottky to Ohmic contact behavior for thin films grown at lower pressures, resulting higher conductivity. Additionally, activation energy decreased with increasing target power but rose significantly with higher deposition pressures, indicating that thin films with Ohmic contact have lower activation energy than those with Schottky contact. These findings underscore the critical role of sputtering parameters, especially target power and plasma pressure, in defect engineering, which directly influences the optical and electrical performance of MoS₂ thin films.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8607-8614"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.285
Chong Su , Tianhao Nie , Jiaxing Liu , Mu Yang
The surface morphology and subsurface crack damage of alumina ceramic coatings were observed under different grinding process parameters. Micro–macro simulations were used to analyze the mechanisms underlying surface formation and crack damage. The results showed that the surface morphology after grinding consisted of fragmented pits, brittle fractures, lamellar spalling, pores, ductile surfaces, and plowing marks. Both ductile and brittle removal processes occurred during grinding, with the ductile removal reaching a maximum rate of 59.22 % during the experiment. Brittle removal primarily occurred at the pores and end of the cutting arc of abrasive grains. In addition, alternating tensile and compressive stresses caused by squeezing and friction of the rounded cutting edge led to the formation of powdery chips on the machined surface. The transformations between tensile and compressive stresses as well as the rebound effects in the grinding contact arc zone resulted in transverse propagation cracks in the alumina coating. The greater the grinding force, the more severe the transverse crack damage. Three types of transverse cracks were observed in the cross-section of the alumina coating. The first type originated from surface pit defects, initially propagating downward and then extending along the grinding direction to form transverse cracks. The second type started at the interface between the bond coat and alumina coat, particularly at the convex peak of the bond coat. The third type initiated at the pores near the middle of the alumina coating and then propagated to both sides, forming transverse cracks.
{"title":"Surface formation and crack damage in grinding of alumina ceramic insulation coating","authors":"Chong Su , Tianhao Nie , Jiaxing Liu , Mu Yang","doi":"10.1016/j.ceramint.2024.12.285","DOIUrl":"10.1016/j.ceramint.2024.12.285","url":null,"abstract":"<div><div>The surface morphology and subsurface crack damage of alumina ceramic coatings were observed under different grinding process parameters. Micro–macro simulations were used to analyze the mechanisms underlying surface formation and crack damage. The results showed that the surface morphology after grinding consisted of fragmented pits, brittle fractures, lamellar spalling, pores, ductile surfaces, and plowing marks. Both ductile and brittle removal processes occurred during grinding, with the ductile removal reaching a maximum rate of 59.22 % during the experiment. Brittle removal primarily occurred at the pores and end of the cutting arc of abrasive grains. In addition, alternating tensile and compressive stresses caused by squeezing and friction of the rounded cutting edge led to the formation of powdery chips on the machined surface. The transformations between tensile and compressive stresses as well as the rebound effects in the grinding contact arc zone resulted in transverse propagation cracks in the alumina coating. The greater the grinding force, the more severe the transverse crack damage. Three types of transverse cracks were observed in the cross-section of the alumina coating. The first type originated from surface pit defects, initially propagating downward and then extending along the grinding direction to form transverse cracks. The second type started at the interface between the bond coat and alumina coat, particularly at the convex peak of the bond coat. The third type initiated at the pores near the middle of the alumina coating and then propagated to both sides, forming transverse cracks.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8544-8557"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.325
Kaustuv Chatterjee , Prabir Pal
Barium zirconate (BaZrO3) has been pursued for chemically inert, refractory materials with high mechanical and thermal stability and its nanoparticles are attractive for various dielectric applications. BaZrO3 is mainly synthesized under high temperatures, beyond the thermal budget for large-scale production. The high-quality phase pure material synthesis with nanoscale particle size at reduced temperature is a key challenge. In this work, phase pure BaZrO3 have been synthesized at temperatures down to 800 °C via a sol-gel auto-combustion technique using acetate salts of the metal precursors (barium acetate and zirconium acetate) and citric acid. The work highlights the necessity of improving metal precursor flux for the formation of nano-size synthesis of BaZrO3 at a relatively lower temperature compared with that of the standard solid-state reaction process. The influence of synthesis temperature on crystallographic structure and crystallite size of the synthesized samples have been studied using powder x-ray diffraction (p-XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) at room temperature. The optimized sample synthesized at 800 °C exhibits a cubic structure with a crystallite size of 12.1 nm as calculated from the XRD refinements, which is one of the lowest reported among sol-gel auto combustion techniques. The crystallite size mentioned above is consistent with the FESEM particle size analysis. Furthermore, the sintered pellet obtained from the optimized powder sample has shown good bulk density of around (92–95) %.
{"title":"Synthesis and characterization of phase pure barium zirconate nanoceramics by citrate acetate using the sol-gel process grown at reduced temperatures","authors":"Kaustuv Chatterjee , Prabir Pal","doi":"10.1016/j.ceramint.2024.12.325","DOIUrl":"10.1016/j.ceramint.2024.12.325","url":null,"abstract":"<div><div>Barium zirconate (BaZrO<sub>3</sub>) has been pursued for chemically inert, refractory materials with high mechanical and thermal stability and its nanoparticles are attractive for various dielectric applications. BaZrO<sub>3</sub> is mainly synthesized under high temperatures, beyond the thermal budget for large-scale production. The high-quality phase pure material synthesis with nanoscale particle size at reduced temperature is a key challenge. In this work, phase pure BaZrO<sub>3</sub> have been synthesized at temperatures down to 800 °C via a sol-gel auto-combustion technique using acetate salts of the metal precursors (barium acetate and zirconium acetate) and citric acid. The work highlights the necessity of improving metal precursor flux for the formation of nano-size synthesis of BaZrO<sub>3</sub> at a relatively lower temperature compared with that of the standard solid-state reaction process. The influence of synthesis temperature on crystallographic structure and crystallite size of the synthesized samples have been studied using powder x-ray diffraction (p-XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) at room temperature. The optimized sample synthesized at 800 °C exhibits a cubic structure with a crystallite size of 12.1 nm as calculated from the XRD refinements, which is one of the lowest reported among sol-gel auto combustion techniques. The crystallite size mentioned above is consistent with the FESEM particle size analysis. Furthermore, the sintered pellet obtained from the optimized powder sample has shown good bulk density of around (92–95) %.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8955-8964"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.313
Qingsong Zhu , Xinyu Lei , Xiaoqin Zha , Saad Melhi , Juanna Ren , Ben Bin Xu , Siyu Hao , Baoji Miao , Huitan Fu , Mohammed A. Amin , Zeinhom M. El-Bahy , Zhanhu Guo
2D MXene can prevent the penetration of corrosive media and can contribute to the improvement of corrosion resistance performance. However, achieving its uniform dispersion in the polymer matrix is challenging due to its large specific surface area and rapid aggregation. In this study, stable dispersion of polydopamine functionalized Ti3C2 MXene (PDA-TM) hybrid in the waterborne epoxy (WEP) matrix was achieved via in-situ polymerization of the PDA layer on the surface of TM. The Fourier-transform infrared (FTIR) spectrum of PDA-TM showed the blue shift of O-H bond at 3438 cm−1 and the Ti-O bond of TM at 612 cm−1. The characteristic peak of PDA-TM in the XRD pattern appeared at 2θ = 3.9° and the PDA bulge became smaller. Both proved the successful synthesis of PDA and TM. The surface wrinkles of the PDA-TM of SEM became more pronounced, and the smooth surface became rougher. This was due to the in-situ polymerization of DA on the surface of TM, which was conducive to avoid tight stacking of TM and expand its interlayer spacing. In addition, The WEP nanocomposite coating showed high impact resistance, strong adhesion, flexibility, and wear resistance. Moreover, PDA-TM decreased the glass transition temperature of WEP from 128.0 to 95.4 °C and improved the reflection loss for electromagnetic wave absorption properties. Furthermore, the |Z|0.01Hz value of the PDA-TM0.5 % (6.072 × 105 Ω cm2) coating was approximately 6 times higher compared to that of the WEP coating after 30-d immersion in 3.5 wt% NaCl solution. The friction coefficient was also a quarter of neat WEP. This indicated that embedding a small amount of PDA functionalized TM nanosheets into WEP coating could improve obviously the corrosion resistance and wear resistance properties. The present research will provide a theoretical basis for the use of TM in the field of anticorrosion and electromagnetic wave absorption.
{"title":"Polydopamine functionalized Ti3C2 MXene hybrid reinforced waterborne epoxy nanocomposites for enhancing anticorrosion coating application","authors":"Qingsong Zhu , Xinyu Lei , Xiaoqin Zha , Saad Melhi , Juanna Ren , Ben Bin Xu , Siyu Hao , Baoji Miao , Huitan Fu , Mohammed A. Amin , Zeinhom M. El-Bahy , Zhanhu Guo","doi":"10.1016/j.ceramint.2024.12.313","DOIUrl":"10.1016/j.ceramint.2024.12.313","url":null,"abstract":"<div><div>2D MXene can prevent the penetration of corrosive media and can contribute to the improvement of corrosion resistance performance. However, achieving its uniform dispersion in the polymer matrix is challenging due to its large specific surface area and rapid aggregation. In this study, stable dispersion of polydopamine functionalized Ti<sub>3</sub>C<sub>2</sub> MXene (PDA-TM) hybrid in the waterborne epoxy (WEP) matrix was achieved via in-situ polymerization of the PDA layer on the surface of TM. The Fourier-transform infrared (FTIR) spectrum of PDA-TM showed the blue shift of O-H bond at 3438 cm<sup>−1</sup> and the Ti-O bond of TM at 612 cm<sup>−1</sup>. The characteristic peak of PDA-TM in the XRD pattern appeared at 2θ = 3.9° and the PDA bulge became smaller. Both proved the successful synthesis of PDA and TM. The surface wrinkles of the PDA-TM of SEM became more pronounced, and the smooth surface became rougher. This was due to the in-situ polymerization of DA on the surface of TM, which was conducive to avoid tight stacking of TM and expand its interlayer spacing. In addition, The WEP nanocomposite coating showed high impact resistance, strong adhesion, flexibility, and wear resistance. Moreover, PDA-TM decreased the glass transition temperature of WEP from 128.0 to 95.4 °C and improved the reflection loss for electromagnetic wave absorption properties. Furthermore, the |Z|<sub>0.01Hz</sub> value of the PDA-TM<sub>0.5 %</sub> (6.072 × 10<sup>5</sup> Ω cm<sup>2</sup>) coating was approximately 6 times higher compared to that of the WEP coating after 30-d immersion in 3.5 wt% NaCl solution. The friction coefficient was also a quarter of neat WEP. This indicated that embedding a small amount of PDA functionalized TM nanosheets into WEP coating could improve obviously the corrosion resistance and wear resistance properties. The present research will provide a theoretical basis for the use of TM in the field of anticorrosion and electromagnetic wave absorption.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8832-8842"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.314
Yajun Zhao , Yanhan Fei , Lanjun Du , Haoyu Geng , Xiangyu Sun , Xingjie Yin , Zhiming Du
The Al2O3/Al co-continuous composites with three-dimensional network structures were successfully prepared by extruding the aluminum alloy melt into the porous Al2O3 ceramic skeleton prepared by the foam replication method. The interface structure, mechanical properties, and strengthening and toughening mechanisms of the composites were investigated. SEM analyses confirmed that the aluminum matrix filled the hollow channels in the foam ceramic struts, and the ceramic was tightly bonded to the aluminum matrix without transition layers. TEM analyses revealed multiple crystallographic orientation relationships at the Al2O3/Al interface, where the two phases were combined in coherent and semicoherent relationships. The dominant mode of interfacial bonding was mechanical bonding, but diffusional bonding and reactive bonding occurred. The composites had excellent strength and toughness, with their flexural strength and fracture toughness values reaching 506 MPa and 16.1 MPa m1/2, respectively. The high strengths of the composites resulted from the joint action of various strengthening mechanisms, such as three-dimensional network structure strengthening, load transfer strengthening, and dislocation strengthening. Through a combination of internal and external toughening mechanisms, such as crack deflection and bridging, the composites obtained high toughness values. A balance between the reinforcement phase continuity and matrix phase continuity was necessary to strengthen and toughen the composites.
{"title":"Interface structure and mechanical properties of Al2O3/Al co-continuous composites with three-dimensional network structures","authors":"Yajun Zhao , Yanhan Fei , Lanjun Du , Haoyu Geng , Xiangyu Sun , Xingjie Yin , Zhiming Du","doi":"10.1016/j.ceramint.2024.12.314","DOIUrl":"10.1016/j.ceramint.2024.12.314","url":null,"abstract":"<div><div>The Al<sub>2</sub>O<sub>3</sub>/Al co-continuous composites with three-dimensional network structures were successfully prepared by extruding the aluminum alloy melt into the porous Al<sub>2</sub>O<sub>3</sub> ceramic skeleton prepared by the foam replication method. The interface structure, mechanical properties, and strengthening and toughening mechanisms of the composites were investigated. SEM analyses confirmed that the aluminum matrix filled the hollow channels in the foam ceramic struts, and the ceramic was tightly bonded to the aluminum matrix without transition layers. TEM analyses revealed multiple crystallographic orientation relationships at the Al<sub>2</sub>O<sub>3</sub>/Al interface, where the two phases were combined in coherent and semicoherent relationships. The dominant mode of interfacial bonding was mechanical bonding, but diffusional bonding and reactive bonding occurred. The composites had excellent strength and toughness, with their flexural strength and fracture toughness values reaching 506 MPa and 16.1 MPa m<sup>1/2</sup>, respectively. The high strengths of the composites resulted from the joint action of various strengthening mechanisms, such as three-dimensional network structure strengthening, load transfer strengthening, and dislocation strengthening. Through a combination of internal and external toughening mechanisms, such as crack deflection and bridging, the composites obtained high toughness values. A balance between the reinforcement phase continuity and matrix phase continuity was necessary to strengthen and toughen the composites.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8843-8854"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.343
Muhammet Karabaş , Uğur Ünal
Protecting hot section parts of gas turbine engines made of SiC/SiC CMCs from atmospheric corrosion has become challenging. Three-layer environmental barrier coatings are recommended to eliminate this problem. However, thermal expansion incompatibilities between layers limit the lifespan of coatings. In this study, environmental barrier coatings were produced with 4 different functionally graded and composite designs to tolerate thermal expansion incompatibilities. For this purpose, 50-50 wt% YbSi-mullite and mullite-Si layers were produced between the layers in three-layer environmental barrier coatings for composite design. In functionally graded designs, 25 wt% graded layers were deposited between Si-mullite, mullite-YbSi, and Si-mullite-YbSi layers. The coatings were subjected to thermal cycle tests above 1450 ± 50 °C in a water vapor environment. Before and after the tests, the coatings were subjected to structural characterizations such as scanning electron microscopy and X-ray diffraction. An evaluation of the damage mechanism of the coating was carried out. According to thermal cycle tests, EBC produced with 50 wt% mullite+Si and 50 wt% mullite+YbSi composite interlayer design exhibited the longest thermal cycle life. The shortest thermal cycle life was observed in EBC produced by functionally grading the mullite+Si layer. The thermal cycle life of EBCs produced with 50 wt% mullite+Si and 50 wt% mullite+YbSi composite interlayers and trilayer functionally graded designs was longer than that of traditional trilayer EBCs. These new designs helped reduce stress accumulation resulting from thermal expansion mismatch between layers, thereby extending the thermal cycle life of the coatings. The study also observed that phase transformations in the YbSi layer, along with water vapor corrosion, were the primary factors contributing to crack formation during the thermal cycle tests.
{"title":"Thermal cycle test of functionally graded and composite environmental barrier coatings in the steam environment","authors":"Muhammet Karabaş , Uğur Ünal","doi":"10.1016/j.ceramint.2024.12.343","DOIUrl":"10.1016/j.ceramint.2024.12.343","url":null,"abstract":"<div><div>Protecting hot section parts of gas turbine engines made of SiC/SiC CMCs from atmospheric corrosion has become challenging. Three-layer environmental barrier coatings are recommended to eliminate this problem. However, thermal expansion incompatibilities between layers limit the lifespan of coatings. In this study, environmental barrier coatings were produced with 4 different functionally graded and composite designs to tolerate thermal expansion incompatibilities. For this purpose, 50-50 wt% YbSi-mullite and mullite-Si layers were produced between the layers in three-layer environmental barrier coatings for composite design. In functionally graded designs, 25 wt% graded layers were deposited between Si-mullite, mullite-YbSi, and Si-mullite-YbSi layers. The coatings were subjected to thermal cycle tests above 1450 ± 50 °C in a water vapor environment. Before and after the tests, the coatings were subjected to structural characterizations such as scanning electron microscopy and X-ray diffraction. An evaluation of the damage mechanism of the coating was carried out. According to thermal cycle tests, EBC produced with 50 wt% mullite+Si and 50 wt% mullite+YbSi composite interlayer design exhibited the longest thermal cycle life. The shortest thermal cycle life was observed in EBC produced by functionally grading the mullite+Si layer. The thermal cycle life of EBCs produced with 50 wt% mullite+Si and 50 wt% mullite+YbSi composite interlayers and trilayer functionally graded designs was longer than that of traditional trilayer EBCs. These new designs helped reduce stress accumulation resulting from thermal expansion mismatch between layers, thereby extending the thermal cycle life of the coatings. The study also observed that phase transformations in the YbSi layer, along with water vapor corrosion, were the primary factors contributing to crack formation during the thermal cycle tests.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 9112-9123"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.323
Ankita Gupta, Gregory N. Morscher
For Ceramic Matrix Composites (CMCs) with an electrically conductive matrix, direct current potential drop techniques have the potential to detect composite state such as conductive constituent content (e.g., Si in melt-infiltrated composites) or local defects such as delamination or porosity. In our study, we aimed to evaluate effectiveness of Electrical Resistance (ER) as a NDE method for different 2D woven SiC-based Melt-infiltrated composites, each exhibiting varying degrees and types of processing defects. We conducted three types of ER measurements: a. Bulk Resistivity b. Through-thickness c. Axial, along the axial length of dogbone specimens in the gauge section. Microstructural analysis was performed to correlate observations with microstructure. The bulk resistivity of the specimens in our study exhibited a linear correlation with the infiltrated Si in the matrix, even with different percentage and type of porosities present, allowing us to comment on Si-content of coupon size specimens. For Through-thickness measurements, absolute values of the measured potential represent Si-content, but it was not sensitive to porosity due to processing defects. In some cases, the local flow of current for axial type measurements is affected by and able to locate the local and distinct type porosity. Resistance was sensitive for regions of poor Si-infiltration i.e., “dry-slurry” type defects as well as for isolated larger rounded pores. It was very sensitive to local surface porosity but not as sensitive for cases where porosity was homogenously present throughout the specimen. Such one-sided axial measurements suit optimally for cases when only one side of the manufactured specimen or fabricated component is easy to access, or the porosity present is one-sided. The results confirm the potential of ER as a valuable tool for assessing the properties and integrity of Si/SiC CMCs in particular and should be applicable to CMCs where the matrix is conductive than the fibers. The technique offers insights into both material composition and the presence of specific types of defects.
{"title":"Electrical resistance of non-oxide ceramic matrix composites: Health monitoring and design considerations","authors":"Ankita Gupta, Gregory N. Morscher","doi":"10.1016/j.ceramint.2024.12.323","DOIUrl":"10.1016/j.ceramint.2024.12.323","url":null,"abstract":"<div><div>For Ceramic Matrix Composites (CMCs) with an electrically conductive matrix, direct current potential drop techniques have the potential to detect composite state such as conductive constituent content (e.g., Si in melt-infiltrated composites) or local defects such as delamination or porosity. In our study, we aimed to evaluate effectiveness of Electrical Resistance (ER) as a NDE method for different 2D woven SiC-based Melt-infiltrated composites, each exhibiting varying degrees and types of processing defects. We conducted three types of ER measurements: a. Bulk Resistivity b. Through-thickness c. Axial, along the axial length of dogbone specimens in the gauge section. Microstructural analysis was performed to correlate observations with microstructure. The bulk resistivity of the specimens in our study exhibited a linear correlation with the infiltrated Si in the matrix, even with different percentage and type of porosities present, allowing us to comment on Si-content of coupon size specimens. For Through-thickness measurements, absolute values of the measured potential represent Si-content, but it was not sensitive to porosity due to processing defects. In some cases, the local flow of current for axial type measurements is affected by and able to locate the local and distinct type porosity. Resistance was sensitive for regions of poor Si-infiltration i.e.<em>, “dry-slurry”</em> type defects as well as for isolated larger rounded pores. It was very sensitive to local surface porosity but not as sensitive for cases where porosity was homogenously present throughout the specimen. Such one-sided axial measurements suit optimally for cases when only one side of the manufactured specimen or fabricated component is easy to access, or the porosity present is one-sided. The results confirm the potential of ER as a valuable tool for assessing the properties and integrity of Si/SiC CMCs in particular and should be applicable to CMCs where the matrix is conductive than the fibers. The technique offers insights into both material composition and the presence of specific types of defects.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8930-8940"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.304
Jiin-Jyh Shyu, Jhan-Ting Luo
Calcium aluminate glasses are particularly appealing for IR photonic applications because of their excellent transmittance from the UV to the mid-IR range (3–5 μm). However, their mechanical performance remains inferior to that of crystalline ceramics. Glass-ceramics generally have enhanced mechanical properties than their parent glasses. This study investigates whether adding TiO2 to a MgO-BaO-CaO-Al2O3 glass composition can act as a nucleating agent to promote uniform nucleation and crystallization within the glass, leading to the formation of glass-ceramics, and to assess its effectiveness in enhancing mechanical properties. The parent glasses were prepared via. conventional melt-quench method. The nucleation kinetics of the glasses was analyzed by differential thermal analysis to find the optimum nucleating condition. Then the glasses were converted into glass-ceramics using two-stage heat-treatment (nucleation-crystallization). This study demonstrates that TiO2 is an effective nucleating agent for calcium aluminate glass-ceramics. It was shown that when the TiO2 content is around 4 wt%, the crystallization behavior primarily results in the formation of a surface crystallization layer (mainly containing the Ca12Al14O33 phase), with very low crystallinity within the glass interior region, leading to a non-uniform microstructure. When the TiO2 content is increased to around 8 wt%, it promotes a shift in crystallization behavior from surface crystallization of Ca12Al14O33 to uniform internal crystallization of Ca3Al2O6. The concentration of Ti is highest at the center of the crystal and gradually decreases toward the glass matrix. The T8 glass-ceramic, nucleated at 755 °C for 16 h followed by 850 °C for 4 h, is opaque to visible light but still allows up to 70 % IR transmission. Compared to the parent glass, this glass-ceramic exhibits a hardness increase of at least 14 %, a dilatometric softening point elevation of 79 °C, and a Young's modulus increase of at least 19 %, making it the glass-ceramic with the best combination of optical and mechanical properties.
{"title":"TiO2-nucleated mid-infrared transparent MgO-BaO-CaO-Al2O3 glass-ceramics with improved mechanical properties","authors":"Jiin-Jyh Shyu, Jhan-Ting Luo","doi":"10.1016/j.ceramint.2024.12.304","DOIUrl":"10.1016/j.ceramint.2024.12.304","url":null,"abstract":"<div><div>Calcium aluminate glasses are particularly appealing for IR photonic applications because of their excellent transmittance from the UV to the mid-IR range (3–5 μm). However, their mechanical performance remains inferior to that of crystalline ceramics. Glass-ceramics generally have enhanced mechanical properties than their parent glasses. This study investigates whether adding TiO<sub>2</sub> to a MgO-BaO-CaO-Al<sub>2</sub>O<sub>3</sub> glass composition can act as a nucleating agent to promote uniform nucleation and crystallization within the glass, leading to the formation of glass-ceramics, and to assess its effectiveness in enhancing mechanical properties. The parent glasses were prepared via. conventional melt-quench method. The nucleation kinetics of the glasses was analyzed by differential thermal analysis to find the optimum nucleating condition. Then the glasses were converted into glass-ceramics using two-stage heat-treatment (nucleation-crystallization). This study demonstrates that TiO<sub>2</sub> is an effective nucleating agent for calcium aluminate glass-ceramics. It was shown that when the TiO<sub>2</sub> content is around 4 wt%, the crystallization behavior primarily results in the formation of a surface crystallization layer (mainly containing the Ca<sub>12</sub>Al<sub>14</sub>O<sub>33</sub> phase), with very low crystallinity within the glass interior region, leading to a non-uniform microstructure. When the TiO<sub>2</sub> content is increased to around 8 wt%, it promotes a shift in crystallization behavior from surface crystallization of Ca<sub>12</sub>Al<sub>14</sub>O<sub>33</sub> to uniform internal crystallization of Ca<sub>3</sub>Al<sub>2</sub>O<sub>6</sub>. The concentration of Ti is highest at the center of the crystal and gradually decreases toward the glass matrix. The T8 glass-ceramic, nucleated at 755 °C for 16 h followed by 850 °C for 4 h, is opaque to visible light but still allows up to 70 % IR transmission. Compared to the parent glass, this glass-ceramic exhibits a hardness increase of at least 14 %, a dilatometric softening point elevation of 79 °C, and a Young's modulus increase of at least 19 %, making it the glass-ceramic with the best combination of optical and mechanical properties.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 8734-8746"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.ceramint.2024.12.363
Juan I. Ahuir-Torres , Xun Chen , Yasemin Akar , Paul A. Bingham , Frankie F. Jackson , Hongyu Li , Luke Mason , Rakesh Mishra , David D. Walker , Guoyu Yu
The optical glass materials are employed in various industries due to its desirable optical properties. These materials nevertheless require an ultra-smooth surface (Ra <1 nm average roughness) for correctly working. The understanding of the polishing process is essential to get the ultra-smooth surface. The polishing process begins at atomic scale, hindering its study in real time using experimental testing. Molecular dynamic (MD) simulation is powerful tool to assess this process at atom scale in real time. Although the influence of various polishing conditions on polished surface features has been evaluated in the literature, the grain chemical composition influence has not been studied yet. In the present paper, this condition influence on optical glass material polishing at atom scale was assessed using MD simulation. Fused silica was employed as optical glass test pieces, and the abrasive grains used were α-quartz, diamond and α-alumina. Force on the grain was from 0.5 pN to 16.0 pN and cut velocity was 20 m/s. Tersoff potential function method was used to represent the covalent bonds of the materials. The results showed simulations at ≥ 2.0 pN were unstable during polishing due to the mechanical failure. Grain sliding also produced a new microstructure in the glass via the dislocation and deformation of the chemical bonds. The material removal rate (MRR) furthermore was directly proportional to the grain force and the hardness of the grain. The increment in the grain force increased the friction force. Grain chemical composition moreover influenced on the polishing phenomena.
{"title":"Influence of the grain chemical composition on the fused silica polishing at atomic scale using molecular dynamic simulations","authors":"Juan I. Ahuir-Torres , Xun Chen , Yasemin Akar , Paul A. Bingham , Frankie F. Jackson , Hongyu Li , Luke Mason , Rakesh Mishra , David D. Walker , Guoyu Yu","doi":"10.1016/j.ceramint.2024.12.363","DOIUrl":"10.1016/j.ceramint.2024.12.363","url":null,"abstract":"<div><div>The optical glass materials are employed in various industries due to its desirable optical properties. These materials nevertheless require an ultra-smooth surface (Ra <1 nm average roughness) for correctly working. The understanding of the polishing process is essential to get the ultra-smooth surface. The polishing process begins at atomic scale, hindering its study in real time using experimental testing. Molecular dynamic (MD) simulation is powerful tool to assess this process at atom scale in real time. Although the influence of various polishing conditions on polished surface features has been evaluated in the literature, the grain chemical composition influence has not been studied yet. In the present paper, this condition influence on optical glass material polishing at atom scale was assessed using MD simulation. Fused silica was employed as optical glass test pieces, and the abrasive grains used were α-quartz, diamond and α-alumina. Force on the grain was from 0.5 pN to 16.0 pN and cut velocity was 20 m/s. Tersoff potential function method was used to represent the covalent bonds of the materials. The results showed simulations at ≥ 2.0 pN were unstable during polishing due to the mechanical failure. Grain sliding also produced a new microstructure in the glass via the dislocation and deformation of the chemical bonds. The material removal rate (MRR) furthermore was directly proportional to the grain force and the hardness of the grain. The increment in the grain force increased the friction force. Grain chemical composition moreover influenced on the polishing phenomena.</div></div>","PeriodicalId":267,"journal":{"name":"Ceramics International","volume":"51 7","pages":"Pages 9278-9291"},"PeriodicalIF":5.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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