Model composites consisting of Si C fiber embedded inβ-Yb_(2)Si_(2)O_(7) matrix were processed by Spark Plasma Sintering method and the feasibility of tunable Si Cf/Yb_(2)Si_(2)O_(7) interface in Si C-based CMCs were...Model composites consisting of Si C fiber embedded inβ-Yb_(2)Si_(2)O_(7) matrix were processed by Spark Plasma Sintering method and the feasibility of tunable Si Cf/Yb_(2)Si_(2)O_(7) interface in Si C-based CMCs were estimated.Weak and strengthened Si Cf/Yb_(2)Si_(2)O_(7) interfaces were achieved by adjusting sintering temperatures.The indentation crack test and fiber push out experiments clearly demonstrated the different debonding mechanisms in the samples.Weak interfaces sintered at 1200 and 1250℃exhibited crack deflection at interface in indentation test.Their low debond energy at the interface,which were comparable to those of Py C or BN,satisfied the well-recognized interfacial debond and crack deflection criteria for CMCs.The interface was strengthened by atomic bonding in model composite sintered at 1450℃,leading to crack penetrating into Si C fiber and high debond energy.The strong interface may be promising in Si Cf/Si C CMC to withstand higher combustion temperature,because Yb_(2)Si_(2)O_(7) will provide plastic deformation capacity,which would serve as weak interphase for crack deflection and energy dissipation.Therefore,it is possible to design the capability of Si C_(f)/RE_(2)Si_(2)O_(7) interface for different requirements by adjusting interfacial strength or debond energy to reach optimal mechanical fuse mechanism in SiC_(f)/SiC CMC.展开更多
High throughput experimentation is employed to establish a ternary system with the compositional range of 30.8 mol.%-75.7 mol.%SiO_(2),16.6 mol.%-61.7 mol.%Yb_(2)O_(3),and 6.3 mol.%-4.1 moll.%Ho_(2)O_(3) through co-sp...High throughput experimentation is employed to establish a ternary system with the compositional range of 30.8 mol.%-75.7 mol.%SiO_(2),16.6 mol.%-61.7 mol.%Yb_(2)O_(3),and 6.3 mol.%-4.1 moll.%Ho_(2)O_(3) through co-sputtering deposition on one combinatorial material chip.Considering their application in advanced SiC_(f)/SiC CMC,the phase composition and mechanical properties of samples with various RE/Si ratios and Yb/Ho ratios are comprehensively investigated.Chemical stability and thermal expansion compatibility between SiC and RE silicates with different compositions are also validated.Optimized materials for the application of environmental barrier coating and interphase for SiC_(f)/SiC CMC are screened respectively according to the above trends and data.This work is a case study to establish a composition-property library for RE_(2)O_(3)-SiO_(2) compounds.It is inspired more complicated multicomponent RE silicates could be prepared and characterized by high throughput experimentation,accelerating the design and screening of promising optimal candidates.展开更多
Ultrahigh-temperature ceramics(UHTCs)have a unique combination of high melting points,high strengths,and high chemical stabilities,which makes them unique materials for a wide range of ultrahigh-temperature(>2000&#...Ultrahigh-temperature ceramics(UHTCs)have a unique combination of high melting points,high strengths,and high chemical stabilities,which makes them unique materials for a wide range of ultrahigh-temperature(>2000°C)applications.Herein,we first report a novel highly porous dual-phase high-entropy UHTCs material composed of a high-entropy boride(HEB)phase and a high-entropy carbide(HEC)phase,which was fabricated via foam-gelcasting-freeze drying technology and high-temperature sintering with mixed borides and carbides as raw materials.The as-fabricated samples have a uniform pore structure and a firm skeleton that consists of random alternating distributions of HEB and HEC particles.The porous dual-phase high-entropy UHTCs samples have ultrahigh porosities of 96.4%–90.1%,low densities of 0.31–0.87 g/cm3,high strengths of 0.45–4.17 MPa and low thermal conductivities of 0.202–0.281 W/(m·K),as well as better oxidation resistance than single-phase HEC.The present results highlight the potential of as-prepared porous dual-phase high-entropy UHTCs as promising materials for ultrahigh-temperature thermal insulation applications.展开更多
Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to ...Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to evaluate the potential application of Yb monosilicate as the interphase of silicon carbide fiber reinforced silicon carbide ceramic matrix composite(SiC_(f)/SiC CMC).Two kinds of interfaces,namely mechanical and chemical bonding interfaces,were achieved by adjusting sintering temperature.SiC_(f)/Yb_(2)SiO_(5)interfaces prepared at 1450 and 1500℃exhibit high interface strength and debond energy,which do not satisfy the crack deflection criteria based on He-Hutchison diagram.Raman spectrum analyzation indicates that the thermal expansion mismatch between Yb_(2)SiO_(5)and SiC contributes to high compressive thermal stress at interface,and leads to high interfacial parameters.Amorphous layer at interface in model composite sintered at 1550℃is related to the diffusion promoted by high temperature and DC electric filed during SPS.It is inspired that the interfacial parameters could be adjusted by introducing Yb_(2)Si_(2)O_(7)-Yb_(2)SiO_(5)interphase with controlled composition to optimize the mechanical fuse mechanism in SiC_(f)/SiC CMC.展开更多
Ta_(1−x)Hf_(x)C_(y)ternary ceramics are highly valued in hypersonic vehicles,and a precise composition design is promising to simultaneously reduce their intrinsic brittleness and enhance their protective capability d...Ta_(1−x)Hf_(x)C_(y)ternary ceramics are highly valued in hypersonic vehicles,and a precise composition design is promising to simultaneously reduce their intrinsic brittleness and enhance their protective capability during oxidation.Herein,the compositiondependent mechanical properties and oxidation behaviors of Ta_(1−x)Hf_(x)C_(y)ternary ceramics over a broad composition range(x=0.22 to 0.78,y=0.66 to 1.00)are efficiently investigated through combinatorial and highthroughput(CHT)experimentation to pave the way for targeted development of novel carbide candidates.Evolution trends in hardness and modulus reveal that the composition range with x=0.22 to 0.60 and y=0.80 to 1.00 is promising to reach an optimal balance between hardness and toughness,which results from competing effects between solid solution strengthening and bonding characteristic transition.High-throughput oxidation elucidates the phase constitution and compactness of oxidation products with various Ta/Hf distributions and temperatures.The accurate compositional range for the formation of a single-phase dense Hf-Ta-O compound layer shifts to a Ta-rich region(x=0.50 to 0.60)due to the preferential formation of Ta-doped HfO_(2) and the structural characteristics of Hf-Ta-O compounds that accommodate compositional deviations.Regarding the broad compositional space of Ta_(1−x)Hf_(x)C_(y),the effects of composition on both mechanical properties and oxidation behavior are systematically investigated,providing fundamental design guidelines and an optimal composition range that holds significant promise for application in subsequent research.展开更多
基金supported by the National Key R&D Program of China under Grant No.2017YFB0703201Natural Science Foundation of China under Grant No.51772302CAS International Cooperation Key Program under Grant No.174321KYSB20180008。
文摘Model composites consisting of Si C fiber embedded inβ-Yb_(2)Si_(2)O_(7) matrix were processed by Spark Plasma Sintering method and the feasibility of tunable Si Cf/Yb_(2)Si_(2)O_(7) interface in Si C-based CMCs were estimated.Weak and strengthened Si Cf/Yb_(2)Si_(2)O_(7) interfaces were achieved by adjusting sintering temperatures.The indentation crack test and fiber push out experiments clearly demonstrated the different debonding mechanisms in the samples.Weak interfaces sintered at 1200 and 1250℃exhibited crack deflection at interface in indentation test.Their low debond energy at the interface,which were comparable to those of Py C or BN,satisfied the well-recognized interfacial debond and crack deflection criteria for CMCs.The interface was strengthened by atomic bonding in model composite sintered at 1450℃,leading to crack penetrating into Si C fiber and high debond energy.The strong interface may be promising in Si Cf/Si C CMC to withstand higher combustion temperature,because Yb_(2)Si_(2)O_(7) will provide plastic deformation capacity,which would serve as weak interphase for crack deflection and energy dissipation.Therefore,it is possible to design the capability of Si C_(f)/RE_(2)Si_(2)O_(7) interface for different requirements by adjusting interfacial strength or debond energy to reach optimal mechanical fuse mechanism in SiC_(f)/SiC CMC.
基金supported by the National Natural Science Foun-dation of China under Grant Nos.U21A2063,52002376National Key R&D Program of China under Grant No.2021YFB3702300+1 种基金Key Research Program of the Chinese Academy of Sciences under Grant No.ZDRW-CN-2021-2-2LiaoNing Revitalization Talents Pro-gram under Grant No.XLYC2002018,Natural Science Foundation of Liaoning Province under Grant No.2020-MS-006.
文摘High throughput experimentation is employed to establish a ternary system with the compositional range of 30.8 mol.%-75.7 mol.%SiO_(2),16.6 mol.%-61.7 mol.%Yb_(2)O_(3),and 6.3 mol.%-4.1 moll.%Ho_(2)O_(3) through co-sputtering deposition on one combinatorial material chip.Considering their application in advanced SiC_(f)/SiC CMC,the phase composition and mechanical properties of samples with various RE/Si ratios and Yb/Ho ratios are comprehensively investigated.Chemical stability and thermal expansion compatibility between SiC and RE silicates with different compositions are also validated.Optimized materials for the application of environmental barrier coating and interphase for SiC_(f)/SiC CMC are screened respectively according to the above trends and data.This work is a case study to establish a composition-property library for RE_(2)O_(3)-SiO_(2) compounds.It is inspired more complicated multicomponent RE silicates could be prepared and characterized by high throughput experimentation,accelerating the design and screening of promising optimal candidates.
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A2063,U2441266,52372071,and 52302076)the International Partnership Program of the Chinese Academy of Sciences(Grant No.172GJHZ2022094FN)the LiaoNing Revitalization Talents Program(Grant No.XLYC2203090).
文摘Ultrahigh-temperature ceramics(UHTCs)have a unique combination of high melting points,high strengths,and high chemical stabilities,which makes them unique materials for a wide range of ultrahigh-temperature(>2000°C)applications.Herein,we first report a novel highly porous dual-phase high-entropy UHTCs material composed of a high-entropy boride(HEB)phase and a high-entropy carbide(HEC)phase,which was fabricated via foam-gelcasting-freeze drying technology and high-temperature sintering with mixed borides and carbides as raw materials.The as-fabricated samples have a uniform pore structure and a firm skeleton that consists of random alternating distributions of HEB and HEC particles.The porous dual-phase high-entropy UHTCs samples have ultrahigh porosities of 96.4%–90.1%,low densities of 0.31–0.87 g/cm3,high strengths of 0.45–4.17 MPa and low thermal conductivities of 0.202–0.281 W/(m·K),as well as better oxidation resistance than single-phase HEC.The present results highlight the potential of as-prepared porous dual-phase high-entropy UHTCs as promising materials for ultrahigh-temperature thermal insulation applications.
基金supported by the National Key R&D Program of China(No.2017YFB0703201)the National Natural Science Foundation of China(No.51772302)CAS International Cooperation Key Program(No.174321KYSB20180008)。
文摘Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to evaluate the potential application of Yb monosilicate as the interphase of silicon carbide fiber reinforced silicon carbide ceramic matrix composite(SiC_(f)/SiC CMC).Two kinds of interfaces,namely mechanical and chemical bonding interfaces,were achieved by adjusting sintering temperature.SiC_(f)/Yb_(2)SiO_(5)interfaces prepared at 1450 and 1500℃exhibit high interface strength and debond energy,which do not satisfy the crack deflection criteria based on He-Hutchison diagram.Raman spectrum analyzation indicates that the thermal expansion mismatch between Yb_(2)SiO_(5)and SiC contributes to high compressive thermal stress at interface,and leads to high interfacial parameters.Amorphous layer at interface in model composite sintered at 1550℃is related to the diffusion promoted by high temperature and DC electric filed during SPS.It is inspired that the interfacial parameters could be adjusted by introducing Yb_(2)Si_(2)O_(7)-Yb_(2)SiO_(5)interphase with controlled composition to optimize the mechanical fuse mechanism in SiC_(f)/SiC CMC.
基金supported by the National Natural Science Foundation of China(Nos.U2441266,U21A2063,52372071,and 52302076).
文摘Ta_(1−x)Hf_(x)C_(y)ternary ceramics are highly valued in hypersonic vehicles,and a precise composition design is promising to simultaneously reduce their intrinsic brittleness and enhance their protective capability during oxidation.Herein,the compositiondependent mechanical properties and oxidation behaviors of Ta_(1−x)Hf_(x)C_(y)ternary ceramics over a broad composition range(x=0.22 to 0.78,y=0.66 to 1.00)are efficiently investigated through combinatorial and highthroughput(CHT)experimentation to pave the way for targeted development of novel carbide candidates.Evolution trends in hardness and modulus reveal that the composition range with x=0.22 to 0.60 and y=0.80 to 1.00 is promising to reach an optimal balance between hardness and toughness,which results from competing effects between solid solution strengthening and bonding characteristic transition.High-throughput oxidation elucidates the phase constitution and compactness of oxidation products with various Ta/Hf distributions and temperatures.The accurate compositional range for the formation of a single-phase dense Hf-Ta-O compound layer shifts to a Ta-rich region(x=0.50 to 0.60)due to the preferential formation of Ta-doped HfO_(2) and the structural characteristics of Hf-Ta-O compounds that accommodate compositional deviations.Regarding the broad compositional space of Ta_(1−x)Hf_(x)C_(y),the effects of composition on both mechanical properties and oxidation behavior are systematically investigated,providing fundamental design guidelines and an optimal composition range that holds significant promise for application in subsequent research.
