Y5Si3C and Y3Si2C2: Theoretically predicted MAX phase like damage tolerant ceramics and promising interphase materials for SiCf/SiC composites
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2019年第3期
论文作者：Yanchun Zhou Huimin Xiang Fu-Zhi Dai
文章页码：313 - 322
摘 要：Researching for interphase materials that can protect SiC fibers from oxygen and water vapor attacks has become one of the most important issues for the applications of SiCf/SiC composites in high-temperature combustion environment. However, such kinds of interphase materials are not available yet. Herein,we report theoretically predicted properties of two promising interphase materials Y5Si3 C and Y3Si2C2.Although crystallizing in different structures, they share the common features of layered structure,anisotropic chemical bonding, anisotropic electrical and mechanical properties, and low shear deformation resistance. The bulk moduli for Y5Si3C and Y3Si2C2 are 78 and 93 GPa, respectively; while their shear moduli are 52 and 50GPa, respectively. The maximum to minimum Young’s modulus ratios are1.44 for Y5Si3C and 3.27 for Y3Si2C2. Based on the low shear deformation resistance and low Pugh’s ratios（G/B = 0.666 forY5Si3C and 0.537 for Y3Si2C2; G: shear modulus; B: bulk modulus）, they are predicted as damage tolerant and soft ceramics with predicted Vickers hardness of 9.6 and 6.9 GPa, respectively.The cleavage plane and possible slip systems are（000 l） and（0001）[1120] and（1010）[0001] forY5Si3C,and those for Y3Si2C2 are {h00} and（010）[101]. Since the oxidation products are water-vapor resistant Y2 Si2 O7, Y2 SiO5 and/or Y2 O3 upon oxidation, and the volume expansions are ca 140% and ca 26% for Y5Si3C and Y3Si2C2, they are expected to seal the interfacial cracks in SiCf/SiC composites. The unique combination of easy cleavage, low shear deformation resistance, volume expansions upon oxidation, and the resistance of the oxidation products to water vapor attack warrant them promising as interphase materials of SiCf/SiC composites for water-vapor laden environment applications.
Yanchun Zhou，Huimin Xiang，Fu-Zhi Dai
Science and Technology on Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology
摘 要：Researching for interphase materials that can protect SiC fibers from oxygen and water vapor attacks has become one of the most important issues for the applications of SiCf/SiC composites in high-temperature combustion environment. However, such kinds of interphase materials are not available yet. Herein,we report theoretically predicted properties of two promising interphase materials Y5Si3 C and Y3Si2C2.Although crystallizing in different structures, they share the common features of layered structure,anisotropic chemical bonding, anisotropic electrical and mechanical properties, and low shear deformation resistance. The bulk moduli for Y5Si3C and Y3Si2C2 are 78 and 93 GPa, respectively; while their shear moduli are 52 and 50GPa, respectively. The maximum to minimum Young’s modulus ratios are1.44 for Y5Si3C and 3.27 for Y3Si2C2. Based on the low shear deformation resistance and low Pugh’s ratios（G/B = 0.666 forY5Si3C and 0.537 for Y3Si2C2; G: shear modulus; B: bulk modulus）, they are predicted as damage tolerant and soft ceramics with predicted Vickers hardness of 9.6 and 6.9 GPa, respectively.The cleavage plane and possible slip systems are（000 l） and（0001）[1120] and（1010）[0001] forY5Si3C,and those for Y3Si2C2 are {h00} and（010）[101]. Since the oxidation products are water-vapor resistant Y2 Si2 O7, Y2 SiO5 and/or Y2 O3 upon oxidation, and the volume expansions are ca 140% and ca 26% for Y5Si3C and Y3Si2C2, they are expected to seal the interfacial cracks in SiCf/SiC composites. The unique combination of easy cleavage, low shear deformation resistance, volume expansions upon oxidation, and the resistance of the oxidation products to water vapor attack warrant them promising as interphase materials of SiCf/SiC composites for water-vapor laden environment applications.
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