Rare earth monosilicates as oxidation resistant interphase for SiCf/SiC CMC: Investigation of SiCf/Yb2SiO5 model composites
Xirui Lv, Mengkun Yue, Xue Feng, Xiaoyan Li, Yumin Wang, Jiemin Wang, Jie Zhang, Jingyang Wang, Jingyang Wang, Jingyang Wang
Abstract
Abstract 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 °C 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 °C 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.