Anzhe Wang,Hailong Liao,Tao Zhang,Minqi Jiang,Fuxiao Guo,Yongzheng Wang
Reliable evaluation of the thermal shock behavior of sharp leading edges (SLEs) was hampered by a lack of available experimental method in past decades. Herein, a novel water spraying method was utilized to investigate the shape effect of ZrB 2 -SiC-Graphite SLEs during thermal shock. Experimental results indicated that the critical failure temperature of ZrB 2 -SiC-Graphite SLEs was most sensitive to the wedge angle, which could lead to a dramatic attenuation by about 35% from 12° to 9°, and was relatively little affected by the tip radius of curvature and the thickness. Simulation results further revealed that the decay of critical failure temperature was mainly due to the significant stress concentration caused by the reduction of wedge angle. Scanning electron microscopy observation proved that cracks tend to bypass graphite flakes due to their weak interfacial bonding, while branching always occurred when encountering hard phases or inclusions.
Reliable evaluation of the thermal shock behavior of complex-shaped components is very important for ultra-high temperature ceramics. Unfortunately progress in this field is hampered by a lack of available experimental methods. Here, a novel water spraying method is proposed to investigate the thermal shock behavior of ZrB 2 -based sharp leading edges (SLEs). Results indicated that the introduction of graphite flakes significantly improved the thermal shock resistance of ZrB 2 -SiC (ZS) SLEs. However, owing to the anisotropies of microstructure and thermal conductivity of ZrB 2 -SiC-G (ZSG) ceramic, the thermal shock resistance and the failure mode of ZSG SLEs were sensitive to the sampling orientation, which also were remarkably influenced by the size and/or shape of SLEs, leading to the variability of critical failure temperature from 750 °C to 375 °C and crack patterns from deflection to wave-shaped.
危险品化学品经营许可证（带存储）