石墨片层结构对超高温陶瓷材料抗热震行为的影响

Effects of Flake Shape Graphite on Thermal Shock Properties of Ultrahigh Temperature Ceramic Materials

通过热压烧结工艺制备了ZrB2-SiC-AlN和ZrB2-SiC-C两种超高温陶瓷材料。并通过淬火实验表征了所制备材料的抗热震行为。结果表明:这两种超高温陶瓷材料的剩余强度衰减机制有所不同,ZrB2-SiC-AlN的剩余强度主要受热震表面裂纹影响,而ZrB2-SiC-C在热震过程中不产生表面裂纹,其剩余强度主要受表面氧化和热震损伤的影响。ZrB2-SiC-C具有相对较高的热震阻力,增加该材料体系的抗氧化能力对于提高该材料体系抗热震行为具有积极的意义。通过有限元分析定性揭示了ZSC具有较高剩余淬火强度的原因。

Ultra high temperature ceramics ZrB2-SiC-AlN and ZrB2-SiC-C were fabricated by hot-press sintering teehnique.Thermal shock resistance of the two materials was characterized by quenching test.The results shorred that the attenuation mechanism of residual strength were different for the two materials.The residual strength of ZrB2-SiC-AlN was affected by surface crack,and it was affected mainly by surface oxidation and thermal shock damage for residual strength of ZrB2-SiC-C.It proved that thermal shock resistance is higher for ZrB2-SiC-C than that for ZrB2-SiC-AlN.It may provid higher thermal shock resistance by improving oxidation resistance of ZrB2-SiC-C.The reason why ZrB2-SiC-C had higher residual strength was explained by finite element analysis qualitatively.