水基流延成型制备ZrB_2和ZrB_2-20vol% SiC复合材料的微观结构和抗热震性能

Microstructure and Thermal Shock Resistance of ZrB_2 and ZrB_2-20vol% SiC Composites from Aqueous Tape Casting

研究了水基流延成型和热压烧结制备的ZrB2和ZrB2-20vol% SiC(ZS20)材料的微观结构和抗热震性能.在ZS20材料中分别观察到了Zr-B-C和Zr-B-W固溶相,而在ZrB2材料中并未发现有固溶相.固溶相的形成使得晶格参数减小,因此ZS20材料中ZrB2的衍射峰向高角度偏移.采用淬火法测得ZrB2和ZS20材料的临界热震温度分别为298℃和306℃,并将实验值与理论计算值进行比较.ZrB2基体与SiC第二相及固溶相之间由于热膨胀系数的差异而在材料内部引入应力,因而ZS20材料抗热震性能的实验值低于理论计算值.

The microstructure and thermal shock resistance of ZrB2 and ZrB2-20vol% SiC（ZS20） composites prepared by aqueous tape casting and hot-pressing were investigated.Zr-B-C and Zr-B-W solid solution phases were formed in ZS20 composites,but not formed in ZrB2 samples.The diffraction peaks for ZrB2 of ZS20 composites shifted to higher 2θ values possibly due to the formation of solid solution phases which resulted in a decrease in lattice parameters.The critical thermal shock values for ZrB2 and ZS20 were measured to be 298℃ and 306℃ respectively using water quench tests.The thermal shock resistance of ZrB2 and ZS20 were also calculated and compared with the experimental data.The results revealed that the measured thermal shock resistance of ZS20 composites was lower than the calculated ones,which might be due to the thermal residual stress in the samples resulted from the difference in thermal expansion coefficient of ZrB2 matrix and SiC second phase as well as the solid solutions phases.