等离子喷涂SiO_2 ZrO_2涂层的抗热震性能

为了改善等离子喷涂ZrO2 涂层的抗热震性能 ,利用热震试验、SEM和EPMA等技术 ,研究了SiO2 添加剂对其显微组织和抗热震性能的影响 .当SiO2 添加剂质量分数小于 3 .0 %时 ,涂层的抗热震性能随SiO2 添加剂的质量分数的增加而提高 ;当其质量分数大于 3.0 %时 ,涂层的抗热震性能随其质量分数的增加而降低 ,3.0 %SiO2 ZrO2 涂层的抗热震起裂次数和抗热震失效次数达到最大值 ,分别由不添加SiO2 涂层时的 32次和 46次提高到 83次和 112次 .在ZrO2 涂层中添加SiO2 会促使涂层中形成气孔 ,并且气孔率和气孔直径随SiO2 添加量的增加而增加 .3 .0 %SiO2 ZrO2 涂层中形成分布均匀、直径约为 1μm的气孔 ,其气孔率约为 10 % ,此时 ,涂层的弹性模量和所受到的应力最小 ,因而涂层的抗热震性能最好

Thermal shock resistance of plasma-sprayed SiO_2 ZrO_2 coating

In order to improve the thermal shock resistance of plasma-sprayed ZrO2 coating, the effect of additive SiO2 on its microstructures and thermal shock resistance was investigated by means of SEM, EPMA and thermal shock tests.When the mass fraction of additive SiO2 is less than 3.0%, the thermal shock resistance of coating increases with the increase of the mass fraction of additive SiO2. But when it is more than 3.0%, the thermal shock resistance decreases with its increase. The lifetimes of fracture initiation and fracture failure of the coating with 3.0% SiO2 reach the maximum values, and they increase from 32 and 46 cycles to 83 and 112 cycles respectively, compared with the values of the coating without SiO2. Adding SiO2 results in the formation of gas cavities in coating, and the proportions and sizes of gas cavities increase with increasing mass fraction of additive SiO2. The gas cavities of about 1 μm are well distributed in ZrO2+ 3.0%SiO2 coating and the proportion is about 10%. This pattern of gas cavity decreases the elastic module to the minimum. The residual stress and thermal stress of coating reach the minimum because they decrease with the decrease of the elastic module, so the thermal shock resistance of 3.0%SiO2 + ZrO2 coating reaches the maximum value.