低压等离子喷涂纳米YSZ涂层的结构及力学性能

采用低压等离子喷涂技术制备具有新型结构的纳米YSZ涂层,研究电弧电流和粉末松装密度对涂层微观结构以及力学性能的影响。结果表明,松装密度为0.95g/cm3的粉末在喷涂过程中因电流升高而引起的晶粒生长的程度远低于松装密度为1.4g/cm~3的粉体。当电流超过350A后,两种粉末所对应的涂层的Weibull模量分布均发生从二元结构向单一值的转变,但转变后涂层的结构均呈现出有别于传统涂层结构的细等轴晶结构。硬度与弹性模量的分析结果表明具有细等轴晶结构的涂层较在350A电流下形成的二元结构纳米涂层具有更高的平均硬度与弹性模量。当采用密度为1.4g/cm~3的粉末时,所对应涂层的断裂韧性Weibull曲线随电流波动较大。

Microstructure and Mechanical Properties of Low Pressure Plasma Sprayed Nanostructured YSZ Coating

Two types of reconstituted nanostructured agglomerates were deposited using low pressure plasma spray (LPPS) . The effects of arc current and the apparent density of agglomerates on coating microstructure were investigated. The results show that during depositing the agglomerates of 0.95 g/cm3, no remarkable grain growth occurs as the current increases from 350 A to 650 A in contrast with that of the agglomerates of 1.4 g/cm3. The plots of Weibull analysis on microhardness (1.96 N load) performed on coatings from the two agglomerates experience a transition from bimodal distribution to a single line when the current beyonds 350 A. Despite of a single Weibull modulus, the coating presents a uniform equiaxed fine grain structure that is quite different from that of the conventional coating. Compared with the coatings with bimodal Weibull modulus, the coating with uniform fine grains shows higher average microhardness and elastic modulus. The fracture toughness of the coatings with the agglomerates of 1.4 g/cm3 remarkably fluctuates with the arc current.