等离子喷涂Al2O3-3%TiO2涂层结构及加载绝缘性能

目的研究等离子喷涂Al2O3-3%TiO2涂层的抗低温冲击性能和外部载荷下的绝缘性能等综合性能,探讨大气等离子喷涂技术作为核聚变反应堆磁体支撑结构绝缘涂层制备方法的可行性。方法采用大气等离子喷涂技术在喷砂处理的A286基体上制备Al2O3-3%TiO2涂层并进行封孔处理,利用XRD、SEM等手段对涂层的微观结构和常规性能进行表征,重点关注了涂层的低温热冲击性能和加载绝缘性能。结果喷涂粉末充分熔融及铺展而沉积为典型的层叠状结构,涂层的结合强度达30 MPa,孔隙率可控制在5%以内。均匀涂刷在涂层表面的硅树脂封孔剂有利于填充涂层孔隙和微裂纹,封孔剂在涂层内部的渗透深度可达到大约100μm。从室温水浴到液氮进行10个循环的热冲击试验后,涂层未发现裂纹和剥落,且热冲击对绝缘性能没有显著影响。250 MPa压缩载荷下,涂层的表面电阻率明显降低,但仍高于30 MΩ/sqr。结论Al2O3-3%TiO2涂层可作为高载荷和低温环境下使用的潜在绝缘材料,而大气等离子喷涂将成为制备核聚变反应堆磁体支撑结构关键部件绝缘涂层的重要选择。

Microstructure and Load-insulation Performance of Plasma-sprayed Al2O3-3%TiO2 Coating

The work aims to study the comprehensive properties of plasma-sprayed Al2O3-3%TiO2 coating,including thermal shock resistance and load-insulation performance under external load,and explore the feasibility of using atmospheric plasma spraying to prepare insulating coatings for the magnet support structure of nuclear fusion reactor.Al2O3-3%TiO2 coating was fabricated on the grit-blasted A286 substrate by atmospheric plasma spraying and then sealing treatment was carried out to the as-sprayed coating.The microstructure and conventional propertie of the coating were studied by XRD and SEM.The low-temperature thermal shock resistance and load-insulation performance of the coating were mainly researched.The feedstock powders were melted and flattened sufficiently,and formed into typical multi-layer structure.The adhesion strength of the coating was above 30 MPa,and the porosity could be controlled below 5%.The silicone resinsealant brushed on the coating surface evenly could fill the coating pores and micro-cracks effectively,and the penetration depth of sealant was approximately 100μm.No cracks and spallation were observed on the coating even after 10 cycles of thermal shock test from water bath at room temperature to liquid nitrogen and the thermal shock had no significant effect on the insulation performance.Under the compression load of 250 MPa,the surface resistivity of coating decreased obviously,but was still higher than 30 MΩ/sqr.Consequently,the Al2O3-3%TiO2 coating can be used as a potential material under high compression load and low-temperature environment,and atmospheric plasma spraying can become an alternative to manufacture insulating coating for the key parts in magnet support structure of nuclear fusion reactor.