热喷涂热障涂层孔隙与涂层性能关系研究进展

孔隙在热障涂层中较为常见,孔隙对热障涂层的性能有利有弊。对热障涂层陶瓷层中孔隙的形成机理进行了综合分析,总结了热障涂层孔隙结构的调控方法,讨论了孔隙结构特征对热障涂层隔热性能和力学性能的影响。孔隙结构的引入将引起力学性能的下降,同时降低热障涂层的热导率,提高隔热效果。孔隙结构特征参数包括孔隙形状、孔隙间距、孔隙倾斜角、孔隙高宽比等,其中孔隙的倾斜角和高宽比对涂层导热性能的影响尤为重要,是孔隙结构的关键特征参数。通过原始粉末孔隙结构的保留、造孔剂(有机造孔剂、无机造孔剂)的搭配造孔、制备工艺(临界等离子喷涂参数、粒子扁平率等)的调节以及后续的孔隙处理,可实现热障涂层孔隙结构的调控。在实际应用过程中应同时兼顾力学性能和隔热性能,最重要的是保证热障涂层的有效寿命,需要综合考虑力学性能与导热性能的匹配。通过热障涂层孔隙结构特征的设计及分布控制,可实现孔隙结构高性能、高可靠性热障涂层的制备。

Relationship between Pores on Thermal Sprayed Thermal Barrier Coatings and Coating Properties

Pores are common in the thermal barrier coatings (TBCs), and its existence has both advantages and disadvantages on performance of TBCs. Formation mechanism of pores in ceramic layer of TBCs was analyzed comprehensively. Regulating methods of pore structure on TBCs were summarized. The effects of pore structure characteristics on heat insulation performance and mechanical properties of TBCs were investigated. The introduction of pore structure would degrade mechanical properties and thermal conductivity, and improve heat insulation effect. Pore structure characteristic parameters included pore shape, distance, slant angle and aspect ratio were proposed. Pore slant angle and aspect ratio were of great significance to thermal conductivity of TBCs, which were also key characteristic parameters of pore structure. The pore structure of TBCs could be regulated by retaining porous structure of original powder, collocating pore-forming with pore formers (organic pore former, inorganic pore former), adjusting preparation processes (critical plasma spray parameter, particle flatness ratio) and treating pores subsequently. The mechanical properties and heat insulation performance shall be adjusted to guarantee effective life of TBCs. High performance and reliable TBCs with pore structure can be prepared based upon structure characteristic design and distribution control of porous structure of TBCs.