热障涂层界面化合物与残余应力演变研究

用超音速氧燃料热喷涂在铁基合金上制备热障涂层粘结层,用大气等离子热喷涂技术制备陶瓷层。研究了高温氧化后其界面化合物和残余应力的演变。结果表明,随着高温氧化的进行,TGO和BC/基体界面均有氧化物生成,但生长形貌和趋势并不一致。TGO由Al2O3层与尖晶石层组成;BC/基体界面氧化物为单一Al2O3,且存在层状和块状两种形貌。合金的热化学动力学引起元素Co和Ni向基底扩散比较严重,Al元素扩散止于界面氧化物层,基本不向铸铁基底扩散,Fe元素会向粘结层方向扩散。TGO残余应力的演化分为0~15 h和15~100 h 2个阶段,且残余应力与TGO的凹凸生长形貌及其物相组成密切相关;而BC/基体界面单一氧化物的残余应力基本稳定,不受其生长形貌影响。

Phase Composition at the Interface and Its Residual Stress Evolution of Thermal Barrier Coatings

The bond coat of thermal barrier coatings was deposited by means of high velocity oxygen fuel process, and the ceramic topcoat was prepared via atmospheric plasma spraying process. Results indicate that the evolution trend between the TGO and the BC/substrate oxides is significantly different with isothermal oxidation ageing. Furthermore, compared to bilayer TGO (alumina layer and spinel layer), the morphologies of the pure alumina at the interface of BC/substrate can be divided into two kinds, bulk and layer. Elements Co and Ni can considerably diffuse from the bond coat to the iron-based substrate, yet element Cr may not diffuse to the iron-based substrate; element Al cannot diffuse to iron-based substrate due to the presence of alumina, but Fe element can diffuse to the bond coat. It can be suggested that the elements inter-diffusion may be critical to the mechanical property of bond coat as well as the evolution of TGO. The evolution of residual stress in TGO can be divided into 0~15 h stage and 15~100 h stage, and it can be closely linked to the rough morphology of TGO as well as its phase composition. However, the residual stress of oxides at the interface of BC/substrate is more stable than that of TGO, and cannot be influenced by its developing morphology