钛合金表面抗高温氧化TiAl3-Al 复合涂层的制备?

Preparation of high-temperature oxidation resistance TiAl3 coatings on Ti alloy

摘要:

采用低温超音速火焰喷涂(LT-HVOF)在钛合金(Ti6Al4V)基体表面制备纯 Al 涂层后进行真空热处理,获得了厚度约300μm的TiAl3-Al复合涂层,并对该涂层在700℃下长时间高温氧化行为进行了研究,用 SEM,EDS和 XRD分析了涂层的形貌、成分及相组成。结果表明：低温超音速火焰喷涂制备的纯 Al涂层结构较为致密,但存在少量的微孔洞,经真空热处理后的纯 Al涂层与钛合金基体间在界面处形成了TiAl3互扩散层；再700℃下静态氧化时,随着时间的增加,涂层表面形成了一层薄而致密的Al2 O3和TiO2的混合氧化层,而涂层中纯Al与基体中的Ti互扩散逐渐转变为TiAl3；氧化约5 h后涂层进入稳态氧化阶段,高温氧化500 h 后涂层未出现剥落等现象,表明 TiAl3-Al 复合涂层能显著提高Ti6Al4V合金的抗高温氧化性能。

Abstract:

In this study,pure Al coating was prepared on titanium alloy (Ti6Al4V)by the LT-HVOF process,TiAl3-Al composite coatings were gained by applying heat treatment at 610℃.Long-term high temperature oxidation behavior at 700℃ of the coatings was investigated.The microstructure,chemical and phase composition of the coatings were investigated using SEM,EDS and XRD.The experimental results show that the pure Al coating fabricated by LT-HOVF is dense and there are some micro-holes in the coating.TiAl3 diffusion layer between pure Al coating and titanium alloy substrate is formed after vacuum heat treatment.Isothermal oxidation test at 700℃ shows that a thin and dense Al2 O3 and TiO2 mixed oxides layer is formed on the surface of the coating.TiAl3 is transformed by interdiffusion between Al coating and Ti alloy substrate.After high temperature oxidation of 5 h,coating entered steady-state oxidation stage.After 500 h high temperature oxidation,spallation is not observed in the coating.The high temperature oxidation resistance ability of titanium alloy (Ti6Al4V)can be significantly enhanced by TiAl3-Al composite coatings.