激光重熔制备TA1表面Ni/Al复合抗高温氧化涂层

为了提高纯钛的高温抗氧化性能,采用电弧喷涂和等离子喷涂方法在纯钛表面制备Ni/Al复合涂层.利用激光重熔使得Ni层与Al层发生冶金反应,对试件进行800℃×40 h连续氧化.根据生成的金属间化合物特征研究纯钛的高温抗氧化行为.结果表明,经过表面改性处理后Ni/Al复合涂层可以显著提高纯钛的高温抗氧化性能.在激光重熔过程中Ni/Al复合涂层中的Al发生熔化扩散并与Ni形成以Ni_2Al_3相为主的扩散层.在氧化过程中Ni/Al复合涂层表面形成连续且致密的α-Al_2O_3氧化膜与大量NiAl相,表面扩散层中的富铝相可为表面提供充足的Al元素,进而对纯钛基体提供有效的高温抗氧化保护作用.

Preparation of Ni/Al composite coating with high temperature oxidation resistance on TA1 surface by laser remelting

In order to improve the high temperature oxidation resistance of pure titanium, a Ni/Al composite coating was prepared on the surface of pure titanium with an arc and plasma spraying method. Laser remelting was employed to accomplish the metallurgical reaction of Ni and Al layers, and the specimens were continuously oxidized at 800 ℃ for 40 h. The high temperature oxidation resistance of pure titanium was studied according to the features of intermetallic compounds. The results show that the Ni/Al composite coating after the surface modification can significantly improve the high temperature oxidation resistance of pure titanium. During the laser remelting process, Al element in the Ni/Al composite coating melts and diffuses to form a diffusion layer with Ni, which is mainly composed of Ni₂Al₃ phase. During the oxidation process, on the surface of Ni/Al composite coating, a continuous and dense α-Al₂O₃ oxidation film forms, and a large amount of NiAl phase precipitates. Furthermore, the aluminum-rich phases in surface diffusion layer can supply sufficient Al element, effectively providing high temperature antioxidation protection for pure titanium substrate.