材料期刊网

本文作者采用粉末包装法制备Cr-Al二元涂层,对Cr-Al二元涂层的制备以及涂层的高温腐蚀性能进行了研究。实验结果表明,在纯Ni上制备Cr含量较高的Cr-Al共渗涂层是困难的,纯Ni上Cr-Al共渗时,Al会同时沉积到纯Ni试样和Cr粉表面上,由于Cr粉表而上铝涂层的形成,大大降低丁Cr的活度,从而抑制了Ni上渗Cr的过程;然而,在纯Ni上用二步法制备Cr-Al二元涂层是可行的,先渗Cr后渗Al能产生理想的Cr-Al二元涂层,涂层具有良好的抗高温氧化和抗热腐蚀性能;而先渗Al后渗Cr则产生有孔洞的Cr-Al二元涂层,涂层的抗高温腐蚀性能很差。

Although aluminide coatings have good oxidation resistant properties, their hot corrosion resistance is not satisfactory. It is thought that Cr-Al coatings may improve the high temperature corrosion resistance over that of aluminide coatings. Is it possible to produce a Cr-Al coating by a single step pack process? How good is the corrosion resistance of the Cr-Al coatings? These problems are discussed in this article. The experimental results show that it is difficult to obtain Cr-Al coatings on pure Ni by a single step pack cemenation process because aluminium deposited on nickle specimen and chromium powder reduces activity of chromium greatly, thereby hampering the chrominizing process. It is possible to form Cr-Al coatings by two-step pack processes. However the order of coating steps is very essential: a useful Cr-Al coating which can resist oxidation and hot corrosion can be produced by means of aluminizing after chrominizing, but an uncompact Cr-Al coating which contains many holes and doos not well resist oxidation and hot corrosion well be formed by chominizing.