稀土和铬对铁基自熔合金喷涂层抗氧化性能的影响

Effect of RE and Chromium on High Temperature Oxidation Property of Iron Base Self-fluxing Alloy Spray-welding Coating

本研究着眼于用稀土对价格低廉的铁基自熔合金粉末进行改性 ,以提高其抗高温氧化性能。结果表明 ,稀土的添加大大提高了合金涂层的高温抗氧化性能 ,具有较大的应用前景。同时分析了稀土提高抗氧化性的机理 ,认为稀土的添加改变了合金氧化过程的扩散动力学 ,从而改变氧化膜的形貌与粘附性 ,提高抗氧化能力。

In this paper,the effects of rare earth(RE) and chromium on the high temperature oxidation resistance of iron base fluxing alloy spray welding coatings is reported.It has shown that the addition of RE greatly enhanced oxidation resistance.Based on the SEM observation and EDAX analysis of the section of samples,the mechanism of RE on the oxidation process has been analyzed.The oxidation process of coatings without RE addition is dominated by outward diffusion of cations, it results in forming a prous scale which is easy to suffer spallation under thermal stress. However,in the case of coatings with RE addition,the mechanism is different.It has been proposed that the segregation of RE atoms on grain boundary will block the path of the outward diffusion cations and alter the morphology of the scale.The microstructure of the scales of the coatings with RE addition is more compacted and has less micro holes.Thus the scale of the coatings with RE addition is more adhesive and protective,resulting in the improvement of oxidation resistance.In addition,the effect of chromium has also been studied and it has been shown that the increase in chromium proportion has no distinctive effect on the oxidation resistance of the coatings studied.