渗铝NiAl－20％Fe金属间合金的高温热腐蚀

HIGH TEMPERATURE HOT CORROSION OF NiAl-20%Fe WITH ITS SURFACE ALUMINIDE COATING

本文研究了在９５０℃空气中，表面涂Ｎａ_２ＳＯ_４盐膜的条件下，ＮｉＡｌ，ＮｉＡｌ－２０％Ｆｅ及渗铝后的高温热腐蚀行为。在热腐蚀过程中，ＮｉＡｌ合金表面能形成Ａｌ_２Ｏ_３膜，显示出一定的耐蚀性能。但Ａｌ_２Ｏ_３膜易开裂，Ａｌ_２Ｏ_３膜的溶解及开裂会引发合金发生快速热腐蚀；２０％Ｆｅ的加入则使ＮｉＡｌ合金的耐蚀性能显著变差，合金表面不能形成单一的Ａｌ_２Ｏ_３膜；渗铝处理可以明显提高ＮｉＡｌ－２０％Ｆｅ合金的耐蚀性能，且渗铝涂层的耐蚀性能优于ＮｉＡｌ合金，这与铝化物涂层中的Ａｌ含量较高，Ａｌ_２Ｏ_３膜的开裂倾向较小有关。

The behaviours of high temperature hot corrosion of NiAl, NiAl-20%Fe (atom fraction) without and with aluminized coating in the presence of Na_2SO_4 film at 950℃in air were conducted. NiAl alloy shows hot corrosion resistance to some extent by the formation of Al_2O_3 scale. But, the cracking and dissolution of Al_2O_3 scale may cause its rapid hot corrosion. Additives of 20%Fe may deteriorate the hot corrosion resistance owing to the absence of an Al_2O_3 scale. Aluminizing treatment may improve corrosion resistance of NiAl-20%Fe by promoting the formation of an Al_2O_3 scale. NiAl-20%Fe with aluminide coating has slower corrosion rate than NiAl alloy, which may be attributed to that the aluminide coating has higher Al content, and the Al_2O_3 scale in coating has better cracking resistance than NiAl alloy.