涂敷Na_2SO_4盐膜的Ni基合金在900℃空气中的热腐蚀

Hot Corrosion of Ni-based Alloys with Na_2SO_4 Coating at 900 ℃

采用涂盐法,在纯Ni、Ni-10Cr、Ni-20Cr和Ni-10Cr-5Al合金上涂敷40～ 45 g/m2厚度Na2SO4盐膜,研究其在900℃空气中的热腐蚀行为.结果表明：纯Ni和3种Ni基合金的抗热腐蚀性能依纯Ni、Ni-10Cr-5Al、Ni-10Cr、Ni-20Cr的次序递增.3种Ni基合金形成了相似的腐蚀膜结构,腐蚀膜大体分3层,外层都是NiO.Ni-20Cr合金中间层为连续的Cr2O3层,内部出现极少的硫化物;Ni-10Cr合金腐蚀膜的中间层是相对深色的NiO和Cr2O3混合层,内侧出现硫化物;而Ni-10Cr-5Al合金腐蚀膜的中间层是NiO、Cr2 O3和Al2O3的混合氧化物,内层是Cr和Al的硫化物,分布在腐蚀膜和基体的界面上,有的分布在合金基体上.在Ni的基础上添加Cr并增加Cr含量均提高了合金的抗热腐蚀性能,但在Ni-10Cr的基础上增加质量分数5％Al却使抗热腐蚀性能下降.

The pure Ni,Ni-10Cr,Ni-20Cr and Ni-10Cr-5A1 alloys were coated with Na2SO4 salt film of 40 ~ 45 g/m2 by the method of coating salt. And the hot corrosion behavior of the four alloys was studied in the air at 900 ~（2. The results indicated that the corrosion resistance of Ni, Ni-10Cr-5AI, Ni-10Cr, Ni- 20Cr was in incremental order. The corrosion film structures of three kinds of Ni-base alloys were similar, generally divided into three layers. The outer layers of three corrosion film were all composed by NiO, and the middle and inside layers were different, described as follow：The middle layer of Ni-20Cr alloy corro- sion film was a continuous Cr203 layer, and the inside layer was composed by a small amount of sulfide. The middle layer of Ni-10Cr alloy corrosion film was mixed with relatively dark NiO and Cr203 layer,and the sulfide appeared on inner side. The middle layer of Ni-10Cr-5A1 alloy corrosion film was oxidation mixed with NiO, Cr203 andA1203, and the inside layer was composed by chromium sulfide and aluminum sulfide, distributed in the corrosion film and substrate interface, some distributed in alloy. Corrosion resist- ance of alloy was improved after adding Cr, and the improved degree was increased with the increase of Cr content,but the corrosion resistance was degraded after adding 5 % A1 to Ni-10Cr alloy.