二元硫酸盐Na_2SO_4-K_2SO_4沉积引起的Fe-Al合金的低温热腐蚀

LOW TEMPERATURE HOT CORROSION OF Fe-Al ALLOYS INDUCED BY Na_2SO_4-K_2SO_4 DEPOSIT

研究了Fe-Al合金当其表面上有二元硫酸盐Na_2SO_4-K_2SO_4沉积时在O_2/SO_2/SO_3气氛中的低温热腐蚀动力学及其影响因素,并分析了腐蚀产物的形貌和结构。将获得的实验结果与一元硫酸盐Na_2SO_4(或K_2SO_4)沉积引起的Fe-Al合金的腐蚀行为加以比较,发现二元硫酸盐沉积导致更为严重的热腐蚀。此现象似应归诸于在一元硫酸盐沉积物中引入第二组分硫酸盐影响了混合盐系相平衡热力学,从而导致了更容易产生引发低温热腐蚀的低熔点硫酸盐共晶。

Low temperature hot corrosion behavior of Fe-Al alloys was studied in the presence of a thin film of Na_2SO_4-K_2SO_4 deposit on their surfaces in O_2/SO_2/SO_3 gas atmospheres in the temperature range of 650～750℃。 The reaction kinetics were measured gravimetrieally,and the alloys corroded were physically examined and analyzed. The results indicated that the binary sulfate deposit induced more severe hot corrosion of the alloys than a unitary sulfate Na_2SO_4 or K_2SO_4 deposit did. On the basis of a discussion on the effect of the addition of either K_2SO_4 to Na_2SO_4 or Na_2SO_4 to K_2SO_4 on thermodynamics of the equilibrium of mixed salts,the accelerated hot corrosion of the alloys caused by the binary sulfate deposit is attributed to the earlier appearance of a ternary sulfate eutectic, Na_2SO_4-K_2SO_4-Fe_2(SO_4)_3,on the alloy surface.