摘要
应用XRD、SEM和EDS等分析方法探讨了温度对表面喷涂二元碱金属硫酸盐的Super304H耐高温腐蚀特性的影响。结果表明:650℃时腐蚀过程以高温氧化为主,腐蚀动力学曲线遵循抛物线规律,基体表面形成相对致密且具有保护性作用的氧化层,腐蚀产物由较多的铁氧化物与部分Cr2O3以及少量的FeS组成,近基体处未见明显的微孔隙与裂纹。提高腐蚀温度至750℃,腐蚀动力学曲线遵循"钟型"规律变化;挥发性腐蚀产物形成,导致腐蚀动力学曲线呈现下降趋势;腐蚀产物以较多的铁氧化物与部分Cr2O3为主,伴生少量的(铁/镍)硫化物以及挥发性腐蚀产物硫酸铬酸钠Na4(CrO4)(SO4);氧化膜增厚且变得疏松多孔,近基体表面孔隙密度与裂纹深度增加,有内硫化发生。分析认为:上述现象的发生归因于低熔点共晶体Na2O·Na2SO4的产生以及Cr2O3在硫酸盐中的碱性熔融;提高温度加速了挥发性产物的形成以及腐蚀的深入发展。
Influence of temperature on the corrosion behavior of Super304 H steel under sulfate deposition was investigated by means of XRD,SEM and EDS.The results show that high temperature oxidation mainly occurs through the total corrosion process at 650 ℃,the kinetic curve follows a parabolic law and the comparatively compact and protective Fe /Cr oxide film produces on the surface of the alloy.The corrosive product is mainly composed of Fe oxide,partly Cr2O3 and minor FeS.Increasing the corrosion temperature to 750 ℃,the kinetic curve reveals a'bell-shaped'trend.The corrosive product is mainly composed of Fe oxide,partly Cr2O3 with minor(Fe /Ni) S and the volatile corrosion product Na4(CrO4)(SO4) which causes a decreasing of the kinetics curve.The high temperature oxidation mainly occurs in the earlier stage with the formation of the corrosive product Fe /Cr oxide,and the oxide scale in the thickness increases and becomes loose as well as porous.Moreover,the porpsity density and crack depth at the interface of scale /alloy increase,and the internal sulfidation occurs.It is argued that the above phenomenon is attributed to the formation of the low melting point eutectic Na2O·Na2SO4and the basic fluxing of Cr2O3 in molten Na2SO4,meanwhile,the increasing of corrosion temperature accelerates the formation of volatile Na4(CrO4)(SO4) and the development of corrosion process deeply.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2014年第11期180-184,共5页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金联合基金项目重点项目(51134013
51171037)
关键词
碱金属硫酸盐
高温腐蚀
低熔点共晶体
内硫化
alkali metal sulfate
high temperature corrosion
internal sulfidation
