两种不锈钢在氯化物熔盐环境中的腐蚀行为研究

CORROSION BEHAVIORS OF TWO KIND OF STAINLESS STEELS IN CHLORIDE MOLTEN SALT ENVIRONMENT

以盐湖水氯镁石资源化利用为目的,研究了太阳能光热发电系统中,NaCl、KCl、MgCl_(2)·6H_(2)O和CaCl_(2)四种氯化物熔盐储热介质在900℃下对201不锈钢和304不锈钢的腐蚀行为。采用SEM分析手段对腐蚀产物形貌进行表征。结果表明:两种金属材料在4种氯化物熔盐中均有不同程度的腐蚀,在MgCl_(2)·6H_(2)O熔盐中的腐蚀程度均较低,可将MgCl_(2)·6H_(2)O作为传热蓄热介质加以利用;与201不锈钢相比,304不锈钢在同种氯化物熔盐腐蚀过程中质量损失较小,腐蚀速率较慢,其主要原因是304不锈钢中的Cr、Ni含量较高,表面生成的Cr2O3和NiCr2O4氧化膜有效降低了其腐蚀程度,因此304不锈钢较201不锈钢更耐蚀。研究结果为盐湖水氯镁石的有效利用、太阳能热发电系统储热介质的选择及金属腐蚀防护提供了理论依据。

For the purpose of the resource utilization of chlormagnesite from salt lake,in the solar thermal power generation system,the corrosion behavior of two typical materials(201 and 304 stainless steel)in four kinds of chloride molten salt storage media(NaCl,KCl,MgCl_(2)·6H_(2)O and CaCl_(2))at 900℃were studied.The morphology of corrosion products was characterized by SEM.The results showed that both of the two metal materials were corroded in the four chloride molten salts chosen,but the degree of corrosion was different.MgCl_(2)·6H_(2)O could be used as heat transfer and storage medium,because the corrosion degree was low in MgCl_(2)·6H_(2)O molten salt.Compared with the 201 stainless steel,the 304 stainless steel has less mass loss and slower corrosion rate during the corrosion process of the same chloride molten salt.The main reason was the high content of Cr and Ni in the 304 stainless steel,which will cause the oxide film of Cr2O3 and NiCr2O4 formed on the surface to effectively reduce the corrosion degree.Therefore the 304 stainless steel is more corrosion resistant than the 201 stainless steel.The study results provide a theoretical basis for the effective utilization of magnesite in salt lake water,the selection of heat storage medium in solar thermal power generation system and the protection of metal corrosion.