GH4033和GH4169合金在520℃熔融NaCl-52 mass% MgCl_2中的腐蚀机理

Corrosion mechanism of GH4033 and GH4169 alloys in molten NaCl-MgCl_2 at 520 ℃

选用两种常见的Ni基高温合金GH4033和GH4169,通过520℃熔融Na Cl-52 mass% MgCl_2完全浸没试样腐蚀实验,测量了160 h内试样在高温熔盐中的腐蚀行为。借助SEM、XRD等方法对腐蚀20 h和160 h试样的表面、横截面形貌及成分进行了表征。结果表明,两种试样的腐蚀动力学曲线均满足分段线性规律。腐蚀20 h后,两种试样表面均疏松多孔,且GH4169出现富含Mg和O的壳层结构。横截面形貌及成分分析表明GH4033和GH4169横截面上腐蚀层深度约为30μm和50μm。两种试样的腐蚀机理分别为Cr、Ni的流失和Fe、Cr的流失。

Two common Ni based high temperature alloy GH4033 and GH4169 were selected, and the corrosion behavior of the samples after immersion in high temperature NaCl-52% MgCl2molten salt for 160 h was measured. Microstructure, cross section morphology and composition on surface of the alloys were characterized by means of SEM and XRD. The results show that the corrosion kinetics curves of the two kinds of samples all meet the linear law, and the average mass loss rate of the GH4033 alloy is lower than that of the GH4169 alloy. After corroding for 20 h, loose and porous structure are observed on the surface of the two samples and a shell structure mainly consisting of Mg and O exists on the surface of the GH4169 alloy. The cross section morphology shows that the corrosion layer depths of the GH4033 and GH4169 alloys are 30μm and 50μm, respectively, and its corrosion mechanisms are Cr and Ni loss and the loss of Fe and Cr, respectively.