As a solar energy storage medium at moderate-to-high temperature, molten chlorate severally corrodes metal vessels. The corrosion behavior and mechanisms of pure nickel (Ni), GH4033 and GH4169 in 793 K molten eutectic NaCl-MgCl 2 were studied. During the initial stage of corrosion, pure Ni and GH4033 gain weight from the many plate-like shells formed on the sample surface. After corrosion for 40 h, all sample surfaces were rather porous and loosened. MgO nuclei that were attached to the loosened microstructure surface fell off with the microstructures, which led to a continual decrease in the sample weight. The three sample surfaces were mainly composed of MgO and Ni or (Ni, Fe) from the sample substrate. Al and Ti were preferentially oxidized and stably excited on the GH4033 surface, which inhibits the corrosion process. The corrosion rate of GH4169 was the highest for the δ phase, which is rich in Nb, and phase boundaries were corroded preferentially. In the anode reaction, metal atoms escape from the corrosion system in the form of chlorides or aqueous chlorides.
To address the issue of poor corrosion resistance for pure BaZrO 3 refractory, BaZrO 3 -Yb 2 O 3 composite refractory was designed and prepared in this study. The wettability of high-temperature alloy melt on the composite refractory, the interfacial reaction mechanism and the physical properties of the material were systematically studied. The wetting experimental results show that the wettability of the high temperature alloy melt on the surface of the BaZrO 3 -Yb 2 O 3 composite refractory is lower than that on the pure BaZrO 3 refractory. This phenomenon can be attributed to the synergistic effect of higher surface roughness and the better thermodynamic stability of the BaZrO 3 -Yb 2 O 3 composite refractory. The results of vacuum induction melting experiments show that the interfacial reaction products of the two refractory crucibles and the superalloy melt are ZrO 2 and BaAl 2 O 4 . Owing to the higher thermodynamic stability of BaZrO 3 -Yb 2 O 3 composite refractory, the thickness of the interfacial reaction layer between the BaZrO 3 -Yb 2 O 3 composite refractory and alloy melt is significantly reduced, which is about 1/3 of the thickness for the interfacial reaction layer than pure BaZrO 3 refractory. In addition, the yield strength of the GH4169 alloy melted in the BaZrO 3 -Yb 2 O 3 crucible is approximately 30% higher than that melted in the pure BaZrO 3 crucible. This is mainly due to the less consumption of the Al element during the reaction process between composite refractory and alloy melt, which increases the content of auxiliary strengthening phase in the alloy more, and thereby optimizes the mechanical properties of the alloy. Meanwhile, the thermal conductivity of the BaZrO 3 -Yb 2 O 3 composite refractory is reduced by approximately 45%, while the compressive strength is nearly doubled, which can effectively reduce the heat loss during the smelting process and significantly prolong the service life of the refractory. This study provides a new technical strategy and theoretical support for solving the technical problems of smelting of GH4169 alloy.
危险品化学品经营许可证（带存储）