Study On Technique Of 1Cr13 Stainless Steel Aluminizing And Its Corrosion Behavior In Molten Salt

Solar energy as a green and renewable energy, which can meet the needs of sustained development of human beings. But solar energy is intermittent, we must use a heat-storage medium to collect heat produced by solar energy and make solar thermal power plant continue work when solar power is not enough. Molten salt for its electrical conductivity, thermal conductivity and high temperature stability is becoming a good heat transfer and heat storage medium in the future. Ternary carbonate which consist of Na2CO3, K2CO3 and Li2CO3 inherited traditional binary carbonate’s advantages such as good thermal stability, without pollution, and overcome some disadvantages like high melting point and viscosity for binary carbonate. Expected to gradually extended to solar power industry. Because of the process of solar thermal power generation always in high temperature conditions, some equipment like molten salt shakers or pump are facing corrosion problems in molten salt. Therefore, is necessary to research the corrosion behavior of metal in molten salt and preparation of heat resistant surface coating for metal.Taking those we said above as a starting point, we choose 1Cr13 stainless steel as matrix which is both not expensive and has antioxidant properties in high temperature. Making Fe-Al alloy layer on stainless steel surface by Hot-dip aluminum, include two process: Hot-dip aluminum and diffusion. First we get aluminum layer on the surface of 1Cr13 stainless steel by hot dip, tested integrity, thickness and uniformity of Hot-dipped coating formed in different temperature and different Hot dipping flux.The result shows we can get best comprehensive performance coating under the 750℃, fluxing in 4%KF + 2% Na F mixed solution. Then take diffusion experiment at different temperatures and different times. Through SEM and EDS analysis show that under 800℃,6h diffusion, we can get certain thickness layer without oxidation or cracking. It’s a relatively good parameter for diffusion process.Then studied the corrosion behavior of 1Cr13 stainless steel and aluminized 1Cr13 stainless steel in different(Na-K-Li)2CO3 molten salt. Using SEM and EDS to detect morphology and elements in corrosion area, using XRD to test the product generated by corrosion and determined corrosion kinetics curves. The result showed that in 60%Na2CO3- 30%K2CO3-10%Li2CO3 and 20%Na2CO3-50%K2CO3-30%Li2CO3 ternary carbonate, 1Cr13 stainless steel’s surface was corroded seriously, however, in molten salt of 30%Na2CO3-30%K2CO3-40%Li2CO3, the outer layer of 1Cr13 stainless steel’s oxide film without loose structure, and the corrosion rate is lowest. To those three kinds of ternary carbonate, aluminizing can improve the corrosion resistance of 1Cr13 stainless steel,formed protective Al2O3 and Li Al O2 composite oxide film on the surface. The thickness of corroded layer and mass gain was decreased significantly, especially in the carbonate of 20%Na2CO3-50%K2 CO3-30%Li2CO3.