Experimental exploration of metallic chloride salt corrosion of stainless steel sheets

Abstract

In recent years, biomass generation in China has been steadily increasing. The high-temperature corrosion of the heating surface of biomass boilers is mainly caused by HCl and alkali metal chlorides in the sediment, which seriously affects the efficiency and safety and the degree of economic utilization of biomass energy. In this paper, the corrosion products were characterized by total-immersion experiments under constant temperature on different thicknesses of 304 stainless steel in various concentrations and types of alkali metal chloride salts. Through thermal microscopy scanning and XRD experiments, the composition, characteristics, and microscopic morphology of corrosion products on stainless steel flakes are determined to find out the corrosion mechanism of stainless steel flakes in solution alkali metal chloride salts. The results show that in a water bath at 80 °C, alkali metal chlorides weaken the corrosion resistance of the stainless-steel sheet by destroying the integrity of its reticular structure, thus promoting the chemical reaction between the iron contained in the stainless steel and other elements to generate various types of corrosion products rich in iron. Meanwhile, among various alkali metal chloride salts, the catalytic effect of saturated CaCl2 on the corrosion of 0.1 mm and 0.01 mm stainless steel sheets at 80 °C is the most significant.