Corrosion of Electroconductive AlN-SiC-MoSi2 Ceramic Composite in sodium hydroxide aqueous solution

Corrosion behavior of an electroconductive AlN-SiC-MoSi2 ceramic composite, hot-pressed with the addition of yttrium oxide (Y2O3) as sintering aid, was studied in 4 M sodium hydroxide (NaOH) solution at room temperature, 40°C, and 70°C, up to 400 h. The measured weight loss and the degree of dissolution of each element (Si, Al, Mo, Y), analyzed in the solutions after the tests, indicate that the corrosion follows linear kinetics (i.e., the rate-controlling step is a chemical reaction). At each testing temperature, grain boundary silicatic compounds were the first and foremost leached phases. Among the main constituents of the composite, aluminum nitride (AlN) was the phase that mainly reacted, particularly at 40°C and 70°C. Molybdenum disilicide (MoSi2) and silicon carbide (SiC) were less affected by corrosion. Corrosion does not influence the electrical resistivity of the composite.