Corrosion Behavior of Silicon Nitride Ceramics in Aqueous Solutions (Part 2)

Abstract

Corrosion behavior of gas-pressure sintered silicon nitride with the additions of yttria and alumina was investigated in boiling sulfuric acid. In the corrosion test ranging from 3 to 12N for 1h, the maximum weight loss was found at the concentration of 3N. The weight and strength of the specimens gradually decreased with time exposed for the corrosion test, although a rapid decrease in strength occurred in the initial stage of corrosion. A gradual decrease in strength with time could be attributed to the growth of corroded layer. The strength was approximately held constant when the corroded layer thickness, which was determined from the depth of the layer with a different color, was less than 100μm; the strength was strongly dependent on the thickness of the corroded layer beyond 100μm.