STRENGTH OF HOT SALT CORRODED STRUCTURAL CERAMICS

Eight structural ceramics, reaction-bonded silicon carbide (RBSC), sin tered silicon carbide (SSC), sintered silicon carbide with 10% alumina (SSCA), sintered silicon nitride (SSN), 99% alumina (AX99), 95% alumi na (AX95), 94% alumina (AX94) and partially stabilised zirconia (PSZ) have been oxidised in air at 1000-degrees-C for 48h in the as-ground c ondition, and with deposits of NaCl, Na2SO4, or NaF, and the strength measured at room temperature. The strength of all the ceramics, except PSZ, was increased on oxidation, and this was progressively reduced a s the ceramic was coated with chloride, sulphate, and fluoride. The re duction in strength for RBSC, SSC, SSCA, SSN, AX99, AX95, and AX94 cor roded in fluoride was by factors of 0.70, 0.75, 0.89, 0.57, 0.86, 0.90 , and 0.75 times respectively. The predominant cause of fracture appea rs to be the result of grinding damage.