Effect of Crack Size on the Tensile Strength of Ceramics in a High-Temperature Corrosive Environment

Abstract

A study was conducted on the effect of crack size or surface roughness on the tensile strength of ceramics used for lower quality fueled gas turbine or diesel engines. In general, in order to remove surface defects or to form the correct shape, ceramic materials have been machined at great cost and with much waste of time. Even if the materials were carefully machined, their surface would be attacked, with considerable damage, by corrosive ashes. The experimental results show that in the case of partially stabilized zirconia at 650°C the existence of artificial corrosive ash containing vanadium pentoxide and sodium sulphate on the flaws significantly enhances their tensile strength. However, in case of silicon carbide at 900°C, no remarkable difference could be found between the results with and without corrosive ash where the hardness indentation method was used as a quantitative tool to simulate mechanical surface defects.