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

Abstract

A study was conduced on the effect of crack size or surface roughness on the tensile strength of ceramics used to the lower-quality fueled gas turbine or diesel engine. In general, removal of the surface defects and/or forming of the correct shape of the ceramic materials requires machining of the part at enormous cost and a large expenditure of time. Even if the materials were carefully machined, the fact that their surfaces would still be extensively attacked by corrosive ashes causing considerable damage, makes such an effort seemingly useless. The experimental results show that in the case of partially stabilized zirconia at 650°C°C, the existence of artificial corrosive ash containing vanadium pentoxide and sodium sulphate on flaws significantly enhances the tensile strength of the ceramic. However, in the case of silicon carbide at 900°C, no remarkable differences could be found between the results with or without corrosive ash. In this experiment, the hardness indentation method was used as a quantitative tool to simulate mechanical surface defects.