The effect of surface polishing on the flexural strength of anorthite-based porcelainised stoneware

Abstract

The effect of surface polishing on the flexural strength of anorthite based porcelainised stoneware was studied. The flexural strength results obtained from both polished and unpolished samples were analysed by using Weibull statistical method. The state of surfaces and microstructures of polished and unpolished samples were also characterised by profilometry and scanning electron microscopy. Typical flexural strength value obtained from anorthite based stoneware body fired at 1210 °C was about 100 MPa. The average flexural strength (σm) and Weibull modulus (m) values for as fired, ground, and ground and polished specimens increased sequentially with polishing degree. The surface roughness measurements and microstructure observations showed that the severity of the surface flaws declined as the polishing process proceeded. The obtainment of better strength behaviour with polishing was attributed to high crystalline to glassy phase ratio of the anorthite based porcelainised stoneware together with the formation of network structure of these anorthite crystals.