STRENGTHENING OF FELDSPATHIC PORCELAIN BY ION-EXCHANGE AND TEMPERING

This study investigated the effectiveness of tempering and ion-exchange treatments on crack growth and bi-axial flexural strength of seven feldspathic porcelains. The results showed that tempering treatment was more effective in strengthening porcelain than was the ion-exchange process as measured by the bi-axial flexural strength. However, the results of initial crack size induced by a microhardness tester showed that ion-exchange yielded a surface that was more resistant to crack initiation than was that yielded by the tempering treatment. EDX and microprobe analyses showed that there was evidence of exchange between Na+ within the porcelain surface and K+ from the ion-exchange agent applied on the surface.