Investigation of the correlation between porcelain phase composition and bending strength using a Rietveld quantitative analysis

Alumina, mullite, and cordierite powder were added to a whiteware porcelain slurry and sintered at 1280 °C to investigate the correlation between porcelain composition and strength. The X-ray diffraction patterns of the sintered bodies show that no new phase was formed, and that the added material remained intact. Except for the sample group to which cordierite was added, the strength increased as the additive content increased. A Rietveld quantitative analysis indicated that the amorphous phase decreased with increasing additional alumina and mullite content, while the amorphous content remained constant regardless of the additional cordierite content. The decrease in the amorphous content increased the strength of the porcelain, which, in the case of the sample with 15 wt.% alumina, increased by 57 %. The dramatic increase in strength is attributed to the increase in residual stress due to the difference in the thermal expansion coefficient between the alumina and the amorphous phase, as well as the increased formation of mullite by the addition of alumina.