Effect of ZrO2 additions on densification and mechanical properties of modified resistant porcelains using economic raw materials

The aim of this work was to determine the effect of temperature and ZrO 2 addition on sintering and mechanical properties of porcelain prepared from local Algerian raw materials. Based on a preliminary work, the new selected composition was 25 wt.% feldspar, 25 wt.% quartz, and 50 wt.% kaolin (25 wt% kaolin Algerian nano-sized halloysite type + 25 wt% kaolin Tamazart) and containing different contents of ZrO 2 (5 and 8 wt%). It should be noticed here that all these used native raw materials are not against the environment. Samples were prepared by sintering the mixture at different temperatures (1000–1250 °C). Subsequently, the obtained phases in the elaborated samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy analyses, Raman spectroscopy, and SEM analysis. The optimum sintering conditions gave a relatively high density (2.47 g/cm 3 ) and relatively excellent mechanical properties for these samples. The obtained porcelains were mainly constituted of quartz, mullite, and amorphous phases. The three-point flexural strength (3PFS), Vickers microhardness (VMH), and apparent porosity (P A ) of porcelains sintered at 1200 °C were 132 MPa, 13.08 GPa, and 1.6%, respectively. The flexural strength value of this specimen is significantly higher than those reported for conventional porcelains (ranged between 60 and 80 MPa) even though for certain commercialized dental porcelains.