The properties of feldspathic dental porcelain from Tanzanian aluminosilicate materials

Abstract

Kaolin and quartz from Pugu and feldspar from Morogoro were used to produce feldspathic dental porcelain bodies. Mineralogical results from XRD revealed the presence of kaolinite, illite, microcline and clinochlore in the kaolin samples; albite, microcline, sanidine in the feldspar samples and only silica in the quartz samples. The chemical results studies by XRF revealed the presence of BaO, SiO2, Al2O3, TiO2, Cr2O3, MnO, K2O, CaO, Cl, SO3, MgO, Na2O, and Fe2O3 in varying proportions. Particle size distribution of all the raw materials were determined and particles <63 μm were used for preparation of batches. The batches of different compositions with ranges: quartz (12-22%), feldspar (75-88%) and kaolin (3-5%) were fired at 1100, 1200 and 1250 oC, and the developed properties were tested. The physico-mechanical properties studied exhibited volumetric shrinkage between 2 and 55.17%, open porosity between 6.67 and 40.00%, water of absorption between 7.1 and 40%, bulk densty of 1.43 – 5.68 g/cm3, and compressive strength at 0.13 - 32.25 MPa. The optimal firing temperature for the best results was found to be 1250 oC. The results obtained indicate that kaolin and quartz from Pugu and feldspar from Morogoro are potential raw materials for the production of dental porcelain.