Effect of Quartz Particle Size on Sintering Behavior and Flexural Strength of Porcelain Tiles Made from Raw Materials in Uganda

The presence of quartz particle size (> 45 µm) has a deleterious effect on physio-mechanical properties of porcelain tiles. The effect is due to various factors including microstructure (pore) after sintering. This study aims at investigating the effect of quartz particle size (QPS) on sintering behavior and flexural strength of porcelain tiles made from raw materials in Uganda. Samples containing fine, medium and coarse QPS were pressed at 40 MPa, fired from 1150-1350°C at a firing rate of 60°C/min, and soaked for 1 hour. The influence of QPS on linear shrinkage, water absorption and flexural strength was determined. Microstructure analysis of the fired samples was carried out using Scanning Electron Microscope (SEM), and phase identification was studies using x-ray diffraction. The SEM showed large-interconnected pores for coarse QPS, and smaller-isolated pores for fine QPS. At optimum sintering temperature, samples with fine, medium and coarse QPS had values of 0.47, 0.9 and 7.1% water absorption respectively. Pressed tiles with ≤5% water absorption are classified as group BIa(porcelain tiles) and those > 0.5-≤3% as group BIb suitable as floor or wall tiles (ISO 13006). Also, the average flexural strength of 33, 18 and 8 MPa was exhibited by samples with fine, medium and coarse QPS respectively. The results indicate that only samples with fine and medium QPS satisfy the requirement ≥ 35±2 MPa and > 12 MPa for floor and wall tiles respectively (ISO 13006).