Simultaneous optimization of linear firing shrinkage and water absorption of triaxial ceramic bodies using experiments design

In the development and manufacture stages of floor and wall ceramic tiles, firing shrinkage and water absorption are basically determined by the combination of raw materials and frequently used as quality control parameters. This configures the ideal scenario to apply the techniques of experiments design, often used in various other areas, to model those properties of such ceramics bodies. In the present study, 10 formulations of three different raw materials, namely a clay mixture, potash feldspar and quartz (triaxial compositions) were selected and used in the experiments design. Those formulations were processed under conditions similar to those used in the ceramics industry: powder preparation (wet grinding, drying, granulation and humidification), green body preparation (pressing and drying), firing (at 1170 °C) and characterization. With the experimental results, regression models were calculated, relating linear firing shrinkage and water absorption with composition. After statistical analysis and verification experiments, the significance and validity of the models were confirmed. The regression models can then be used to select the best combination of those three raw materials to produce a ceramic body with specified properties.