Using statistical techniques to model the flexural strength of dried triaxial ceramic bodies

Due to the simplicity of experimental determination and sensitivity to raw materials and/or processing changes, bending strength is frequently used as a quality control parameter in the development and manufacture stages of floor and wall ceramic tiles. This configures the ideal scenario to apply the techniques of experiments design, often used in a lot of other areas, to model the dry bending strength of such ceramics bodies. In the present study, three different raw materials, namely a clay mineral, sodium feldspar and quartz, were selected and eight formulations thereof (triaxial compositions) were used to obtain the limiting conditions of the experiments design. Those formulations were then 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) and characterization. The use of this methodology enabled the calculation of a regression model relating the dry bending strength with composition. After statistical analysis and a verification experiment, the significance and validity of the special-cubic model obtained was confirmed.