Mesoporosity, thermochemical and probabilistic failure analysis of fired locally sourced kaolinitic clay

A dense and mesoporous ceramic from locally sourced Nigerian clay under fracture-strength test were produced and the reliability analysis of the fractured strength was conducted using a three-parameter Weibull probability distribution. The samples were prepared by addition of starch (0-20wt%), pressed at 60 MPa and fired at 1300 °C. The as-received Nigerian clay, dense and porous ceramic were characterized using XRD, XRF, TGA/DTA, PSD, multi-point BET and FESEM. The fracture strength of the samples (33 each) was determined using a three-point bending test. The fracture strength data were analyzed using three-parameter Weibull probability distribution. From the characterization results, a mullite ceramic formed at a sintering temperature of 1300 °C. The threshold strength for the three-parameter Weibull provides the strength below which the dense and the porous ceramic will not fail. The Weibull moduli of the ceramics at different starch compositions show that failure modes in these materials are not identical. The Weibull modulus increases with increase in percentage starch from 0% to 15%. However, the value decreases with 20% starch addition. Reliability analysis provides a detailed interpretation and assessment of the fracture strength of the porous ceramics.