Mechanical properties and thermal expansion of clay ceramics measured on laboratory samples

Abstract

Cylindrical laboratory samples (∅11 mm) were prepared from a mixture of kaolin and clay (35 wt.%), corundum and chamotte (35 wt.%), and feldspar (30 wt.%) from a wet mass by a vacuum extruder. Other samples (cross-section 11x11 mm) were cut from the interior of the large blank. The mechanical strength, the Young’s modulus and the thermal expansion were measured on both types of the samples before and after firing. It was noted that: a) the glaze significantly influences the values of mechanical strength and Young’s modulus of the samples; b) the mechanical strength and the Young’s modulus of the green cylindrical laboratory samples may be 3 times higher than the mechanical strength and the Young’s modulus of the green samples cut from the blank; c) the mechanical strength and the Young’s modulus of the laboratory samples after high-temperature firing are 1.2-1.4 times higher than those of the samples cut from the blank interior; d) the thermodilatometric curves of both types of green samples are slightly different in the temperature intervals 20-150 °C and 450-850 °C; e) the thermodilatometric curves after high-temperature firing of both types of samples are identical.