Production of a Mullite-Zirconia Ceramic by the Plasma-Spark Method

Mullite-zircon ceramics obtained by plasma-arc sintering with an addition of Y2O3 in the range 1250 - 1450A degrees C and with and without a clay addition are compared based on crystalline phase growth, apparent density, degree of sintering, Vickers hardness, ultimate compressive strength, and the strength of the linear correlation between the degree of sintering and the mechanical properties (Vickers hardness and ultimate compressive strength). The addition of clay to the initial component mixture that is to be sintered helps speed up mullitization, while the addition of Y2O3 increases the rate of formation of the cubic ZrO2 solid solution in the product within the temperature range 1250 - 1450A degrees C. The clay addition produces specimens with the highest values for apparent density and degree of sintering, which also makes their values for Vickers hardness and ultimate compressive strength higher than the corresponding characteristics of the specimens obtained with only the Y2O3 addition. The linear correlation between degree of sintering and mechanical properties is strongest for the specimens obtained from sintered mixtures without an addition of clay.