Development and microstructural analysis of beta-SiAlONs produced by spark plasma sintering

Abstract

The development of refractory material (β-SiAlON) with excellent properties, such as good mechanical integrity and wear resistance is vital in order to ensure that the product will perform satisfactorily in service. In this study, ceramic powders, namely: β-Si3N4, AlN, Al2O3 and Y2O3 were sintered by using the spark plasma sintering technique, for the production of β-SiAlON. The Scanning Electron Microscopy (SEM) analysis of the β-SiAlON produced was carried out in order to evaluate the densification of the samples developed. The physical experiments were conducted using feasible combinations of the process parameters for the production of the β-SiAlON namely; the temperature, holding time, heating rate and z-value. The results obtained indicated that the sintering process parameters are critical parameters which influences the production and morphology of the β-SiAlON, hence the need for adequate process control. The optimum values of the process conditions which produced the least porosity were found to be temperature (1600 °C), holding time (5 min), heating rate (75 °C/min) and z-value (1.5). The SEM results also show the evidence of increasing densified samples with increase in the temperature, heating rate and z-value up to the optimum with significant evidence of porosity below or above these values. This work will assist material developers using the SPS technique in their quest for process control and efficiency.