Development and preliminary process design of beta-SiAlONs by the spark plasma sintering process

Abstract

There is a need for improvement in the existing ceramic-based products such as the cutting tools due to the structural failures often experienced and the increasing operational costs. The development of refractory material (β-SiAlON) with excellent properties, such as high strength and wear resistance, is vital in order to meet the service requirements. In this study, the spark plasma sintering (SPS) technique was used for the sintering of ceramic powders, namely, β-Si3N4, AlN, Al2O3, and Y2O3, during the production of β-SiAlON. The density, wear behavior, hardness, and microstructure of the β-SiAlON produced were evaluated and optimized in relation to the effect of the sintering parameters in the following range: sintering temperature (1450–1750 °C), holding time (5–10 min), heating rate (50–100 °C/min), and the z-value (0–1.5). The approach is based on the Taguchi method which uses the signal-to-noise ratio and the analysis of variance to predict the optimum sintering parameters for maximum densification, superior wear resistance, and hardness of the resulting products. Thus, the properties of the sintered materials produced via the physical experimentations were measured as the products’ quality characteristics and statistically analyzed to determine the contribution of each process parameter to the measured properties. The following are combination of optimum parameters which produced excellent mechanical properties: maximum density (1600 °C, 10 min, 75 °C/min, and 1.5), superior wear resistance (1600 °C, 7.5 min, 100 °C/min, and 0.75), and hardness (1600 °C, 5 min, 75 °C/min, and 1.5). Hence, work provides an insight into the process design and determination of the optimal combination of the process parameters for the development of β-SiAlON with excellent mechanical properties via the SPS technique.