Spark plasma sintering of alpha/beta-SiAlON ceramic end mill rods: Electro-thermal simulation, microstructure, mechanical properties, and machining performance

Spark plasma sintering (SPS) is a highly efficient method for the preparation of alpha/beta-SiAlON ceramics. However, the rapid preparation of large-scale alpha/beta-SiAlON ceramic components with reliable mechanical properties is difficult via SPS due to their near-insulating properties. In this study, high-performance alpha/beta-SiAlON ceramic end mill rods with large aspect ratios were successfully prepared via SPS. Two different types of sintering processes (namely vertical-round-rod (VRR) and horizontal-square-rod (HSR) processes) were developed, and their effects on the phase composition, microstructure, mechanical properties, and machining performance of the alpha/beta-SiAlON ceramic end mill rods were studied. The electric and temperature field distributions during sintering were studied through an electro-thermal simulation. The simulated and experimental temperature distributions are in good agreement. In contrast to VRR samples, HSR samples with a small axial size show a uniform temperature distribution and satisfactory microstructures within a certain range of dimensions as well as the expected phase composition; furthermore, elongated beta-SiAlON grains are preferentially oriented in the direction perpendicular to the sintering pressure direction. As a result, the HSR samples exhibit better mechanical properties and machining performance than the VRR samples.

Automated summary

In this study, high-performance alpha/beta-SiAlON ceramic end mill rods with large aspect ratios were successfully prepared via Spark plasma sintering (SPS). Two different types of sintering processes (vertical-round-rod and horizontal-square-rod) were developed and compared, and it was found that the horizontal-square-rod samples showed better mechanical properties and machining performance due to their uniform temperature distribution and preferred grain orientation.