Spark plasma sintering of a/B-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 a/β-SiAlON

ceramics. However, the rapid preparation of large-scale a/β-SiAlON ceramic components with

reliable mechanical properties is diffcult via SPS due to their near-insulating properties. In this

study, high-performance a/β-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 aB-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 B-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.