Consolidation and mechanical properties of WC-Al2O3 composite prepared via high energy ball milling and spark plasma sintering

Abstract

The rapid sintering of WC-Al2O3 ceramic composite containing 15 wt% Al2O3 was investigated with focus on mechanical properties and consolidation using Spark Plasma Sintering (SPS). The initial WC-15 wt% Al2O3 powders were milled for 1, 4, and 10 h followed by sintering via SPS at 1550 °C. The morphology, structure and mechanical properties of the powders and sintered sample were carefully investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), laser particle size and Vickers hardness techniques, respectively. The results showed morphological modification of the WC and Al2O3 phases, accompanied by fragmentation and refinement of the composite particles. As milling time increased, the mean particle size decreased from 2.46 to 1.63 μm. Furthermore, a decrease in crystallite sizes was accompanied by an increase in micro-strain. Changes in the lattice parameters of both phases were observed. The process has the advantage of increase densification (98.84–99.65%) and decrease porosity of samples. The formation of the W2C phase was identified by XRD and the quantitative analysis showed that the percentage of W2C ranged from 1.81 to 12.47%. The ceramic composite showed a maximum Vickers hardness of 19 GPa.