Microstructure, Mechanical and Wear Properties of W-Si-C Composites Consolidated by Spark Plasma Sintering

Abstract

W-Si-C composites with high relative densities and good mechanical and wear properties were successfully prepared by spark plasma sintering. The influence of SiC content on the relative density, microstructure, mechanical properties and wear characteristics was investigated. The results indicated that the reaction between SiC and W at their interface produced W2C and W5Si3. SiC also reacted with oxygen impurities at the W grain boundary to form SiO2. The purification of the grain boundaries of W was carried out by SiO2 synthesis. Reactive sintering reduces the free energy of the system and facilitates the densification process of W-Si-C composites. This results in a significant increase in the relative density of W-Si-C composites, which reaches a maximum of 98.12%, higher than the 94.32% of pure tungsten. The hardness significantly increases from 4.33 GPa to 8.40 GPa when the SiC content is 2 wt% compared to pure tungsten due to the generation of the hard ceramic phase and the increase in relative density. The wear resistance of the W-Si-C composites was significantly improved with little SiC addition. The wear rate significantly decreased from 313.27 × 10−3 mm3/N·m of pure tungsten to 5.71 × 10−3 mm3/N·m of W-0.5 wt% SiC. SEM analyses revealed that the dominant wear mechanism of pure tungsten was attributed to fatigue wear, while that of W-Si-C composites was due to abrasive wear.