Vacuum Tribological Properties of Fe₃Al/WS₂ Composites

Fe₃Al based composites with 10%, 20% and 30% WS₂ by weight percent were produced by hot press sintering method. The composition and structures of samples were analyzed using X-ray diffraction and scanning electron microscopy The tribological properties of samples were tested under 4×10^-4 Pa vacuum using a home-built vacuum tribometer. The results show that the addition of WS₂ could obviously decrease the friction coefficient of Fe₃Al intermetallic, and the friction coefficient of the composites was nearly independent of the WS₂ content from 10% to 30%. The wear rate decreased gradually with increasing WS₂ amount. Impressively, the wear rate of the Fe₃Al-30%WS₂ composite was about one order of magnitude lower as compared to that of the Fe₃Al intermetallic. The friction coefficient and wear rate of the composites were influenced by applied load and sliding speed. The worn surfaces of the Fe₃Al intermetallic were rough with a lot of delamination pits and traces, which was characteristic of severe fatigue wear. The wear mechanism of the Fe₃Al-10%WS₂ composite was abrasive wear and fatigue wear. The Fe₃Al-20%WS₂ and Fe₃Al-30%WS₂ composites demonstrated smooth worn surface with appearance of mild fatigue wear. It could be concluded that the addition of WS₂ to Fe₃Al could improve the tribological performance under vacuum.