Tribological characteristics of sintered tungsten cermet composites

The mechanical properties and tribological characteristics of WC based composites developed using hybrid combinations of metallic and ceramic binders as sintering agents was investigated. Co/Co-Cr-Ni and varied weight proportions of Yttria stabilized Zirconia were blended along with WC and densified using spark plasma sintering process. The microstructure, hardness, toughness, and wear properties were used to characterize the composites produced. The results indicate that the composites containing varied amounts of the metallic and ceramic binders (zirconia) can be densified using the SPS technique as the relative densities were all above 92%. However, the relative densities somewhat decreased with increase in the zirconia content. The average grain/phase size in the composites increased with increase in the zirconia content. The hardness increased with increase in the zirconia content of the composites. However there was significant improvement in the toughness with increase in the zirconia content. The coefficients of friction of the cermets ranged between 0-0.15 irrespective of the force of wet sliding utilized for the wear test. The WC-Co based cermet containing 20% Zirconia was noted to have the least coefficient of friction of all the cermets belonging to this series while in the case of the composite series based on WC-Co-Ni-Cr, the composite without zirconia had higher coefficients of friction in comparison with the other composites in this series.