Tribological Behaviour of TiB_2 Reinforced Cu-matrix Composites Produced by Mechanical Alloying and Spark Plasma Sintering

摘要

Elemental copper and 0.5wt% titanium di-boride (TiB_2) powders were mechanically alloyed in aplanetary ball mill with different milling duration, and sintered by spark plasma sintering (SPS). Themicrostructural analysis reveals that dispersion of TiB_2 particles in the matrix is more homogeneous onincreasing milling time. A final density higher than 96% of the theoretical one is obtained. The betterdispersion strengthening after long milling time promotes increased hardness and dry sliding wearresistance against high speed steel. The tribological behavior of all the materials is initially given bysevere adhesion, characterized by high friction coefficient and finally by triboxidation showing lowerfriction coefficient. In the case of composites a higher temperature during the sliding test is reacheddue to the lower thermal conductivity, enhancing the formation of a protective oxide layer. In metalmatrix composites (MMC’s) the TiB_2 particles and the harder oxide debris promote two body abrasion,responsible of the higher friction coefficient compared to un-milled copper.