Аңдатпа
Both zirconia and tungsten carbide are known for hardness, fracture toughness, and wear resistance. However, when joined together by means of powder metallurgy, the mutual influence of both substances may lead to enhancement of the refractory matrix, which can be used for a special composite additionally reinforced with diamond. The research involved an elecrtoconsolidation apparatus for sintering at relatively low temperatures and nanopowders to keep submicron structural features of the sintered composites. In this work, the results for WC addition up to 50 wt.% to zirconia are presented demonstrating increase of fracture toughness by 63% compared to pure zirconia and by 2% compared to pure binderless WC. On the other hand, addition of few per cent of zirconia to WC-Co system increased the fracture toughness by 9%, which was by 63% higher than for pure zirconia. In the case of hardness, it decreased by 9% when 10 wt.% of WC were added to zirconia, which was by 49% smaller than that of pure binderless WC. In turn, addition of ZrO2 to the WC-Co matrix reduced its hardness by 6% only, keeping it at the level of pure zirconia hardness. After preliminary tests, a matrix was selected to produce a composite reinforced with diamond grits, and wear tests for this material were carried out. The results of specific wear rate were of the order of 10-13 m3·(N·m)-1 corresponding with the range of anti-wear materials. High wear resistance may be attributed to the known phenomenon of the stress-induced phase transformation of zirconia, but also to zirconia-promoted better densification of the WC-Co powder system during the sintering process.