Structure et propriétés de la matrice des composites WC-W-Ni-Cu-Zn-Si renforcés avec des diamants synthétiques

Abstract
Although seems very attractive for economical reasons, the natural by synthectic diamonds replacement in the metal-diamond composites elaboration comes up against theirs less thermochemical stability. In order to avoid the possible reinforcement degradation and poor matrix-to-reinforcement bonding resulting from extensive interfacial reactions, processing temperatures below of about 1050 °C are required. On effect, the Cu-Sn-Ni binding alloys utilised in the metal-natural diamond composites elaboration by consecrated method - sintering by infiltration of loose mixture of powders, having processing temperatures of about 1150-1225°C, becomes unsuitable. The author's investigations have found as adequate for this purpose certain Cu-Zn-Si alloys (65. .70) - (25. .30) - (2.5..3.5) % having the liquidus temperatures 851..870°C, as well as a good wettability of solids. Also, certain WC-W-Ni (30. .90) - (0..40) - (3..16) % mixtures of powders ware found as appropriates. Solving Ni and, partial, both W and WC, the above mentioned infiltrating alloys act as a liquid phase and make possible the sintering process at temperatures of about 1025°C, leading to a good mechanical encapsulation of diamond grains, a fine structure of metal matrix and, consequently, to mechanical properties of the matrix comparable with those obtained with Cu-Sn-Ni binding alloys at the processing temperatures upper with about 200°C.