Abrasive wear behavior of MoSi 2-Nb composites

Abstract

Previous research at the US Bureau of Mines has shown monolithic MoSi[sub 2] to be extremely wear resistant in a severe two-body abrasive environment. MoSi[sub 2] is attractive as a wear-resistant material because of its high hardness, high elastic modulus, low density, and excellent resistance to elevated temperature oxidation and hot corrosion. As with most intermetallic compounds, the low temperature fracture toughness is poor; however, reinforcing MoSi[sub 2] with SiC or Nb, for instance, has resulted in improved fracture toughness. It is also known that the wear rate of many materials can be reduced by a factor of up to ten by the introduction of a suitable reinforcement phase. While soft ductile phases have been effective in improving the fracture toughness of brittle matrices, it is intuitive that the addition of these phases should have a negative impact on wear resistance, i.e., the softer phase will wear at an accelerated rate. This study has been undertaken in order to make a preliminary assessment of the effect of adding a ductile reinforcement (Nb) on the abrasive wear resistance of MoSi[sub 2]. The wear behavior of the MoSi[sub 2]-Nb composites produced for this study are compared with the behavior of monolithic MoSi[submore » 2], Nb, aluminides, and ceramics.« less