Study on Wear of a Ceramics/Metal Composite

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In order to understand characteristics of friction and wear of composites, a composite slider consisting of ceramics (MnNiO ceramics) and metal (CoNbZr amorphous metal) is tested against a rotating disk made of zirconia. The results show that gross wear rate of composites is governed by the inverse rule to some extent. The inverse rule is useful for material design since it is possible to predict gross wear volume of composites by using the this rule.On the other hand, when a composite material is worn out, an uneven worn surface with a level difference is generally formed between constituents. It is necessary to clarify the mechanism of formation of the uneven surface in order to understand the mechanism of wear of composites. We carry out wear tests of composites with respect to the uneven surface, and then take applied load and sliding velocity as parameters of test conditions. It is observed that the shape and the level difference between ceramics surface and metal surface strongly depend on the sliding conditions. The notable features are as follows: (1) With the increase of pressure, the level difference between constituents becomes large. (2) In case of large pressure and high sliding velocity, a shape like a hawk nose appears at the leading edge of ceramics surface and a relatively deep groove at the leading edge of metal surface. In this study, the mechanism of formation of the uneven surfaces is also investigated theoretically by using the theories of elastisity and heat conduction. It is obtained from the numerical analysis that elastic deformation of constituents and local reduction in strength due to frictional heating play important roles in forming uneven worn surfaces of composites.