Mechanical and tribological properties of Mo2BC ceramic toughened by copper
High strength and toughness Mo2BC/Cu ceramic matrix composites were fabricated by in-situ reaction fast hot-pressing sintering method.The effect of Cu content on the microstructure,mechanical and tribological properties was investigated.The wear and toughening mechanisms of the composites were discussed as well.The results show that Cu is distributed uniformly in the Mo2BC matrix and plays a role of refining grains.The maximum mass fraction of Cu addition is confirmed to be7.5％for Mo2BC/Cu composites.The flexural strength and fracture toughness of as-sintered composites increase with the increase of Cu content.When the mass fraction of Cu is 7.5％,the flexural strength and fracture toughness of Mo2BC/Cu composites have the highest values of 625.1 MPa and 7.4 MPa·m1/2,which increase by 24％and 62％compared with that of Mo2BC ceramic,respectively.Plastic deformation,grain pull-out,crack bridging and deflection are the main toughening mechanisms.The addition of Cu significantly improves the friction and wear properties of Mo2BC/Cu composites.When the mass fraction of Cu is 2.5％,the friction coefficient of the composite can be as low as 0.36,showing that the wear loss is the lowest and the wear resistance is the best.The main wear mechanisms are slight two-body abrasion and oxidation wear.
ceramic matrix compositesMo2BChigh strength and toughnessfriction and wear
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