Friction and wear behaviors of Sialon–Si3N4 graded nano-composite ceramic materials in sliding wear tests and in cutting processes

Sialon–Si3N4 graded nano-composite ceramic materials were fabricated by hot-pressing. Sliding wear tests against Inconel 718 were conducted on these graded ceramic composites using the pin-on-disk method. The friction coefficient and the wear rate were measured. The tribological and wear behaviors were discussed in relation to its mechanical properties and microstructure. The results showed that the graded material exhibits good mechanical properties which were attributed to its synergistic strengthening and toughening mechanisms induced by the graded compositional structure and the addition of nano-sized particles. The friction coefficient and the wear rate of the reference material were higher than those of the graded material. Both the friction coefficient and the wear rate of the composites decreased with the increase of the sliding speed. The wear mechanisms of the composites were adhesion, chipping and abrasion in sliding wear tests. The cutting performance and wear mechanisms of the graded tools were also investigated via turning of Inconel 718. The graded tools showed better cutting performance compared to the homogeneous ones, as a result of their enhanced mechanical properties, higher abrasion and fracture resistance. The main wear mechanisms in the machining tests were adhesion, abrasion and flaking.