Effect of α-/β Si3N4-phase ratio and microstructure on the tribological behaviour up to 700°C

The present work analyses the effect of mechanical and microstructural characteristics in the tribological behaviour of Si3N4 materials. Special attention was given to the alpha/beta phase ratio and the coarseness of the microstructure. Wear experiments were performed in a pin-on-disc tribometer using self-mated Si3N4 pairs varying the sliding speed and the test temperature. In the case of fine and medium microstructures, fracture and delamination was the main wear mechanism while for heterogeneous coarse material deformation related to intergranular microfracture was prevalent. The latter present higher wear rates at room temperature and low sliding speed but showed the best wear resistance when either sliding speed or temperature were increased. (C) 2000 Elsevier Science S.A. All rights reserved.