Materiali ceramici a valenza industriale - Relazione tecnica sui test d'usura

The dry sliding behaviour of a ZrB2 and a ZrB2-SiC composite was evaluated in a disc-on-pin configuration. ZrB2 pins were coupled to ZrB2, ZrB2-SiC and Al2O3 discs. Moreover, Al2O3 pins were coupled to ZrB2 discs to study the influence of the different contact conditions. Friction and wear rate were compared to those of a self-mated Al2O3. The steady state friction of the self-mated ZrB2 was about 1.1 compared to 0.7 of the self-mated Al2O3. Coupling the ZrB2 pins to the ZrB2-SiC discs or Al2O3 discs did not significantly reduce the friction coefficient; the same high value was measured when Al2O3 pins were coupled to ZrB2 discs. The ZrB2-based discs worn about three order of magnitude more than the self-mated Al2O3 discs. The ZrB2 pin wear rate was almost double when coupled to the ZrB2 or ZrB2-SiC disc than when coupled to the Al2O3 disc. The Al2O3 pins showed the lowest wear rate when coupled with the Al2O3 disc and a slightly higher wear rate when coupled to ZrB2 discs. The contact condition, disc or pin, had a higher influence on ZrB2 than on Al2O3