Abstract:
The Ni
3Al based composite coating was prepared by plasma spraying. The influences of 316L and Al
2O
3 counterpart material on the tribological behaviors of the coating at 25 ℃ to 800 ℃ were investigated. The results showed that under the synergistic action of precipitation of soft metal Ag, brittle-plastic transformation of BaF
2/CaF
2 and tribo-oxidation, the friction coefficient and wear rate of Ni
3Al/316L and Ni
3Al/Al
2O
3 tribo-pairs had the similar trend with the increase of temperature, and the Ni
3Al/Al
2O
3 tribo-pairs had better performance. At 25 ℃, the coating coupled with 316L adhesive wear and abrasive wear occurred, while brittle peeling and abrasive wear occurred when the coating coupled with Al
2O
3 of high hardness, resulting in rougher coating surface and higher friction coefficient. However, the thermal conductivity of Al
2O
3 was low, and a large amount of frictional heat generated under the action of high contact stress cannot be dissipated rapidly. The stripped material was stored in the peeling hole or adhered to the worn surface, resulting in a lower wear rate of Ni
3Al/Al
2O
3 friction pair. At 200~600 ℃, the Al
2O
3 of high hardness had a strong plough effect on the coating, resulting in a higher friction coefficient of Ni
3Al/Al
2O
3 friction pair. Meanwhile, Al
2O
3 promoted the plastic deformation of the coating, inhibited the fatigue stripping of the material, and made the coating with lower wear rate. At 800 ℃, the high hardness of Al
2O
3 promoted the formation of a lubrication film with high oxide content on the worn surface, so that the Ni
3Al/Al
2O
3 friction pair had low friction coefficient but high wear rate.