SLIDING WEAR OF A PLASMA-SPRAYED AL2O3 COATING

Wear behaviours of plasma-sprayed Al2O3 coating in conformal contact s liding under dry and lubricated conditions against steel AISI D2 have been investigated under different loads at various speeds. A tangentia l impact wear model is proposed to explain the wear rise with speed an d SEM analysis is carried out to identify the wear mechanisms. The res ults indicate that the wear behaviour of the Al2O3 coating in conforma l contact differs from that in linear contact. The wear rate is lower in conformal contact in steady-wear state. Secondly, there exists a ma ximum-wear load both in dry sliding and lubricated sliding. Thirdly, t here exists a minimum-wear sliding velocity of about 1 m s(-1) and a m aximum-wear velocity of about 5 m s(-1) in dry sliding. The proposed t angential impact wear model could explain the wear rise of plasma-spra yed Al2O3 coating with the increased speed at the velocity range 1-3 m s(-1). Furthermore, in a lubricated situation, the wear of plasma-spr ayed Al2O3 is small at low velocities below 1 m s(-1), and then increa ses sharply, proportional to the kinetic energy of the moving specimen , from 1 to 2.8 m s(-1). Finally, the failure types of plasma-sprayed Al2O3 coating when sliding against steel AISI D2 in conformal contact are: plastic deformation, adhesive wear and brittle fracture.