EFFECTS OF CO2-LASER SURFACE HARDENING IN THE UNLUBRICATED WEAR OF DUCTILE CAST-IRON AGAINST ALUMINA

The microstructure of a ferrito-pearlitic ductile cast iron has been m odified by CO2 laser surface hardening. Analysis of the laser-processe d surfaces showed a dramatic increase in microhardness. Dry sliding we ar of laser-treated specimens against an alumina counterbody has been investigated by ''ball-on-disk'' testing. The evolution of the wear co efficient, as well as metallographic observations, revealed an oxidati onal wear mechanism. The wear resistance of the laser-treated samples was significantly enhanced. The laser-treated cast iron has a better r esistance to abrasion and plastic enhanced. The laser-treated cast iro n has a better resistance to abrasion and plastic deformation. The imp rovement of the wear resistance was due to the fine and homogeneous mi crostructure produced after laser-treatment. Wear plots showing the ev olution of wear coefficient with normal load, sliding velocity, and hu midity have been established. The wear of the laser-treated cast iron is not influenced by the variation of operating conditions (normal loa d, sliding velocity, and relative humididy).