Study on the effect of laser post-treatment on the properties of nanostructured Al2O3-TiB2-TiN based coatings developed by combined SHS and laser surface alloying

Nanostructured, hard and wear resistant composite coatings of Al2O3, TiB2 and TiN were formed on a low carbon steel (AISI 1025) substrate by combined self-propagating high-temperature synthesis (SHS) and laser surface alloying (LSA). A precursor powder mixture of Al, TiO2 and hBN preplaced on the substrate surface underwent SHS at the high temperatures induced by the laser incidence. The products of SHS were subsequently laser alloyed onto the substrate to form the coatings. The high power laser beam was again passed over the coatings to re-melt the coating top layer. This laser post-treatment caused distinct enhancements in microhardness and tribological performance by the modification of the microstructure of the top portion of the coatings.