Microstructure and wear resistance of laser cladding nano TiC/micro TiB2/C-276 composite coatings on 316L stainless steel

Abstract

Four metal-ceramic composite coatings were prepared by laser cladding (LC) using Hastelloy C-276, nano-TiC and micro-TiB2 as raw materials to improve the surface properties and extend the service life of 316L stainless steel. The microstructure and mechanical properties were analyzed by metallographic microscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD), Vickers hardness experiments, and friction and wear testing. The TiC and TiB2 phases were detected in the coating, exhibiting homogenous distribution as their content increased. As a result, the strengthening effect of the coating was enhanced, improving microhardness relative to that of the 316L substrate. The wear test revealed that the Hastelloy coating exhibited poor wear resistance, but the addition of TiC and TiB2 particles improved the wear resistance by reducing the wear rate. The lowest average coefficient and wear rate were attained at 50% and 70% ceramic contents, respectively. However, abundant hard particles on the surface easily fell off during the wear, which further impeded the surface degradation and increased the friction coefficient.