Influence of ZrB2 addition on microstructural development and microhardness of Ti-SiC clad coatings on Ti6Al4V substrate

Abstract

The microstructural features and microhardness of ZrB(sub2) reinforced Ti-SiC coatings on Ti-6Al-4V substrate were studied.The deposition of these coatings was achieved via laser cladding technique. A 4.0 KW fiber delivered Nd: YAG laser was used to deposit the coatings on the titanium substrate at a laser power of 700 W and laser scan speed of 0.8 m/min. An initial Ti-SiC coating was deposited with no ZrB2 addition followed by deposition of two other coatings with the incorporation of ZrB(sub2) powder at 5% and 10% wt. The coatings were examined using scanning electron microscope (SEM) coupled with Energy dispersive spectroscopy (EDS). SEM images of Ti-SiC-ZrB(sub2) coatings revealed good metallurgical bond between the coatings and the substrate, and also, a significant increment in dendritic formation and inter-dendritic eutectics during solidification within the á-Ti matrix, exhibiting the presence of newly formed phases as the weight percentage of ZrB(sub2) increased. Back scattered electron (BSE) images also showed the dissolution effect of SiC particles, as the particle-matrix bond strength is influenced by ZrB2 addition. Furthermore, the microhardness of the Ti-SiC coating was enhanced with increasing ZrB(sub2) weight percentage. XRD analysis revealed dominant compounds formed during laser material processing. This study deepens the knowledge of possible microstructural features associated with Ti-SiC-ZrB2 cermet coatings.