Feasibility study of adding buffer layers for the laser deposition of high-ceramic content (TiB + TiC)–Ti coatings using B4C/Ti powders

Wear-resistant coatings have been widely used to improve the tribological properties of titanium-based parts, structures, and tools, such as engine blades, tanker trucks, heat exchangers, and drilling bits, in the aerospace industries, chemical industries, offshore engineering, and oil and gas engineering. In the view of the applications in the fabrication of wear-resistant coatings on titanium substrates, the laser deposition of ceramic reinforced titanium coatings is widely investigated. Reported investigations show that the (TiB + TiC) reinforced titanium matrix composite coatings with high ceramic content can significantly increase the hardness and wear resistance. However, due to the low compatibility between ceramics and titanium, a high ceramic content always leads to a relatively low bonding quality and the generation of cracks and defects. To fabricate the high ceramic content (TiB + TiC)–Ti coatings, this study investigates the feasibility of adding buffer layers for the first time. The phase compositions, microstructures, element compositions, and mechanical properties of the different layers have been analyzed by XRD, SEM, EDS, and instruments to measure hardness and wear resistance. The deposited gradient coatings are free of fabrication defects with good metallic adhesion with titanium substrates. In the center of the top coating layers, the extremely high-volume content of ceramic reinforcements (including the major component of TiB and TiC and the minor component of TiB2, B25C, and unreacted B4C) leads to high microhardness and excellent wear resistance. These results suggest that adding buffer layers is a feasible method to fabricate high-ceramic content coatings on titanium-based structures and tools.