Improving the wear and corrosion properties of laser cladded Ni-based composite coatings via regulating in-situ TiB2-TiC

Abstract

In-situ ceramics have been proven to be efficient reinforcing phases, which possess a pure and stable bonding interface within the metal matrix composite (MMC). To clarify the effect of in-situ binary ceramics on Ni-based coatings fabricated by laser cladding, varying contents of TiB2-TiC (from 10 wt% to 35 wt%) are synthesized as reinforced phases via regulating the content of pure Ti, B4C, and Ni-coated graphite. It is found that the porosity defects are reduced when the designed content of TiB2-TiC exceeded 15 wt%. Notably, the concentrated growth of TiB2-TiC is observed due to the decreased nucleation rate with the increased content of ceramic phases. Consequently, the sizes and contents of TiB2-TiC are increased, leading to a gradual transformation from fine blocky shapes into larger petal-like particles. Furthermore, the wear spalling Ni-based composite coating was reduced since larger petal-shaped TiB2-TiC particles serve as supporting skeletons. Among them, the C30 sample (with 30 wt% TiB2-TiC) exhibits the smallest wear volume in reciprocating sliding friction tests, which is approximately 46.4 % lower than that of the original Ni-based coating. In addition, TiB2-TiC could prevent the diffusion of OH− and Cl− in the corrosive solution, and the corrosion current density of the MMC coatings with in-situ TiB2-TiC is reduced by an order of magnitude compared to the Ni-based coating. This study provides guidance for the preparation of MMC coatings with excellent wear and corrosion resistance.