Abstract:To avoid high crack sensitivity of TiB-Ti composite coating during laser cladding process, network-like structure composite coating was fabricated with laser in-situ technique on titanium alloy using 5 μm TiB₂ powder as the cladding material. The microstructure, phase structure and properties of the coatings were analyzed by SEM, XRD, EPMA, TEM, hardness tester and fretting wear meter. It was observed that the outer ring of the network-like structure was mainly TiB strengthening phase, while the inner ring was α-Ti grain, and the interface between TiB and Ti matrix was very clean and had a consistent orientation relationship. The hardness of the cladding layer with network-like structure gradually decreased from the surface toward the interface, but the average hardness was nearly two times that of the substrate. In the fretting wear test, it was found that the wear resistance of the cladding layer with network-like structure was larger than that of the substrate under low load (40 N). The results revealed that the hardness and fretting wear resistance of the titanium-based composite coating could be improved by the introduction of network-like structure.

Key words: laser cladding forming; titanium matrix composite coating; TiB-Ti; fretting wear