Coatings by laser cladding

There are three processes, where solid feedstock materials are used for surface modification processes with a laser: cladding, dispersing and alloying. Currently, in industrial practice laser cladding with a history of about 30. years is by far the most important of these processes and is predominantly applied for wear protection of mechanical parts. For hard phase-containing coatings, laser cladding is performed as a one-step process. A metallurgical bonding of the coating to the substrate is created, but dilution of substrate elements into the coating is kept as low as possible. In the historical development different types of laser have been used, diode laser are currently the most important type. Coating properties can be improved and productivity can be increased by hybrid technologies, e.g. by the additional use of inductive heating. There are innumerable combinations of hard phases, also in respect of their concentration, size and morphology, and metallic binder alloys. However, coarse cast and spheroidized tungsten carbides and blends with Ni-based and Co-based alloys have gained the highest importance. Fine grained structures can be achieved by the use of cubic hard phases on the base of TiC and VC.