Currently, intricate problems of surface treatment can be solved through precision cladding using advanced laser technology. However, the high price of CO2 and Nd:YAG lasers, the effort required for beam guiding as well as the low absorption of the CO2 irradiation limit the applications. In light of this, a new and promising solution is provided by the current availability of high-power diode lasers: it makes laser cladding essentially more efficient and practicable.
By one-step cladding with a 1.4 kW diode laser, protection layers of Co-based alloys, a carbide-reinforced Ni alloy, and alumina can be deposited onto steels and aluminium-based light alloys.
The width of single tracks is up to 5 mm, with a layer thickness of 0.2 to 1.5 mm. For tasks of repair and remanufacturing, multilayer stacking of metal alloys can be easily performed. The layers are dense and with a fine dendritic structure and are metallurgically or chemically bonded to the substrate.
For the Co- and Ni-based alloys, the cladding rate is 0.5 kg/h. This high value is due to the higher absorption degree of the 0.94 μm diode irradiation compared to the 10.6 μm CO2 irradiation. Comparison of the cladding results for tracks produced with CO2 and diode lasers has shown that 1.4 kW diode power is equivalent to 3.9 kW CO2 laser power. Thus, the absorption obviously increases by a factor of at least 2.5. In addition to the higher efficiency, the resulting tracks appear to be of better quality.
Thus far, examples of applications are the repair of wear-damaged punches and dies, and the hardfacing of engine valves.