Abstract
The intermetallic compound coating made by a laser and plasma hybrid spraying has been studied. The laser plasmahybrid spraying system (LPHS) was constructed with a 5 kW CO2, laser and a low pressure plasma spraying equipment. In this system, the plasma sprayed layer was rapidly remelted and solidified by the CO2 laser irradiation. It is possible to synthesize intermetallic compound coatings from the simply mixed powder using this system. To improve the cavitation erosion resistant of Ti-alloy, a NiTi coating on the Ti-alloy is investigated. The NiTi intermetallic compound is known as an erosion resistance material. In a case of only plasma spraying process, Ti and Ni particle were separated mutually in the coatings, but by the laser plasma hybrid spraying, Ni-Ti intermetallic compound was formed in the coating. And the coating was joined metallurgically with substrate and contained few defects. The ratio of phases, such as NiTi, NiTi2 and Ni3Ti was varied with the laser irradiation conditions and powder mixed ratio.
To evaluate the erosion resistance of coatings, vibratory cavitation erosion was evaluated. The cavitation erosion resistance of the coatings was about 70 times as much as Ti-6Al-4V substrate.
