Abstract: HA coatings were deposited onto TiAl6V4 substrate by microplasma spraying (MPS) as well as by atmospheric plasma spraying (APS). The morphology, phase compositions and crystallinity of the coatings were studied by means of optical, scanning electron microscopy and X-ray diffraction. The results show that the decomposition of HA can be significantly reduced during MPS than during APS. In addition to HA, only β-TCP and amorphous phases form during MPS. MPS coating crystallinity is clearly influenced by spray distance. Shorter spray distances (<80mm) result in high crystallinities, which are much higher than those of APS coatings. But with a spray distance of 130 mm, the coating crystallinity is very low. β-TCP, α-TCP, TTCP, CaO and amorphous phases form during APS. Compared with APS coatings, MPS coatings are less decomposed during spraying, due to the less overheating of HA particles.

Key words: hydroxylapatite, microplasma spraying, coating