Microstructure and Properties of HVOF Sprayed AP40 Bioactive Glass-ceramic Coatings

AP40 glass-ceramic coatings on TiAl6V4 substrate were deposited by HVOF process.The morphology,microstructure and phase compositions of the coatings were studied by means of optical,scanning electron microscopy and X-ray analysis.The effects of heat treatment on the microstructure and mechanical properties of coatings were also investigated.The tensile bonding strength of the coating was evaluated in accordance with the DIN EN 582—1994.The results show that the typical lamellar microstructures of AP40 coatings which contain little porosity and unmelted powder.The phases is made up of HA,FA,W(β-wollastonite) and so on;The spray parameters influence significantly the porosity of the coatings.A suitable heat-treatment can increase the coating crystallinity,reduce the porosities and increase the bond strength.