Fig. 1 shows the morphology of HA/YSZ/Ti-6Al-4V composite powders prepared by slurry mixing method. EDX analysis of the composite powders shows that thesmall white particles are YSZ and the gray spherical particles are HA (Ca and P elements). Ti-6Al-4V powders are fully coated by HA powders and YSZ particles. The advantages of using HA and YSZ coated Ti-6Al-4V composite powders are to ensure uniform phase composition within the plasma sprayed coating, and prevent the Ti alloy from oxidation during plasma spraying. The composite powders have a particle size of 45–106 mm and this particle size range is favorable to plasma spraying, as there would be uniform melting of the powders in the plasma flame. Fine powders o30 mm may have difficulty penetrating the plasma column to get into the hot zone, while large particles (> 120 mm) are unlikely to be melted.
Fig. 1. Morphology of HA/YSZ/Ti–6Al–4V composite powder prepared by slurry mixing method.
The XRD pattern of the composite powders is shown in Fig. 2. It is clear thatwell-crystallized HA and YSZ coated Ti–6Al–4V powders are obtained after the sintering and consolidating processes, indicating that the composite powders consist of tetragonal/cubic zirconia (t-ZrO2+c-ZrO2), highly crystalline HA and oxide-free Ti peaks. Moreover, there was no sign of decomposition of HA, and the reaction of phases is not observed after debinding and consolidation.
Fig. 2. XRD pattern of HA/YSZ/Ti–6Al–4V composite powder.
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