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4823 |
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Influence of HA microstructure on layer build-up coatings by cold spray |
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Sergi Dosta* / Thermal Spray Centre (CPT) - Universitat de Barcelona, SPAIN A. Martin / Thermal Spray Centre (CPT) - Universitat de Barcelona, Spain N. Cinca/ Thermal Spray Centre (CPT) - Universitat de Barcelona, Spain A. Concustell/ Thermal Spray Centre (CPT) - Universitat de Barcelona, Spain IG. Cano/ Thermal Spray Centre (CPT) - Universitat de Barcelona, Spain JM. Guilemany/ Thermal Spray Centre (CPT) - Universitat de Barcelona, Spain |
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Cold Spray (CS) has been a suitable technique to produce Hydroxyapatite (HA) coatings. The use of low temperatures avoids HA amorphization preventing premature failure implant and maintains HA microstructure on the coating. So, the obtention of HA coatings with controlled crystallinity will be favorable for calcium and phosphate ions release and posterior osseointegration. Two different HA powders with the same morphology but different crystallinity were sprayed by CS. Crystalline HA (C-HA) and nano-crystalline HA (NC-HA) feedstock powders were successful sprayed onto Ti6Al4V alloy substrate and preserved their microstructure. Different spraying conditions were tested in order to produce HA coatings. However, it was observed that NC-HA powders were more suitable to build up coatings up to 300µm in comparison with C-HA coatings which, by using the same spraying parameters, just few microns of uniform layers were reached. These results show the importance of feedstock materials with emphasis to crystallite size. The analyses have been carried out through optical, scanning and transmission electron microscopy for the examination of the micro-and nanoscale coating features. Posterior analysis will also determine the influence of such microstructure on the in-vitro results. |