Calcium phosphate coatings deposited by laser ablation at 355 nm under different substrate temperatures and water vapour pressures

Calcium phosphate coatings were deposited on Ti-6Al-4V by laser ablation with a 355 nm Nd:YAG laser at different substrate temperatures. Two series of coatings were deposited at water vapour pressures of 10 and 45 Pa by varying the substrate temperature from 20 to 600 °C. Characterisation of their structure and adhesion has been carried out in order to study the effect of the deposition temperature and the water vapour pressure on the coating properties. It has been found that a high temperature favours the synthesis of crystalline phases. Ca rich phases are synthesised at 10 Pa while hydroxyapatite is obtained at 45 Pa with some alfa tricalcium phosphate. Scratch test measurements have shown, that the coating-substrate adhesion for coatings deposited at 45 Pa is remarkably increased at substrate temperatures higher than 400 °C, but the highest adhesion has been found for amorphous coatings obtained at 10 Pa and 200 °C.