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Titanium aluminium nitride (Ti 1Àx Al x N) coatings are utilized in industrial applications because of their excellent tribological and anticorrosive properties. Recently these coatings have been proposed for biomedical applications. In this paper, the biocompatibility and bioactivity of Ti 1Àx Al x N coatings, having various aluminium contents, x, deposited on AISI 304SS stainless steel, have been studied. Coatings were synthesized by magnetron co-sputtering by varying the power applied to the aluminium target.Morphology, chemical composition and microstructure were studied by SEM, AFM, XPS and XRD.Biocompatibility was assessed by measuring haemolytic and cytotoxic characteristics. Haemolysis was measured following the ASTM F756 norm. The in vitro cytotoxicity was assessed with human osteoblasts by means of the lactate dehydrogenase (LDH) release assay. Bioactivity was measured by soaking the samples in a simulated body fluid (SBF) and analysing the surfaces by XPS, XRD and SEM. It was found that all the Ti 1Àx Al x N coatings exhibited good biocompatibility and bioactivity, precipitating hydroxyapatite and monetite. The aluminium content in the Ti 1Àx Al x N coatings increases the quantity of calcium and phosphates groups precipitated in the beginning of the process, but it was also observed an influence of the roughness in the quantity of apatite precipitated after 1 month of immersion in SBF. The coating with x ¼ 0.69 exhibited the higher bioactivity.

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Biomaterials are increasingly used for bone tissue regeneration because of their potential to overcome the morbidity caused by autologous bone grafts and allografts. A combination of properties is required, as biocompatibility, osteoconductivity, good mechanical strength and fracture toughness. In this research, a compound of alumina matrix with calcium titanate and calcium phosphate is proposed. Magnesium stearate was used as porogen agent. The aim of this research was to evaluate the effect of porosity on the crystalline phases formed, as well as the growing pattern and types of calcium phosphates formed after soaking in Hanks’ solution. It was found that the resultant porosity does affect the crystalline phases formed after sintering. It was also found that hydroxyapatite and octacalcium phosphate precipitates after soaking in Hank’s solution, and that the porosity affects the growing pattern.

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