E. Matykina

Metal release from ceramic coatings for dental implants.

OBJECTIVES Two types of ceramic coatings on commercially pure titanium for dental implant applications with different Ca/P ratios in the range from 1.5 to 4.0, and two different thicknesses (∼5 and ∼15μm) were examined with the aim of underpinning the effect of coating composition, thickness and microstructure on the corrosion behavior and hydroxyapatite forming ability in SBF. METHODS Bioactive coatings were formed on Ti by plasma electrolytic oxidation (PEO). The composition, structure, and morphology of the materials were characterized before and after the immersion in simulated body fluid solution (SBF) at 37°C for up to 4 weeks. All the materials were screened with respect to metal ion release into SBF. RESULTS Only thick PEO coating with overstoichiometric Ca/P ratio of 4.0 exhibited capacity to induce the precipitation of hydroxyapatite over the short period of 1 week. Long term Ti(4+) ion release from all PEO-coated materials was 2-3 times lower than from the uncoated Ti. Metal ion release is attributed mostly to chemical dissolution of the coating at initial stages of immersion. SIGNIFICANCE The long term stability was greater for thin PEO coating with overstoichiometric Ca/P ratio of 2.0, which exhibited ∼95ngcm(-2) of Ti(4+) ions release over 4 weeks. Thin PEO coatings present economically more viable option.

Ultra-fine grained pure Titanium for biomedical applications

Ti-based materials are one of the most important materials used in biomedical engineering. Recently, commercially pure (CP) Ti has attracted significant attention of research community due to its full biocompatibility with human body, and there is an ongoing demand to improve its mechanical properties without sacrificing other beneficial properties. A possible approach to achieving this aim is to use the method of severe plastic deformation (SPD) to obtain an ultra-fine grained (UFG) microstructure. Significant grain refinement by SPD processing leads to an improvement in mechanical and functional properties. This paper gives an overview of a range of the properties that can be achieved in the UFG CP Ti including microstructural features, mechanical properties, corrosion performance and biocompatibility. Attention is paid to the main SPD processing techniques developed for the fabrication of UFG CP Ti. Current and potential applications of UFG CP Ti in biomedical engineering are also considered.

Recent advances in energy efficient PEO processing of aluminium alloys

Abstract Plasma electrolytic oxidation (PEO) coatings developed under voltage-controlled mode on various commercial wrought, gravity cast and rheocast aluminium alloys were discussed with respect to enhancement of their tribological and corrosion performance and minimization of the PEO energy consumption. It is demonstrated that use of conventional porous anodic film precursors reduces the PEO energy consumption by up to 50%. The wear of 6082 alloy with PEO coatings with added α-Al2O3 particles is two times lower compared with electrolytic hard chrome. The long-term corrosion resistance of the PEO-coated A356 rheocast alloy is enhanced via use of a precursor and hydrophobic post-treatment.

Efficiency of anodising of Al–Cu alloy in sulphuric acid at low potentials

Abstract The effect of copper on anodising of aluminium in sulphuric acid at low potentials has been examined for a sputtering-deposited Al–0·75 at.-%Cu alloy, using ion beam analysis and transmission electron microscopy. The aim was to determine the relationship between the potential and oxygen generation, with copper in the anodic film in either a metallic or oxidised form. The findings revealed that ∼30 to 40% of the cell charge is used in oxygen generation at potentials between 2 and 8 V(SCE). The charge of Al3+ ions in the film indicated overall efficiencies of film growth that increased from 23 to 41% over the potential range.