S. Lederer, P. Lutz, W. Fürbeth
Galvanotechnik 3/2020, S. 464-471.
Titanium and its alloys have been used for several decades in osteosynthesis and implant technology. Because of the natural passive layer consisting of titanium oxide, they are also biocompatible and show excellent corrosion resistance. However, the thin oxide layer (a few nanometers) can be damaged and harmful metal ions (e.g. Al, V) can be released into the body and thus into the blood circulation. The plasma-electrolytic oxidation (PEO) or micro-arc oxidation (MAO) is an electrochemical method that enables to functionalize the surface structure of the substrate. Thus the natural oxide layer can be thickened in order to improve wear and corrosion protection. By varying the electrical and chemical process parameters, surface morphology, layer composition, porosity and layer thickness can be adjusted. The addition of ceramic nanoparticles leads to a further enhancement of the mechanical properties. If the anodization is carried out in a electrolyte containing calcium and phosphorus, biocompatible hydroxyapatite can be produced, which improves the osseointegration of the implant.