| Abstract [eng] |
Bioceramic coatings of Al2O3 and Ti are used in medicine due to their inertness, biocompatibility and mechanical resistance. Al anodization is often used to obtain bioceramic Al2O3 coatings, but wear of anodized coatings remains one of the major problems. Several lipids were investigated to simulate friction in biological systems. Experiments showed that nanothin layers of Ti and its oxides significantly improve the biocompatibility and friction resistance of anodized coatings. Independently of the method (ALD or magnetron) used to form nanothin layers of Ti or its oxides, the layers of 10–75 nm thickness reduce COF below 0.2 retaining it 20 to 60 friction cycles. Nanothin layers of Zr and Hf oxides which belong to the group of IVB also reduce static friction, although they were less effective tribologically than Ti/TiO2. A novel method based on Raman spectroscopy has been developed to evaluate the penetration of hydrophilic azo compounds and hydrophobic compounds into the pores of the anodized foil. It has been found that the formation of tribofilms on the anodized coating takes place not only due to tribochemical reactions of the lubricants in the friction zone but also due to their chemical interaction with compounds present in the pores of anodized coating. In some cases their synergy reduces COF to ~0.1 and suppresses wear by more than 3 orders under dry friction conditions. Such dramatic wear reduction opens many new opportunities for anodized coatings. |
