Institute of Chemistry of Far Eastern Branch of Russian Academy of Sciences, Vladivostok, Russia:

S. V. Gnedenkov, Professor, Deputy Director for Science, Head of Department of Electrochemical Systems and Surface Modification Processes
S. L. Sinebryukhov, Assistant Professor, Head of Laboratory of Non-stationary Surface Processes
D. V. Mashtalyar, Senior Researcher, Laboratory of Biomedical Purpose Composite Coatings, e-mail: madiva@inbox.ru
K. V. Nadaraia, Junior Researcher of Laboratory of Non-Stationary Surface Processes

Method of the composite polymer-containing coatings formation on magnesium alloys is presented. This way significantly improves the functional properties of processed material. Initially, coatings have been formed on the treated alloy by plasma electrolytic oxidation (PEO). Such coatings have a convolute and rough surface with a good adhesion to the substrate. Then composite coating has been obtained by dipping of the sample in tetrafluoroethylene telomeric solution for sealing pores and microdefects in the base PEO-layer. Optimal modes of the subsequent heat treatment of composite polymer-containing coatings have been developed in order to obtain the best protective properties. Composite coating obtained by tree-fold application of telomere has highest anticorrosion properties and wear resistance. For such coating corrosion current density in 3% NaCl solution does not exceed a value of 1.43·10^–9 A/cm², and wear tested by “ball-ondisk” method using corundum ball was reduced down to 5.7.10–6 mm³/(N·m). For the composite coating the wear was abated by three order of magnitude, and the polarization resistance was increased by four orders of magnitudes in comparison with the bare alloy. Improving of corrosion and mechanical properties is the result of presence in the composite coating the chemically stable fluoropolymer used as a dry lubricant during friction. It has been shown, that the morphological structure of surface varies depending on the multiplicity of application by tetrafluoroethylene telomeric solution on the surface of base PEO-layer. It has been established, that composite coatings have hydrophobic properties: values of contact angle vary in the range from 143^о to 168^о depending on the multiplicity of application with telomere.

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