Composite coatings formed on the PEO-layers with the use of solutions of tetrafluoroethylene telomers

摘要

A method of the formation of the composite polymer-containing coatings on a MA8 magnesium alloy (Mg-Mn-Ce system) pretreated by the plasma electrolytic oxidation with subsequent application of the organofluorine component such as telomeric tetrafluoroethylene (TFE) solutions in pentafluorochlorobenzene, ethyl acetate and trifluorotrichlorethane (Freon 113) was developed. A comparative study of the morphological, electrochemical, and tribological characteristics and wettability of the formed protective layers has been carried out. It has been shown that application of polymeric material on the base PEO-coating provides a significant effect on the morphology and properties of samples surface. The data of electrochemical studies of composite coatings indicate more than 38-fold the decrease of the corrosion current density (I-C = 6.3 x 10(-9) A cm(-2)) as compared to the base PEO-coating. It has been found that the best corrosion properties are demonstrated by the samples formed in the TFE telomeric solution in pentafluorochlorobenzene. Evaluation of the wear resistance of composite layers revealed a decrease in wear (4.6 x 10(-9) mm(3) (N m)(-1)) of composite coatings by 2 orders of magnitude in comparison with the PEO-coating. The highest wearproof effect has been obtained by the coatings formed using TFE telomeric solution in Freon 113. The contact angle for formed composite layers attains to 142 +/- 2 degrees; such a result has been demonstrated by the composite layers obtained using TFE telomeric solution in ethyl acetate.