Multifunctional polymer-containing coatings on magnesium alloys

The results of surface modification of magnesium alloys by plasma electrolytic oxidation (PEO) and post-treatment in suspension of tetrafluoroethylene (TFE) telomeric solution or superdispersed polytetrafluoroethylene (SPTFE) dispersion have been presented. Electrochemical, tribological properties and wetting ability of obtained protective composite coatings were investigated. The fabricated coatings decrease both the corrosion current density (1.7×10-9–5.4×10-11 A/cm2) and wear (9.8×10-6–7.6×10-7 mm3/(N m)) by orders of magnitude as compared to bare magnesium alloy (5.3×10-5 A/cm2 and 3.8×10-3 mm3/(N m)) and base PEO-coating (2.4×10-7 A/cm2 and 1.7×1-3 mm3/(N m)). Moreover, coatings obtained by means of PEO and polymer dispersion dipping possess hydrophobic and superhydrophobic properties. Such multifunctional coatings have high corrosion resistance and good friction coefficient under dry wear conditions that extends the application field of magnesium alloys

Formation of PEO Coatings Modified by SiC Nanoparticles on the MA8 Magnesium Alloy

The properties of coatings formed on the MA8 magnesium alloy by the plasma electrolytic oxidation in electrolytes containing silicon carbide nanoparticles in concentrations of 2, 4 and 6 g/l have been investigated. It has been shown that coatings, which contain nanoparticles, have a significant advantage in microhardenss and adhesive strength in comparison with the surface layers obtained without their use

Composite Coatings of AMg3 Alloy Formed by a Combination of Plasma Electrolytic Oxidation and Fluoropolymer Spraying

This paper presents the results of an investigation of the changes in the corrosion, wear resistance, and wettability of composite coatings formed on the AMg3 alloy through plasma electrolytic oxidation (PEO) and subsequent spraying with an organofluorine polymer. The evaluation of the electrochemical properties of the composite layers revealed a decrease in the corrosion current density compared with the PEO coating (from 3.8 × 10−8 to 3.1 × 10−11 A/cm2). The analysis of the wear resistance of composite coatings established that the application of this type of coating reduced the wear of the samples by two orders of magnitude when compared with the PEO layer. Using the contact-angle measurement, it was found that with an increase in the number of polymer spray applications, the wettability of coatings decreased, so the contact angle for the composite coating with triple fluoropolymer application increased by 134.3° compared to the base PEO coating

Icephobic Performance of Combined Fluorine-Containing Composite Layers on Al-Mg-Mn–Si Alloy Surface

This paper presents the results of an evaluation of anti-icing properties of samples obtained by plasma electrolytic oxidation (PEO) with a subsequent application of superdispersed polytetrafluoroethylene (SPTFE) and polyvinylidenefluoride (PVDF). A combined treatment of the samples with SPTFE and PVDF is also presented. It is revealed that impregnation of a PEO layer with fluoropolymer materials leads to a significant increase in surface relief uniformity. Combined PVDF–SPFTE layers with a ratio of PVDF to SPTFE of 1:4 reveal the best electrochemical characteristics, hydrophobicity and icephobic properties among all of the studied samples. It is shown that the decrease in corrosion current density Ic for PVDF–SPFTE coatings is higher by more than five orders of magnitude in comparison with uncoated aluminum alloy. The contact angle for PVDF–SPFTE coatings attain 160.5°, which allows us to classify the coating as superhydrophobic with promising anti-icing performance. A treatment of a PEO layer with PVDF–SPFTE leads to a decrease in ice adhesion strength by 22.1 times compared to an untreated PEO coating