Morphology and chemical composition of composite electrochemical coatings Zn-Al2O3 and Zn-PTFE

Issue 25(1) 2020
Pages 59-63

Inna G. Botryakova, Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Russian Federation

Ali D. Aliev, Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Russian Federation

Nikolay A. Polyakov, Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Russian Federation


Keywords: zinc coatings, composite electrochemical coatings, morphology

http://www.doi.org/10.31615/j.corros.prot.2020.95.1-8

 

The effect is studied of addition of hydrophilic aluminum oxide and hydrophobic polytetrafluoroethylene on the morphology and chemical composition of zinc coatings from acidic electrolytes. Inclusion of hydrophobic polytetrafluoroethylene particles into zinc coatings from acidic zinc electrolytes in the absence of any surfactants is more facilitated than that of hydrophilic aluminum oxide particles of various dispersion and phase composition. The formation of composite electrochemical Zn-Al2O3 and Zn-polytetrafluoroethylene coatings is determined by the state of the surface of the growing zinc deposit (its comparative hydrophobicity) that facilitates the adhesion of hydrophobic polytetrafluoroethylene particles. Addition of aluminum oxide particles into the electrolyte causes no fundamental changes in the overall surface morphology of the zinc deposits. However, a relatively large number of inclusions of aggregates of nanosized aluminum oxide particles are observed over the entire coating surface. The concentration of aluminum oxide inclusions in Zn-Al2O3 composite coatings reaches 5...7 wt.%. The surface of Zn-polytetrafluoroethylene deposit is represented by globules. The total polytetrafluoroethylene content in the obtained composite coatings reaches 30 wt.%. An increased oxygen content is found in such coatings. It is probably explained by formation of a relatively larger amount of surface zinc oxide due to the significant development of the surface morphology of the deposits.