Study of Plasma Electrolytic Oxidation Coatings on Aluminum Composites

Abstract

Coatings, with a thickness of up to 75 µm, were formed by plasma electrolytic oxidation (PEO) under the alternating current electrical mode in a silicate-alkaline electrolyte on aluminum composites without additives and alloyed with copper (1-4.5%). The coatings' structure was analyzed by scanning electron microscopy, X-ray microanalysis, X-ray photoelectron spectroscopy, nuclear backscattering spectrometry, and XRD analysis. The coatings formed for 60 min were characterized by excessive aluminum content and the presence of low-temperature modifications of alumina γ-Al 2 O 3 and η-Al 2 O 3. The coatings formed for 180 min additionally contained high-temperature corundum α-Al 2 O 3 , and aluminum inclusions were absent. The electrochemical behavior of coated composites and uncoated ones in 3% NaCl was studied. Alloyage of aluminum composites with copper increased the corrosion current density. Plasma electrolytic oxidation reduced it several times.

Formation of Nanoporous Mixed Aluminum-Iron Oxides by Self-Organized Anodizing of FeAl₃ Intermetallic Alloy

“…Considering the low anodization voltage, the lack of an amorphous form of aluminum oxide, which is typical for aluminum anodization [17], is unusual. However, at high current densities, one would expect a plasma electrolytic oxidation mechanism, which allows the formation of a crystalline oxide with the predominance of the Al2O3 phase [18,19]. A similar effect in the formation of a mixture of oxides was observed during the anodization of an intermetallic FeAl phase [10].…”

A study of the electrolyte composition influence on the structure and properties of MAO coatings formed on AMg6 alloy

“…One of the most promising plasma technologies, which allows both base material modification and coating formation, is microarc oxidation (MAO). In the literature, this technology is also called: plasma electrolytic oxide (PEO) [12,13] or anodic spark deposition (ASD) [14]).…”

Plasma Electrolytic Oxidation of Metals and Alloys

“…The present Special Issue covers 10 papers: Six articles [1][2][3][4][5][6] discuss the Plasma Electrolytic Oxidation PEO of titanium [2,4,6] and its alloys [1,3,5], two papers talk about the PEO processing of aluminum alloys [7] and composites [8], and one on magnesium alloys [9]. The tenth paper is a review regarding soft sparking issues in PEO [10].…”

“…Alloyage of aluminum composites with copper (1-4.5 wt%) were treated by PEO; the results are presented in [8]. Coatings, with thickness of up to 75 µm, were formed on the surface.…”

“…The requirements, therefore, not only concern mechanical strength, but also significant protection of the materials against corrosion and wear resistance. Here, plasma electrolytic oxidation (PEO) comes into play to obtain hard and wear-resistant oxide coatings [7,8]. In comparison to the PEO treatments mentioned earlier that last 3 to 5 min, plasma electrolytic oxidation of aluminum and its alloys take one to three hours to obtain strong coatings with proper thickness and structure [7].…”