Properties of synthesised oxide-ceramic coatings in electrolyte plasma on aluminium alloys

• Published in: Surface & coatings technology 1998-03, Vol.100, p.219-221
• Main Authors: Nykyforchyn, H.M., Klapkiv, M.D., Posuvailo, V.M.
• Format: Article
• Language: English
• Subjects: Aluminium alloys; Electrolyte; Oxide-ceramic coating; Plasma
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/S0257-8972(97)00617-8

The effect of alloying of aluminium alloys by copper, magnesium, silicon, zinc and lithium on the phase contents, thickness and microhardness of oxide-ceramic coatings was investigated. All of these coatings were obtained by high-temperature synthesis in plasma of spark discharges in the metal-electrolyte system at an electric voltage of 10 7 V m −H. Coatings consist of α-, γ- and δ- phases of Al 2O 3. In the case of alloying by silicon, Al 2SiO 5 is formed as well. The thickness of the coating reaches a maximum of 500 μm. The coatings of the thickness of 150–220 um and the microhardness of 15–36 GPa (depending on the alloying type and consist electrolyte content) were received when the cathodic and anodic current densities were related as 1.5 during 60 min or 0.9 during 120 min. The coatings obtained on the lithium-containing aluminium alloys have the highest microhardness. The total fraction of copper and magnesium must not be less than 3.5%. The oxide-ceramic coatings, synthesised in electrolyte plasma, are dielectric and have a high resistance to wear and corrosion.