Plasma electrolytic fabrication of oxide ceramic surface layers for tribotechnical purposes on aluminium alloys

Abstract

Abstract The problem of technical and economical optimization of the process of micro-arc discharge oxidation of high-strength aluminium for the fabrication of oxide ceramic layers for tribotechnical purposes is considered in terms of experimental design. To estimate the effectiveness of the process, a generalized parameter is used which accounts for oxide mass yield as a principal parameter, and mechanical and geometrical characteristics of the layer as restricting parameters. The methods of chemical weight, scanning electron microscopy, optical and durometric analyses are used. The influence of the silicate–alkali electrolyte composition and the amount of electricity carried through the cell on the layer properties is discussed. The response surface of the generalized parameter is plotted with the aid of desirability functions. The area of regimes corresponding to 2–3 g l −1 KOH and 2–3 g l −1 Na 2 SiO 3 electrolyte composition and (2.50–3.33)×10 3 C m −2 of carried electricity is outlined for the most effective fabrication of uniform oxide layers with 165–190 μm thickness and 18–23 GPa hardness.