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

The problem of technical and economical optimization of the process of micr o-are 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 gener alized 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 m icroscopy, optical and durometric analyses are used. The influence of the s ilicate-alkali electrolyte composition and the amount of electricity carrie d through the cell on the layer properties is discussed. The response surfa ce of the generalized parameter is plotted with the aid of desirability fun ctions. The area of regimes corresponding to 2-3 g l(-1) KOH and 2-3 g l(-1 ) Na2SiO3 electrolyte composition and (2.50-3.33) x 10(3) C m(-2) of carrie d electricity is outlined for the most effective fabrication of uniform oxi de layers with 165-190 mu m thickness and 18-23 GPa hardness. (C) 1998 Else vier Science S.A.