Effect of the base material condition on the structure and properties of Al2O3 oxide layers

Abstract

The paper presents a new method for modelling oxide layers for tribology related needs. The most recent world trends in the machine-building sector, in particular with reference to piston machines, are heading towards reducing their lubrication and cooling. Hence, a question arises, what the upper layer of a ceramic material should be like in order to maintain low wear and low frictional resistance. An oxide layer for tribological needs has been formed on an AlMg₂ alloy as a result of hard anodizing in SAS electrolyte. This electrolyte enables the control of oxide layer production parameters, which allowed obtaining for the tests an oxide coating with a wide range of changes in porosity and micro-hardness µHV. Anodizing has been carried out by means of the direct-current method, using a stabilized feeder, GPR-25H30D, for a constant electrical charge density of 180 Amin/dm². A lead plate has been acted as the cathode in the anodizing process. By means of a scanning electron microscope (SEM), the surface morphology and structure, and the chemical composition of the layers have been analyzed.