IMPROVEMENT OF THE EFFICIENCY OF TECHNOLOGY OF ALUMINUM-SILICON ALLOYS MICRO-ARC OXIDATION

The article covers the issue of improvement of micro-arc oxidation of the most used aluminum casting alloys - aluminum-silicon alloys (silumins). Using the method of micro-arc oxidation, the authors used the AK6M2 and AK9pch silumins samples to get the oxide layers samples, synthesized in the base-composition electrolyte and adding to the electrolyte a small amount of nano-sized silica dioxide powder SiO₂. The authors carried out the experimental study of the micro-arc oxidation process performance, the transverse structure of the obtained oxide layers, their phase composition, surface morphology, microhardness, tribological and thermal insulating characteristics. It was found, that the electrolyte modification with nanosized silicon dioxide powder SiO₂ significantly increases the productivity of micro-arc oxidation process. The oxide layers formed in the electrolyte, modified by silicon dioxide nanoparticles, display the improved transverse macrostructure and microrelief in comparison with the base variant. The authors found out the simultaneous increase of high-temperature strong phases content and the reduction of metastable low-temperature phases content in the oxide layer. The study revealed the increase of microhardness and wear resistance of the oxide layers, as well as the significant reduction of thermal conductivity of the oxide layers synthesized in the electrolyte when adding silicon dioxide nanoparticles.