Study of influence of micro-arc oxidation process duration on the characteristics of thermal control coatings for space applications

Thermal control coatings were obtained on the AMg6 aluminum alloy with the aid of micro-arc oxidation (MAO) process. The dependences of the thickness, roughness, porosity and thermal control properties of the coating on MAO process duration were studied. The thermal control properties (solar absorbance αs and emissivity ε) were investigated by ultraviolet–visible-near infrared spectrophotometer instrument and solar absorption reflectometer. The analysis of thickness, roughness and MAO process duration influence on the thermal control properties of the coating was carried out.

Features of the structure and properties formation of AMG6 alloy under the equal channel angular pressing

The results of experimental studies of changes in the structure, microhardness, and wear resistance of the AMG6 aluminum alloy during equal channel angular pressing (ECAP) are presented in this work. The evolution of the fine structure and the formation of secondary phases in the AMG6 alloy during ECAP were studied. The dark-field image of the structure of the AMg6 alloy in the matrix reflex showed the splitting of the material into small disoriented fragments of about 0.5 μm in size with a small-angle disorientation boundary (about 2–5°). Optimal method and modes of ECAP of the AMG6 aluminum alloy were selected of the bases of experimental research, which make it possible to obtain a workpiece with enhanced tribological and mechanical characteristics. It was established that the most intensive grinding of the grain structure in the AMG6 alloy occurs at ECAP-12 at a channel angle intersection of 120°. It is shown that with a decrease in grain size, the microhardness of the alloy AMG6 after ECAP increases by 4 times, compared with the initial state.The results of the test samples for abrasive wear showed a decrease in mass loss after 12 passes of ECAP, which indicates an increase in the wear resistance of the alloy AMG6 by 13–14 %, compared with the initial state.