Application of planetary ball mill for manufacturing shielding composite coatings based on polyester powder paints to protect magnesium alloys

The authors have studied the possibility of imparting shielding properties to the coating based on polyester powder paint by adding stainless steel powder and mechanical treatment of the powder mixture in a planetary ball mill to protect the magnesium alloys. Properties of the mixtures, structure and physical-mechanical characteristics of coatings were investigated at variation of the treatment time and the filler weight fraction. The ultimate goal of the studies was to optimize the structure and properties of the coatings while keeping their physical and mechanical properties at initial level as well as by providing them with a new functional grade - shielding of electromagnetic radiation (EM-radiation). The mechanical treatment was performed in a planetary ball mill MF 4/0,5 at the total rotation speed of steel bawls of 800 rev/min. Filler particles and powder paint were put in the required amounts into the planetary mill where they were jointly mechanically treated for 20...80 min with a time step of 10 min. The effect of the mechanical treatment time on powder mixture properties were evaluated by measurement of the bulk density. As a result of complex tests simulating various atmospheric and mechanical impacts, it was found that the designed coating with a filler content of 12,5 wt. % and time of the powder mixture treatment in a planetary mill of 40 minutes ensures the formation of the coating film with the thickness of 70 μm possessing the required functional and protective characteristics. Thus, the suggested technique for coating formation on products made of magnesium alloys, which consist of: adding shielding filler, treatment of the powder mixture in a planetary ball mill and electrostatic spraying, can be used to protect spacecraft electronics to operate in the open space. The results of the researches carried out can be used in the applied tasks of geotechnologies when designing the equipment, used at space vehicles for monitoring and exploring mineral sources.