Solid-lubricating Coatings for Foil Gas Dynamic Bearings of High-speed Electric Machines for More Electric Aircraft

The article analyzes the properties of a thin-layer solid-lubricant coating “AIS-2”, formed on the surface of a foil gas-dynamic bearing of the petal type based on a composite material “Adgelast”, as well as the role of the components that form such coating. “Adgelast” in its physical state is a fluid, homogeneous system with a conditional viscosity 17.0–22.0 s, dry residue content 18.0–20.0%, including: high-molecular compounds, such as fluoroplast suspensions, polyamides; surfactants; organic solvents; fine fillers, pigment-soot; water. By functional purpose – it is a mono system that has many functional properties: high adhesive and cohesive strength with metal and layers of deposited composite material, respectively, resistance to high loads and pressure/hit, low tribological parameters. Composite material is applied in painting chambers equipped with inlet ventilation on a highly alloyed steel surface, prepared in advance, in several layers, by pneumatic spraying at normal temperature and pressure, thus excluding defects on the coating. Heat treatment of the applied composite material and the formation of the coating is carried out in electrical cabins at the appropriate modes. While using the x-ray phase analysis method, it was interesting to study the role of components that make up the composite material and form the “AIS-2” coating, in particular: suspensions of fluoroplastics, fillers, polyamide, as well as the role of modifying mixtures developed by us that provide a multi-component fluoroplast – polyamide system homogeneity, sedimentation and coagulation stability during long-term (years) storage and transportation, high performance and solid-lubricating properties of the “AIS-2” coating on foil gas-dynamic bearing of the petal type (support units), in aviation high-speed turbomachines.