Tribotechnical Coatings for Space Application

Abstract

The need to use solid lubricating coatings (SLCs) arose with the launch of the first space satellites, in which cold welding of articulated joints took place. SLCs have the following main advantages [1, 2, 4]: low evaporation in a vacuum, low friction coefficient, and performance in zero gravity. They can be used in outer space conditions over a wider temperature range than frost-resistant plastic lubricants. The selection of the most suitable SLC [3–6] requires a thorough study of their tribotechnical characteristics depending on the design of friction units, frictional interaction parameters, and environmental characteristics. SLCs are capable of operating in a wide range of temperatures in air, vacuum, and gas environments; they have a radiation resistance of 10⁶–10¹⁰ rad depending on the binder; they are capable of withstanding high contact loads and are insensitive to zero gravity. The most widespread SLCs are in the form of suspensions of solid lubricant with a binder, applied by a spray gun with subsequent curing by heat treatment. A wide range of coatings has been developed: VNIINP-213, VNIINP-512, VNIINP-513, APF-5, EONIT-3, and Dimolits. We conducted tribological testing of the above coatings using various friction pair configurations, in air and vacuum, at various temperatures, and across a wide range of loads and sliding speeds. These data are important for selecting coatings for friction components being developed for spacecraft.