The tribological properties of several silahydrocarbons for use in space mechanisms

Abstract Silahydrocarbons are members of a relatively new class of liquid lubricants with great potential for use in space mechanisms. They are unimolecular species consisting of silicon, carbon, and hydrogen. They possess unique wear, viscosity, and volatility properties while retaining the ability to solubilise conventional additives. The tribological properties of several members of this class, including tri‐, tetra‐, and penta‐compounds, are presented. These properties include viscosity‐temperature, viscosity—pressure, vapour pressure, lubricant life, traction, and reciprocating and four‐ball wear rates. Lubricant lifetimes were determined using a vacuum ball bearing simulator, the spiral orbit tribometer. Wear was measured using a Cameron Plint reciprocating tribometer and wear rates with a vacuum four‐ball tribometer. Conventional viscometry was used for viscosity—temperature measurements and a Knudsen cell for vapour pressure. Thermogravimetric analysis was also used for volatility measurements. Pressure—viscosity coefficients (α—values) were estimated from elastohydrodynamic lubrication film thickness measurements. These properties are compared to those of existing state‐of‐the‐art space lubricants.