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 solubilize conventional additives. The tribological properties of several members of this class, including tri-, tetra-and penta-compounds, are presented.These properties include: viscositytemperature, viscosity-pressure, vapor pressure, lubricant lifetimes, traction, reciprocating and four ball wear rates. Lubricant lifetimes were determined using a vacuum ball bearing simulator, the spiral orbit tribometer (SOT).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 vapor pressure. Thermogravimetric Analysis (TGA) was also used for volatility measurements. Pressure viscosity coefficients (α values) were estimated from EHL film thickness measurements. These properties are compared to existing state-of-the-art space lubricants.

Tribological behavior of WS2-based solid/liquid lubricating systems dominated by the surface properties of WS2 crystallographic planes

“…The SiCH and FCPSO oils were synthesized by the State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, suitable for space applications due to the extremely low volatility, high viscosity index, wide running temperature, low pour point and excellent lubrication property, [35][36][37] and their typical properties are listed in Table 1. The SiCH and FCPSO oils were synthesized by the State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, suitable for space applications due to the extremely low volatility, high viscosity index, wide running temperature, low pour point and excellent lubrication property, [35][36][37] and their typical properties are listed in Table 1.…”

Life of scanner bearings with four space liquid lubricants

“…This oil was synthesized and formulated by Nye Lubricants, with the same additive package as used in the Pennzane 2001. Originally developed by the Air Force for high-temperature aircraft bearing applications, it has low vapor pressure and relatively low coldtemperature viscosity, making it a potentially good candidate for future space applications [5,6]. For example, the kinematic viscosity of this formulation is considerably lower than that of the Pennzane 2001 TM oil at −40°C (13 110 cSt vs 81 000 cSt), making it attractive for cold space mechanism applications without heaters.…”

“…At the time the intermediate test results were reported, the Pennzane 2001 bearing lives were much longer than those with the baseline perfluorinated oils and six of the eight Pennzane-lubricated bearings were still running. The present investigation reports the final life test results, with the addition of a new pentasilahydrocarbon oil which has a good vapor pressure and good low temperature viscosity properties [5,6]. The use of titanium carbide (TiC) coated balls as a means to increase bearing life over that of standard 440-C stainless steel balls was also evaluated with Pennzane 2001.…”

Effect of chemical structure on film‐forming properties of seed oils

“…The fi lm thickness and related elastohydrodynamic lubrication (ehl) properties of a number of categories of lubricating oils of varying chemical structures have been investigated by several groups [13][14][15][16][17][18][19][20][21][22][23][24]. In almost all of these investigations, the properties of oils of a specifi c category were compared relative to that of a commonly used oil category, mainly polyalphaolefi ns (PAO).…”

“…The categories of oils investigated include mineral oils (MOs) [13,14], paraffi nic oils (POs) [15][16][17][18], dicyclo hexane [19], PAO [13,14,[17][18][19][20][21][22], multialkylated pentane (Pennzane) [17,18], carboxylic esters (EST) [13,19,23], polyphenyl ethers (PPE) [20], vegetable oils [15,16], glycerol [15], ionic liquids (ILs) [22], chlorotrifl uoro ethylenes (CTFE) [20,21], perfl uorinated polyalkyl ethers (PFPAE) [17,18,20,24], alkyl/aryl methyl siloxanes (MS) [20], trifl uoro propylmethyl siloxanes (FS) [20] and silahydrocarbons (SiR 4 ) [17,18].…”