Pressure-Viscosity Behaviour and Film Thickness in EHL Regime of Lubrication of Ionic Liquids

摘要

There are an important number of studies available in the literature on the tribological and tribochemical behaviour in the boundary regime of ionic liquids (ILs) as lubricants or additives. Nevertheless, research on the behaviour of ILs at EHL conditions is scarce. Values of pressure-viscosity coefficients, α, are needed to know the regime at the operating conditions and to characterize the EHL regime but unfortunately only numerical values for this coefficient at some temperatures for 14 ILs have been reported. The correct way to determine this coefficient is using experimental viscosity values measured in broad ranges of pressure. However, there are also few ILs for which there are literature viscosities at high pressures. According to the American Gear Manufacturers Association under EHL the central film thickness, h_(cent), obeys the relation h_(cant) ∝η_0~(0.69) α~(0.56) being η_0 the dynamic viscosity. In this work we provide the values of η_0~(0.69) α~(0.56) for six ILs, using the definition of Bair et al. named universal (or general film-forming) pressure-viscosity coefficient.