The Effect of Water on the Tribological Properties of Aviation Lubricants

The influence of water and ice on the performance properties of lubricants is analysed. The tribotechnical properties of Era VNIINP 286M and AeroShell Grease 33 aviation lithium greases at low temperatures, in the presence of water in the grease, are presented. The research was conducted using a test rig simulating a block-on-ring sliding contact. AeroShell Grease 33 demonstrates high demulsifying properties in emulsions with a water content of up to 20 %, at temperatures ranging from -10 to +10 °C. Experiments showed that the presence of water in AeroShell Grease 33 does not reduce the wear resistance of the tribosystem under sliding conditions. The temperature variation in the tribotechnical contact was analysed in relation to the heat capacity of the emulsion, depending on the concentration of dissolved water in the lubricant. The mechanism of structural adaptation, based on the principle of the optimal mechanical scheme of contact interaction in sliding pairs lubricated with lithium grease emulsions, was identified. This mechanism involves the formation of a microrelief on the contact surfaces, increasing the relative bearing length of the profile to up to 25 % under conditions of effective demulsifying action of the grease. It was established that the microgeometric parameters of the structural adaptability of friction pairs are characterised by a reduction in both maximum profile height and equilibrium roughness.