Effects of molecular structure of aliphatic diols and polyalkylene glycol as lubricants on the wear of aluminum

The lubrication characteristics of aliphatic diols and polyalkylene glycol on the aluminum-steel friction surface were investigated by using a FALEX machine. Aluminum wear is not influenced by the viscosity of diol and polyalkylene glycol, but the molecular structure dose have a significant effect. The lubricant compounds having OH groups on both ends of molecule increased aluminum wear but the wear substantially decreased when OH groups were etherificated with alkyl groups. Wear also decreased when alkyl group(s) was added to the diol. The nascent aluminum surface reacts with alcohol to partially form aluminum alkoxide. As a result, the oxidation layer declines, and wear increases. Furthermore, the wear of aluminum is increased by such a molecular structure that makes it difficult for an anti-wear layer to form on the friction surface.