Effect of electrochemical and mechanical parameters on the lubrication behaviour of Al2O3 nanoparticles in aqueous suspensions

The effect of alumina nanoparticles suspended in an aqueous acetate buffer solution on the tribocorrosion behaviour of a 316L steel/alumina sliding contact was investigated using a reciprocating wear test rig equipped with an electrochemical cell. Through the addition of 10% volume of alumina nanoparticles to an acetate buffer solution it was possible to reduce the coefficient of friction by a factor of 2 and the stainless steel wear by a factor of 10 and this over a range of electrochemical and mechanical conditions. The presence of alumina particles caused a significant wear on the alumina counter part. The lubricating behaviour of the suspension was comparable to a commercial oil in water emulsion used for metal cutting. The lubricating effect was attributed to a third body formed by nanoparticles trapped within the contact. The agglomeration state of the alumina particles and their size were found to play a critical role.