2015 Volume 60 Issue 11 Pages 752-759
Tribological performance of polyalkylmethacrylates (PAMAs) with different alkyl groups was studied under the rolling-sliding conditions. First, the coefficient of friction for the oils containing PAMA together with tricresylphosphate (TCP) evaluated with a mini traction machine (MTM) significantly depended upon kinds of PAMA. That is, higher the adsorption ability to the metal surface as well as surface coverage maintaining property of PAMA showed lower coefficient of friction, higher contact resistance and thinner tribofilm derived from TCP. Then, the effect of fatigue life of polymer structure on the rolling bearings was evaluated with a Unisteel fatigue tester for the oils containing PAMA together with the package additive for Automatic Transmission Fluid (ATF). The polymer structure significantly affected the fatigue life and the PAMA (C1Mix) containing methylmethacrylate showed the longest life. A close correlation was observed between the fatigue life and frictional properties evaluated by MTM for the same formulated oils. These results indicate that the polymer having high adsorption ability as well as high coverage maintaining property extend the fatigue life by preventing metal-to-metal contact as well as reducing the ratio of tribofilm showing high friction on the contact.
