Abstract: The micropitting resistance of three phosphorous anti-wear agents with different structures of alkyl phosphate, aryl phosphate and phosphorodithioate in industrial gear oil was investigated by MPR and FZG testing machines. The results indicated that three kinds of anti-wear agents could improve the micropitting resistance of gear oils in different degrees. The thermal decomposition temperature of alkyl phosphite ester was high and the structure stability was good. In the oil testing, the micro-pitting area on the roller surface was 3.12%, the track width change rate was 26.6%, the profile deviation of gear surface was 5.64 μm, and the micropitting surface is 75.12%. The experimental results of alkyl phosphite ester were superior to those of phosphorodithioate and aryl phosphate ester and had better resistance to micropitting corrosion performance. The results of MPR tester and FZG testing machine for oil micropitting corrosion resistance test had a good correspondence.

Key words: P-containing anti-wear agent, industrial gear oil, micropitting resistance property