Abstract:

To improve the quality of Ni60A coatings deposited by supersonic plasma spraying technology, and to investigate the rolling contact fatigue of coatings. Four main parameters (spraying voltage, spraying current, argon gas flow rate and spraying distance) of supersonic, plasma spraying processing are optimized, through evaluation of microhardness and porosity by orthogonal test of four factors three levels. The microstructure of Ni60A powders and coatings is analyzed by means of scanning electron microscope. The microhardness and porosity of coatings are measured by microhardness instrument and image processing method. Rolling contact fatigue life of the coatings is investigated using a RM-1 rolling contact fatigue/wear competitive life test machine, and then the map of Weibull distribution failure probability is plotted. The results show that the quality of Ni60A coatings deposited by supersonic plasma spraying technology can be improved by orthogonal test, four main parameters optimized by orthogonal test is conformed, spraying current is 370 A, spraying voltage is 170 V, argon gas flow rate is 110 L/min, and spraying distance is 110 mm. The microhardness of coatings deposited by optimized parameters is 1 086 HV0.2, and the porosity is 1.05%. Under different contact stress, the contact fatigue life of the Ni60A coatings accords with Weibull distribution, and the rolling contact fatigue life of the coatings under a specific load within a certain range can be predicted.

Key words: coatings, fatigue life, optimization, rolling contact fatigue, Weibull distribution, Ni60A