Research on Contact Fatigue and Tribological Performance of Si₃N₄ Ceramic Ball and 8Cr4Mo4V Bearing Steel

In order to meet the application requirements of ceramic ball bearings used in aviation engines, the rolling contact fatigue and tribological performance of the tribo-parts between Si₃N₄ ceramic and 8Cr4Mo4V bearing steel lubricated with 4050 aviation lubricating oil were investigated with experiment method in this paper, by using a ball and rod rolling contact fatigue test rig and a multifunctional friction and wear test rig named UMT forshort, respectively. With the experimental contact fatigue data obtained from the ball and rod rolling contact fatigue test, the Weibull probability life curve of rolling contact fatigue was obtained for the tribo-parts of the Si₃N₄ ceramic ball and 8Cr4Mo4V bearing steel by using least-square fitting approach. Under the condition of drip lubrication with 4050 aviation lubricating oil, the surface damage behavior of the tribo-parts of the Si₃N₄ ceramic balls and 8Cr4Mo4V bearing steel disks was analyzed and compared with that of the tribo-parts of the 8Cr4Mo4V bearing steel balls and 8Cr4Mo4V bearing steel disks. Then, a thermal mechanical coupling contact analysis method was employed to obtain the thermomechanical response for the sliding contact between a Si₃N₄ bearing steel ball and an 8Cr4Mo4V bearing steel disk, as well as the thermomechanical response for the sliding contact between an 8Cr4Mo4V bearing steel ball and an 8Cr4Mo4V bearing steel disk. And the influence of the sliding velocity and the contact stress on the heat partition of the frictional heat and temperature rise on the contact interface induced by the frictional heat were analyzed for the tribo-parts of the Si₃N₄ ceramic balls and 8Cr4Mo4V bearing steel disks as well as the tribo-parts of 8Cr4Mo4V bearing steel balls and 8Cr4Mo4V bearing steel disks. The research results indicated that under the condition that the number of stress cycles of the Si₃N₄ balls was twice that of 8Cr4Mo4V rods during the rolling contact fatigue experiment, the 8Cr4Mo4V rods still experienced fatigue spalling first, while the Si₃N₄ balls did not experience fatigue, which implied that the Si₃N₄ ceramic balls had an excellent rolling contact fatigue performance. Under the condition of drip lubrication with 4050 aviation lubricating oil, the friction coefficient of the tribo-parts of the Si₃N₄ ceramic balls and 8Cr4Mo4V steel disks was lower than that of the tribo-parts of the 8Cr4Mo4V steel balls and 8Cr4Mo4V steel disks, the surface wear of the tribo-parts of the Si₃N₄ ceramic balls and 8Cr4Mo4V steel disks was slighter than that of the tribo-parts of 8Cr4Mo4V steel balls and 8Cr4Mo4V steel disks, and the maximum temperature rise on the contact interface of the tribo-parts of Si₃N₄ ceramic balls and 8Cr4Mo4V steel disks induced by the frictional heat was relatively smaller than that of the tribo-parts of the 8Cr4Mo4V steel balls and 8Cr4Mo4V steel disks. As a whole, the tribo-parts of the Si₃N₄ ceramic and 8Cr4Mo4V bearing steel showed an excellent contact fatigue and tribological performance compared with the tribo-parts of the 8Cr4Mo4V steel balls and 8Cr4Mo4V steel disks.