Study on tribological properties of boronized and textured composite surface and its application on camshaft connecting-rod type hydraulic motor

Abstract With the high parameter development of low-speed and high-torque hydraulic motors, higher requirements have been placed on the tribological performances of their moving parts. Connecting rod slipper pair, as key friction pair, directly affects the leakage of hydraulic motors. In this paper, a composite wear-resistant surface is fabricated by combining the surface texture and boronizing technology, and the texture parameters are optimized by orthogonal tribological test and then applied to the connecting rod slipper pair for hydraulic motor bench test. For the tribological test: (i) the lubrication performance of composite surface is mainly provided by dynamic pressure generated by dimple texture under oil lubrication condition, (ii) the wear rate increases with the increase of texture diameter and depth, while decreases first and then increases with the increase of area density under starved lubrication condition. The hydraulic motor bench test shows that the wear of the composite treated connecting rod is obviously improved, and the leakage is 47.6% lower than that of connecting rod without treatment. The result demonstrates that the composite surface has the ability to capture wear debris and provide dynamic pressure dues to the textured surface, and thus its wear resistance is obviously improved with collaborative use of the high-hardness boride layer.