Research On Tribological Properties Of Porous UHMWPE

There were mainly three ways to improve the dry-run performance of helicopter transmission system: Promote high-temperature resistance performance of friction pairs; Enhance the wear resistance of friction pairs; Increase the storage structure of transmission system. In this paper, from the view of increasing the oil storage structure of the helicopter transmission system, porous structure was applied to UHMWPE and the tribological characteristics of UHMWPE under dry sliding condition was investigated. This research aimed to provide experimental basis for the use of porous UHMWPE into helicopter transmission system bearing cage.In this paper, the basic properties of UHMWPE samples were tested. It included porosity of UHMWPE samples, the oil absorption capacity, oil output ability and hardness. The tribological properties of UHMWPE were systematically researched and the influences of structure with different porosity on its tribological properties were explored. The tribological properties of porous UHMWPE samples under the conditions of boundary lubrication were analyzed. The main contents and conclusions were as follows:1. Template-leaching technique was adopted to prepare UHMWPE with different porosities. Extraction effect that different extractants had on the filler was compared. The preparation process of porous UHMWPE samples was optimized. Proper experimental fixture and parameters were chosen.2. The factors that influence the porosities of UHMWPE samples were researched. It showed the porosity of porous samples was mainly decided by the content of the fillers. By comparing the total porosity and surface porosity of the samples, the result showed that when the filler content was bigger, the porous samples were prone to have interconnected open-pore microstructures.3. The influences that different rotating speeds had on the friction coefficient of samples were researched. Under the condition of dry friction, the friction coefficient increased with the increases of speed. Under the condition of little oil lubrication, the friction coefficient decreased with the increases of speed.4. The influences that different lubrication conditions had on the friction coefficient of UHMWPE samples were researched. It showed the porous structure was the important factor influencing the friction coefficient of porous UHMWPE samples. Under the condition of dry friction, the friction coefficient of porous UHMWPE samples were higher than dense UHMWPE samples. Under the condition of little oil lubrication, the friction coefficient of porous UHMWPE samples decreased with the increase of its porosity. When the porosity of samples was 30%, 40% and 50%, the friction coefficient was lower than the density of UHMWPE samples.