| Rubber O-ring have some advantages,such as simple structure,good sealing property and low friction,which are widely used in hydraulic equipment.Rubber sealant are critical and necessary components.Many problems,such as friction,wear,sealing and lubrication,are widespread occurrence in hydraulic seal attributting to dynamic seals.According to statistics,wear accounted for 80%in the failure of hydraulic system sealant.However,with the development of high speed and high pressure hydraulic system,wear failure is more prominent for sealing.Thus,research on the tribological characteristics of rubber sealant is extremely important in engineering for reducing sealant wear and lengthening service life.The cylinder-on-plate type and pin--on-plane type have been carried out to simulate friction wear of nitrile rubber under dry and different lubricated conditions.The effect of surface roughness of metalic counterpart on tribological characteristics of NBR O-ring have been analysed under different conditions.The wear scars of NBR and metalic counterpart have been observed by 3D optical profilometer,SEM and EDS.Based on data obtained in this study,some conclusions can bedrawn as follows:(1)Studies showed that the direction of strip texture had weak effect on the minimum friction coefficient and wear rate under dry condition;with the decrease of surface roughness,the characteristics of adhesive wear,abrasive wear and adhesive wear were appeared on the worn rubber surface in turn under dry condition.Compared with the direction perpendicular to the sliding direction,the tribological properties of the rubber/metal pair were better when direction of the strip texture is parallel to the sliding direction.(2)Studies showed that surface roughness had the greatest influence on the friction(3)coefficient in the BL,the surface roughness had less influence on the friction coefficient in the ML and the surface roughness had the least influence on the friction coefficient in the HL;the damage characteristics of nitrile rubber under lubrication condition were affected by coupling effects of lubricating state and surface roughness.(4)Studies showed that it did not mean that the lower the surface roughness on the counterpart was the better,under different conditions,there was an optimal value of the surface roughness on the counterpart.the surface roughness was about 0.1?m under dry condition;the optimal value of surface roughness as follow under lubrication condition:R_a=0.03~0.085,R_q=0.035~0.105,R_z=0.22~0.6;when the surface roughness was less than0.118?m,longer lubrication time could be obtained under starved lubrication condition.(4)Studies showed that particle size on the surface of micro-convex rough texture had an important influence on the coefficient of friction between the friction pair,grindings behaviour and wear mechanism.For large abrasive particles,the wear mechanisms were pure abrasive wear;for small abrasive particles,The wear mechanisms were adhesive wear,oxidation wear and fatigue wear.In addition,friction-reducing durability of oil lubrication was superior to grease lubrication;with the decrease of the surface roughness,the friction-reducing extent increased slowly and then increased rapidly,but durability of friction-reducing decreased firstly and then increased gradually and the smoother the surface,the better the antifriction and wear resistance,the wear mechanism of NBR transformed from serious abrasive wear to slight abrasive wear. |
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