| With the development of science and technology,material science is developing in the direction of characterizing high performance,functionality and composite. High polymer based composites are especially in favor with the public for its excellent comprehensive performance and wide application area. It develops therefore rapidly. The designs of composite material using inorganic filling compounds to reinforce Ultra High Molecular Weight Polyethylene (UHMWPE) and an improvement on thermal conductivity of polymer working as tribological material were selected as the major research subject in this thesis. The pure UHMWPE and a series of UHMWPE-base composites reinforced by Cu powder or CuO powder were prepared by means of heat moulding. Their tribological behaviors were studied. The effect of sliding velocity,lubricant and ambient temperature on the friction and wear of UHMWPE and UHMWPE-base composites has been systematically investigated. The thermal conduction and mechanical property of UHMWPE and its composites have been tested. The relation between thermal conduction and tribological properties as well as the relation between mechanical property and tribological properties has been discussed. The variation of tribological properties of UHMWPE and its composites under the condition of alternating action of static creep deformation-to-sliding friction-to-static creep deformation has been studied. The deformation mechanism of a kind of tribological material such as thermoplastic polymers under this condition was discussed. The major conclusions of this thesis are listed as follows:(1) The influence of sliding velocity on polymers' tribological behaviors concerns mainly with the effect of friction heat. Pairing up with steel and at the condition of dry friction,the pure UHMWPE has an increasing friction coefficient and wear value with the increase of sliding velocity,and so does its composites. The UHMWPE-base composite reinforced by Cu powder which makes up 15% of the composite by weight and the UHMWPE-base composites reinforced by CuO powder which makes up 10%-15% of the composites by weight are more capable of enduring higher sliding velocity than the pure UHMWPE. As for UHMWPE-base composites reinforced by Cu powder,the one whose filling Cu powder makes up 15% of the composite by weight has lower friction coefficient and smaller wear value than the others. And as for UHMWPE-base composites reinforced by CuO powder,the one whose filling CuO powder makes up 10%-15% of the composite by weight has better tribological properties than the others. Filling Cu or CuO powder has changed the wear mechanism of rubbing pairs of UHMWPE-steel. When pure UHMWPE pairs up with steel,adhesive wear takes place. But after the Cu or CuO power are putted in,adhesive wear and abrasive wear take place at the same time,and the percentage of abrasive wear increases accordingly with the increase of filler.(2)It is found that distilled water as lubricant can markedly reduce the accumulation of friction heat and temperature rise on the frictional surfaces of polymer. So the heat fatigue and adhesive wear decrease. Moreover,a lubricating film forms on the interface between the counterpart and polymer when distilled water acts as polar lubricant. The contacting surfaces of both sides of the rubbing pair can be separated by the water film. Therefore,Pairing up with steel and under the condition of water lubricating,UHMWPE and its all composites filled with Cu or CuO powder exhibit excellent tribological properties. Under the condition of distilled water working as lubricant,the weight percentage of Cu or CuO powderin composites has less influence on tribological properties of composites.(3) The result showed that when ambient temperature rises to a certain degree,the frictional surface of UHMWPE and its composites melt and gelatinize. When they rub against steel in a gelatinous situation,the friction coefficient keeps constant with the prolonging of friction time.(4) It is found that the filling compounds,either Cu... |
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