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Tribological studies on neat polyetherketone (PEK) and glass fiber reinforced PEK composite were carried out at room and elevated temperature (120 °C). The objective of this study was to characterize for friction and wear properties under dry reciprocating sliding condition at different experimental conditions. The polymer specimens were made to oscillate against steel cylinder as a counterpart. This kind of contact condition are frequently found in bushes, sliding bearing, electronic parts, seals, etc. The friction and wear behavior of neat PEK and composite was quite different at room temperature and elevated temperature. It was observed that glass fiber reinforcement is beneficial in controlling the wear of PEK matrix at room temperature than at elevated temperature. The test results are discussed by considering the surface properties i.e. material removal and film transfer formation. Scanning electron micrographs and optical micrographs of the worn polymer and steel cylinder was used to study the wear mechanisms.
The friction and wear properties of polyetherimide composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120 °C) was investigated. The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. In case of carbon fiber composite abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated.
Tribological properties of neat polyetherimide (PEI), glass, carbon fiber, and solid lubricants filled PEI composites are presented in this article. The aim of this study was to investigate the friction and wear properties of these composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120 °C). The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. Incorporation of carbon fiber in the PEI matrix has increased the wear rate at RT, while at elevated temperature this trend was opposite. Abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated. Tribological performance of neat PEI and glass fiber composite was similar with each other at RT. Scanning electron micrographs and optical micrographs of the worn polymer specimens and the steel cylinders was used to study the possible wear mechanisms. The present test results were also compared with data available on the reciprocating wear of PEI and composites in the literature and trends have been reported.
Pristine, reduced, and alkylated graphene oxides are applied as lubricating additives in paraffin grease. It has revealed that their crystalline structure governs the tribological properties of grease for steel tribo-pair. The microstructural analyses of grease samples showed that a loose fiber network of soap in the presence of graphene-based additive allows their facile release for efficient lubrication. The surface analyses based on the microscopic and elemental mapping show the development of a graphene-derived protective film on the worn scars, which protected the tribo-surfaces and subsided the wear. The reduced graphene oxide (rGO) with the interlamellar distance of 0.35 nm in the (002) plane provided minimum resistance to shear and exhibited maximum reduction in coefficient of friction (COF) for the paraffin grease. The presence of oxygen functionalities in the basal of pristine and alkylated graphene oxide (GO) compromised the interlamellar shearing under tribo-stress; consequently, higher COF than that of rGO.
The tribological behavior of neat and filled PEEK and PEKK composites were compared in air and vacuum conditions. Very low friction and wear coefficient were obtained at low sliding speed while severe wear occurred at high speed. Experimental results are discussed by analysing the transfer film and wear debris.
Tribological properties of ultrahigh-molecular weight polyethylene (UHMWPE) and cross-linked polyethylene (XLPE) were studied in two different wear modes. Firstly, reciprocating sliding wear studies under non-conformal contact investigated the effects of counterface surface roughness (polished, lapped and ground) of Ti6Al4V on the friction and wear of the polyethylenes. Secondly, two-body abrasive wear studies in conformal contact against different abrasive grit size papers were also carried out to ascertain the wear sensitivity of the polyethylenes under these adverse conditions. Wear mechanisms were studied using optical and scanning electron micrographs. The results of the reciprocating sliding wear studies showed that surface roughness of the counterface influenced friction and wear characteristics although no correlation was found between the coefficient of friction and specific wear rate. XLPE demonstrated wear sensitivity, particularly under severe abrasive wear condition. The results indicated that the performance of the polyethylenes greatly depends upon the tribological system under which it is operating.