الفهرس 
AbstractOnly 14 pages are availabe for public view
 |  | from | 88 |  |  |
| | | from | 88 | | |
Abstract
Polymer bearing importance is in a continuous increase for different reasons as demand for light weight, energy saving, ecological reasons and new smart application. Polymeric materials are being used in different usages and purposes in bearing manufacturing as for races, cages, lining, rolling elements and swivels, hence tribological behavior is important for failure prevention and supporting usage expansion. Reinforcing polymer matrices had been studied during searching for new enhanced performance with longer lifetime and less expensive cost. In this research, tribological properties of different polymers had been investigated as unfilled polymers and as reinforced matrices. Materials used in this study are polymethyl methacrylate (PMMA), epoxy, low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP). Silicon carbide nano fibers had been used as a reinforcement for each material with the filling percentages of 0.1, 0.3, 0.5, 0.7 and 1.0 wt. % content dispersed in polymer matrix. Experiments had been carried out using a rotating test rig under normal loads of 5 N, 10 N and 15 N. Results showed that the hardness of SiCNF/LDPE composites apparently increased by dispersing SiCNF, while it slightly increased for SiCNF/epoxy composites, SiCNF/HDPE composites and SiCNF/PP composites, but there was no apparent improvement in hardness of PMMA filled by SiCNF.
Friction coefficient trends of composites generally tend to increase by the increase of SiCNF content then reduce, minimum values appear at 0.7 wt. % SiCNF content in PMMA composite subjected to 15N, 0.5 wt. % SiCNF content in epoxy composites at 15 N, 0.3 wt. % SiCNF content in LDPE composites at 15 N and 0.1 wt. % SiCNF content in HDPE and PP composites at 15 N normal load applied for each.
Scar width trends decrease and retain to increase with the increase of SiCNF content in PMMA, epoxy, LDPE and HDPE composites, and tends to decrease in SiCNF/PP with the increase of SiCNF. Minimum values appear at 0.5, 0.3, 0.5, 0.5 and 0.5 wt. % SiCNF content in PMMA, epoxy, LDPE, HDPE and PP composites respectively at 5 N load applied.
Scratch test experiments had been carried out for confirming different composites behaviors and investigating the abrasion wear resistance gained by composites. Experiments had been carried out using normal loads of 2 N, 4 N, 6 N, 8 N and 10 N. Scratch test investigation showed minimum values of friction coefficient of composites at 0.7 wt. % SiCNF content for PMMA, LDPE and HDPE composites subjected to loads of 4 N, 6 N and 8 N respectively, while for epoxy composites and PP composites appear at 1.0 wt. % SiCNF subjected to 10 N for each. Scratched scar width values trending to decrease with the increase of SiCNF content in PMMA, epoxy and LDPE composites, while for HDPE composites scar width increases then decreases, and increases with the increase of SiCNF content in PP composites. Lowest scar width values appear at 1.0 wt. % SiCNF content in PMMA and LDPE composites subjected to 10 N, at 0.7 wt. % SiCNF content in HDPE and PP composites subjected to 2 N and at 0.3 wt. % SiCNF content in epoxy composites subjected to 2 N.