الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 71 |  |  |
| | | from | 71 | | |
Abstract
The objective of the study is to study the friction coefficient displayed by the sliding of steel pin against polymeric sheets in the presence of magnetic field. Tests were carried out at dry, paraffin, and glycerin oils dispersed by metallic particles. In this work, iron (Fe), copper (Cu), aluminum (Al) and graphite (C) particles were used as filling materials. Besides, magnetic field was applied with different fluxes controlled by changing the applied voltages at 3, 6, 9 and 12 volts.
Friction has been studied for a steel pin / PMMA sheet and steel pin / PTFE sheet without any lubricants. After that, these counter faces lubricated with particles and oil, separately. The next step is dispersing the oils by 10% by weight of the tested particles. Where, the grain size of the particles added is up to 80 microns. Finally, friction was observed for these lubricating cases at the presence of the magnetic field. Where, the friction force was measured by a load cell with a digital display. The normal loads used were 2, 4, 6, 8, 10, 12, 14 and 16 N and 2 mm/s sliding velocity.
For steel pin sliding against dry PMMA counterface, the friction gave the highest friction coefficient. While, adding the used different types of lubricants, the friction decreased. Presence of magnetic field increased the friction when the oil was dispersed by Fe particles. Glycerin dispersed by 10 wt % Fe gave friction higher than that in pure glycerin condition. Dispersing Al in both paraffin and glycerin oils recorded the lowest friction values at wet lubricated conditions. The more the magnetic field increased, the less the friction decreased for Al with both oils. While, in case of Cu and C it was observed the slight effect of magnetic field. That behaviour can be explained on the basis that Cu formed a layer on PMMA surface and the friction between this layer and the steel pin was relatively high, while C has conducted the electric current.
In the case of the steel pin sliding against PTFE sheet, with the presence of Al in either dry or wet conditions, friction coefficient showed the highest friction values. At this case, friction increased with increasing the magnetic flux. Similarly, friction values for Cu, in both dry and wet conditions, were high and they increased with the magnetic field increasing. Finally, the presence of C, as an electrical conductive material, has very slight effect by magnetic field.