Copper – graphite composites found many applications such as sliding bearings and
electric brushes due to their high wear resistance and excellent electrical and
thermal conductivity.Current research aims to study the effect of graphite content
and milling time on physical properties of copper – graphite composites made by
powder metallurgy route. Copper and graphite powders with 0,5,10,15,20 and
25vol% graphite, were milled mechanically using ball mill for 1,3,5,7 and 9 hours.
The milled mixture was cold pressed at 700 MPa for 30 second, followed by
sintering at 900 oC for one hour. In the present work it was found that increasing
both milling time and graphite content results in a decrease in the bulk density, the
apparent density and the thermal conductivity. It was found that the bulk density
ranges between (8.47-5.25) g/cm3, the apparent density ranges between (8.55-5.7)
g/cm3 and the thermal conductivity ranges between (226.5-89.5) W/m.k. On the
other hand both total and apparent porosity were increased with increasing graphite
content and milling time. It was also found that water absorption is directly
proportional with the apparent porosity and is ranges between (0.1-1.5)%.
Microscopic examinations were used to consolidate and interpret the results.
سيف صباح ارحيم | Saif Sabah Irhayyim | 1290