Effect of Pressing Pressure on properties of Copper–10% Graphite Composites Prepared by Powder Metallurgy Technique

Abstract

Copper metal has excellent thermal and electrical properties. It is suitable to use in many
applications but it possesses relatively high friction and wear rate, So this research aimed to
improve the behavior of the wear and reduce friction as well as mechanical and physical
properties through the preparation of composite material with a copper as a metal matrix
reinforced with graphite who works solid lubricant for the purpose of use in many applications
such as electric brushes, mechanical sliding bearings, and other applications that require
excellent thermal and electrical conductivity as well as low wear behavior.
Adoption of powder metallurgy technique used copper as the metal matrix with 99.7%
purity and ( ≤ 63 μm) particle size reinforcing with graphite 99.8% purity and (≤ 63 μm) particle
size to prepare the (Cu-10% graphite) composite, Since they were mixing the percentages of
the samples in the mechanical blender for 30 min. and then pressed the mixing in cold uniaxial
pressing at different pressure of (600,700,800,900,1000) MPa and sintering at 900 oC for one
hour.
The result has shown that both bulk and apparent density increasing with increase the
amount of pressure. The true and apparent porosity decreasing with increasing the pressure.
This study found that the water absorption proportional with porosity and ranged between
0.711% and 0.28%. Also this result appeared the composite hardness proportional with
increases the pressure Which in working to reduce wear rate. The microstructures used to
promote and interpret the results.