Study on Cu/graphite composite powders by magnetic suspension impact grinding
MU Hongliang1，FENG Liu2，WU Liqing1，LIU Zhichao1，ZHENG Fei3，ZHAO Zengdian3
1. School of Material Science and Engineering，Shandong University of Technology，Zibo 255000，China；
2. Analysis & Testing Center，Shandong University of Technology，Zibo 255000，China；3. School of Chemistry
and Chemical Engineering，Shandong University of Technology，Zibo 255000，China
Abstract：Cu/Graphite composite powders are widely used in the field of electrical contact components due to
their excellent electrical conductivity and thermal conductivity, high mechanical strength and excellent self-lubrication
performance. However, the solid solubility of graphite in Cu is limited, and the density difference between the
Cu and graphite is large, so it is hard to get the uniform Cu/Graphite composite powders. At present, high-energy
ball milling is one of the main methods to prepare composite powders, which has simple process and low cost,
while its efficiency is low, and the interfacial strength of Cu and graphite is weak. Therefore, it is necessary to find
a new technology to prepare Cu/Graphite composite powers with uniform size and high interfacial strength. A new
magnetic suspension impact grinding technology was proposed for preparing Cu/Graphite composite powders. The
effects of grinding time and graphite contents on the microstructure of composite powders such as particle size and
graphite defects were investigated. The combined state of Cu/Graphite composite powders was discussed, and the
efficiency of magnetic suspension impact grinding and high energy ball milling were compared and then analyzed.
The results show that the particle size of the Cu/Graphite composite powders decreases first and then increases
with the extension of grinding time. The addition of graphite is helpful to refine the composite powders; the Cu particles
in the composite powders are face-centered cubic nano particles with micro strain, part of the C atoms in the
graphite are solid dissolved in the lattice spacing of Cu, and the particle surfaces are wrapped by a thin graphite layer. Compared with the high-energy ball milling method, the magnetic suspension impact grinding technology possess
the advantages of much higher efficiency, and the obtained composite powders distribute evenly in size, also
have better bonding interfaces between Cu and graphite particles. The composited powders with 10% graphite contents
present smaller size and the higher uniformity as the grinding time is 3 h.
2022, Vol. 32 
