Abstract
Copper-graphite composites were prepared by spark plasma sintering (SPS) with copper powder and copper-coated graphite powder. The effect of particle size of raw material powder on the current-carrying friction properties of copper-graphite composites was studied. The results show that the friction coefficient of the composites decreased with the decrease of the particle size of copper-coated graphite powder, the friction coefficient of the composites increased with the decrease of the particle size of the copper powder, the wear rate of the composites increased with the decrease of the particle size of the copper-coated graphite powder, and the wear rate of the composites increased significantly with the decrease of the particle size of the copper-coated graphite powder. The current carrying properties of composites with different particle size ratios and QCr0.5 pairs are good and fluctuate little. The current-carrying friction properties of 150 μm copper powder and 75 μm copper-coated graphite powder were found to be the best. The wear surface could be divided into mechanical wear area and arc erosion area. The main area of arc erosion was less than 15% of the total area, and it was mainly distributed in the friction outlet area. The main forms of mechanical wear included furrow, rolling deformation, cold welding, and tearing, among other forms. Graphite film was formed on the surface. The surface quality of the composite prepared by 150 μm copper powder and 75 μm copper-coated graphite powder was the best, the Sa was 3.22 μm, rolling deformation was the most adequate, no large tear pit and furrow appeared, and the carbon content on the worn surface was much higher than that in the composite. The behavior of arc erosion was mainly melting and splashing, and the particle size of the original powder had little effect on it.
Highlights
Copper-carbon composites are widely used as current carrying friction materials [1], which are applied in the fields of electric brushes, high and low pressure contacts, and skateboards, among other items.Friction and wear properties [2] and current carrying properties [3] are the most important properties of copper-carbon composites for current-carrying friction
Copper-graphite composites were prepared by spark plasma sintering (SPS) with copper powder and copper-coated graphite powder
The copper-graphite composites prepared by the SPS plasma sintering process had good surface bonding and dense materials
Summary
Copper-carbon (graphite, carbon fiber, carbon nanotubes, graphene and other sp hybrid carbon materials) composites are widely used as current carrying friction materials [1], which are applied in the fields of electric brushes, high and low pressure contacts, and skateboards, among other items.Friction and wear properties [2] and current carrying properties [3] are the most important properties of copper-carbon composites for current-carrying friction. The copper matrix forms a three-dimensional network structure in the composites [4], which meets the requirements of electrical conductivity and mechanical properties in the service process of the materials. The particle size of raw material powder [8,9] affects the sintering process of the material, affecting the density and other parameters of the sintered material. Much research has been carried out on the influencing factors of material properties in powder metallurgy, including the sintering process [10], sintering temperature and time [11,12], composition and content of materials [13,14], and the service conditions and environment [15,16]. There are few reports on the effect of raw material particle size on the current-carrying friction properties of sintered materials
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