Enhanced mechanical and tribological properties of low-cost core-shell structured microcrystalline graphite/Cu composites

In the past, microcrystalline graphite (MG) was mainly used for the preparation of carbon enhancers and flame retardant, and is a low value-added inorganic mineral. There are very few reports of MG being compounded with Cu to produce friction materials. Carbon coated microcrystalline graphite/Cu (Carbon@MG/Cu) composites were prepared by coating MG with phenolic resin and mixing it with Cu. The effect of the phenolic resin coating on the mechanical and tribological properties of the composites was investigated by comparison with pure Cu, microcrystalline graphite/Cu (MG/Cu). The hardness and flexural strength of pure Cu were 39.8 HV and 72.3 MPa, respectively. The protection of the amorphous carbon shells led to a significant improvement in the mechanical properties of Carbon@MG/Cu, with hardness and flexural strengths of 72.3 HV and 103.8 MPa. The poor bonding between the MG and Cu severely affects its mechanical properties. Pure Cu has the highest wear rate (10.6 x 10-7(mm3/(N center dot m)), while Carbon@MG/Cu has a stable coefficient of friction (0.19) and the lowest wear rate (4.3 x 10- 7 (mm3/(N center dot m)) compared to pure Cu and MG/Cu. We provide a method to prepare graphite/Cu composites with high mechanical and tribological properties based on low-cost MG, which helps to solve the problem of reuse of MG and increase its industrial added value.