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In order to adapt to the current rapid development of aerospace，automotive，and high-end equipment manufacturing industries，using graphene quantum dots (GQDs) with unique properties as the second phase additive，Ni-based nanocomposite coatings were prepared by supercritical pulse electrodeposition technology.The effect of pulse frequency on the microstructure，corrosion resistance，microhardness，wear resistance and other properties of composite coatings under supercritical conditions was investigated.Results showed that when the pulse frequency was 2 000 Hz under supercritical conditions，the microstructure of the prepared coating was densified and uniform，with better sphericity.XRD results showed that supercritical conditions could change the preferred orientation of crystallization and the appropriate pulse frequency could refine the coating grains and reduce the grain size.At a pulse frequency of 2 000 Hz under supercritical conditions，the properties of the prepared coating were more excellent.Electrochemical experiments showed that it had the largest capacitive arc radius，the highest self-corrosion potential，the lowest corrosion current density，and the largest capacitive modulus，so the coating had the most excellent corrosion resistance.The coating prepared at 2 000 Hz pulse frequency had the highest microhardness，reaching 835.4 HV2 N，and had the best wear resistance with a wear scar cross-sectional area of the coating of 1 582 μm2.The microhardness and wear scar cross-sectional area were 126%，107%，121%and 134%，and 47.6%，57.1%，71.5%and 44.3%of the coatings prepared with pulse frequencies of 100，1 000，3 000 Hz and under room temperature and pressure，respectively.Under supercritical conditions，the graphene quantum dot composite coating prepared at a pulse frequency of 2 000 Hz had excellent corrosion resistance and wear resistance.

The supercritical nickel-graphene composite coating was prepared by supercritical carbon dioxide fluid(SCF-CO2) assisted pulsed composite electrodeposition technique with graphene oxide (GO) as the second phase additive. The effect of pulse duty cycle on the microstructure and mecha-nical properties of the coatings was investigated. The results show that the microstructure of composite coating can be refined significantly by the combination of supercritical carbon dioxide fluid and graphene oxide. The change of the (111) and (200) peaks in the XRD patterns of the composite coating shows that change occurs in preferred orientation during the crystallization process. The change of duty cycle has great influence on the mechanical properties of the coatings. The micro-hardness of the supercritical nickel-graphene composite coating is as high as 756.8HV0.2 and the cross-sectional area of wear scar is 4385μm2 at 50% duty cycle. Compared with the nickel-graphene comp-osite coating prepared under conventional conditions, the microhardness and wear resistance of super-critical nickel-graphene composite coating are increased by 1.6 and 11 times.

Graphene, a two-dimensional carbon material made up of a single atomic layer structure, shows unique physical and chemical properties.Graphene reinforced metal matrix composites have attracted more and more attention due to excellent properties.In this paper,the synthesis methods of graphene reinforced metal matrix composites were reviewed.The research progress of graphene reinforced metal matrix composites in strength,thermal conduction,conductivity and corrosion resistance was comprehensively analyzed.Finally, on the basis of pointing out the importance of the study on interfacial bonding mechanism, the development trend of graphene reinforced metal matrix composites in improving the performance and extending the scope of application was prospected.