| Graphene is the name given to a flat monolayer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice. Graphene is endowed with many excellent physical and chemical properties by its special crystal structure. Such as the strength of the graphene is more than 100 times of steel, is the best of known materials, and the Young modulus of the graphene can also gets 1100MPa.In this article, the author has studied on the preparation of graphene oxide, graphene and surface modification treatment of graphene. The author has successfully plated copper on the surface of graphene, thus getting the graphene-Cu as reinforcement phase. The purpose of plating copper on the surface of graphene is to improve the wettability and gravity segregation of graphene and aluminum substrate. The method of compacting-rolling was adopt to prepare graphene-Cu reinforced aluminum composite. The microstructure, mechanical properties and tribological properties of the composite were studied.The author has got the following conclusions:(1) Modified Hummers method was adopt to prepare graphite oxide. After ultrasonic treatment, relatively pure graphene by deoxidizing graphene oxide has been gotten by hydrazine hydrate. With the oxidation treatment of low temperature for 60 minutes, middle temperature for 120 minutes and high temperature for 30 minutes, graphite oxide was gotten. Graphene oxide was gotten through ultrasonic treatment. The reduction of graphene oxide by hydrazine hydrate were taken under the conditions of 60℃,80℃,98℃, respectively. Relatively pure graphene was obtained when the reduction temperature is 98℃.(2) Two methods, graphene oxide intercalated copper plating and graphene surface direct copper-plating, were adopted to plate copper. Compared the copper plating product of the two different methods, the author found that direct copper plating on the surface of graphene can successfully prepare graphene-Cu.(3) The method of mixing-compacting-rolling was adopted to prepare different mass fraction of graphene-Cu reinforce aluminum composite. The compacting temperature was 450℃, and the rolling temperature was 500℃.(4) The rules of the influence of graphene-Cu content on the microstructures and mechanical properties of graphene-Cu/Al composite were obtained. Graphene and copper mainly exist in aluminum substrate in the form of graphene-Cu. When the mass fraction of graphene-Cu is low, it is dispersing well in aluminum substrate; when the content of graphene-Cu is higher, it’s always reuniting at grain boundary. With the increasing of graphene-Cu content, the tensile strength and hardness of the composite show a trend of increasing first and then decreasing. The tensile strength can reach its maximum 181MPa with the mass fraction of graphene-Cu is 3%, and the hardness can reach its maximum 52.7HV with the mass fraction of graphene-Cu is 4%. The tensile strength and hardness are increased by 80% and 30% respectively as compared with aluminum substrate. With the increasing of graphene-Cu content, the compactness of the composite conforms to the mixed law and showed a trend of decrease, but the compactness can be above 96% totally.(5) The wear mechanism of graphene-Cu/Al composite was analysised deeply. With the increasing of graphene-Cu content, the friction coefficient of the composite showed a trend of decrease, its wear rate is significantly lower than that of aluminum substrate. The wear rate of the composite decreased beginning, and when the mass fraction of graphene-Cu more than 5%, it increased. Analysis SEM images of the worn surface, the conclusion that the wear mechanisms of the composite were mainly adhesive wear and fatigue wear coexistence was contained. With the increasing of graphene-Cu mass fraction, the wear mechanism of the composite changed gradually from adhesive wear to fatigue wear. |
PDF Full Text Request