▎ 摘　　要

NOVELTY - Preparing nano-graphene oxide in-situ strengthened copper-chromium electrical contact material comprises e.g. preparing graphene oxide nanosheets using high-purity graphite powder, concentrated sulfuric acid, sodium nitrate and potassium permanganic acid in the ratio of 1-1.5 g: 25-30 ml: 0.5-1 g: 6-9 g , sequentially adding the concentrated sulfuric acid, sodium nitrate and graphite into a three-necked flask, under constant stirring, keeping the temperature of the reaction system at 0-5 degrees C for the first stage reaction for 30-60 minutes, dividing the potassium permanganate into three parts, adding one part every 8-12 minutes, under continuous stirring conditions, keeping the temperature of the reaction system at 10-20 degrees C and reacting for 1.5-2.5 hours, controlling the temperature of the reaction system to 30-35 degrees C for 3 hours, controlling the temperature of the reaction system to 85-95 degrees C. USE - The method is useful for preparing nano-graphene oxide in-situ strengthened copper-chromium electrical contact material. ADVANTAGE - The method: is simple, consumes less energy and improves performance; overcomes the poor affinity of graphene and copper matrix and poor interface bonding force; adopts graphene oxide, and nano-carbides, which improves the overall performance of the electrical contact material. DETAILED DESCRIPTION - Preparing nano-graphene oxide in-situ strengthened copper-chromium electrical contact material comprises (1) (a) preparing graphene oxide nanosheets using high-purity graphite powder, concentrated sulfuric acid, sodium nitrate and potassium permanganic acid in the ratio of 1-1.5 g: 25-30 ml: 0.5-1 g: 6-9 g , (b) sequentially adding the concentrated sulfuric acid, sodium nitrate and graphite into a three-necked flask, under constant stirring, keeping the temperature of the reaction system at 0-5 degrees C for the first stage reaction for 30-60 minutes, dividing the potassium permanganate into three parts, adding one part every 8-12 minutes, under continuous stirring conditions, keeping the temperature of the reaction system at 10-20 degrees C and reacting for 1.5-2.5 hours, controlling the temperature of the reaction system to 30-35 degrees C for 3 hours, controlling the temperature of the reaction system to 85-95 degrees C, adding deionized water for the fourth stage of reaction for 25-35 minutes to obtain the reaction product, (c) slowly adding 30% hydrogen peroxide with a concentration of 30% to the reaction product, stirring at 33 degrees C in a water bath until the solution turns brown, adding dilute hydrochloric acid to the mixing system, stirring evenly, performing centrifugal washing 15-25 times under the condition of the centrifugal speed of 4000 rotations/minute until sulfate is not detected in the supernatant after centrifugation, adding deionized water to the lower residue after centrifugation, carrying out centrifugal water washing 15-25 times until the pH of the upper solution obtained after centrifugal water washing is 5.5-6.5, placing precipitate at 70-90 degrees C for vacuum drying treatment 20-30 hours, preparing graphene oxide nanosheets, (2) taking ingredients 30 wt.% chromium powder, 69.5-69.9 wt.% pure copper powder and 0.1-0.5 wt.% graphene oxide nanosheets, (3) placing the chromium powder and pure copper powder into a ball milling tank for ball milling and mixing for 3.5-4.5 hours to obtain mixed metal powder, (4) adding the graphene oxide nanosheets to deionized water for ultrasonic dispersion to prepare graphene oxide suspension, (5) adding mixed metal powder to the graphene oxide suspension, mechanically stirring the mixture for 50-70 minutes, transferring in a vacuum freeze dryer for freeze-drying for 20-30 hours, preparing graphene oxide/copper-chromium mixed powder, and (6) transferring graphene oxide/copper-chromium mixed powder to a graphite mold, and placing the graphite mold in a sintering furnace with a vacuum of 0.06-1 Pa for vacuum hot pressing for sintering, controlling the heating rate in the sintering furnace to 8-11 degrees C/minute, and continuously applying uniaxial pressure on the graphite mold while heating, controlling the uniaxial pressure on the graphite mold, when the furnace temperature rises to 650 degrees C, the pressure is 30 MPa, relieving the pressure after 1 hour of maintaining the pressure, raising the temperature to 950 degrees C, maintaining the temperature, after 1 hour, cooling with the furnace, and when the temperature drops to room temperature, taking out the sample to obtain the finished electrical contact material.