▎ 摘　　要

NOVELTY - Cyanide-free graphene composite coating is plated on surface of copper substrate with silver plating layer and silver graphene plating layer. The coating is prepared by preparing solution in which pre-silver plating solution is prepared by utilizing 5-50g/L silver nitrate, 50-400g/L potassium iodide, 10-200g/L sodium thiosulfate and 1-10g/L nitric acid and has pH value of 1-7. The composite plating solution is prepared by utilizing 5-90g/L silver nitrate, 60-600g/L potassium iodide, 10-400g/L sodium thiosulfate, 1-10g/L nitric acid, 1-50g/L dispersant and 5-100g/L nano-graphene sheet. USE - Cyanide-free graphene composite coating. ADVANTAGE - The cyanide-free graphene composite coating has excellent electrical conductivity, contact resistance of 15-30 mu m (additional torque 5-20Nm), excellent thermal conductivity of 350-500Wm1x K-1, excellent wear resistance at normal temperature and normal pressure, friction coefficient of 0.06-0.22 at 280g, long mechanical life test (clamping force of 400-600N), good corrosion resistance, good curing capability, excellent comprehensive performance, satisfies outdoor working condition at high voltage, and has great application value. DETAILED DESCRIPTION - Cyanide-free graphene composite coating is plated on surface of copper substrate with silver plating layer and silver graphene plating layer. The coating is prepared by preparing solution in which pre-silver plating solution is prepared by utilizing 5-50g/L silver nitrate, 50-400g/L potassium iodide, 10-200g/L sodium thiosulfate and 1-10g/L nitric acid and has pH value of 1-7. The composite plating solution is prepared by utilizing 5-90g/L silver nitrate, 60-600g/L potassium iodide, 10-400g/L sodium thiosulfate, 1-10g/L nitric acid, 1-50g/L dispersant and 5-100g/L nano-graphene sheet and has pH value of 1-7. The degreasing solution is prepared by utilizing 50-600g/L sodium hydroxide, 20-100g/L sodium carbonate and 5-80g/L trisodium phosphate. The pickling solution is prepared by utilizing 20-200g/L nitric acid and 30-150g/L sulfuric acid. The nanophase composite clad layer is prepared by utilizing cathode with purity of not less than 99.95%, and oxygen-free thin copper as plating substrate, and anode as electroplating substrate with purity of 99.99%. The 400-3000# waterproof abrasive paper is utilized uniformly polishing oxygen-free thin copper plating substrate. The oil of oxygen free thin copper plating substrate is removed by soaking it in degreasing solution for 5-10 minutes. The to remove oil. The oxygen-free copper substrate is cleaned with deionized water after degreasing, The ;clean oxygen-free copper substrate is soaked into pickling solution for 5-15 seconds, and washed with deionized water. The pre-silver plating is performed by switching on circuit and placing oxygen-free copper substrate in the pre-silver plating solution at 25-80 degrees C for 30-600 seconds with current density of 0.1-1.5A/dm2. The pre-silver-free oxygen-free copper substrate is washed with deionized water into composite bath, and subjected to magnetic stirring at current density of 0.1-2.5A/dm2 at speed of 300-1500 revolutions per minute at 25-80 degrees C for 20-60 minutes, and subjected to electroplating for 1-5 hours. The electroplated part of substrate is washed with deionized water and dried to obtain copper substrate having a silver graphene composite coating on its surface.