▎ 摘　　要

NOVELTY - Graphene nanosheet silver mixed powder is dried, added to stainless steel mold with diameter of 20 mm, placed in hydraulic press under pressure of 500 MPa, uniaxially cold formed, placed in high-vacuum-resistant furnace, vacuum sintered at 175 degrees C for 2 hours and cooled to room temperature, to obtain sintered granules. Sintered granules are added to mold comprising hydraulic cylinder rod with diameter of 6 mm and processed, to obtain tin-silver lead-free graphene composite solder material. USE - Preparation of tin-silver lead-free graphene composite solder material (claimed). ADVANTAGE - The method enables preparation of tin-silver lead-free graphene composite solder material having excellent strength. DETAILED DESCRIPTION - Graphene and sodium dodecyl in mass ratio of 3:1 are mixed, to obtain mixture (a). Mixture of dimethylformamide is added to mixture (a) such that the mass and volume ratio of mixture (a) and mixture of dimethylformamide is 1 mg:1 ml. The mixture is ultrasonic processed for 2 hours. Silver nitrate solution with molar concentration of 0.06 mol/ml is added to mixture such that the volume ratio of silver nitrate solution and dimethylformamide is 1:2, ultrasonically processed for 30 minutes, heated at 70 degrees C for 1 hour, filtered, washed with water and cleaned with alcohol, to obtain silver graphene nanosheets. Predetermined amount of silver graphene nanosheets and indium-tin-silver-copper (In96.5Sn-3.0Ag-0.5Cu) alloy powder with particle size of 25-45 mu m as base material are mixed, to obtain mixture (b). The content of silver graphene nanosheet is 0.03-0.1 %mass. The mixture (b) is poured to planetary mill pot, and predetermined amount of ethanol is added. The mixture is added to ball mill comprising stainless steel balls as milling media, vacuum sealed, argon as protective gas, and processed at 300 rpm for 5 hours, to obtain base material with graphene nanosheet silver mixed powder. Graphene nanosheet silver mixed powder is dried, added to stainless steel mold with diameter of 20 mm, placed in hydraulic press under pressure of 500 MPa, uniaxially cold formed, placed in high-vacuum-resistant furnace, vacuum sintered at 175 degrees C for 2 hours and cooled to room temperature, to obtain sintered granules. Sintered granules are added to mold comprising hydraulic cylinder rod with diameter of 6 mm and processed, to obtain tin-silver lead-free graphene composite solder material.