| The commonly used silver-based electrical contact material is a silver-oxide electrical contact material,but due to the low conductivity of the oxide,and the bonding with silver substrate is poor,resulting in electrical contact materials work temperature higher,Life expectancy.Graphene has high conductivity and thermal conductivity;and there is interfacial bonding between graphene and silver,which is conducive to the preparation of high performance silver-graphene electrical contact material.At present,domestic and foreign silver-graphene electrical contact materials less public reports.This paper is devoted to the preparation of silver-graphene electrical contact material,and its electrical properties were studied.In this paper,silver-GNA composite powders were prepared by chemical deposition and ball-milling mixing.Graphene Nanoplatelets Aggregates(GNA)was sold by Alfa Aesar Company as raw materials.Then,the powder was prepared into silver-GNA block by hotpressing process.The wire was prepared by hot-extrusion and cold-drawing process,and finally processed into rivet and study its electrical properties.The main conclusions of this paper are as follows:(1)The composite powder with 12%,17%,22%and 27%volume fraction of aggregates of graphene nanoplatelets was prepared by chemical liquid deposition method.By analyzing the densities,electrical conductivity and microhardness of hot pressed samples,It is concluded that with the increase of the precentage of graphene nanoplatelets aggregates,those all decrease and the decrease rate of conductivity and microhardness decreases.(2)The microstructures,tensile strength,microhardness and elongation of hot extruded rods with diameter of Φ4.5mm were analyzed.The results show that when the content of graphene nanoplatelets aggregates is 12%,the electrical contact material has high resistance to welding,molding and density.(3)The filaments of Φ1.36 mm were prepared by cold drawing,and only when the content of graphene nanoplatelets aggregates was 12%can finish it,other components were fracture with different degrees.The electrical performance test showed that the rivet material had a lower material transfer.Friction and wear tests show that the material has a good wear properties,wear very little.(4)It is concluded that when the ball milling ratio is 4:1,the ball milling time is 4 hours,experimental results are the best.The densities,electrical conductivity and microhardness of sample decreased with the increase of GNA content.The comparison of densification,conductivity and.microhardness of the hot pressed samples under the two methods showed that the chemical liquid deposition method was better than the ball milling method. |
