Study On The Preparation And Modification Of AgCuO Electrical Contact Materials

Preparing AgCuO composite powders by chemical coprecipitation way,we analyzed the influence of solution instillment way on powder morphology and size.Combined the mechanical blending method with the chemical coprecipitation way,We prepared AgCuOTiC composite powders.Then we prepared AgCuO and AgCuOTiC block materials by way of cold pressing,sintering and repressing and resintering,analysed the influence of molding process on the block material's organization and properties,and get the optimized process parameter to ensure the blocks' densty to continue to increase.By process of cold rolling,we prepared sheet materials,analyzed the relationship among property,composition and organization.We also tested their electrical properties.Finally got the following conclusion:1.Studying the preparation process of AgCuO and AgCuOTiC powder and block material and finding that:(1)Preparing AgCuO composite powders by chemical coprecipitation way,when instilling Na2CO3 to AgNO3 and Cu(NO3)2 mixed solution,particle size is in microns,when instilling in the opposite way,particle size is smaller in nanometer,the powders distribution of both the two way is fine.Preparing AgCuO and AgCuOTiC block material by way of cold pressing,sintering and repressing and resintering,the optimized process parameter to ensure the blocks' relative densty to continue to increase was as follows:initial pressure was 225 Mpa,initial burning condition was at 500? exhausting for 2h,and sintering at 770? for 2h,repressure was 750 Mpa,reburning condition was at 600? exhausting for 2h,and resintering at 820? for 2h,secondary repressure was 900 Mpa,finally the density was 97.40%.From initial burning to secondary repressing,the amount of AgCuO's stomata was fewer and fewer,organizations tend to be homogeneous,effectively reduced the internal residual gas;(2)Preparing AgCuOTiC composite powders by combining the mechanical blending method with the chemical coprecipitation way,using vacuum sintering condition to prepare AgCuOTiC block material,the optimized process parameter to ensure the blocks' relative densty to continue to increase was as follows:initial pressure was 225 Mpa,initial burning condition was at 500? exhausting for 2h,and sintering at 7700C for 2h,repressure was 900 Mpa,finally the density was 96.14%.The organization was especially unhomogeneous with TiC not ultrasonic.TiC ultrasonic in water for 0.5h can greatly improve the uniformity of the organization;2.Studying the cold rolling processing performance and its property of AgCuO and AgCuOTiC block materials and finding that:Preparing AgCuO and AgCuOTiC sheet mater by cold rolling processing for many times,finally the thickness could be between 0.15mm?0.25mm.Cold rolling processing could further improve the density of material.Adding TiC can improve the tensile strength of AgCuO,meanwhile,the tensile strength of homogeneous material was better than unhomogeneous material.Both of the organization of AgCuO(9.5)TiC(0.5)while its organization was unhomogeneous and AgCuO(9)TiC(1)present slight rolling deformation zone.Fracture morphology presents the characteristic of ductile,while the fracture morphology of material adding TiC is flatter than the one not adding TiC.Adding TiC may reduce the plastic property.Adding TiC could reduce the electrical resistance,thus improving the electrical conductivity.Unhomogeneous organization could improve the electrical resistance thus reducing the electrical conductivity;3.Testing arc erosion resistance and breakdown voltage resistance property of AgCuO and AgCuOTiC bulk materials and finding that:Adding TiC could improve the arc erosion resistance property and breakdown voltage resistance.Unhomogeneous organization could cause the arc erosion resistance property unstable.