Preparation And Properties Of AgCr Contact Material By Mechanical Alloying

Electrical contact is responsible to connect and break the circuit and carry current. Because of its special role, performance of electrical contact materials directly impacts on the reliability, stability, accuracy and service life of electronic products. In the process of connecting and breaking the circuit, electrical contactor comes under electrical erosion, so that it can't normal work. Thereby, study on electrical contact materials which have the strong anti-electrical erosion has important significance.This paper studies preparation and properties of AgCr contact material, which is prepared by mechanical alloying. Firstly, it researches effect of milling technology on phase, grain size, micro-strain and morphology of AgCr powder by X-ray diffraction and SEM, which includes milling speed and the ratio between the weight of balls and materiel. Secondly, though studying milling technology and sintering temperature impact on density, hardness, conductivity and optical structure of AgCr alloy material, we have gained the best technological parameters with which AgCr alloy material is produced by mechanical alloying. Lastly, though exploring electrical properties of AgSnO2 contactor, silver covering copper-base contactor and AgCr contactor under the DC by analysis of circuital current, contact resistance, SEM micrographs and elemental analysis of contact surface, we can examine whether the AgCr contactor has strong capacity of anti-electric erosion.The results show that Cr phase can be partial solid solution to the Ag phase after a certain time of milling when the milling speed reaches a certain value. AgCr alloy material with superior performance is prepared under the appropriate milling technique and proper sintering temperature. AgCr alloy material which includes Cr content 12 wt% has density of 9.62 g/cm3, hardness of 122.3 HV and conductivity of 4.03μΩ·cm.and its micro structure structure simultaneously showed that the organization distributes more evenly and reunion is not obvious. So this material has good development and application.Comparative analysis of the electrical contact performance indicates that AgCr contact material is superior to silver covering copper-base material with respect to anti-electric erosion. Also it shows that AgCr contactor is more amount of material transfer than the AgSnO2 contactor, but contact surface of AgSnO2 material exist cracks, also steady contact resistance of AgCr contact material and ratio of connecting and breaking of circuit have no change. In summary, AgCr contact material has the good electrical contact performance.