Microstructure And Mechanical Properties Of The Ag-cu Alloy Of Copper And Aluminum Composite Contact Line

In order to adapt our country's economic development,electrified railway is continuously enhanced its speed.The contact lead,using in electrined railway,is been acquired having high-temperature softening resistant performance,higher strength,electivity,wear resistance,anti-fatigue properties and so on.According to the properties of electro-contact lead materials , to provide reliable experimental and theoretical basis for general adoption of market principle of new-style Cu cladding Al contact wire by our school independent research and development, the new contact wire of the high-temperature softening resistant performance,wear resistance,anti-fatigue properties are research on systems. Research showed that:(1)By softening recrystallization studies on Ag-Cu alloy,the softening temperature is about 390℃, at this time alloy hardness HB84.90.It has risen obviously than the copper contact wire. This is due to alloying elements in solid solution strengthening effect of silver;recrystallization temperature range of between 350~450℃by the investigation of microstructure evolution and kinetics analysis of static recrystallization.Based on the experiment data of Cu-Ag alloy annealing process,the activation energy was calculated to be about 77.68kJ·mol-1,and the time for recrystallization completion at350,390℃are 414.4,167.7min.The breaking load of the Cu cladding Al contacts wire is 47KN,which dropped approximately 20% after annealing 1h at 390℃.There are the fracture features characteristic of dimple in copper and aluminum.(2)Steel friction pair of the contact wire wear is much less than the friction pairs of copper wire wear, it is an order of magnitude difference between them. In the context of experimental conditions,the wear and tear is not to 40mg with steel friction,but the wear and tear is to 279mg in the 50N test and close to 1000mg in the 100N test with copper friction. The friction coefficient decreases with the increase in load, and then stabilized. With the sliding velocity increases, the friction coefficient gradually reduced;through the Cu-Ag alloy contact wire wear surface morphology of the macro-and micro-analysis showed that the worn surface of the plastic deformation of a large number of signs of sliding direction, a clear furrow and cutting traces its lines in the same direction with the slide, When with steel and iron to rubbing, wears the surface to have the black oxide of copper production, has the abrasive in the attrition initial period to wear, along with the time extension, the partial silver copper will be stuck to the steel and iron friction subtabulation surface, wears the mechanism to transform by the abrasive attrition into the adhesive wear. Spalling pits and adhesive blocks with copper friction were significantly bigger than the steel friction .(3)By using different strain rate control, deformation of the cold silver alloy of copper at room temperature for low cycle fatigue test results showed that: 38% rate of silver-copper alloy processing cycle than the 19% rate of silver-copper alloy processing cycle;With the response rate of increase, behind the Central area also increased; as the cycle times of increased stress Has been gradually reduced, resulting in fatigue softening;sample after the break there are three obvious characteristics of fatigue: the source of crack, crack zone, blink off area; silver-copper alloy has a crack along the grain and grain wear in two ways, with the expansion of grain and grain boundary to expand into each other, that the sample crack grain wear expansion-oriented.