铜铝复合接触线银铜合金的组织性能研究

【作者】 孙洪波；

【导师】 杨斌；

【作者基本信息】 江西理工大学 ， 材料加工工程， 2010， 硕士

【摘要】 为适应我国经济发展,电气化铁路在不断提速,因此对电气化铁路用的接触导线的要求也在不断提高,要求具有高温抗软化性能、高强、高导、高耐磨,抗疲劳等性能。本文针对电接触导线材料性能要求,以为我校自主研制开发的新型铜铝复合接触线早日市场化提供可靠的试验和理论依据为背景,对新型接触导线用银铜合金的耐高温抗软化性能、磨损性能、疲劳性能等方面进行系统的研究。研究表明:(1)通过对接触线用银铜合金软化再结晶的研究,测得银铜合金软化温度约为390℃,此时合金硬度为HB84.90;银铜合金再结晶温度范围在350~450℃之间。银铜合金退火过程中发生再结晶的激活能为77.68KJ·mol-1;合金在350,390℃退火时的再结晶完成时间分别约为414.4,167.7min。铜铝复合接触线的拉断力为47KN,软化后其拉断力下降了约20%。从断口形貌上看,铜铝断口上都分布着较多的深韧窝,均表现为韧性断裂。(2)钢铁摩擦副对接触导线的磨损要远远小于铜摩擦副对导线的磨损,相差一个数量级以上。在实验条件范围内,与钢铁对磨时最大的磨损量也不到40mg,而与铜摩擦副对磨时,在50N试验力下最大磨损为279mg,在100N试验力下磨损量接近了1000mg;摩擦系数随载荷的增加而降低,然后趋于稳定,随着滑动速度的增大,材料的摩擦系数逐渐减小;通过对磨损试样表面形貌的宏观和微观分析表明,磨损表面有大量的塑性变形迹象,滑动方向上有明显的犁沟和切削痕迹,其纹路与滑动方向一致。与钢铁对磨时,磨损表面有黑色氧化铜生成,在磨损初期发生磨粒磨损。随着时间的延长,部分银铜会粘着到钢铁摩擦副表面,磨损机制由磨粒磨损转变为粘着磨损。铜摩擦副的剥落坑和粘着块明显比钢铁摩擦副的大,其磨损机制为粘着磨损。(3)采用不同应变幅控制,对冷变形银铜合金进行室温低周疲劳试验研究表明:加工率为38%的银铜合金循环周期大于加工率为19%的银铜合金循环周期。增大变形量,提高加工率,不仅可以达到表面硬度的要求,而且疲劳寿命也略有提高。在低应变幅下,滞后回线细长而尖锐;随着应变幅的增加,滞后环面积也随之增大。扫描电镜下观察表明,疲劳试样断裂后存在三个明显疲劳特征区:疲劳核心区、疲劳裂纹扩展区、瞬断区。纵向剖面金相观察表明,裂纹分别起源于材料表面和内部的缺陷。试样的裂纹扩展存在穿晶和沿晶两种方式,其主要扩展方式为穿晶扩展。更多还原

【Abstract】 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.更多还原