【作者】 严石；

【导师】 梅炳初； 周卫兵；

【作者基本信息】 武汉理工大学 ， 材料学， 2010， 硕士

【摘要】 铁路的电气化和高速化是目前世界铁路运输发展的趋势。随着我国列车速度的不断提高,研制性能优良的受电弓滑板材料成为我国研究学者追求的目标。炭滑板因其电阻率较大,而且强度不足易发生事故；浸金属滑板的制备工艺复杂,造价高；而传统的粉末冶金受电弓滑板对导线的磨耗严重。为了解决这些滑板存在的问题,本文尝试制备性能优良的陶瓷颗粒增强铜基复合材料。碳硅化钛(Ti3SiC2)作为一种新型结构-功能陶瓷材料,具有金属和陶瓷的优良性能,如低密度、高熔点、良好的导电导热性、高弹性模量、高断裂韧性、易加工等,同时还具有超低的摩擦系数和优良的自润滑性能。二硼化钛颗粒增强铜基复合材料也因具有高强度、高导电性以及良好的高温性能而广泛地应用于电接触材料。故课题将尝试将二硼化钛强化铜与碳硅化钛弥散强化铜结合,制备TiB2/Ti3SiC2/Cu复合材料。该材料将综合二硼化钛、碳硅化钛和铜的优良性能,从而成为一种值得研究的新型高性能受电弓滑板材料。本文重点研究了增强相二硼化钛及碳硅化钛颗粒表面化学镀铜,应用X-射线衍射结合扫描电镜研究增强相颗粒表面的镀铜相组成及显微结构特征。通过在二硼化钛、碳硅化钛表面化学镀铜来解决其与铜的润湿性问题；通过球磨混料法来解决各相的分散性问题。本文通过调整原料的起始配比、烧结温度、冷压成型压力及增强相碳硅化钛粒径等工艺参数,探索制备性能优异的TiB2/Ti3SiC2/Cu复合材料。重点研究了在850℃、950℃和1050℃三个温度点下,成型压力0-40MPa,Ti3SiC2粒径100～400目,采用无压烧结制备Ti3SiC2体积含量为10%、20%,二硼化钛体积含量为0-30%,其余为铜粉的复合材料的性能。在确定最优工艺与最佳配比后,进行无压烧结与热压烧结性能对比。应用四探针电阻率测量仪、HB-3000布氏硬度计、MTS-810型材料试验机及JB-5型冲击试验机研究复合材料的电性能和力学性能,应用扫描电镜结合电子能谱研究复合材料显微结构及断裂机制。研究结果表明,无压950℃,成型压力40MPa,保温2.0h,Ti3SiC2平均粒径75μm条件下,在碳硅化钛含量为10%,二硼化钛含量为4%时复合材料的综合性能最佳。其电阻率为7.437μΩ·cm,硬度为67.5HBS,拉伸强度为71.597MPa。在其它工艺相同情况下,采用热压烧结此试样,其综合性能远优于无压烧结试样。其电阻率为5.337μΩ·cm,硬度为95HBS,拉伸强度为258.94MPa,冲击韧性为3.47 J／cm2。通过金相照片可见在二硼化钛含量较低时,各增强相在基体中分散较均匀。通过断面的扫描电镜分析了复合材料的显微结构。初步探讨了碳硅化钛及二硼化钛作用在复合材料中的断裂机制。复合材料在拉伸和冲击载荷作用下,其断裂机制类似,为铜基体、TiB2-Cu界面处基体韧断与Ti3SiC2-Cu界面脆断的混合断裂。更多还原

【Abstract】 Railroad’s electrification and the high speed are the tendencies which the present world railway transportation develops. With the speed of the continuous improvement of our trains, developed excellent performance pantograph slider material has become a goal pursued by researchers. Carbon slider is prone to arouse accidents for its high electrical resistivity and low strength. Immersed metal carbon slider need complicated producing process which leads to high cost. And common pantograph slider prepared by powder metallurgy technology usually causes serious abrasion of the conducting wire. To solve these problems, this thesis will attempt to preduce excellent copper matrix composites reinforced by ceramic particles. Ti3SiC2 is a kind of novel structural-functional ceramics material, it combines the merits of both metals and ceramics. It has outstanding properties, such as low density, high melting point, nice electrical and thermal conductivity, high elastic modulus, high fracture toughness and machinability. And more significantly, it has very low friction coefficient and nice self-lubricating property. Copper matrix composites reinforced with TiB2 particles have been widely used as electrical contact materials because of its high strength, high electrical conductivity, and excellent high temperature. Therefore, this paper will try to combine the TiB2 reinforced copper and Ti3SiC2 dispersion strengthened copper, prepared the TiB2/Ti3SiC2 reinforced Cu composites. This material may integrate the excellent properties of TiB2, Ti3SiC2 and copper. So it becomes to a new material for pantograph slide plates worthy of study.In this thesis, we main studied electroless plating copper on TiB2 and Ti3SiC2. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were utilized to investigate the phase composition and the morphology characteristics of the products. This paper resolved the problem of wettability through electroless plating copper on TiB2 and Ti3SiC2. Mixture through the ball milling method to make it uniform dispersion.In this thesis, In order to find the ideal TiB2/Ti3SiC2 reinforced copper composite material, various raw materials ratios in volume fraction, different sintering temperatures, unequal pressing pressure and granularity of Ti3SiC2 were investigated. Under the three temperature points 850℃、950℃and 1050℃, Molding pressure ranges from 0 to 40MPa, granularity of Ti3SiC2 ranges from 100 to 400mesh, the performance of composite material which prepared by pressureless sintering, content Ti3SiC2 for 10% and 20%, TiB2 for 0-30%, the rest of the powder is copper were especially studied. Affer determining the optimum process and the best ratio, the performance of composite material which prepared by hot pressing compared with which prepared by pressureless sintering. Four-probe resistivity meter, HB-3000 Brinell hardness tester, the MTS-810 material testing machine and the JB-5 impact testing machine were utilized to investigate the electrical properties of composite materials and mechanical properties, the application of scanning electron microscopy(SEM) coupled with energy-dispersive spectroscopy (EDS) study of microstructure and fracture mechanism of composite materials.Results indicated that composite materials has best performance when pressureless sintering temperatures of 950℃, molding pressure of 30MPa, soaking time of 2.0h, Ti3SiC2 average granularity of 75μm, Ti3SiC2 volume content of 10%, TiB2 volume content is 6%. Resistivity, hardness, tensile strength of the composites respective is 7.437μΩ·cm,67.5HBS,71.597MPa. Wherein the other processes were same for the experiment, integrated performance of composite materials which prepared by hot pressing were better than the samples which prepared by pressureless sintering. And resistivity, hardness, tensile strength, toughness of the composites respective is 5.337μΩ·cm,95HBS,258.94MPa,3.47J/cm2. We can find each reinforcement phase in the matrix is more uniform dispersion by Metallographic photos when the content of TiB2 is lower. The microstructure of the composites was investigated by using SEM. And the fracture mechanism of the composites was analyzed. The breakage is due to tearing of matrix near Cu-TiB2 interface, in addition, the interfacial debonding and Ti3SiC2 cleavage crack have a prominent effect on the failure mechanism of composite under tensile and impact loads.更多还原