Cu/NbC纳米复合材料的原位合成及其在电触头材料应用中的功能梯度行为

摘要

原料Cu，Nb和石墨粉末置于高能振动盘式研磨仪，在氩气气氛中研磨7 h制备Cu−5%NbC(体积分数)粉末。采用两步压制法及在真空900°C烧结1 h条件下制得Cu−NbC功能梯度材料和复合材料样品，研究样品的显微组织、物理性能和力学性能。场发射扫描电镜、能量色散 X 射线和 X 射线衍射结果表明，样品经烧结处理后，晶粒尺寸为18~27 nm的纳米结构基体中含有大小为42 nm的纳米颗粒增强相，证实了所制复合材料的高温热稳定性。Cu−15%NbC复合材料样品的硬度是纯Cu样品硬度的5倍。相对于纯Cu样品，磨损后Cu−15%NbC复合材料样品的体积磨损量减小，且电导率降低至36.68%IACS。相对于复合表面中的复合材料样品，Cu/NbC功能梯度材料样品在具有与复合材料相同的硬度和磨损性能的条件下，显示出75.83% IACS的较高电导率。因此，具有良好力学性能和电学性能的Cu/NbC功能梯度材料将成为很好的电触头材料。%Cu−15%NbC (volume fraction) powder was synthesized using the starting powders of Cu, Nb and graphite in a high energy vibratory disc mill for 7 h of milling under argon atmosphere. A composite sample and a Cu/NbC functionally graded material (FGM) sample were produced by using the two-step press and sintering at 900 °C for 1 h under vacuum. The microstructure and physical and mechanical properties of the specimens were investigated. The field emission scanning electron microscopy, energy dispersive X-ray and X-ray diffraction analysis confirmed the synthesis of the nanostructure matrix of 18−27 nm with the nanoparticles reinforcement of 42 nm after sintering, verifying the thermal stability of this composite at high temperature. The hardness of Cu−15%NbC was five times greater than that of the pure Cu specimen. The volume reduction of the sample after the wear test decreased in comparison with the pure Cu specimen. The electrical conductivity of the composite specimen decreased to 36.68% IACS. The FGM specimen exhibited high electrical conductivity corresponding to 75.83% IACS with the same hardness and wear properties as those of the composite sample on the composite surface. Thus, Cu/NbC FGM with good mechanical and electrical properties can be a good candidate for electrical contact applications.