齿轮表面碳化硼薄膜的制备及性能研究

发布时间：2018-02-22 21:17

本文关键词： 碳化硼薄膜磁控溅射机械性能摩擦学性能　出处：《兰州交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：碳化硼薄膜具有硬度高、耐磨性好和摩擦系数低等特点,是一种很有潜力的齿轮表面防护材料,有望成为一种新型固体润滑薄膜,在表面工程领域将有广阔的应用前景。磁控溅射沉积技术是一种常见的物理气相沉积方法,因其操作工艺简单、沉积薄膜速度较快、基底材料温度较低、制备的薄膜结合强度较好、薄膜的结构致密而均匀、内应力低等一系列优点而被广泛应用于薄膜材料的制备。本论文采用闭合场非平衡直流磁控溅射技术,通过调整基底负偏压、石墨靶电流和碳化硼靶电流等工艺参数,在38CrMoAl齿轮钢表面制备碳化硼薄膜,并利用SEM(Scanning electron microscope,扫描电子显微镜)、TEM(Transmission electron microscopy,透射电子显微镜)、AFM(Atomic force microscopy,原子力显微镜)、XPS(X-ray photoelectron spectroscopy,X射线光电子能谱)、XRD(X-ray diffraction,X射线衍射)、Raman(Raman spectroscopy,拉曼光谱)、纳米压入仪和摩擦磨损试验机等对碳化硼薄膜的微观结构、机械性能和摩擦学性能进行研究,探索出了具有良好机械性能和优异摩擦学性能非晶碳化硼薄膜的制备工艺,并对最佳工艺参数制备的非晶碳基碳化硼薄膜同目前已经大量投入市场应用的商业化生产的类金刚石薄膜进行了对比研究。得到的主要结论如下:(1)基底负偏压对碳化硼薄膜的机械性能影响很大,随着偏压的增大,薄膜的显微硬度、弹性模量、膜基结合力出现先增加后降低的规律,薄膜内应力则是先减小后增大的;而基底负偏压对碳化硼薄膜的摩擦学性能影响不大。(2)共溅射碳化硼靶材和石墨靶材能够显著增加薄膜的厚度,优化碳化硼薄膜的结构和性能,尤其能够提高其摩擦学性能。(3)碳靶电流为3.5A,碳化硼靶电流为0.5A时制备的BCx/a-C薄膜呈柱状结构,微观结构致密且为非晶态,并且具有良好的机械性能和优异的摩擦学性能,其膜基结合力、显微硬度和弹性模量分别可达60N、15.7GPa和195GPa,稳定阶段摩擦系数低至0.05,磨损率低至5×10-8mm-3N-1m-1。(4)通过高温下在润滑油中浸泡和循环热震实验表明BCx/a-C薄膜具有良好的热震稳定性,而干摩擦条件下的启停实验反应了薄膜的启停可靠性有待提高,主要原因是薄膜的厚度较小。(5)通过比较研究发现,BCx/a-C薄膜较Cr/a-C薄膜具有更好的机械性能和摩擦学性能,尤其在高温环境下BCx/a-C薄膜表现出了更优异的耐磨性能。
[Abstract]:Because of its high hardness, good wear resistance and low friction coefficient, boron carbide film is a potential material for gear surface protection and is expected to become a new type of solid lubrication film. Magnetron sputtering deposition is a common physical vapor deposition method, because of its simple operation, fast deposition speed and low substrate temperature. The thin films are widely used in the preparation of thin films due to their good bonding strength, compact and uniform structure, low internal stress, etc. In this paper, the closed field nonequilibrium DC magnetron sputtering technique is used. Boron carbide film was prepared on the surface of 38CrMoAl gear steel by adjusting the technological parameters such as negative bias voltage of substrate, graphite target current and boron carbide target current. SEM(Scanning electron microscope, scanning electron microscope (SEM), transmission electron microscopy( TEM), atomic force microscope (AFEM), X-ray photoelectron specular X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy (Raman spectroscopy), nano-pressure injector, friction and wear tester, etc. Microstructure of boron carbide films, The preparation process of amorphous boron carbide thin films with good mechanical properties and excellent tribological properties has been investigated by studying the mechanical and tribological properties. The results of comparison between the amorphous carbon based boron carbide thin films and the commercial diamond films which have been widely used in the market have been carried out. The main conclusions are as follows: 1) negative bias voltage on the substrate. The mechanical properties of boron carbide film are very important. With the increase of the bias voltage, the microhardness, elastic modulus and adhesion of the film increase first and then decrease, and the internal stress of the film decreases first and then increases. The negative bias voltage on the substrate has little effect on the tribological properties of boron carbide films. (2) Co-sputtering boron carbide targets and graphite targets can significantly increase the thickness of the films, and optimize the structure and properties of the boron carbide films. In particular, the tribological properties of the BCx/a-C thin films were improved when the carbon target current was 3.5A and the boron carbide target current was 0.5A. The BCx/a-C thin films had columnar structure, compact microstructure and amorphous state, and had good mechanical properties and excellent tribological properties. The adhesion strength, microhardness and elastic modulus of the film can reach 60Nm 15.7 GPA and 195GPA, respectively. The friction coefficient is as low as 0.05 and the wear rate is as low as 5 脳 10-8mm-3N-1m-1.4. the results of immersion in lubricating oil at high temperature and cyclic thermal shock test show that the BCx/a-C film has good thermal shock stability. The start-up and stop experiments under dry friction conditions show that the reliability of the films needs to be improved, the main reason is that the thickness of the films is smaller than that of the BCxa-C thin films. The results show that the BCx / a-C films have better mechanical and tribological properties than the Cr/a-C thin films. Especially in the high temperature environment, BCx/a-C film shows better wear resistance.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ128;TB383.2

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