铸造烧结铜基表面复合材料的工艺及其组织和性能研究

发布时间：2019-03-23 18:40

【摘要】：现代工业生产中,机械设备往往要长期处在一个比较恶劣的工作环境下工作。机械零部件很容易发生磨损,腐蚀。导致机械设备失效,企业损失严重。所以要求机械设备材料具备很高的耐磨损,耐腐蚀,耐高温能力,能应用在恶劣的工作条件下。改变材料表面性能,是防治这个问题发生的最好的方法。表面改性方法到目前为止已经有很多,其中包括:热喷涂,激光熔覆,电镀,热扩渗,化学渗,铸渗等方法。铸造烧结法是一种用于制备金属基表面复合材料的新技术,具有工艺简单,节省材料,大热流密度,烧结时间短等优点,所制备的金属基表面复合材料工件具有优良的综合性能。本文分别采用了自熔性Ni60合金粉末,自熔性Cu粉,自熔性Cu粉+Al粉+CuO粉等合金体系浇注纯铜熔液进行铸造烧结工艺的探索,探索了不同合金粉末烧结体系及工艺参数对铜基表面铸造烧结复合层形成的影响。采用光学显微镜、扫描电镜、能谱仪、X衍射仪等微观分析手段对铸造烧结复合层的微观组织、物相的组成、分布及形貌、烧结层与基体的结合情况等进行了分析。同时还研究了添加Al2O3增强颗粒对铸造烧结复合层的组织和性能的影响。研究结果表明:1)铜基合金粉末整体烧结效果不太好,加入1%Al+4%CuO反应体系可以在一定程度上改善铜基合金粉末的烧结效果,进一步提高Al+CuO反应体系的加入量,由于反应剧烈,反而会降低烧结层与基体的结合效果和烧结层的致密度。在自熔性铜基合金粉末中加入Al2O3会使其与试样的界面结合强度降低,而烧结层的孔隙也越来越多,致密化程度不断降低,但是其硬度随着Al2O3的增加而增加。2)镍基表面烧结层能与基体表面实现冶金的结合,烧结层具有较高的强度和致密度,铸造烧结效果明显好于自熔性铜镍基表面烧结层。镍基表面烧结层明显分为两层:外层为Ni60/Al2O3复合层,内层为扩散层。复合层相组成主要是Ni基固溶体,硬质相硼化物CrB,金属间化合物Cr3Ni2。3)Ni60-Al2O3烧结得到的复合材料硬度相对于基体材料都有了比较明显的提高。加入Al2O3含量10%时硬度达到最大。复合层Al2O3含量10%时导热系数最大,更利于高温工作,20%时致密性不够好,导热系数最小。加入适量的Al2O3含量可以提高镍基表面烧结层的耐磨性能,当Al2O3含量10%时耐磨性最好;Al2O3含量达到20%时耐磨性变差;Al2O3含量20%时,烧结层的结合强度较低,摩擦时粉末颗粒会脱落,从而严重影响烧结层的耐磨性。
[Abstract]:In modern industrial production, machinery and equipment often have to work in a harsh working environment for a long time. Mechanical parts are prone to wear and corrosion. It leads to the failure of machinery and equipment, and the loss of enterprises is serious. Therefore, mechanical equipment materials are required to have high wear resistance, corrosion resistance, high temperature resistance, and can be used in harsh working conditions. Changing the surface properties of materials is the best way to prevent and cure this problem. So far, there are many surface modification methods, including thermal spraying, laser cladding, electroplating, thermal diffusion, chemical infiltration, casting infiltration and so on. Casting sintering is a new technology for preparing metal matrix surface composites. It has the advantages of simple process, material saving, high heat flux, short sintering time and so on. The fabricated metal matrix surface composite workpieces have excellent comprehensive properties. In this paper, self-fusing Ni60 alloy powder, self-fluxing Cu powder Al powder CuO powder and other alloy systems were used to investigate the casting sintering process of pure copper. The effects of different sintering systems and technological parameters on the formation of cast sintering composite layer on Cu-based surface were investigated. By means of optical microscope, scanning electron microscope, energy dispersive spectroscopy and X-ray diffractometer, the microstructure, phase composition, distribution and morphology of the cast-sintering composite layer and the bonding between the sintered layer and the matrix were analyzed. At the same time, the effect of Al2O3 reinforced particles on the microstructure and properties of cast-sintering composite layer was also studied. The results show that: 1) the sintering effect of Cu-based alloy powder is not very good. The addition of 1%Al 4%CuO reaction system can improve the sintering effect of Cu-based alloy powder to a certain extent, and further increase the amount of Al CuO reaction system. Because of the intense reaction, the bonding effect between the sintered layer and the matrix and the density of the sintered layer will be reduced. Adding Al2O3 to the self-fluxing Cu-based alloy powder will reduce the interfacial bonding strength of the sample, and the porosity of the sintered layer will also increase, and the densification degree will decrease continuously. However, the hardness increases with the increase of Al2O3. 2) Ni-based surface sintering layer can combine with the matrix surface in metallurgy. The sintering layer has higher strength and density, and the casting sintering effect is obviously better than that of self-fluxing Cu-Ni-based surface sintering layer. The sintering layer on Ni-based surface is obviously divided into two layers: the outer layer is Ni60/Al2O3 composite layer and the inner layer is diffusion layer. The phase composition of the composite layer is mainly Ni-based solid solution, and the hardness of the composite sintered with the rigid phase boride CrB, intermetallic compound Cr3Ni2.3) Ni60-Al2O3 is obviously higher than that of the matrix material. The hardness reached the maximum when the content of Al2O3 was 10%. When the Al2O3 content of the composite layer is 10%, the thermal conductivity is the largest, which is more conducive to the high temperature work. The density of the composite layer is not good enough at 20% and the thermal conductivity is the smallest. The wear resistance of Ni-based sintering layer can be improved by adding appropriate amount of Al2O3, the wear resistance is the best when the content of Al2O3 is 10%, the wear resistance is worse when the content of Al2O3 is up to 20%. When the content of Al2O3 is 20%, the bonding strength of the sintered layer is low, and the powder particles will fall off during friction, which will seriously affect the wear resistance of the sintered layer.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG24;TB33

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