真空熔覆Ni60-WC复合涂层工艺及性能研究

发布时间：2018-10-24 06:18

【摘要】：人类文明从石器时代、铜器时代、铁器时代、工业时代以及信息时代一路走来,对于能源以及材料的利用方式也在逐渐改变。相比于其他材料,金属材料具有优异的加工性能与使用性能,使得金属材料在如今林林总总的材料中依然有着不可替代的地位。但是金属材料也有一定的局限性,例如容易在各种腐蚀介质中发生腐蚀,硬度高的金属材料其塑性、加工性较差等。金属表面处理是一种提高材料表面质量性能的重要手段。通过表面处理,使得金属材料的表面具有良好的耐磨、耐蚀性能,同时保持基体的金属特性,从而达到扩大金属材料应用领域,提高构件寿命,减少资源消耗的目的。碳化钨颗粒由于其优异的物理化学性能常被用于金属表面处理。将碳化钨颗粒应用于金属表面涂层的常用工艺有激光熔覆、热喷涂、钎焊等方法。这些方法中都存在一些问题,如涂层不能与基体形成良好的冶金结合,涂层结合强度低、涂层中存在较大的残余应力等。本文探索研究了采用真空熔覆法制备碳化钨涂层的工艺,并成功应用于螺杆钻具径向轴承套的表面。论文主要工作如下:(1)柔性金属布成型工艺研究。制备柔性金属布是真空熔覆方法有别于激光熔覆、热喷涂的特点之一。通过将粉末状增强相颗粒制备成金属布,一方面提高了原材料利用率,另一方面增加了对增强相的包覆能力,使得真空熔覆技术可以应用于工件的内表面、外表面以及其它异形面。通过对比Ni60、WC粉末含量配比以及轧制参数对金属布性能的影响,结果表明在Ni含量在40~50wt.%,轧制速率为2m/min,单次压下量50%,20-30℃下可以制备出厚度均匀、组织致密、性能良好的柔性金属布。(2)真空烧结工艺研究。真空熔覆工艺主要解决涂层如何与基体材料形成冶金结合的问题。真空烧结过程包括两个阶段:在第一阶段烧结温度550℃,可以使金属布中的有机粘结剂完全挥发;第二阶段烧结温度1150℃,保证Ni60粉末熔化使涂层粉末颗粒具有一定的流动性,并使熔体状的Ni60包覆WC颗粒对基体形成良好的包覆。(3)涂层性能评价。主要对涂层结合强度、磨损性能、腐蚀性能三个方面进行测试分析。通过制备不同的试样分别测试了涂层界面的剪切结合强度、拉伸结合强度。结果表明涂层平均剪切结合强度可达151MPa,平均拉伸结合强度可达200MPa。涂层的耐磨性能主要依据环块摩擦磨损试验进行评价,对磨材料为整体淬火45钢。结果表明涂层耐磨性比45钢提高了14倍。通过极化曲线表征了涂层的耐腐蚀性能,结果表明涂层自腐蚀电位为-588m V,自腐蚀电流密度为2.7μA/cm2,涂层耐腐蚀性能介于45钢与304不锈钢之间,适用于一般耐腐蚀环境中。
[Abstract]:From the Stone Age, the Bronze Age, the Iron Age, the Industrial Age and the Information Age, the use of energy and materials is gradually changing. Compared with other materials, metal materials have excellent processability and use performance, which makes metal materials still have irreplaceable position in all kinds of materials. However, metal materials also have some limitations, such as corrosion in various corrosive media, high hardness of metal materials plastic, poor workability and so on. Metal surface treatment is an important means to improve the surface quality of materials. Through surface treatment, the surface of metal materials has good wear resistance and corrosion resistance, while maintaining the metal properties of the matrix, thus expanding the application field of metal materials, increasing the life of components and reducing the consumption of resources. Tungsten carbide particles are often used in metal surface treatment because of their excellent physical and chemical properties. Laser cladding, thermal spraying and brazing are commonly used to apply tungsten carbide particles to metal surface coating. There are some problems in these methods, such as the coating can not form a good metallurgical bond with the substrate, the bonding strength of the coating is low, and there are large residual stresses in the coating. The preparation process of tungsten carbide coating by vacuum cladding has been studied and successfully applied to the surface of radial bearing sleeve of screw drill tool. The main work of this paper is as follows: (1) Research on forming process of flexible metal cloth. The preparation of flexible metal cloth is one of the characteristics of vacuum cladding, which is different from laser cladding and thermal spraying. On the one hand, the utilization ratio of raw materials is improved, and the coating ability of the reinforcing phase is increased, which makes vacuum cladding technology applicable to the inner surface of workpiece. External surfaces and other special-shaped surfaces. By comparing the effect of Ni60,WC powder content ratio and rolling parameters on the properties of metal cloth, the results show that when the content of Ni is 40 ~ 50wt., the rolling rate is 2 m / min, the single reduction amount is 50 ~ 30 鈩，

本文编号：2290560