【作者】 刘毅辉；

【导师】 冯拉俊； 雷阿利；

【作者基本信息】 西安理工大学 ， 材料学， 2004， 硕士

【摘要】 本文将热喷涂法与机械球磨法相结合，提出一种新的超细铜锌粉末的制备方法。在采用常规热喷涂工艺参数进行粉末制备的基础上，讨论了球磨时间、球磨助剂、热处理条件对粉末性质的影响，得出最佳的制备方案。该方法可以制备出粒度分布均匀、性质稳定，粒度为200～500nm的超细铜锌粉末。针对超细铜锌粉在液体介质中团聚严重的实际，采用沉降法及分光光度法研究了该粉末在不同的分散剂作用下的分散效果。采用正交试验方法优化了分散剂配方，分析了影响分散性能的各种因素，讨论了各种分散剂的作用机理，找到了不同分散剂的最佳作用条件，从而提高了超细铜锌粉的分散稳定性，为得到性质稳定的超细粉体提供了有效途径。 采用筛分法、重力沉降法、分光光度法、扫描电镜法、透射电镜法和X射线衍射法对不同阶段的铜锌粉末的粒度、形貌、成分等性质进行了分析，结果表明：球磨工艺及热处理参数对铜锌粉的性能有重要影响。在初始阶段随球磨时间的增加，粉末粒度变大，继续球磨，粉末粒度变小，细化到一定程度后粉末粒度不再随球磨时间的延长显著变化。球磨助剂的加入提高了球磨效率，改善了球磨效果，并且使粉末的分散性得到明显改观。热处理后粉末的粒度增大，微细颗粒的比例减小，表面出现裂纹，降低了粉末的硬度，同时粉末团聚作用减弱。因此，采用球磨与热处理交替进行的工艺处理后，可得到粒度为200～500nm的铜锌粉末。西安理工大学硕士学位论文 通过对热喷涂球磨法制备的超细铜锌粉的分散性进行预试验和优化试验，发现分散剂浓度、分散时间、pH值、温度和外加离子浓度对分散作用效果有重要影响。在单一分散剂中，表面活性剂类分散剂作用效果较好。在复合分散剂中，不同类型分散剂的混合物具有良好的分散效果，这是由不同类型分散剂的协同效应所致。只有在分散剂浓度、分散时间、pH值、温度和外加离子浓度的最佳组合条件下，才能得到稳定的分散体系。在大量试验的基础上，研究出两种较好的超细铜锌粉的分散剂配方:(l)硬脂酸(0.75%)，硅酸钠(2.5%)，氯化钠(1%)，分散时间二5h，pH沟，温度二70℃;(2)吐温一80(4%)，月桂酸钠(2 .5%)，氯化钠(1%)，分散时间二Zh，pH二5，温度=25℃。这两种分散剂可改善铜锌粉的分散状态，较好地解决制备过程中的团聚问题，这为超细铜锌粉的应用提供了条件，为超细粉末分散剂的研究提供了重要依据。更多还原

【Abstract】 The methods of thermal spray and mechanical ball milling are combined in this paper and a new method of preparation of Cu-Zn ultrafine powders is brought forward. On the basis of preparing powders with usual technological parameters of thermal spray, the influences on powders properties of ball milling time, assistant reagents of ball milling and conditions of heat treatments are discussed, and then it comes to the optimal preparation project. The Cu-Zn ultrafine powders of 200~500nm can be prepared by this technic. In allusion to agglomerates of Cu-Zn ultrafine powders in liquid media, dispersing effects of the powders under the action of different dispersants are studied by the methods of sedimentation and spectrophotometery. By the method of orthogonal experiment, this paper optimizes the formulae of dispersants and analyzed kinds of factors that affect dispersing properties. The action mechanism of different dispersants is discussed and the best action conditions of these dispersants are presented. This improves the dispersing stability of Cu-Zn ultrafine powders and provides with effective methods for the preparation of ultrafine powders with steady properties.Powders properties of different phases such as the granularity, theshape and the component have been analyzed by the methods of sieving, gravity sedimentation, spectrophotometry, scan electronic microscope (SEM), transmission electronic microscope (TEM) and X-Ray diffraction (XRD). The results show that technic of ball milling and parameters of heat treatments are important influencing factors to properties of Cu-Zn powders. At the first stage of ball milling, the granularity of powders increases with prolonging the time. But if ball milling continues, the granularity will minish. When minishing to a certain extent, the granularity of powders don’ t change greatly along with prolonging the time of ball milling. Assistant reagents can improve efficiency and ameliorated effects of ball milling. The dispersing of powders changes for the better obviously. After heat treatments, the granularity of powders increases and ultraf ine grains decreases. Cracks appear on the surface of powders. So the rigidity of powders descends. At the same time agglomeration of powders weakens. Consequently, adopting the alternation technic of ball milling and heat treatments, Cu~Zn powders of 200?00nm can be available.Through preparative experiments and optimized experiments on Cu~Zn ultrafine powders that are prepared by the method of thermal spray and ball milling, the author finds that dispersants concentration, dispersing time, pH, temperature and adscititious ions have significant influences on dispersing effects. Among single dispersant, there are better action effects for surfactant. Among compound dispersants, there are favorable dispersing effects for the admixture of different kinds of dispersants. This results from cooperation function of different kinds of dispersants. So only with the best combination of dispersants concentration, dispersing time, pH, temperature and adscititious ions, steady dispersing system can be obtained. Two optimum formulae of compound dispersants for Cu-Zn ultrafinepowders are obtained on the basis of multitude experiments. They are as follows: (1) Stearic Acid (0.75%), Sodium Silicate (2.5%), Sodium Chloride (1%), Dispersing Time (5h), pH(9), Temperature (70C), (2) Tween-80 (4%), Sodium Laurate (2.5%), Sodium Chloride (1%), Dispersing Time (2h), pH (5), Temperature (25癈). These two dispersants can ameliorate dispersing state of Cu-Zn powders and solve the problem of agglomeration reasonably in the process of preparation. This provides with foundation for application of Cu-Zn ultrafine powders and study on dispersant for ultrafine powders.更多还原