轻质磁性微球的制备及应用初探

【作者】 赵雯；

【导师】 张秋禹；

【作者基本信息】 西北工业大学 ， 应用化学， 2004， 硕士

【摘要】 传统的磁性颗粒具有密度大的特点，限制了其在某些特殊领域的应用，如磁性颗粒密度大引起磁流变液沉降及隐身技术中传统吸收剂密度大使飞机增重等问题。若能降低磁性颗粒的密度，就能推广其应用领域。 在这种背景下，本文选择空心玻璃微球和聚苯乙烯微球两种轻质载体，采用化学镀镍的方法在载体表面沉积一层磁性物质——镍，得到两种轻质磁性微球，并初步探讨其在磁流变液和微波吸收剂中的应用。 在空心玻璃微球化学镀镍的研究中，我们发现化学镀镍的关键是前处理工艺。我们研究了先偶联、再活化的前处理工艺。通过正交试验确定了最佳偶联条件，并探讨了偶联处理对活化效果的影响。研究发现空心玻璃微球经过偶联处理后对钯的吸附能力提高了很多，使得化学镀镍中微球表面的活性点大大增加。此外，还研究了镀液pH值、装载量等工艺条件的影响，得到了最佳pH值和装载量范围。 在聚苯乙烯微球化学镀镍的研究中，我们发现活化效果的好坏直接影响到磁性微球产率的高低。化学镀镍得到的磁性微球的表观主要决定于活化微球的表观，只有严格控制活化工艺，引入颗粒细小的活化微球进行化学镀镍，才能得到颗粒细小、均匀的磁性微球。 通过测试两种轻质磁性微球的密度、镀层形貌、成分及晶体结构，表明：得到的镍包覆空心玻璃微球(平均密度3.0g/cm~3)和镍包覆聚苯乙烯微球(平均密度2.7g/cm~3)的密度远远低于传统磁性颗粒的密度(7～8g/cm~3)；产物包覆率较高，包覆完整，镀层均匀、致密；镀层的主要成分为Ni，其晶体结构与单质镍相似，为面心立方结构；对于镍包覆空心玻璃微球，400℃热处理可以使Ni-P合金镀层晶化，并使晶粒长大，有利于提高镀层的磁性能。 轻质磁性微球在磁流变液和微波吸收剂中的应用表明：作为磁性颗西北工业大学硕士论文摘要粒，可以明显改善磁流变液的沉降稳定性，在磁场下的粘度比初始粘度有所提高;作为微波吸收剂，表现出电损耗的吸波性能。 综上所述，使用化学镀镍法对空心玻璃微球、聚苯乙烯微球进行包覆，可以得到包覆率高、包覆完整、镀层均匀、致密的轻质磁性微球，这些轻质磁性微球有着广阔的应用前景。更多还原

【Abstract】 The conventional magnetic particles have a characteristic of heavy density, which limit their applications in some special fields. For example, conventional magnetic particles in magnetorheological fluids (MRF) can easily subside and make MRF unstable. Conventional magnetic particles work as microwave absorber in stealth plane may increase the weight of the plane. If the density of magnetic particles can be reduced, their applications would be widened.In this paper, two kinds of low-density magnetic microspheres were prepared by electroless plating Ni on hollow glass microspheres and polystyrene microspheres. In addition, their applications in MRF and microwave absorber were discussed.Pretreatment process is very.important in electroless plating nickelon hollow glass microspheres. And a new pretreatment process was investigated, which included coupling and activation. The optimum coupling conditions were determined by orthogonal tests. The effection of coupling process on activation effect was analyzed. The research showed that coupled microspheres had an enhanced capacity to absorb Pd, resulting in more active points on the surface of micro-spheres. In addition, influences of other parameters such as PH valve of plating bath and loadage were studied.The research of electroless plating nickel on polystyrene microspheres showed that activation process had an effect on the yield of magnetic microspheres. The apparent of the product was influenced by the activated microspheres that were introduced into the reaction system.The properties of the products, such as density, morphology and crystal texture of the coating, were analyzed. Based on the results, the conclusions could be drew as follows:The average density of Ni-coated hollow glass microspheres and Ni-coated polystyrene microspheres are 3.0 g/cm3 and 2.7g/cm3, respectively, which are lower than the density of conventional magnetic particles (7~8 g/cm3).The SEM photography shows that the coating is complete, uniform, and fine.The EDS and XRD analysis prove that the main component of the coating is Ni, which crystal texture is similar to pure nickel.Heat treatment on Ni-coated hollow glass microspheres can crystallize the Ni-coating, which is beneficial for improving the magnetism of the products.The two kinds of low-density magnetic microspheres were applied in MRF and microwave absorber. The results were obtained as follows:The sediment stability is evidently improved and the apparent viscosity of MRF under magnetic field is larger than the initial viscosity.The microwave absorber has a property of absorption by the electrical loss mechanism.In a word, complete, uniform and fine-coated low-density magnetic microspheres can be prepared by electroless plating Ni on hollow glass microspheres and polystyrene microspheres. As one of the promising materials, low-density magnetic microspheres will be wildly used in the future.更多还原