Preparation Of Ferromagnetic Fluids And The Research On The Performance As A Kind Of Lubricant Additives

The magnetic material is one of the old and broad-spectrum functional materials, and the magnetic material is correlated with aspects of national economy, such as informatization, automatization, mechatronics, and national defence and so on. The magnetic liquid has magnetic property of solid and liquidity of liquid, so it shows better performance than other magnetic materials under the control of magnetic field. With the appearance and development of nanoscale science and technology, nano magnetic liquid as a kind of new functional materials exploits a new road for the development of new materials, fills new activity and shows comprehensive application foreground.At present, the nano magnetic particles have many reported preparation methods, such as chemical co-precipitation method, sol-gel method, hydro-thermal method, microemulsion method etal. But the article used the ultrasonic nanometer grinder developed independently by this topic group, in other words, the supersonic -machinery method was used to prepare the magnetic particles, simultaneously chemical co-precipitation method was also used to compare with it. Then, the proper surface active agent was selected to modify the surface, thus the stable magnetic liquid with good suspension property and good dispersibility was prepared. Finally, the performance of antiwear and reducing friction of modified magnetic particles as the lubricant additive were tested and discussed.This article content mainly included:1) Preparation of Nanometer magnetic particlesAt first, ultrasonic nanometer grinder was researched and tested by the orthogonal experiments. Each factor effecting the preparation of nanometer particles was analyzed; the mean size of particles as judging index, the optimal processing parameter was determined and built the foundation for the later period experiments. At second, experiments were done according to the determined optimal processing parameter, and the magnetic particles smaller than 100nm with narrow size distribution and regulate shape were prepared. At the same time, the chemical co-precipitation method was also used. The appearance, size and magnetization of magnetic particles were measured and characterized by the Laser Particle Size Analyzer, Scanning Electron Microscope and Transmission Electron Microscope. At last, the supersonic -machinery method was compared with the chemical co-precipitation method.2) Research on the magnetic particles superficial modificationThrough consulting massive literatures and doing the primary exploratory experiment, several kind of surface active agents were selected, the single surface active agents and the composite surface active agents were tested in the experiment, and the kind of dispersant agents, the amount used ,the disperser and stable mechanism were discussed. Thus the appropriate surface active agent was discovered, and the stable magnetic liquid with good suspension property and good dispersibility was prepared.3) Study on the tribological properties of magnetic particles as a lubricant additiveThe modified nanometer particles were added into the lubricant oil. Fe₃O₄ particles were verified whether they had the performance of antiwear and reducing friction or not by the multi-purpose friction and abrasion testing machine. The experiments made us known that Fe₃O₄ particles as lubricant additive played good part in antiwear and reducing friction. The quality of tribological properties was related with the proportion of Fe₃O₄ particles. When the percentage composition of Fe₃O₄ particles in the lubricating oil was between 1‰and 3‰, the result of antiwear and reducing friction was better. And the CoFe₂O₄ particles were more suitable for using under the low load. When the percentage composition of CoFe₂O₄ particles in the lubricating oil was 1‰, the tribological properties were deal relatively.The detailed research in the preparation process of magnetic fluid was shown in this article, and the corresponding attribute and analysis were carried on. Some extremely valuable data were obtained, and that did significant the exploration especially the study on the tribological properties of the oils adding magnetic nano-particles...