| Rare earth permanent magnet materials system is appliated broadly. Due to the rare earth crisis and rising prices, there non-rare-earth permanent magnet materials system has a great application prospect. The ConC nano permanent magnetic material is one of the typical representatives in non-rare-earth permanent magnet materials systems. The ConC nanopermanent magnetic thin film now mainly has been produced by magnetron sputtering and ion sputtering method which need relatively expensive equipments. At the same time, the application of ConC nanopermanent magnetic thin film which its coercive force and saturation magnetization intensity could not reach the requirements of the permanent magnent materials is restricted. Therefore, it is very significant to study the relationship of the three aspects which the ConC systhesis of permanent magnet materials, microstructure and magnetic properties. In this paper, the first step is synthesis nanoscale cobalt power based on the hythrothermal method, by changing the temperature, concentration of sodium citrare and sodium hydroxide to change the morphology of nanoscale cobalt power. Synthesis of high surface activity cobalt power is the raw materials for the heat treatment. Study the composition of the ConC(CNTs) phase after heating treatment of cobalt power and carbon nanotubes, and study the ConC(G) phase composition through cobalt power and graphite heat-treating. Research different parameters such as heat treatment temperature and the content of carbon have an effect on microstructure and magnetic properties. At the same time, it also studies the direct synthesis nanoscale ConC powder phase structure and study the relationship of formation mechanism, microstructure and magnetic properties by adjusting the hydrothermal synthesis process parameters, such as temperature, time and so on. The main conclusions are as follows:1. It has close relationship of hydrothermal synthesis of nano-sized cobalt powder morphology and the parameters, such as temperature, sodium citrate, sodium hydroxide. Nanoscale cobalt powder morphology which is syntheticed by hydrothermal method at 140℃ is sliced prismatic microstructure. With the increasing of hydrothermal temperature, the sliced prismatic microstructure gradually become spherical. The main formation mechanism are the theory of ostwald ripening and oriented attachment. The grain size is the smallest at 140℃, then it becomes large with the increasing systhesis temperature, the optimal synthesis process of Cobalt powder in this experiment is following, the temperature is 140 ℃, the concentration of sodium citrate is 15mmol, the molar ratio of sodium hydroxide and cobalt chloride is 6:1.2. ConC(CNTs), ConC(G) nano permanent magnetic material by heat treatment, is composed of C, Co and Co3C three-phase hybrid structure. And coercive force first increases and then decreases with the increase of temperature, however saturation magnetization intensity increases with the temperature. Taken into account, the most suitable temperature is 400℃ for this experiment. No matter graphite or carbon nanotubes, the ConC occures phase transformation at 500℃. With the increasing of heat treatment temperature, ConC nanoparticles microstructure is hexagon sheet at the beginning, then become the spherical gradually.3. ConC(CNTs) and ConC(G) nano permanent magnetic material by hydrothermal method, is composed of C, Co and Co3C three-phase hybrid structure at 200 ℃. ConC(CNTs) nanostructured microspheres turned into hollow-nanostructured microspheres with time. Magnetic coercive force is 218.19Oe, saturation magnetization intensity is 103.46emu/g. The ConC(G) nano materials increases with time by the chain into a hexagon layered. Coercive force was 180.58Oe, saturation magnetization intensity was 103.08 emu/g. |
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