Research on Preparation of Cenospheres Coated with Barium Ferrite |
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Author | WangCaiFang |
Tutor | XiongWeiZuo |
School | Huazhong University of Science and Technology |
Course | Materials Science |
Keywords | M-type barium ferrite Cenospheres Composite coating Sol-gel |
CLC | TG174.44 |
Type | Master's thesis |
Year | 2004 |
Downloads | 234 |
Quotes | 3 |
This paper for the first time with the sol-gel method of cenospheres based ferrite coating composite . Using thermal gravimetric and differential thermal analyzer (TG-DTA) analysis xerogel changes in the heating process ; phases determined by X -ray diffraction (XRD) samples using a vibrating sample magnetometer (VSM) magnetic It can be measured ; with a scanning electron microscope (SEM) and transmission electron microscopy (TEM) of an atomic force microscope (AFM) observation analyzes the morphology and particle size of the powder and coating . Is studied in the experiment Preparation of M type barium ferrite in the process of sol-gel process conditions ( including the ratio of the composition of the sol , the starting pH of the solution , the concentration of the solution , the bath temperature, a complexing agent , a dispersing agent , select , the type of the intermediate product , heat treatment , etc. ) on the barium ferrite powder phase composition , particle size, morphology . The preparation excellent barium ferrite has two key steps : ( 1 ) adjusting the pH value of the initial solution is about 7.0, can guarantee that the only pure M type barium ferrite to generate the final product ; ② xerogel precombustor by the two-step heat treatment , i.e. the dry gel at 450 ℃ preheat treatment 1h to ensure the organic precursor is completely converted to the γ-Fe2O3, and then treated at 850 ° C tempering for 3 h . Sol-gel method cenospheres base ferrite coating before washing cenospheres distributed processing to remove impurities cenospheres . By multiple coating or pre- added part of the ultrafine ferrite powder to ferrite sol , can greatly increase the thickness of the coating . With respect to the pure barium ferrite material , doped rare earth ions than the saturation magnetization of the material after the ratio of the residual magnetization and the coercive force will be a multiple of the increase , while the area of the hysteresis loop also significantly increased . At the same time cenospheres based Adulteration Nd ions than the saturation magnetization of the composite coating change , but a slight increase in the residual magnetization , coercive force several times increase in the area of the hysteresis loop greatly increase.