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利用柠檬酸–硝酸盐溶胶–凝胶自蔓延燃烧法,在室温下制备了以粉煤灰空心微珠为基核、以镍铁氧体为包覆壳体的复合粉体,分析了复合粉体的物相、形貌、表面成分与电磁参数,探讨了复合粉体的形成机理。研究表明,自蔓延燃烧过程中,镍铁氧体通过非均匀成核方式在空心微珠表面成核、生长、延展,最终形成完整包覆层。自燃烧复合粉体包覆层含有少量Fe Ni3相,经900℃热处理后消失。由于包覆层物相、结构及基核间的微小区别,使得在2~18 GHz,自燃烧复合粉体的介电常数、磁导率与热处理复合粉体存在一定差异。
The composite powders with hollow fly ash hollow microspheres as base and nickel ferrite as the coated shell were prepared by citric acid-nitrate sol-gel self-propagating combustion method at room temperature. Body phase, morphology, surface composition and electromagnetic parameters, discussed the formation mechanism of composite powder. The results show that during self-propagating combustion, nickel ferrite nucleates, grows and expands on the surface of hollow microbeads by non-uniform nucleation, finally forming a complete coating. Self-combustion composite powder coating containing a small amount of Fe Ni3 phase, after 900 ℃ heat treatment disappeared. Due to the slight difference between the phases, the structure and the nuclei, the dielectric constant, permeability and heat-treated composite powders of self-combustion composite powders are different at 2 ~ 18 GHz.