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Synthesis of Magnetic Metal Fibers Prepared by Thermal Decomposition of Gel Precursor Fibers

Author: DengCheng
Tutor: SongYongCai
School: National University of Defense Science and Technology
Course: Materials Science and Engineering
Keywords: sol-gel method thermal decomposition magnetic metal fibers preparation electromagnetic properties
CLC: TB333
Type: Master's thesis
Year: 2005
Downloads: 120
Quote: 4
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Abstract


In this paper, the Ni, Ni-Co, Fe and Ni-Fe magnetic fibers were prepared by thermal decomposition reducing method of gel precursor fibers. With the metal-salt and complexing agent as the raw materials, this method included preparation of precursor sol with good spinnability through complex reaction, dry spinning, gelating process and thermal decomposition.The study showed that the spinnability of the precursor sol was influenced by many factors; using IR, XRD, SEM and chemical analysis technics, the structure of the precursor sol was characterized, and the molecular structures of precursor sol was deduced; in the phase of thermal decomposition, the thermal decomposition atmosphere, temperatures and time were studied, and the transition of the precursor fibers in thermal decomposition process was also studied; at last the electromagnetic properties of these magnetic metal fibers were tested.Through study, the precursor sol contained Ni element with good spinnability had been synthesized with citric acid and nickel carbonate basic as the starting reagents, and the molar ratio of citric acid to nickel ion is 1.5:1 at 50℃. The nickel fibers with face-centered cube structure were prepared through dry spinning, gelating process and thermal decomposition in H2 atmosphere at 500℃in tube furnace, and the diameter of the fibers obtained was about 10~20μm without crack on the surface.Using nickel carbonate basic, cobaltous carbonate basic and citric acid as the raw materials, the molar ratio of citric acid to nickel and cobalt ion 1.5:1 at 50℃, the precursor sol with different ratios of Ni and Co element was prepared. At last the Ni-Co alloy fibers were obtained through thermal decomposition in H2 atmosphere.The precursor sol contained Fe element with good spinnability was synthesized with ferric citrate as the raw material, through dissolving-aggregation reaction in aqueous solution and controlling the pH value to acidulous with aqueous ammonia. The iron fibers were finally prepared in H2 atmosphere at 500℃for 2h, and the diameter of the fibers obtained was about 10~15μm without crack on the surface.The precursor sol contained Ni and Fe element was synthesized by mixing these precursor sol contained Ni and Fe element respectively at room temperature with stirring. Through thermal decomposition, the Ni-Fe alloy fibers were obtained.

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