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Study on the Preparation of Nitride in High Magnetic Field and by Mechanical Alloying

Author: MengQingLin
Tutor: ZuoWeiPing
School: Northeastern University
Course: Materials Science
Keywords: Strong magnetic field Nitriding Atomic diffusion Pure iron Mechanical alloying Nitrogen-containing martensite Fe16N2
CLC: TG156.82
Type: Master's thesis
Year: 2008
Downloads: 28
Quote: 0
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Abstract


Iron nitride having a good corrosion resistance, wear resistance and oxidation resistance, and excellent magnetic properties, widely used in various areas of industrial production, such as a magnetic recording medium and a vibration-damping material. Their preparation, there are still a lot of problems need to be addressed, such as a longer period of preparation process, the purity of the product was prepared enough. So, it is necessary to explore new technology or some adjunct. This paper studies the impact of a strong magnetic field and mechanical alloying process of the formation of nitride and by X-ray diffraction analysis, scanning electron microscopy, Mossbauer spectroscopy, optical microscope and the nitrided layer depth measurement software to characterize the experimental results. Specific conclusions are as follows: a strong magnetic field on the formation of nitride (1) nitriding direction perpendicular to the magnetic field direction, nitriding temperature of 550 ° C (high temperature), does not change the phase composition of the compound layer in a strong magnetic field, that pure iron in the magnetic field The compound layer after nitriding and non-magnetic phase composition are ε-Fe2-3N and γ'-Fe4N. Wherein the strong magnetic field in the thickness of the compound layer is about 8.64μm, and slightly smaller than the thickness of the compound layer in the non-magnetic field (8.853μm). However, X-ray diffraction analysis showed that in the strong magnetic field in the sample, the volume fraction ε phase nitriding sample is less than the non-magnetic field, i.e., a strong magnetic field on the formation of ε phase inhibition, while the strong magnetic field on the precipitation of the nitride diffusion layer also have an impact. (2) nitriding direction perpendicular to the magnetic field direction at the lower temperature (T = 494 ° C, 450 ° C, 410 ° C and 400 ℃) nitriding, as the temperature decreases, the pure iron nitriding capacity is reduced. But the strong magnetic remain from the compound layer γ'-Fe4N and ε-Fe2-3N generation inhibition. (3) in the nitriding process, applying a strong magnetic field in the direction of impact the results of nitriding. Pure iron after the 550 ° C 2h nitriding diffusion layer, the precipitation of nitrides long needle density relationship is: parallel to the direction of the magnetic field (H = 12T) Sample nitride precipitation density, followed without magnetic field samples nitride precipitation density perpendicular to the direction of the magnetic field (H = 12T) Sample nitride precipitation density minimum. Mechanical alloying of the mixed powder of 2.Fe and nitrides and the product annealing stability of pure iron powder at 550 ℃ nitriding 2h ε nitride powder can be obtained, the mass ratio of the iron powder and nitriding for the 4:3 sample 16h ball-milling, the x-ray diffraction spectrum of the milled product still exists a diffraction peak of the nitride; substance ratio of the iron powder and nitriding becomes 5:2, the milling after 16h, nitride diffraction peaks disappear, the milled product is over-saturated nitrogen-containing α-Fe; low temperature annealing, a nitride of the milled product is re-precipitated.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Heat treatment > Heat treatment process > Chemical treatment > Nitriding, cyaniding, carbonitriding
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