Method for directly preparing samarium-iron alloy powder through spray pyrolysis reduction method

Abstract

The invention discloses a method for directly preparing samarium-iron alloy powder through a spray pyrolysis reduction method. A mixed aqueous solution of samarium salt and iron salt is used as a spray precursor solution, spherical samarium-iron composite oxides are prepared through the ultrasonic spray pyrolysis method, and samarium-iron alloy is obtained through hydrogen prereduction and then calcium reduction or directly through calcium reduction. According to the method, the cost of raw materials is low, the mole ratio of samarium and iron in the samarium-iron alloy can be easily obtainedby adjusting the proportion of the samarium salt and the iron salt in the precursor solution, the samarium and iron dispersity during reduction diffusion is good, the reduction temperature is low, thereaction time is short, samarium volatilization can be effectively reduced, and agglomeration of the samarium-iron alloy powder can be effectively restrained. According to the method, the pure-phasesamarium-iron alloy powder with the size being 0.5-10 micrometers and in the form of nearly spherical particles can be directly prepared without the need of a follow-up ball-milling crushing process,samarium-iron alloy grains are complete, following improvement on the performance of samarium iron nitrogen is facilitated, and samarium iron nitrogen has good flowing machinability when combined withmacromolecules.

Description

technical field [0001] The invention belongs to the technical field of metal magnetic material preparation, and relates to a method for directly preparing samarium-iron alloy powder by a spray pyrolysis reduction method, specifically a method for synthesizing spherical samarium-iron composite oxides by spray pyrolysis first, and then obtaining a nearly spherical, Pure phase samarium-iron alloy with a size of 0.5-10 microns. Background technique [0002] In 1990, Coey et al. introduced N atoms into Sm through a gas-solid reaction. 2 Fe 17 alloys, obtained Sm with excellent intrinsic magnetic properties 2 Fe 17 N x (x≈3), its saturation magnetization μ 0 m s =1.54T, anisotropy field H a =17.5MA / m (about 3 times that of Nd-Fe-B) and Curie temperature T c =475°C (about 160°C higher than Nd-Fe-B), and Sm 2 Fe 17 N x The rare earth content contained in NdFeB is lower than that of NdFeB, which is conducive to the protection of precious rare earth resources in our country...

AI Technical Summary

Problems solved by technology

Both the alloy smelting method and the melt rapid quenching method are prepared by smelting metal samarium Sm and iron Fe first, because the melting point of iron (1538°C) is obviously higher than that of samarium (1072°C), and the saturated vapor pressure of samarium is very low. Volatilization, so when the two are co-melted, the volatilization of samarium will be extremely large, and the volatilization of samarium will cover the smelting observation window, making the operation difficult; at the same time, these two methods have high requirements for equipment, especially the rapid quenching of the melt The pure-phase samarium-iron alloy must be obtained under a very high degree of subcooling and precise samarium content, so the process is difficult to control; in addition, the alloy powder obtained by the melt rapid quenching method is in the shape of scales, which cannot reach the level of samarium-iron-nitrogen and high Fluidity requirements for composite processing of molecular materials

The mechanical alloying method is to mix iron powder and samarium powder and then perform ball milling in a planetary high-energy ball mill. Through the ball milling process, a solid phase reaction occurs to prepare samarium-iron alloy. The mechanical alloying method has a long cycle and high energy consumption, which limits its application in industrial production. application, and the powder cannot be completely oxidized during the long-term ball milling process, and the high stress of the powder obtained by ball milling will also reduce the magnetic properties

The reduction diffusion method mixes samarium oxide with iron powder and calcium particles, uses Ca to reduce samarium oxide into samarium metal and then alloys it with iron to obtain a samarium-iron alloy. Reduce the cost of raw materials, but the traditional reduction and diffusion method is to directly mix the samarium

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