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Method for preparing gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling

A soft magnetic material, -fe4n technology, applied in the direction of magnetic materials, magnetic objects, metal processing equipment, etc., can solve the problems that it is difficult to achieve pure phase, low N purity, affecting soft magnetic properties, etc., and achieve the goal of overcoming solid solubility Confinement, homogeneity of elements and structures, effect of reduced size

Active Publication Date: 2019-03-01
无锡市临碳电子科技有限公司
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AI Technical Summary

Problems solved by technology

[0003] However, γ'-Fe 4 The preparation of N is challenging, and most of the material preparation work so far has been based on the preparation of thin-film materials
There have been some reports on the preparation of granular materials, but the γ'-Fe 4 The purity of N is relatively low, and most of it is mixed with other iron nitride phases or other undesirable forms and particle sizes. The method used generally uses ammonia as a nitrogen source to provide nitrogen atoms, and the nitrogen content of the obtained materials is generally 6%. around, not more than 10%, is low in γ'-Fe 4 A mixture of N, it is difficult to achieve a pure phase, which seriously affects the γ'-Fe 4 Excellent soft magnetic properties of N
According to γ'-Fe 4 According to the requirements of the atomic ratio of N, the content of nitrogen atoms should be about 20%, but the solid solubility of nitrogen atoms in iron is only 11.7%, so according to the conventional nitrogen doping method, only about 50% of the purity can be obtained at most. γ'-Fe 4 N, therefore, the main obstacle to the preparation of this material is the content of nitrogen atoms, how to overcome the solid solubility of nitrogen atoms in iron, so as to improve the γ'-Fe 4 The purity of N is the bottleneck in the preparation of this material

Method used

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  • Method for preparing gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling
  • Method for preparing gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling
  • Method for preparing gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling

Examples

Experimental program
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Effect test

Embodiment 1

[0034] The starting material was pure iron with a purity of 99% (Alfa Aesar); liquid nitrogen was provided by PRAXAIR; a high energy ball milling system CM5100 (Luomen) was operated in planetary rotation mode.

[0035] Wear-resistant stainless steel balls are used as the grinding medium with a mass-to-sample ratio of 10:1. The tank is continuously cooled with liquid nitrogen from the integrated cooling system before and during the grinding process, making the samples brittle and retaining their volatility Nitrogen. Liquid nitrogen circulates in the system and is continuously replenished from the external filling system, which is precisely controlled to keep the temperature at -196°C;

[0036] The iron feedstock and ball milling product were handled in a nitrogen atmosphere inside a glove box, which protected the particles from oxidation. The milling time was 90 hours and the rotational speed was 3000 rpm. The mill run was stopped for 5 minutes every hour. The direction of r...

Embodiment 2

[0043] Referring to the method conditions of Example 1, the annealing temperature is replaced by 200°C or 250°C, and other conditions remain unchanged, the prepared γ'-Fe 4 N material.

[0044] The resulting material was characterized by XRD spectroscopy, as figure 2 As shown, for the sample prepared after freeze-milling, it exhibits a broad bcc Fe peak, consistent with the metastable supersaturation of N conversion to Fe. Annealing at 200°C for 10 minutes resulted in a slight change in the powder, γ'-Fe 4 Slight sharpening of the N peak. Annealing at 250 °C for 10 min resulted in sharp bcc Fe and γ′-Fe4N peaks. Annealing at 300 °C results in more γ'-Fe 4 N peak and sharper bcc Fe. Furthermore, further increasing the annealing temperature, slightly above 300 °C, had no significant effect on the XRD peaks; indicating that the high-energy cryogenic cooling process produces broad BCC Fe with nitrogen supersaturation, and short post-annealing can lead to sharp BCC and γ′-Fe ...

Embodiment 3

[0048] Referring to Example 1, the weight ratio of the ball and the iron powder material was replaced from 10:1 to 30:1, and other conditions remained unchanged, and the iron-nitrogen material was prepared. The magnetic properties of the obtained iron-nitrogen material are similar to those obtained in Example 1, and the yield is about 30% of that of the material in Example 1.

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Abstract

The invention discloses a method for preparing a gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling, and belongs to the field of soft magnetic materials. According to the method, high-energy low-temperature grinding in the liquid nitrogen is utilized to obtain a nano material FexN with a nitrogen atom supersaturation degree; and at low temperature, the material is crispy and the surface volume ratio is very high, so that 22% of nitrogen atoms are adsorbed on the surface of a sample; after the temperature is up to 300 DEG C, annealing is carried out to ensure that alpha-Fe directly undergoes phase change to be converted to gamma'-Fe4N, so as to prepare a nanocrystal gamma'-Fe4N soft magnetic material. The method is simple to convenient to operate, low in cost and suitable for large-scale industrial production, and is a novel replacement method for preparing high-level soft magnetic materials with ideal magnetism. The gamma'-Fe4N soft magnetic material prepared by the method has the advantages of being high in Ms, low in coercive force and high surface resistivity, and can be applied to transformer and inductors operated in high-frequency semi-conductor switches.

Description

technical field [0001] The invention belongs to the field of soft magnetic materials, in particular to a method for preparing γ'-Fe by using liquid nitrogen high-speed ball milling 4 N method for soft magnetic materials. Background technique [0002] Since the early 1950s, people have studied iron nitride materials, initially to study the nitriding phenomenon on the surface of steel to improve the hardness and oxidation resistance of the steel surface. With the in-depth research on iron nitride materials, it has been found that iron nitride materials have excellent ferromagnetic properties, good wear resistance, corrosion resistance, and oxidation resistance, and are good high-density magnetic recording media and thin-film magnetic heads. candidate materials. So people began to study more deeply on iron nitride materials. Due to the different nitrogen content in iron nitride materials, iron nitride materials have different crystal structures, and there are many phases, esp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/153B22F9/16B22F1/00B22F1/142
CPCH01F1/15308H01F1/15333H01F1/15341B22F9/16B22F1/142B22F2009/043C22C33/0228C22C1/053B22F2009/042H01F41/0246H01F1/147B22F9/04B22F2302/20H01F41/02
Inventor 姜岩峰李茹姜淋馨
Owner 无锡市临碳电子科技有限公司
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