CN1229767A

CN1229767A - Method for preparing iron nitrogen Nm alloy and iron nitrogen-boron nitride nm composite material

Info

Publication number: CN1229767A
Application number: CN 98126243
Authority: CN
Inventors: 姚斌; 苏文辉
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 1998-12-19
Filing date: 1998-12-19
Publication date: 1999-09-29
Anticipated expiration: 2018-12-19
Also published as: CN1069289C

Abstract

A process for preparing nm-class Fe-N alloy and its compound material uses Fe or FeO as iron source and the solid h-BN as nitrogen source, and includes such technological steps as mixing iron source with nitrogen source in volume ratio of 1 : (20-0.38), loading the mixture and stainless steel balls in weight ratio of 1 : (5-20) into ball mill, and grinding for 30-120 hrs under the protection of argon gas to obtain nm-class epsilon-FexN alloy and epsilon-FexN/BN compound material. Its advantages include simple process to prepare nitrogen source, easily controlled technological conditions and high output. The product features firm binding between epsilon-FexN alloy and BN substrate, and higher saturated magnetization, coercive force and resistivity.

Description

A kind of iron nitrogen Nm alloy and iron nitrogen-boron nitride nm composite material preparation method

The invention belongs to a kind of preparation method of magnetic Nano material, particularly the preparation method of Fe-N Alloys and matrix material thereof.

Magnetic nanometer composite material is generally by non magnetic isolator be dispersed in the magnetic nanoparticle of its inside (10～100nm) form.The small-size effect of nano particle and with the high density interface of matrix and the insulativity of matrix, make magnetic nanometer composite material show the physics and the chemical property of many excellences, store at high density information, fields such as magnetic cooling have important use to be worth.Said Fe-N alloy of the present invention and matrix material thereof mainly are meant ε-Fe _xN Nanoalloy and with ε-Fe _xThe N alloy is a magnetic nanoparticle, is ε-Fe that matrix is formed with BN _xThe N/BN nano composite material.

Existing preparation ε-Fe _xThe method of N alloy and matrix material thereof all is to be nitrogenous source with the nitrogenous gas, utilizes the method for High Temperature Gas one solid reaction, prepares the Fe-N alloy of various structures.Such as, with NH ₃/ H ₂Gas is nitrogenous source, with γ-Fe ₂O ₃Powder is placed in the crucible, places tubular oven, is heated to 723K under argon shield, charges into volume ratio again and be 1: 2 H ₂And NH ₃, replace the argon gas in the tubular oven, under 723～773K temperature, be incubated 4 hours, finish nitrogenize, at last resultant is chilled to room temperature, products obtained therefrom is acicular, the size ε-Fe in μ m magnitude ₃N, its saturation magnetization and coercive force are respectively 135emu/g and 540Oe.For another example, with FeCl ₃6H ₂O, (NH ₂) ₂CO, H ₃BO ₃And NH ₃Be raw material, utilize thermochemical method to prepare spheric, granularity ε-Fe at 10～100nm ₃The N/BN nano composite material.Its process is that solid feed is soluble in water, and strong mixing is with NH ₃Inject, make solution be strong basicity, reheat dehydrates into gelinite.Gelinite is placed crucible, and elevated temperature heat is decomposed under the nitrogen atmosphere in silica tube, charges into NH with the 1000sccm flow velocity in silica tube ₃, simultaneously, rise to 773K with the temperature rise rate of 25K/min, be incubated 5 hours.Product ε-the Fe that obtains _xThe saturation magnetization of N/BN nano composite material and coercive force are respectively 140emu/g and 50Oe.

From the above, although the product that obtains cleaning, technology is quite complicated, yields poorly, and the cost height is not suitable for industrial production.

The objective of the invention is to start with the solid material is nitrogenous source, utilizes high-energy ball-milling process, makes production technique simple, and cost reduces, and output improves, to be fit to industrial production in enormous quantities.

The objective of the invention is to realize by following technological process.With iron (Fe) or iron protoxide (FeO), solid-state hexagonal boron nitride (h-BN) is a raw material, through being mixed with out batch mixing, is placed in the ball grinder with Stainless Steel Ball, carries out ball milling under argon shield, can make ε-Fe _xN phase Nanoalloy and ε-Fe _xThe N/BN nano composite material.

Fe is or/and the volume ratio of FeO and h-BN can be 1: (20～0.38), their purity can be at 95at% or purer.The weight ratio of batch mixing and Stainless Steel Ball can be 1: (5～20).The ball milling time was at 30～120 hours.

As Fe or/and the volume ratio of FeO and h-BN during greater than 1: 0.38, find also not have or ε-Fe seldom through the ball milling of considerable time (above 120 hours) _xThe N phase alloy generates; And when the volume ratio of Fe in the Fe/BN batch mixing was too low, the magnetic property of products obtained therefrom was relatively poor.In order to prepare ε-Fe with high saturation and magnetic intensity and high-curie temperature _xN can make Fe or/and the volume ratio of FeO and h-BN is controlled at 1: (0.38～2.0) scope.Not only can obtain the ε-Fe of having of single phase than high saturation and magnetic intensity _xThe N semi-hard magnetic alloy, even can obtain permanent magnet material.The weight ratio of batch mixing and Stainless Steel Ball, Fe is or/and the height of FeO purity, and the intensity of ball milling, and all there is bigger influence the ball milling time.And the selection of ball milling time is proper, is very important to product and the maintenance better magnetic properties that makes.When the weight ratio of Fe/BN batch mixing and Stainless Steel Ball was too big, the ball milling time was long, and weight ratio too hour can cause the sky mill waste between Stainless Steel Ball.Thereby batch mixing and Stainless Steel Ball weight ratio are too big or too little all to be unfavorable for enhancing productivity.

In order to reduce production costs, enhance productivity, Fe is or/and the granularity of FeO can be selected 50 μ m so that thinner.Purity can be selected 95～98at%, and the purity of h-BN is at 95～99at%, and the weight ratio of batch mixing and Stainless Steel Ball is 1: (10～14).Satisfying under the above-mentioned condition, as Fe or/and FeO and h-BN volume ratio are 1: when (1.2～2.2), ball milling is 60～75 hours on high energy ball mill, can make the ε-Fe of particle in tens nanometers _xThe N phase alloy, and be in amorphous BN (a-BN) matrix of several nanometers with spherical disperse in granularity, the good ε-Fe of magnetic property formed _xThe N/BN nano composite material.

Experiment shows, ε-Fe _xα-Fe+a-BN--Fe-N amorphous--ε-Fe has been experienced in the formation of N alloy _xThe process of N phase.In the ball milling, have only as Fe or/and after the particle size of FeO reached a certain critical size, N and Fe diffusion reaction just took place form the Fe-N amorphous.The quantity of Fe-N amorphous layer and N content thereof increase with the increase of ball milling time, and when N content was increased to certain value, amorphous Fe-N changed unstability into ε-Fe _xThe N alloy.And, ε-Fe _xThe particle size of N alloy and N content increase with the prolongation of ball milling time.Here be also noted that at h-BN to be converted in the a-BN process that B and N atom with unsaturation dangling bonds are to occur in pairs, but in mechanical milling process, only observing Fe-N does not have the Fe-B phase mutually, illustrate that N has stronger alloy formation ability than B and Fe.

ε-Fe of the present invention _xThe method of converting of N Nanoalloy and nano composite material thereof, because equipment cost is low, the solid feed source is sufficient, and complete processing is easy to control, and ball milling is easy and simple to handle, again can mass production, thereby be fit to very much industrial production.Product ε-Fe that method of the present invention makes _xN alloy original position in the mechanical milling process of Fe and h-BN generates, and be evenly distributed on the insulation BN matrix, combine firmly and interface cleanness with the BN base, grain-size and phase composition can be by the controls of ball milling parameter, also can be made into bulk material, have bigger saturation magnetization and higher coercive force again, have high resistivity.Thereby do highly dense magnetic recording material etc., actual application value is arranged.

Embodiment 1:

Fe and h-BN volume ratio are 1: 5.4 mixed powder, the weight ratio of batch mixing and Stainless Steel Ball 1: 15.Under argon shield, on the high energy vibration ball mill, through 35 hours ball millings, existing ε-Fe _xN occurs mutually, continues ball milling to 55 hour, and product is ε-Fe _xThe N/BN nano composite material.At this moment, the XRD spectrum has only ε-Fe _xN and a-BN diffraction mutually.Continue ball milling to 60 hour, TEM bright field image and ε-Fe again _xThe electron diffraction of N shows, ε-Fe _xOn amorphous BN matrix, its particle size is 10～20nm to N with spherical disperse, and the particle of amorphous BN is thinner, is several nanometers.

Embodiment 2:

Fe and h-BN volume ratio are 1: 1.2 mixed powder, and the weight ratio of batch mixing and Stainless Steel Ball is 1: 13.Through 72 hours ball millings, get ε-Fe _xThe N phase alloy.TEM bright field image and electron diffraction experiment show formed ε-Fe _xThe N alloy is a Nanoalloy.

Embodiment 3:

Fe and h-BN volume ratio are 1: (12.5～2.2) batch mixing, the weight ratio of batch mixing and Stainless Steel Ball are 1: 10.Through about 40 hours ball milling ε-Fe is arranged _xN occurs mutually, and when the weight ratio of batch mixing and Stainless Steel Ball be 1: 15, through about 36 hours ball milling ε-Fe is arranged just _xThe N alloy occurs.Explanation forms ε-Fe under the situation of different ball material weight ratios _xThe ball milling asynchronism(-nization) that the N alloy is used.Yet make α-Fe identical with the critical grain-size that diffusion reaction takes place h-BN.

Embodiment 4:

The volume ratio of Fe and h-BN was respectively 1: 12.5, and 1: 5.4 and 1: 1.2, the ball milling time, α-Fe and BN complete reaction in the sample formed ε-Fe about 60～70 hours _xThe N alloy.Test shows ε-Fe _xThe saturation magnetization of N/BN increases with the rising of the ratio of Fe in batch mixing, with ε-Fe _xThe increase of N content among the N and reducing.Test also shows, although the ε-Fe that forms under three kinds of proportionings _xN content difference among the N, but their coercive force is much at one.ε-Fe is described after chemical ingredients is evenly distributed _xThe coercive force of N alloy and composition relation are little.

Embodiment 5:

Fe and BN volume ratio are 1: 0.38 Fe/BN mixed powder ball milling to 180 hour, still do not have ε-Fe _xThe N alloy forms, and has only the γ-Fe (N) of minute quantity to form mutually.

Claims

1 one kinds of ε-Fe _xN Nanoalloy and ε-Fe _xThe preparation method of N/BN nano composite material is characterized in that with iron being placed in the stainless steel jar mill with Stainless Steel Ball or/and iron protoxide and solid-state hexagonal boron nitride are the batch mixing that feedstock production goes out, and carries out ball milling under argon shield, makes ε-Fe _xN phase Nanoalloy and ε-Fe _xThe N/BN nano composite material.

2. according to the described ε-Fe of claim 1 _xN Nanoalloy and ε-Fe _xThe preparation method of N/BN nano composite material is characterized in that said iron or/and the volume ratio of iron protoxide and solid-state hexagonal boron nitride is 1: (20～0.38), and their purity is at 95at% or purer; The weight ratio of batch mixing and Stainless Steel Ball is 1: (5～20); The ball milling time is at (30～120) h.