CN111454062B

CN111454062B - AlMgB14Preparation method of ceramic material powder

Info

Publication number: CN111454062B
Application number: CN201910058650.4A
Authority: CN
Inventors: 张景贤; 姜金华; 刘宁
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2019-01-22
Filing date: 2019-01-22
Publication date: 2022-03-08
Anticipated expiration: 2039-01-22
Also published as: CN111454062A

Abstract

The invention relates to AlMgB₁₄The preparation method of the ceramic material powder comprises the following steps: adopting absolute ethyl alcohol as a solvent, and carrying out ball milling and mixing on raw material powder to obtain mixed slurry, wherein the raw material powder comprises Al powder and MgB powder with the mass ratio of 1 (1.2-1.4) to (3.6-4.2)₂Powders and boron powders; and drying the mixed slurry, prepressing and forming to obtain a block, and sintering in a protective atmosphere.

Description

AlMgB14Preparation method of ceramic material powder

Technical Field

The invention relates to AlMgB₁₄A method for preparing ceramic material powder. Belonging to the field of ceramic preparation process and application.

Background

Since 2000, Ames laboratories paired with AlMgB₁₄Have been extensively studied for their preparation and use. AlMgB₁₄Has ultra-high hardness and is manufactured only from 1/10 parts of diamond and cubic boron nitride. The advantages of excellent wear resistance, high temperature stability and heat resistance, low density and the like are widely researched in the fields of cutting tools, armors, heat-resistant coatings and the like. However, how to realize the mass preparation of high-purity AlMgB₁₄Powder remains one of the problems limiting its application.

Ahmed et Al (Tribology International 39 (2006)) 129-₁₄. The method has long ball milling time and complex process, and is difficult to realize batch production.

Chinese patent CN 105755304A discloses a method for preparing AlMgB by mixing Mg powder, Al powder and B powder in a certain mass ratio, mechanically ball-milling and sintering₁₄A method for preparing powder. However, Mg is easy to volatilize in the high-temperature sintering process, and the service life of the sintering furnace is greatly shortened in the mass production process. Mg, Al and B powder is easy to be oxidized by ball milling in the air, and is not easy to prepare high-purity AlMgB₁₄And (3) powder.

Xie et al (Advances in Applied Ceramics 116(2017)341-347) adopt MgB₂And AlB₂Iso-boronizingThe material is used as a raw material, mechanically ball-milled under protective atmosphere (high-purity argon) and then sintered to prepare AlMgB₁₄And (3) powder. However, the method is complicated in process and not suitable for mass production, and the obtained AlMgB₁₄The powder has more sintering impurity phases and lower purity.

Research shows that the impurity content influences AlMgB₁₄The properties of ceramics are critical. Analysis of MgAl, L.Lewis et al (Materials Science and Engineering A351(2003)117-122)₂O₄And the like, and adverse effects on mechanical properties. How to reduce MgAl₂O₄The content of impurities has become one of the key factors restricting the application thereof.

Richard Bodkin at A Synthesis and Study of AlMgB₁₄(2005) The method for preparing AlMgB by using Mg powder, Al powder and B powder as raw materials and using methanol as a grinding medium₁₄A method of (1). Mg reacts with H in the ball milling process₂The reaction of O is extremely explosive, so the purity requirement of methanol is higher. And the Mg granularity is higher in the market, and Mg is easy to settle in the slurry without adding a dispersing agent in the ball milling process, so that the yield is reduced.

AlMgB₁₄The applications in various fields have been extensively studied and achieved with certain results. Due to the impurity content, especially oxygen, the subsequent sintering and material properties are strongly affected. Therefore, the purity of the starting material is very critical. At present, high-purity AlMgB is prepared₁₄Often requiring mixing in a glove box and high energy ball milling under a protective atmosphere. The preparation process is complicated, the production conditions are high, the equipment requirement is high, and the preparation cost is greatly improved.

Disclosure of Invention

In order to solve the problems, the invention aims to provide the AlMgB with simple process, strong operability, low cost, mass production and high purity₁₄A method for preparing powder.

The invention provides an AlMgB₁₄The preparation method of the ceramic powder comprises the following steps:

adopting absolute ethyl alcohol as a solvent, and carrying out ball milling and mixing on raw material powder to obtain mixed slurry, wherein the raw materialsThe powder comprises Al powder and MgB powder with the mass ratio of 1 (1.2-1.4) to 3.6-4.2₂Powders and boron powders; and drying the mixed slurry, prepressing and forming to obtain a block, and sintering in a protective atmosphere.

According to the method, the aluminum alloy powder comprises Al powder and MgB in a certain mass ratio₂And (3) ball-milling the raw material powder of the powder and the powder B in absolute ethyl alcohol, uniformly mixing, drying, prepressing to form a block body, and carrying out high-temperature reaction. The technical process provided by the invention adopts ball milling in absolute ethyl alcohol, the ball milling granularity is uniform, the material mixing is uniform, and the ball milling speed is greatly improved; the production process is simple, the requirement on the preparation environment is low, and batch production can be realized. The invention adopts absolute ethyl alcohol as ball milling medium, shortens ball milling time, reduces the types and content of metal oxide impurities, and uses MgB₂And metal Mg is replaced, the risk of the experiment is reduced, and batch production can be realized.

Preferably, the boron powder is amorphous boron powder.

Preferably, the purity of the Al powder is more than 99.9%, and the particle size is 1-10 μm; the MgB₂The purity of the powder is more than 99.9%, and the particle size is 5-15 mu m; the purity of the boron powder is more than 99.9%, and the particle size is 1-5 mu m.

The raw material powder can also comprise Al powder and MgB powder₂0.5 to 6 weight percent of dispersant based on the total mass of the powder and the boron powder.

Preferably, the dispersant is at least one of polyvinylpyrrolidone, triolein, KD-1 and fatty acid polyglycol ester.

The addition of a dispersant (e.g., polyvinylpyrrolidone, PVP) helps prevent the Al powder from settling during the drying (drying) process, and also helps reduce further oxidation of the metal powder and boron powder (especially amorphous boron powder) during the drying process.

Preferably, the absolute ethanol is analytically pure.

The pre-pressing forming mode can be dry pressing forming and/or cold isostatic pressing forming, the pressure range of the dry pressing forming and/or the cold isostatic pressing forming is 10-100 MPa, and the pressure maintaining time range is 10-300 seconds.

The sintering may include: a first sintering process of preserving heat for a period of time at 400-; and a second sintering process of preserving heat for a period of time at 1200-1300 ℃, wherein the temperature rise rate of the second sintering process is below 30 ℃/minute, and the heat preservation time is 1-4 hours; the degree of vacuum was kept below 0.05Pa during the sintering in the first sintering step. The pre-pressed block can be placed in a vacuum sintering furnace for high-temperature reaction. The sintering temperature is low, the heat preservation time is short, and the production cost is effectively reduced. The invention adopts Al powder and MgB₂The preparation temperature of the powder and the powder B as raw materials is low, and the prepared AlMgB₁₄The purity of (2) is higher.

Preferably, the protective atmosphere is a high-purity argon atmosphere.

The invention also provides AlMgB prepared by the method₁₄Ceramic powder. Obtaining AlMgB₁₄The purity of the powder is high (80-92%). For example, AlMgB produced by the production method according to an embodiment of the present invention₁₄The ceramic powder is tested by an XRD diffractometer, and AlMgB is obtained by Rietveld calculation₁₄The purity of the powder is about 90 percent.

AlMgB according to the invention₁₄The preparation method of the ceramic powder has the advantages of simple process, strong operability, low cost, batch production, low impurity content, high activity and the like.

Drawings

FIG. 1 shows AlMgB prepared according to an embodiment of the present invention₁₄A flow chart of the powder;

FIG. 2 shows AlMgB prepared in example 3 of the present invention₁₄XRD pattern of the powder;

FIG. 3 shows AlMgB prepared in example 4 of the present invention₁₄SEM image of powder.

Detailed Description

The present invention is further described below in conjunction with the following embodiments, which are intended to illustrate and not to limit the present invention.

The invention relates to AlMgB₁₄Ceramic materialThe preparation method of the material powder adopts absolute ethyl alcohol as a solvent and comprises Al powder and MgB powder with the mass ratio of 1 (1.2-1.4) to 3.6-4.2₂The powder and boron powder are ball-milled and mixed, evenly mixed, dried, pre-pressed into blocks and placed in a sintering furnace (such as a vacuum sintering furnace) for high-temperature reaction (figure 1). The invention adopts absolute ethyl alcohol as ball milling medium, shortens ball milling time, reduces the types and content of metal oxide impurities, and uses MgB₂And metal Mg is replaced, the risk of the experiment is reduced, and batch production can be realized. The method has simple preparation process, is easier to realize batch production, and greatly reduces the production cost.

The raw material powder comprises Al powder and MgB₂Powders and boron powders. The boron powder may use amorphous boron powder, so that the reactive binding energy may be reduced. Or the amorphous boron powder can be presintered for 1-2h at 1500 ℃ in vacuum, and the oxide on the surface of B volatilizes to reduce the oxygen content of the powder. AlMgB can be reduced after pretreatment₁₄MgAl in (1)₂O₄Content, thereby improving purity. With MgB₂The raw materials can reduce the risk of the experiment and are safer. Al powder and MgB are adopted₂When the powder and the amorphous B powder are used as raw materials, the preparation temperature can be low, and the prepared AlMgB₁₄The purity of (2) is higher.

In a preferable scheme, the purity of the Al powder is more than 99.9 percent, and the particle size is 1-10 mu m; MgB₂The purity of the powder is more than 99.9%, and the particle size is 5-15 mu m; the purity of the boron powder is more than 99.9%, and the particle size is 1-5 mu m. By using high-purity (e.g. 99.99%) Al powder having a particle size of 1 to 10 μm, high-purity (e.g. 99.9%) MgB powder having a particle size of 5 to 15 μm₂The powder is high-purity (such as 99.99%) boron powder with the grain size of 1-5 mu m, and can obtain uniformly dispersed slurry, so that AlMgB is improved₁₄The purity of (2). More preferably, the purity of the Al powder is 99.99% or more, and the purity of the boron powder is 99.99% or more.

Hereinafter, AlMgB of the present invention is exemplified₁₄A method for preparing ceramic powder.

Firstly, raw materials are prepared, wherein the raw materials comprise Al powder and MgB₂Powder,Boron powder, and a dispersant can also be included. Weighing Al powder and MgB according to a certain proportion₂Powder and boron powder. Al powder and MgB₂The mass ratio of the powder to the boron powder can be 1 (1.2-1.4) to 3.6-4.2, and the proportion range has the advantage of high feasibility.

As described above, a suitable amount of dispersant may be added. The dispersant may be in the form of a powder (i.e., Al powder, MgB powder) in total₂Total mass of powder and boron powder) 0.5 wt% to 6 wt%. The dispersant can be polyvinylpyrrolidone (PVP), triolein, KD-1, fatty acid polyglycol ester, etc. The addition of a dispersant (e.g., polyvinylpyrrolidone, PVP) helps prevent the Al powder from settling during the drying (drying) process, and also helps reduce further oxidation of the metal powder and boron powder (especially amorphous boron powder) during the drying process.

Then, the raw materials are ball-milled and mixed by adopting absolute ethyl alcohol as a solvent. In the invention, absolute ethyl alcohol is used as a solvent, and the absolute ethyl alcohol which is preferably used is analytically pure (more than or equal to 99.7 percent), so that the reaction with water (such as H generation) can be avoided₃BO₃) Increasing the oxygen content of the powder. The wet mixing conditions (ball milling parameters) may be: raw material powder: anhydrous ethanol: the mass ratio of the grinding balls is about (3-7): 10-12): 13, the rotating speed of the planetary ball mill is 300-380 r/min, and the time is 1-5 h. The invention adopts the wet ball milling to shorten the ball milling time and save more energy.

Ball-milling in absolute ethyl alcohol to obtain uniform mixture, drying, and prepressing to obtain block. The raw materials can be mixed, dried and sieved (figure 1) to obtain mixed powder. The drying mode can be vacuum drying or rotary steaming and drying. The drying schedule may include: the drying temperature is 60-100 ℃, and the time is determined according to the content of ethanol. The mesh size range of the sieve can be 100-300 meshes. The forming mode can be dry pressing forming and/or cold isostatic pressing forming, the pressure range of the dry pressing forming and/or the cold isostatic pressing forming is 10-100 MPa, and the pressure maintaining time range is 10-300 s. Due to the different bearing capacities of the grinding tools, the preferred pre-pressing conditions are: and (3) pre-pressing at 20-25 MPa for 10-30 s to obtain a biscuit, wherein the biscuit is well formed and the service life of the grinding tool is long. Through pre-compaction forming, the sintering difficulty of the powder can be reduced.

And then, sintering the pre-pressed block body in a protective atmosphere. The sintering regime may include: a first sintering step: keeping the temperature at 400 ℃ and 600 ℃ for 1-4h, wherein the heating rate is below 30 ℃/min; a second sintering process: keeping the temperature of 1200-1300 ℃ for 1-4h for reaction sintering, wherein the heating rate is below 30 ℃/min. The vacuum degree in the sintering process of the first sintering procedure is less than 0.05 Pa. Through sintering at 400-600 ℃ and 1200-1300 ℃ respectively, the dispersing agent can be effectively removed, the volatilization of Mg element can be reduced, and the purity of the reaction product can be improved. The pre-pressed block can be placed in a vacuum sintering furnace for high-temperature reaction. The sintering temperature is low, the heat preservation time is short, and the production cost is effectively reduced. The protective atmosphere may be a high purity argon atmosphere.

Thus, high-purity AlMgB is obtained₁₄Ceramic powder. For example, AlMgB produced by the production method according to an embodiment of the present invention₁₄The ceramic powder is tested by an XRD diffractometer, and AlMgB is obtained by Rietveld calculation₁₄The purity of the powder is about 90 percent.

According to the method of the invention, the preparation conditions are improved by using non-toxic ethanol as the grinding medium. By using MgB₂And the metal Mg is replaced, so that the risk of the experiment is reduced. And Polyvinylpyrrolidone (PVP) and the like are added as dispersing agents to greatly reduce the sedimentation caused by mismatching of density and granularity of metal powder and ceramic powder in the ball milling process, so that the ball milling powder is dispersed more uniformly. In addition, the invention adds the dispersing agent (PVP) and the like to ball mill in absolute ethyl alcohol, so that the raw materials are dispersed more uniformly, and the preparation process is simple. Compared with the method, the method has the advantages of less sintering impurity phase, higher purity, low cost and the like.

Compared with the prior art, the invention has the advantages that:

the ball milling time is short, the sintering temperature is low, the heat preservation time is short, and the requirement on the preparation environment is low;

ball milling is carried out in absolute ethyl alcohol, the ball milling granularity is uniform, the mixing is uniform, and the ball milling speed is improved;

the experimental safety coefficient is high, the repeatability is strong, and batch production can be realized.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values of the following examples;

in the following examples, reagents, materials and instruments used are all conventional reagents, conventional materials and conventional instruments, which are commercially available, if not specifically mentioned, and the reagents involved therein can also be synthesized by conventional synthesis methods.

Example 1

Al powder (purity 99.9%, particle size 1 μm) and MgB were weighed in a mass ratio of 1:1.2:3.6₂Powder (purity 99.9%, particle size 5 μm), amorphous B powder (purity 99.9%, particle size 1 μm), raw material powder: absolute ethanol (analytical grade): the grinding ball is milled for 1h in a ball mill at the speed of 380r/min, wherein the mass ratio of the grinding ball is 5:10:13 and the dispersant PVP (3 wt%). And drying the slurry, and then performing dry pressing molding under the pressure of 20MPa for 30 s. Placing the mixture in a vacuum sintering furnace for heating, wherein the sintering system is as follows: keeping the temperature at 400 ℃ for 1h, wherein the heating rate is 10 ℃/min and the vacuum degree is 0.05 Pa; and (ii) keeping the temperature at 1200 ℃ for 4h for reaction sintering, wherein the heating rate is 10 ℃/min. The sintering protective atmosphere is high-purity argon atmosphere. Thus, AlMgB was obtained₁₄And (3) powder.

Example 2

Weighing Al powder and MgB according to the mass ratio of 1:1.2:4₂Powder, amorphous B powder, raw material powder (mass ratio): anhydrous ethanol: the grinding ball is milled for 1h in a ball mill at the speed of 380r/min, wherein the mass ratio of the grinding ball is 5:10:13 and the dispersant PVP (4 wt%). And drying the slurry, and then performing dry pressing molding under the pressure of 20MPa for 30 s. Placing the mixture in a vacuum sintering furnace for heating, wherein the sintering system is as follows: keeping the temperature at 600 ℃ for 1h, wherein the heating rate is 10 ℃/min and the vacuum degree is 0.05 Pa; (ii) keeping the temperature at 1250 ℃ for 3h for reaction sintering, wherein the heating rate is 10 ℃/min.

Example 3

Weighing Al powder and MgB according to the mass ratio of 1:1.3:3.6₂Powder, amorphous B powder, raw material powder (mass ratio): anhydrous ethanol: the grinding balls are milled for 1h in a ball mill at a speed of 380r/min, wherein the mass ratio of the grinding balls is about 5:10:13 and the dispersant PVP (6 wt%). And drying the slurry, and then performing dry pressing molding under the pressure of 20MPa for 30 s. Placing the mixture in a vacuum sintering furnace for heating, wherein the sintering system is as follows: keeping the temperature at 600 ℃ for 2h, wherein the heating rate is 10 ℃/min and the vacuum degree is 0.05 Pa; (ii) keeping the temperature at 1300 ℃ for 3h for reaction sintering, wherein the heating rate is 10 ℃/min.

Example 4

Weighing Al powder and MgB according to the mass ratio of 1:1.4:3.6₂Powder, amorphous B powder, raw material powder (mass ratio): anhydrous ethanol: the mass ratio of the grinding balls is about 3:10:13 and the dispersant PVP (2 wt%), and the mixture is ball milled for 2 hours in a ball mill at the speed of 300 r/min. And drying the slurry, and then performing dry pressing molding under the pressure of 20MPa for 30 s. Placing the mixture in a vacuum sintering furnace for heating, wherein the sintering system is as follows: keeping the temperature at 400 ℃ for 1h, wherein the heating rate is 10 ℃/min and the vacuum degree is 0.05 Pa; (ii) keeping the temperature at 1300 ℃ for 2h for reaction sintering, wherein the heating rate is 10 ℃/min.

Example 5

Weighing Al powder and MgB according to the mass ratio of 1:1.4:3.6₂Powder, amorphous B powder, raw material powder (mass ratio): anhydrous ethanol: the grinding balls are milled for 2 hours in a ball mill at a speed of 300r/min, wherein the mass ratio of the grinding balls is about 3:10:13 and the dispersant PVP (4 wt%). And drying the slurry, and then performing dry pressing molding at 25MPa for 30 s. Placing the mixture in a vacuum sintering furnace for heating, wherein the sintering system is as follows: keeping the temperature at 400 ℃ for 1h, wherein the heating rate is 10 ℃/min and the vacuum degree is 0.05 Pa; (ii) keeping the temperature at 1300 ℃ for 3h for reaction sintering, wherein the heating rate is 2 ℃/min.

Example 6

Weighing Al powder and MgB according to the mass ratio of 1:1.4:4₂Powder, amorphous B powder, raw material powder (mass ratio): anhydrous ethanol: the grinding balls are milled for 2 hours in a ball mill at a speed of 300r/min, wherein the mass ratio of the grinding balls is about 3:10:13 and the dispersant PVP (6 wt%). And drying the slurry, and then performing dry pressing molding at 25MPa for 30 s.Placing the mixture in a vacuum sintering furnace for heating, wherein the sintering system is as follows: keeping the temperature at 600 ℃ for 2h, wherein the heating rate is 10 ℃/min and the vacuum degree is 0.05 Pa; (ii) keeping the temperature at 1300 ℃ for 4h for reaction sintering, wherein the heating rate is 10 ℃/min.

Table 1 shows the composition and content of the product obtained by sintering each example

Table 1 shows the phase composition and the content of each phase calculated by Rietveld of the sintered product in the example of the present invention, and example 4 shows the highest content of the target product and the lowest content of the impurity phase. FIG. 2 shows AlMgB prepared in example 3 of the present invention₁₄XRD pattern of the powder. As can be seen from FIG. 2, AlMgB is mainly contained in the powder obtained by the preparation₁₄A small amount of MgAl₂O₄And MgB₄. FIG. 3 shows AlMgB prepared in example 4 of the present invention₁₄SEM image of powder. As can be seen from FIG. 3, MgAl₂O₄Mainly distributed in AlMgB₁₄The powder size is about 1 μm.

Claims

1. AlMgB₁₄The batch preparation method of the ceramic powder is characterized by comprising the following steps:

analytically pure absolute ethyl alcohol with the purity of more than or equal to 99.7% is used as a solvent, and wet ball milling and mixing are carried out on raw material powder to obtain mixed slurry; the raw material powder comprises Al powder and MgB powder with the mass ratio of 1 (1.2-1.4) to 3.6-4.2₂Powders and boron powders; the boron powder is amorphous boron powder or pretreated amorphous boron powder which is pre-sintered for 1-2 hours at 1500 ℃ under vacuum to volatilize oxides on the surface of the boron powder;

the raw material powder also comprises Al powder and MgB₂0.5-6 wt% of dispersant based on the total mass of the powder and the boron powder; the dispersant is polyvinylpyrrolidone, triolein and KD-1, at least one of fatty acid polyglycol esters; and

drying the mixed slurry, performing pre-pressing forming to obtain a block, and sintering in a protective atmosphere to obtain AlMgB with the purity of 80-92%₁₄And (3) powder.

2. The method according to claim 1, wherein the Al powder has a purity of 99.9% or more and a particle diameter of 1 to 10 μm; the MgB₂The purity of the powder is more than 99.9%, and the particle size is 5-15 mu m; the purity of the boron powder is more than 99.9%, and the particle size is 1-5 mu m.

3. The production method according to claim 1, wherein the preliminary press molding is performed by dry press molding and/or cold isostatic press molding, the pressure range of the dry press molding and/or cold isostatic press molding is 10 to 100MPa, and the dwell time is 10 to 300 seconds.

4. The method of manufacturing according to claim 1, wherein the sintering comprises: a first sintering procedure of keeping the temperature for a period of time at 400-600 ℃, wherein the heating rate of the first sintering procedure is below 30 ℃/min, and the heat preservation time is 1-4 hours; and a second sintering process of preserving heat for a period of time at 1200-1300 ℃, wherein the temperature rise rate of the second sintering process is below 30 ℃/min, and the heat preservation time is 1-4 hours; the degree of vacuum was kept below 0.05Pa during the sintering in the first sintering step.

5. The method of claim 1, wherein the protective atmosphere is a high purity argon atmosphere.

6. AlMgB prepared according to the method of any one of claims 1 to 5₁₄Ceramic powder.