阅读说明：本技术 一种抗热氧化钕铁硼复合磁粉及其制备方法和应用 (Thermal oxidation resistant neodymium iron boron composite magnetic powder and preparation method and application thereof ) 是由 刘荣明 耿赵文 熊君 张康 胡国辉 黄可淼 李志宏 贾立颖 王倩 李炳山 于 2019-08-14 设计创作，主要内容包括：本发明提供了一种抗热氧化钕铁硼复合微粉及其制备方法与应用,属于永磁材料粉体制备技术领域。本发明提供的抗热氧化钕铁硼复合微粉,包括钕铁硼粉和聚四氟乙烯粉,所述钕铁硼粉和聚四氟乙烯粉的质量比为(90～95)∶(5～10)。实施例的数据表明：本发明提供的复合微粉,在200℃以内条件下,均没有发生明显变化,即使在300～450℃高温条件下,变化幅度明显低于钕铁硼粉原料的变化幅度,说明本发明提供的钕铁硼复合微粉抗热氧化性得到明显提升。本发明提供的抗热氧化钕铁硼复合微粉的制备方法采用多路气流吹粉混合的形式,多种组分间能够均匀混合,分散均匀,进而有助于各组分性能的发挥。(The invention provides heat-resistant oxidation neodymium iron boron composite micro powder and a preparation method and application thereof, belonging to the technical field of permanent magnet material powder preparation. The heat-resistant oxidation neodymium iron boron composite micro powder provided by the invention comprises neodymium iron boron powder and polytetrafluoroethylene powder, wherein the mass ratio of the neodymium iron boron powder to the polytetrafluoroethylene powder is (90-95) to (5-10). The data of the examples show that: the composite micro powder provided by the invention has no obvious change under the condition of within 200 ℃, and the change amplitude is obviously lower than that of the neodymium iron boron powder raw material even under the high-temperature condition of 300-450 ℃, so that the heat oxidation resistance of the neodymium iron boron composite micro powder provided by the invention is obviously improved. The preparation method of the heat-resistant oxidized neodymium iron boron composite micro powder adopts a multi-path airflow powder blowing and mixing mode, and multiple components can be uniformly mixed and dispersed, so that the performance of each component can be exerted beneficially.)

1. The heat-oxidation-resistant neodymium-iron-boron composite magnetic powder is characterized by comprising neodymium-iron-boron powder and polytetrafluoroethylene powder, wherein the mass ratio of the neodymium-iron-boron powder to the polytetrafluoroethylene powder is (90-95) to (5-10).

2. The heat-oxidation-resistant neodymium-iron-boron composite micro powder according to claim 1, characterized by further comprising samarium-cobalt magnetic powder and/or organic antioxidant; the mass of the samarium cobalt magnetic powder is 1-5% of that of the neodymium iron boron powder; the mass of the organic antioxidant is 1-5% of that of the neodymium iron boron powder.

3. The heat-oxidation-resistant neodymium-iron-boron composite micro powder as claimed in claim 1, wherein the particle size of the heat-oxidation-resistant neodymium-iron-boron composite micro powder is 0.1-200 μm.

4. The heat-oxidation-resistant neodymium-iron-boron composite micro powder as claimed in claim 1, wherein the neodymium-iron-boron powder is neodymium-iron-boron surface modified micro powder; the surface modification mode comprises phosphorization modification and/or coupling modification.

5. The heat-oxidation-resistant neodymium-iron-boron composite micro powder according to claim 4, wherein when the surface modification mode is phosphating modification, the preparation method of the neodymium-iron-boron surface modified micro powder comprises the following steps: carrying out phosphating treatment on the neodymium iron boron powder raw material in a spraying mode to obtain neodymium iron boron surface modified micro powder; the phosphating solution for spraying comprises, by mass volume concentration, 10-25 g/L of water-soluble acrylic acid, 1-5 g/L of molybdate, 30-50 g/L of phosphate and 0.5-5 g/L of fluoride.

6. The heat-oxidation-resistant neodymium-iron-boron composite micro powder according to claim 4, wherein when the surface modification mode is coupling modification, the preparation method of the neodymium-iron-boron surface modified micro powder comprises the following steps: stirring and mixing a coupling agent and dispersion liquid of a neodymium iron boron powder raw material, and heating and coating to obtain neodymium iron boron surface modified micro powder; the coupling agent is a silane coupling agent and/or a titanate coupling agent.

7. The heat-oxidation-resistant neodymium-iron-boron composite micro powder according to claim 4, wherein when the surface modification mode is phosphating modification and coupling modification, the preparation method of the neodymium-iron-boron surface modified micro powder comprises the following steps: coating neodymium iron boron powder raw materials with a coupling agent to obtain coupled coated micro powder; and (3) carrying out phosphating treatment on the coupled coated micro powder in a spraying mode to obtain the neodymium iron boron surface modified micro powder.

8. the preparation method of the heat-oxidation-resistant neodymium-iron-boron composite micro powder disclosed by any one of claims 1 to 7 comprises the following steps:

And under an inert atmosphere, mixing the components of the thermal oxidation resistant neodymium iron boron composite magnetic powder in an air flow powder blowing manner to obtain the thermal oxidation resistant neodymium iron boron composite micro powder.

9. The method of claim 8, wherein different components are fed to the mixing device in different powder-laden airflows during the mixing process.

10. The application of the heat-resistant oxidized neodymium iron boron composite micro powder of any one of claims 1 to 7 or the heat-resistant oxidized neodymium iron boron composite micro powder obtained by the preparation method of any one of claims 8 to 9 in a high-temperature resistant injection magnet.

Technical Field

The invention belongs to the technical field of permanent magnet powder preparation, and particularly relates to heat-resistant oxidized neodymium iron boron composite magnetic powder and a preparation method and application thereof.

Background

The Nd-Fe-B (NdFeB) permanent magnet material is mainly prepared from elements such as rare earth metal Nd, iron, boron and the like through a powder metallurgy process. As the strongest magnetic material at present, the magnetic material is widely applied to the fields of electroplating devices, machinery, medical treatment, automobiles and the like, and has very wide application prospect.

A magnet prepared by mixing and granulating magnetic powder, a polymer binder, various processing aids and the like according to a certain proportion and then performing injection molding on the granules at a proper temperature by an injection molding machine is called an injection magnet. The injection magnet not only has excellent magnetic property, but also has the characteristics of high dimensional precision, good mechanical property, easy large-scale production and the like, so the injection magnet is widely applied.

In recent years, the preparation of neodymium iron boron injection magnets with high use temperature, heat oxidation resistance and other characteristics becomes a focus of domestic attention and a trend of future development. The neodymium iron boron magnetic powder is used as a main body of the injection magnet and plays a decisive role in the heat oxidation resistance of the injection magnet. The rare earth element neodymium in the neodymium-iron-boron alloy has active property, so that the corrosion resistance and the oxidation resistance of the whole neodymium-iron-boron alloy become very poor, the neodymium-iron-boron alloy is easy to oxidize particularly under the high-temperature condition, the service life of the neodymium-iron-boron permanent magnet is seriously influenced, and the stability and the reliability of a product are reduced.

disclosure of Invention

In view of this, the present invention aims to provide a thermal oxidation resistant neodymium iron boron composite magnetic powder, and a preparation method and an application thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

The invention provides heat-oxidation-resistant neodymium-iron-boron composite magnetic powder which comprises neodymium-iron-boron powder and polytetrafluoroethylene powder, wherein the mass ratio of the neodymium-iron-boron powder to the polytetrafluoroethylene powder is (90-95) to (5-10).

Preferably, samarium cobalt magnetic powder and/or organic antioxidant are also included; the mass of the samarium cobalt magnetic powder is 1-5% of that of the neodymium iron boron powder; the mass of the organic antioxidant is 1-5% of that of the neodymium iron boron powder.

Preferably, the particle size of the heat-resistant oxidized neodymium iron boron composite micro powder is 0.1-200 mu m.

Preferably, the neodymium iron boron powder is neodymium iron boron surface modified micro powder; the surface modification mode comprises phosphorization modification and/or coupling modification.

Preferably, when the surface modification mode is phosphating modification, the preparation method of the neodymium iron boron surface modified micro powder comprises the following steps: carrying out phosphating treatment on the neodymium iron boron powder raw material in a spraying mode to obtain neodymium iron boron surface modified micro powder; the phosphating solution for spraying comprises, by mass volume concentration, 10-25 g/L of water-soluble acrylic acid, 1-5 g/L of molybdate, 30-50 g/L of phosphate and 0.5-5 g/L of fluoride.

Preferably, when the surface modification mode is coupling modification, the preparation method of the neodymium iron boron surface modified micro powder comprises the following steps:

Stirring and mixing a coupling agent and dispersion liquid of a neodymium iron boron powder raw material, and heating and coating to obtain neodymium iron boron surface modified micro powder; the coupling agent for spraying is a silane coupling agent and/or a titanate coupling agent.

Preferably, when the surface modification mode is phosphating modification and coupling modification, the preparation method of the neodymium iron boron surface modified micro powder comprises the following steps: coating neodymium iron boron powder raw materials with a coupling agent to obtain coupled coated micro powder; and (3) carrying out phosphating treatment on the coupled coated micro powder in a spraying mode to obtain the neodymium iron boron surface modified micro powder.

The invention provides a preparation method of the heat-resistant oxidation neodymium iron boron composite micro powder, which comprises the following steps:

And under an inert atmosphere, mixing the components of the thermal oxidation resistant neodymium iron boron composite magnetic powder in an air flow powder blowing manner to obtain the thermal oxidation resistant neodymium iron boron composite micro powder.

Preferably, during the mixing process, different components are fed into the mixing device in different powder-carrying gas flows.

The invention also provides application of the heat-resistant oxidation neodymium iron boron composite micro powder in the technical scheme or the heat-resistant oxidation neodymium iron boron composite micro powder prepared by the preparation method in the technical scheme in a high-temperature-resistant injection magnet.

The invention provides heat-oxidation-resistant neodymium-iron-boron composite micro powder which comprises neodymium-iron-boron powder and polytetrafluoroethylene powder, wherein the mass ratio of the neodymium-iron-boron powder to the polytetrafluoroethylene powder is (90-95) to (5-10). The neodymium iron boron composite micro powder has the advantage that on the premise that the magnetic property is ensured, the oxidation resistance is improved under the action of the polytetrafluoroethylene powder dispersed in the neodymium iron boron composite micro powder. The data of the examples show that: the composite micro powder provided by the invention has no obvious change under the condition of 200 ℃, and the change range is obviously lower than that of a neodymium iron boron powder raw material even under the high-temperature condition of 300-450 ℃; the heat oxidation resistance of the neodymium iron boron composite micro powder is obviously improved.

The preparation method of the heat-resistant oxidized neodymium iron boron composite micro powder adopts a multi-path airflow powder blowing and mixing mode, and multiple components can be uniformly mixed and dispersed, so that the performance of each component can be exerted beneficially.

Drawings

FIG. 1 is a scanning electron microscope photograph of neodymium-iron-boron phosphide powder in example 1;

FIG. 2 is a graph showing the change in weight of neodymium-iron-boron powder as a raw material, composite fine powder obtained after phosphating, and composite fine powder obtained after coupling modification, with respect to temperature.

Detailed Description

The invention provides heat-oxidation-resistant neodymium-iron-boron composite micro powder which comprises neodymium-iron-boron powder and polytetrafluoroethylene powder, wherein the mass ratio of the neodymium-iron-boron powder to the polytetrafluoroethylene powder is (90-95) to (5-10).

In the invention, the particle size of the heat-resistant oxidized neodymium iron boron composite micro powder is preferably 0.1-200 μm, more preferably 1-150 μm, and even more preferably 10-50 μm. According to the invention, the particle size and the composition proportion of the heat-resistant oxidation neodymium iron boron composite micro powder are controlled, so that on one hand, the relative ratio surface area of the composite micro powder is improved, on the other hand, the high temperature resistance and the moisture resistance of the composite micro powder are improved through the common matching of the neodymium iron boron powder and the polytetrafluoroethylene powder, and further, the heat oxidation resistance is improved, and meanwhile, the corrosion resistance of the composite micro powder is improved.

The mass ratio of the neodymium iron boron powder to the polytetrafluoroethylene powder in the heat-resistant oxidized neodymium iron boron composite micro powder provided by the invention is (90-95) to (5-10), preferably (91-93.5) to (5-9), and more preferably 92 to 8.

In the invention, the neodymium iron boron powder is preferably neodymium iron boron surface modified micro powder, and the surface modification mode preferably comprises phosphorization modification and/or coupling modification.

In the invention, when the surface modification mode is phosphating modification, the preparation method of the neodymium iron boron surface modified micro powder preferably comprises the following steps: and (3) carrying out phosphating treatment on the neodymium iron boron powder raw material in a spraying mode to obtain neodymium iron boron surface modified micro powder, namely phosphated micro powder. The sources of the neodymium iron boron powder raw materials are not particularly required by the invention, and the neodymium iron boron powder raw materials are prepared by using commercial products or modes known by the technical personnel in the field; in the embodiment of the invention, the neodymium-iron-boron powder raw material is preferably obtained by crushing neodymium-iron-boron cast sheets. In the present invention, the particle size of the neodymium iron boron powder raw material is preferably 0.1 to 200 μm, and more preferably 0.5 to 180 μm.

In the invention, the phosphating solution for spraying preferably comprises 10-25 g/L of water-soluble acrylic acid, 1-5 g/L of molybdate, 30-50 g/L of phosphate and 0.5-5 g/L of fluoride by mass volume concentration; further preferably, the water-soluble acrylic acid-containing paint comprises 15-20 g/L of water-soluble acrylic acid, 2-3 g/L of molybdate, 40-45 g/L of phosphate and 1-5 g/L of fluoride. In the present invention, the molybdate is preferably sodium molybdate and/or potassium molybdate; when the molybdate is a mixture of sodium molybdate and potassium molybdate, the mass ratio of the sodium molybdate to the potassium molybdate is preferably (15-25): (1-5). In the present invention, the phosphate is preferably sodium phosphate and/or potassium phosphate; when the phosphate is a mixture of sodium phosphate and potassium phosphate, the mass ratio of the sodium phosphate to the potassium phosphate is preferably (5-9): (1-3). In the present invention, the fluoride is preferably sodium fluoride and/or potassium fluoride. In the invention, the mass ratio of the volume of the phosphating solution for spraying to the neodymium iron boron powder raw material is preferably (1-5) L to (100-900) g, and more preferably (1-5) L to (500-850).

The invention preferably adopts a spraying mode to carry out phosphating treatment on the neodymium iron boron powder raw material to obtain phosphated micro powder. In the present invention, the spraying rate is preferably (100 to 500) rnL/min, and more preferably (150 to 400) mL/min.

In the invention, preferably, under an inert atmosphere, gas atomization is carried out on phosphating solution to obtain atomized solution; and spraying the atomized liquid onto the neodymium iron boron raw material to realize phosphating. In the invention, the atomization rotating speed of the gas atomization is preferably 2000-10000 r/min, more preferably 4000-8000 r/min, and even more preferably 5000-6000 r/min.

According to the invention, preferably, in the spraying process, the environment temperature of the neodymium iron boron magnetic powder raw material is controlled to be 30-60 ℃, and further preferably 35-50 ℃. According to the invention, by controlling the environmental temperature in the spraying process, the phosphating solution is uniformly distributed on the surface of the neodymium iron boron powder raw material, and a phosphating layer is uniform and compact, so that the high temperature resistance of the neodymium iron boron powder is improved, the high-temperature decomposition is avoided, and the thermal oxidation resistance of the neodymium iron boron powder is further improved; and the corrosion resistance is effectively improved by the dense phosphate coating. In the process of phosphating, the liquid-solid interface generates electrochemical reaction to generate insoluble ferric phosphate which is deposited on the surface of the neodymium-iron-boron powder raw material to form a phosphating film, so that oxygen and water vapor are prevented from entering a magnetic powder matrix, and the antioxidation effect is further realized.

in the invention, when the surface modification mode is coupling modification, the preparation method of the neodymium iron boron surface modified micro powder preferably comprises the following steps:

And stirring and mixing the coupling agent and the dispersion liquid of the neodymium iron boron powder raw material, and heating and coating to obtain the neodymium iron boron surface modified micro powder.

In the present invention, the coupling agent is preferably a silane coupling agent and/or a titanate coupling agent.

In the present invention, the dispersion of the neodymium iron boron powder raw material is preferably obtained by dispersing the neodymium iron boron powder raw material in an ammonia-ammonium chloride buffer solution; the invention has no special requirement on the concentration of the dispersion liquid of the neodymium iron boron powder raw material, so that the raw material can be uniformly dispersed in the buffer solution.

In the invention, the mass ratio of the coupling agent to the neodymium iron boron powder raw material in the dispersion liquid is preferably (1-4) mM: 15g, and more preferably 2 mM: 15 g. In the invention, the stirring and mixing time is preferably 30-45 min.

In the invention, the heating and coating temperature is preferably 40-120 ℃, and more preferably 50-100 ℃. In the stirring and mixing process, a coupling agent is coated on the surface of a neodymium iron boron powder raw material, silane is hydrolyzed to generate silanol, and a covalent bond is formed by the shrinkage reaction of a hydrogen bond; the organic films which are mutually condensed to form a net structure after being heated cover the surface of the magnetic powder. In the heating coating process, silicate ester is preferably added into the mixed material liquid and is coated on the surface of the neodymium iron boron powder raw material.

In the invention, when the surface modification mode is phosphorization modification and coupling modification, the preparation method of the neodymium iron boron surface modified micro powder comprises the following steps: coating neodymium iron boron powder raw materials with a coupling agent to obtain coupled coated micro powder; and (4) carrying out phosphating treatment on the coupled coated micro powder in a spraying mode to obtain the neodymium iron boron surface modified micro powder. In the present invention, the coupling agent coating treatment is identical to the scheme of coupling modification carried out separately in the foregoing technical scheme, and is not described herein again. The mode of phosphating the coupled coated micro powder by adopting a spraying mode is consistent with the mode of directly phosphating the neodymium iron boron powder raw material in the technical scheme, and is not repeated herein.

in the present invention, the particle size of the polytetrafluoroethylene powder is preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0.5 μm.

The heat-resistant oxidized neodymium iron boron composite micro powder provided by the invention preferably also comprises samarium cobalt magnetic powder and/or organic antioxidant. In the invention, when the heat-resistant oxidized neodymium iron boron composite micro powder comprises samarium cobalt magnetic powder, the mass of the samarium cobalt magnetic powder is preferably 1-5% of the mass of neodymium iron boron powder in the heat-resistant oxidized neodymium iron boron composite magnetic powder, more preferably 1.5-4.5%, and even more preferably 2-3%; when the heat-resistant oxidation neodymium iron boron composite micro powder comprises the organic antioxidant, the mass of the organic antioxidant is preferably 1-5% of the mass of neodymium iron boron powder in the heat-resistant oxidation neodymium iron boron composite micro powder, more preferably 1.5-4.5%, and even more preferably 2-3%. In the invention, the organic antioxidant is preferably benzotriazole; the organic antioxidant is preferably provided in the form of granules, and the particle size of the organic antioxidant granules is consistent with that of the heat-resistant oxidized neodymium iron boron composite micro powder, and the details are not repeated herein.

The invention also provides a preparation method of the heat-resistant oxidized neodymium iron boron composite micro powder, which comprises the following steps:

And under an inert atmosphere, mixing the components of the thermal oxidation resistant neodymium iron boron composite magnetic powder in an air flow powder blowing manner to obtain the thermal oxidation resistant neodymium iron boron composite micro powder.

In the present invention, the inert gas preferably includes argon or helium having a purity of 99.99% or more. In the present invention, the pressure of the inert atmosphere is preferably 0.1 MPa.

The present invention does not require a mixing device, and may be practiced using multiple powder mixing devices as are well known to those skilled in the art.

In the embodiment of the present invention, the following is specifically provided: taking inert atmosphere as powder-carrying airflow, and enabling different components to enter a cavity of the mixing device through different air inlet pipelines under the action of the powder-carrying airflow for mixing; the powder-loaded air flow is discharged through an air outlet pipeline of the mixing device.

the invention also provides the application of the heat-resistant oxidized neodymium iron boron composite micro powder in the technical scheme in a high-temperature-resistant injection magnet. The invention has no special requirement on the mode of preparing the high-temperature resistant injection magnet by adopting the composite micro powder, and can be prepared by adopting the injection magnet preparation mode which is well known by the technical personnel in the field.

the following will explain the fine powder of anti-thermal oxidation neodymium iron boron composite provided by the present invention, its preparation method and application in detail with reference to the examples, but they should not be construed as limiting the scope of the present invention.