阅读说明：本技术 一种提高粘结永磁铁氧体磁粉各向异性的方法 (Method for improving anisotropy of bonded permanent magnetic ferrite magnetic powder ) 是由 李昕 裴晓东 骆艳华 汪祥 鲍维东 张倩倩 张金艳 鲍思凯 于 2020-12-25 设计创作，主要内容包括：本发明公布了一种提高粘结永磁铁氧体磁粉各向异性的方法,步骤为：将粘结磁粉添加助熔剂后加入球磨罐中,加水球磨,出料后滤干,将含水磁粉加入压机中,人工施加磁场将磁粉充磁取向后,再加压压制成圆形毛坯。将毛坯放入马弗炉中二次烧结,待炉内冷却后,取出磁块,加润滑剂放入振动粉碎机中粗破碎后,在加入到球磨罐中破碎,磁粉出罐后,用清水洗涤三次。烘干后过筛分散,放入马弗炉中回火,得各向异性粘结永磁铁氧体磁粉。本发明的方法施加外磁场充磁取向后,再进行二次烧结,促进磁粉晶粒沿磁场取向方向二次生长,提高磁粉各向异性,从而提升磁粉磁性能。(The invention discloses a method for improving anisotropy of bonded permanent magnetic ferrite magnetic powder, which comprises the following steps: adding the bonded magnetic powder into a fluxing agent, adding the bonded magnetic powder into a ball milling tank, adding water, ball milling, discharging, filtering, adding the water-containing magnetic powder into a press, manually applying a magnetic field to magnetize the magnetic powder, orienting, and then pressurizing and pressing into a round blank. And (3) placing the blank into a muffle furnace for secondary sintering, taking out the magnetic block after cooling in the furnace, adding a lubricant, placing the mixture into a vibration crusher for coarse crushing, adding the mixture into a ball milling tank for crushing, taking the magnetic powder out of the tank, and washing the magnetic powder with clear water for three times. And drying, sieving, dispersing, and tempering in a muffle furnace to obtain the anisotropic bonded permanent magnetic ferrite powder. The method of the invention applies an external magnetic field to magnetize and orient, and then carries out secondary sintering, promotes the secondary growth of magnetic powder grains along the magnetic field orientation direction, improves the anisotropy of the magnetic powder, and thereby improves the magnetic performance of the magnetic powder.)

1. A method for improving the anisotropy of bonded permanent magnetic ferrite magnetic powder is characterized by comprising the following steps:

1) adding the bonded magnetic powder into a fluxing agent, adding the bonded magnetic powder into a ball milling tank, adding water for ball milling, discharging, filtering, drying, adding the water-containing magnetic powder into a press, magnetizing, orienting, and pressing into a round blank;

2) putting the blank into a muffle furnace for secondary sintering, taking out the magnetic block after cooling in the furnace, adding a lubricant, putting into a vibration crusher for coarse crushing, then adding into a ball milling tank for crushing, taking the magnetic powder out of the tank, and washing with clear water for three times;

3) and drying, sieving, dispersing, and tempering in a muffle furnace to obtain the anisotropic bonded permanent magnetic ferrite powder.

2. The method for improving anisotropy of a bonded permanent magnetic ferrite magnetic powder according to claim 1, wherein the flux is one or a mixture of sodium chloride, bismuth oxide and boric acid, and the amount of the flux added is 0.1-1%.

3. The method for improving the anisotropy of a bonded permanent magnetic ferrite magnetic powder according to claim 1, wherein the magnetic powder is ball milled after adding a flux, the ball milling time of the magnetic powder is 10-13h, and the particle size of the magnetic powder is controlled to be 0.8-2 μm.

4. The method as claimed in claim 1, wherein the magnetic powder after ball milling is dried and then added into a press, and after magnetizing orientation, the mixture is pressed into a round blank under pressure, and the magnetizing field strength of the press is 8000,10000 Oe.

5. The method as claimed in claim 1, wherein the pressed blank is sintered for the second time at 1180-1220 ℃ for 1-3 h.

6. The method according to claim 1, wherein the lubricant is calcium gluconate.

7. The method for improving the anisotropy of bonded permanent magnetic ferrite magnetic powder according to claim 1, wherein after the blank sintering is finished, a lubricant is added and placed into a vibration crusher for coarse crushing, and then the mixture is added into a ball milling tank for fine milling, wherein the vibration crushing time is 4-8min, and the ball milling crushing time is 2-4 h.

8. The method for improving the anisotropy of bonded permanent magnetic ferrite magnetic powder according to claim 1, wherein after the ball milling is finished, the magnetic powder is sieved and dispersed, and is placed into a muffle furnace for tempering, wherein the tempering temperature is 900-.

Technical Field

The invention relates to a production method of a magnetic material, in particular to a method for improving anisotropy of bonded permanent magnetic ferrite magnetic powder.

Background

The injection-molded ferrite is a magnet formed by mixing ferrite magnetic powder and resin and then performing an injection molding process. The magnetic field magnetizing device is characterized by being capable of axially magnetizing in a single pole, radially magnetizing in multiple stages and axially and radially magnetizing in a composite mode. The product has smooth and clean appearance, no flaw, high dimensional precision, good consistency, no subsequent processing, stable performance, shock resistance and impact resistance, can be complicated, is an indispensable signal source and constant magnetic source in precision micromotors and automation industries, and has the advantages that other magnets cannot replace and compare with.

Bonded permanent magnetic ferrite magnetic powder is one of the main raw materials of injection-molded ferrite, and mature preparation methods are already available at present and are discussed in many patents (CN101894648A, bonded ferrite magnetic powder and preparation method thereof, and bonded magnet; CN107399964, a preparation method of bonded ferrite magnetic powder). However, the permanent magnetic ferrite magnetic powder prepared by the traditional process method is all isotropic magnetic powder, and the magnetic performance of the magnetic powder is improved to a limited extent. The magnetic performance of the anisotropic magnetic powder is superior to that of the isotropic magnetic powder, the magnetic performance of the magnetic powder can be obviously improved by improving the anisotropy of the magnetic powder, and particularly the residual magnetism of the magnetic powder can be greatly improved.

Disclosure of Invention

In order to solve the above disadvantages, the present invention provides a method for improving anisotropy of bonded permanent magnetic ferrite magnetic powder, the preparation method comprises the following steps: 1) adding the bonded magnetic powder into a fluxing agent, adding the bonded magnetic powder into a ball milling tank, adding water for ball milling, discharging, filtering, drying, adding the water-containing magnetic powder into a press, magnetizing, orienting, and pressing into a round blank;

2) putting the blank into a muffle furnace for secondary sintering, taking out the magnetic block after cooling in the furnace, adding a lubricant, putting into a vibration crusher for coarse crushing, then adding into a ball milling tank for crushing, taking the magnetic powder out of the tank, and washing with clear water for three times;

3) and drying, sieving, dispersing, and tempering in a muffle furnace to obtain the anisotropic bonded permanent magnetic ferrite powder.

Furthermore, the added fluxing agent is one or a mixture of sodium chloride, bismuth oxide and boric acid, and the addition amount of the fluxing agent is 0.1-1%.

Furthermore, the magnetic powder is added with a fluxing agent and then ball milled, the ball milling time of the magnetic powder is 10-13h, and the particle size of the magnetic powder is controlled to be 0.8-2 mu m.

Further, after the magnetic powder after ball milling is filtered and dried, the magnetic powder is added into a press, and after magnetizing and orientation, the magnetic powder is pressed into a round blank, wherein the magnetizing magnetic field intensity of the press is 8000-10000 Oe.

Further, the pressed blank is sintered for the second time, the temperature of the secondary sintering is 1180-1220 ℃, and the heat preservation time is 1-3 h.

Further, after the blank is sintered, adding a lubricant, placing the mixture into a vibration crusher for coarse crushing, then adding the mixture into a ball milling tank for fine milling, wherein the vibration crushing time is 4-8min, and the ball milling crushing time is 2-4 h.

Further, after the ball milling is finished, sieving and dispersing the magnetic powder, and putting the magnetic powder into a muffle furnace for tempering at the temperature of 900-930 ℃ for 1 h.

Compared with the prior art, the invention has the advantages that: compared with other methods for preparing the bonded ferrite magnetic powder, the bonded ferrite magnetic powder is subjected to secondary sintering after an external magnetic field is applied for magnetizing and orienting, so that the secondary growth of magnetic powder grains along the magnetic field orientation direction is promoted, the anisotropy of the magnetic powder is improved, and the magnetic performance of the magnetic powder is improved; meanwhile, the method is simple and easy to implement, the process is convenient to control, and the magnetic performance of the bonded permanent magnetic ferrite magnetic powder can be greatly improved.

Drawings

FIG. 1 is a schematic diagram comparing XRD of examples and comparative examples;

four lines in the figure, from top to bottom; example 1, example 2, comparative example 1, comparative example 2.

Detailed Description

In order to make the examiner further understand the steps, features and other objects of the present invention, the following detailed description is given in conjunction with the accompanying preferred embodiments, which are only for illustrating the technical aspects of the present invention and are not limitative of the present invention.

The invention provides a method for improving anisotropy of bonded permanent magnetic ferrite magnetic powder, which comprises the following steps: 1) adding the bonded magnetic powder into a fluxing agent, adding the bonded magnetic powder into a ball milling tank, adding water for ball milling, discharging, filtering, drying, adding the water-containing magnetic powder into a press, magnetizing, orienting, and pressing into a round blank;

2) putting the blank into a muffle furnace for secondary sintering, taking out the magnetic block after cooling in the furnace, adding a lubricant, putting into a vibration crusher for coarse crushing, then adding into a ball milling tank for crushing, taking the magnetic powder out of the tank, and washing with clear water for three times;

3) and drying, sieving, dispersing, and tempering in a muffle furnace to obtain the anisotropic bonded permanent magnetic ferrite powder.

The fluxing agent is one or a mixture of sodium chloride, bismuth oxide and boric acid, and the addition amount of the fluxing agent is 0.1-1%.

And adding a fluxing agent into the magnetic powder, and then performing ball milling on the magnetic powder, wherein the ball milling time of the magnetic powder is 10-13h, and the particle size of the magnetic powder is controlled to be 0.8-2 mu m.

And filtering the ball-milled magnetic powder, adding the ball-milled magnetic powder into a press, magnetizing and orienting, and then pressing into a round blank, wherein the magnetizing magnetic field intensity of the press is 8000-10000 Oe.

And (3) performing secondary sintering on the pressed blank, wherein the temperature of the secondary sintering is 1180-1220 ℃, and the heat preservation time is 1-3 h.

And after the blank is sintered, adding a lubricant, putting the blank into a vibration crusher for coarse crushing, and then adding the blank into a ball milling tank for fine milling, wherein the vibration crushing time is 4-8min, and the ball milling crushing time is 2-4 h.

After the ball milling is finished, sieving and dispersing the magnetic powder, and putting the magnetic powder into a muffle furnace for tempering at the temperature of 900-930 ℃ for 1 h.

Example 1

1503.2g of iron oxide red, 216.2g of strontium carbonate and 3.6g of barium carbonate are put into a sand mill, water is added for even mixing and grinding for 2 hours, and the materials are discharged, dried, pelletized and presintered. Heating to 1320 ℃, and sintering for 2h to prepare the strontium ferrite pre-sintering material.

Adding 0.5% of bismuth oxide and 0.3% of sodium chloride into the pre-sintered material, adding the pre-sintered material into a ball milling tank, adding water into the ball milling tank, ball milling the pre-sintered material for 13 hours, discharging the pre-sintered material, filtering the pre-sintered material to dry, adding water-containing magnetic powder into a press, magnetizing the pre-sintered material under a 10000Oe magnetic field, orienting, and pressing the pre-sintered material into a round blank. And (3) putting the blank into a muffle furnace, sintering at 1200 ℃ for the second time, cooling in the furnace, taking out the magnetic block, adding 0.33% of calcium gluconate, putting the magnet into a vibration crusher, coarsely crushing for 6min, adding the magnet into a ball milling tank, finely milling for 3h, and washing the magnet powder with clear water for three times after the magnet powder is taken out of the tank. And (4) drying, sieving, dispersing, and putting into a muffle furnace to temper for 1h at 920 ℃ to obtain the anisotropic bonded permanent magnetic ferrite powder.

Example 2

1336.5g of iron oxide red, 216.2g of strontium carbonate and 3.6g of barium carbonate are put into a sand mill, water is added for even mixing and grinding for 2 hours, and the materials are discharged, dried, pelletized and presintered. Heating to 1320 ℃, and sintering for 2h to prepare the strontium ferrite pre-sintering material.

Adding 0.55% of bismuth oxide and 0.35% of sodium chloride into the pre-sintered material, adding the pre-sintered material into a ball milling tank, adding water into the ball milling tank, ball milling the pre-sintered material for 13 hours, discharging the pre-sintered material, filtering the pre-sintered material to dry, adding water-containing magnetic powder into a press, magnetizing the pre-sintered material in a 8500Oe magnetic field to orient the pre-sintered material, and pressing the pre-sintered material into a round. And (3) putting the blank into a muffle furnace, sintering at 1200 ℃ for the second time, cooling in the furnace, taking out the magnetic block, adding 0.33% of calcium gluconate, putting the magnet into a vibration crusher, coarsely crushing for 4min, adding the magnet into a ball milling tank, finely milling for 13h, and washing the magnet powder with clear water for three times after the magnet powder is taken out of the tank. And (4) drying, sieving, dispersing, and putting into a muffle furnace for tempering at 930 ℃ for 1h to obtain the anisotropic bonded permanent magnetic ferrite powder.

Comparative example 1

1503.2g of iron oxide red, 216.2g of strontium carbonate and 3.6g of barium carbonate are put into a sand mill, water is added for even mixing and grinding for 2 hours, and the materials are discharged, dried, pelletized and presintered. Heating to 1320 ℃, and sintering for 2h to prepare the strontium ferrite pre-sintering material. And adding 0.33% of calcium gluconate into the cooled pre-sintered material, coarsely crushing the pre-sintered material in a vibration crusher for 6min, adding the pre-sintered material into a ball milling tank, finely milling the pre-sintered material for 3h, and washing the pre-sintered material with clean water for three times after the magnetic powder is taken out of the tank. And (4) drying, sieving, dispersing, and putting into a muffle furnace to temper for 1h at 920 ℃ to obtain the bonded permanent magnetic ferrite powder.

Comparative example 2

1336.5g of iron oxide red, 216.2g of strontium carbonate and 3.6g of barium carbonate are put into a sand mill, water is added for even mixing and grinding for 2 hours, and the materials are discharged, dried, pelletized and presintered. Heating to 1320 ℃, and sintering for 2h to prepare the strontium ferrite pre-sintering material. And adding 0.33% of calcium gluconate into the cooled pre-sintered material, coarsely crushing the pre-sintered material in a vibration crusher for 4min, adding the pre-sintered material into a ball milling tank, finely milling the pre-sintered material for 3h, and washing the pre-sintered material with clean water for three times after the magnetic powder is taken out of the tank. And drying, sieving, dispersing, and putting into a muffle furnace for tempering at 930 ℃ to obtain the bonded permanent magnetic ferrite magnetic powder.

The prepared permanent magnetic ferrite magnetic powder is detected by XRD pattern, and the result is shown in figure 1. Through analysis, the magnetic powder after magnetizing, orienting and re-burning has obvious (008) plane peak position, which shows that the abnormal growth of magnetic powder crystal grains occurs in the easy-to-magnetize C axis, and is beneficial to improving the magnetic performance of the magnetic powder.

The method for detecting the green compact magnetic property of the magnetic powder comprises the following steps: weighing 1.4g of paraffin and 20g of magnetic powder. After paraffin is melted, magnetic powder is added and stirred uniformly, 7g of mixed sample is weighed, a tablet machine is used for pressing the mixed sample into a round blank with the diameter of 20mm under the pressure of 7Mpa for 10s under the pressure maintaining, and a B-H instrument is used for detecting the magnetic property of the blank.

Table 1 shows a list of magnetic properties of green compacts of examples and comparative examples. The bonded permanent magnetic ferrite magnetic powder after magnetization orientation has obviously improved compact magnetic performance, especially remanence.

TABLE 1 summary of magnetic Properties of the green compacts of examples and comparative examples

It should be noted that the above embodiments are intended to demonstrate the practical application of the preparation method provided by the present invention, and are not intended to limit the scope of the present invention. Various modifications, substitutions, or improvements may occur to those skilled in the art that fall within the spirit and scope of the present invention. The scope of the invention is to be determined by the claims appended hereto.