CN103357872A - Sintering technology of NdFeB (neodymium iron boron) magnet - Google Patents
Sintering technology of NdFeB (neodymium iron boron) magnet Download PDFInfo
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- CN103357872A CN103357872A CN2012101908861A CN201210190886A CN103357872A CN 103357872 A CN103357872 A CN 103357872A CN 2012101908861 A CN2012101908861 A CN 2012101908861A CN 201210190886 A CN201210190886 A CN 201210190886A CN 103357872 A CN103357872 A CN 103357872A
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Abstract
The invention relates to a sintering technology of an NdFeB (neodymium iron boron) magnet. According to the technology, argon is filled in a vacuum sintering furnace periodically to generate a partial pressure atmosphere with pressure fluctuation, so that gas flow at a gap of a sintering material boat is reinforced, gas substances released by an NdFeB material in a sintering process are diluted, and pollution of the substances to the NdFeB magnet in the sintering process is reduced.
Description
Technical field
The present invention relates to a kind of sintering process of neodymium iron boron magnetic body.
Background technology
Neodymium iron boron magnetic body is called as third generation rare earth permanent magnet, and it adopts powder metallurgical technique to make by the people such as Sagawa of SUMITOMO CHEMICAL particulate metal company in nineteen eighty-three at first.Because it has high remanent magnetism, high-coercive force, high energy product and characteristics cheaply, is widely used in the fields such as electroacoustic, motor, instrument, Magnetic resonance imaging.
In general, the process for making of sintered Nd-Fe-B permanent magnet device is: the broken meal → air-flow processed of alloy casting → hydrogen grinds fine powder → compressing under the magnetic field → sintering → machining → surface treatment → use of magnetizing.
Wherein sintering is a committed step, and the quality of sintering process is directly determining performance and the qualification rate of neodymium iron boron product.A requirement of sintering process is to guarantee that product is not oxidized in sintering process.Because the absorption of neodymium iron boron powder has the materials such as a large amount of nitrogen, oxygen, carbon, these materials discharge in the different temperatures section of sintering process, the material demand that discharges is in time extracted or is diluted, otherwise the rich neodymium that will consume in the neodymium iron boron magnetic body causes material oxidation mutually.
Traditional sintering method is to adopt high-vacuum sintering technique.Mention a kind of method of energy-saving sintering neodymium iron boron in patent of invention 200710045427.3 claims 1, what describe namely is vacuum sintering technology, this technological requirement includes the step of using diffusion pump to vacuumize in sintering process, usually use oil diffusion pump can obtain the vacuum of 1E-1Pa.High-vacuum sintering has following shortcoming:
First shortcoming is that oil diffusion pump makes and is heated by resistive, and it is more to consume electric energy, is approximately about 15% of whole sintering process electricity consumption;
Second shortcoming is that NdFeB material will discharge a large amount of gas in sintering process, and these gases can accelerate the inefficacy of diffusion pump oil, and common 1～February is renew oil more, causes larger waste.
Another kind of sintering method is the dividing potential drop sintering process.The dividing potential drop sintering process requires product sintering in the inert gas atmosphere that flows, and described inert gas adopts argon gas usually, and described inert gas pressure is usually less than a standard atmospheric pressure.The material that discharges in the sintering process can spread and be mixed in the inert gas, and is discharged from air-flow.The shortcoming of dividing potential drop sintering is that the sintering boat inside of relative closure can not form enough inert gas flows, causes nitrogen, oxygen, carbon enrichment, causes the neodymium iron boron oxidation.
Also mentioned the dividing potential drop sintering process in patent of invention 200710045427.3 claims 2, this technological requirement enters 800 ℃ at sintering procedure, and the product venting was incubated after 60 minutes, and beginning dividing potential drop sintering after the product venting finishes, is opened the diffusion pump pumping high vacuum.Although this patent of invention is mentioned the dividing potential drop sintering, but the concrete grammar of dividing potential drop sintering do not described, and the dividing potential drop sintering of mentioning in this patent of invention be limited to sintering procedure enter 800 ℃ and be incubated 60 minutes after the beginning, stop when the product venting finishes, all the other stages still need diffusion pump to participate in vacuumizing.
Summary of the invention
The inventor has studied the pluses and minuses of high-vacuum sintering and existing dividing potential drop sintering process, discovery is artificial pressure oscillation of making inert gas atmosphere in the dividing potential drop sintering process, the inside and outside air pressure balance of meeting disturbance sintering boat, make place, sintering boat slit produce air-flow, can avoid like this enrichment of the harmful substances such as nitrogen, oxygen, carbon in the sintering boat, avoid the neodymium iron boron product oxidation.
Based on above-mentioned discovery, the inventor has proposed a kind of sintering process of neodymium iron boron magnetic body, it is characterized in that in the process of whole intensification and insulation, according to periodically passing into argon gas cycle time in sintering furnace, comprises described cycle time:
1) blanking time, close the argon gas valve in blanking time, stop in sintering furnace, passing into argon gas;
2) open the argon gas valve in the duration of ventilation, duration of ventilation, in sintering furnace, pass into argon gas;
In described blanking time and duration of ventilation, continue the sintering body of heater is vacuumized.
According to sintering process of the present invention, in sintering process, can not use the diffusion pump pumping high vacuum.Concrete operation step is: the fire door of feeding → close → be evacuated to 3E-3Pa → begin heating also passes into argon gas → close heating according to technique of the present invention periodicity in the sintering furnace, and applying argon gas is air-cooled → and product comes out of the stove.
The inventor has further studied the zone of reasonableness of described cycle time and described blanking time and duration of ventilation, find by above-mentioned sintering process, be 22～330 seconds described cycle time, described blanking time, length was in 0.1～10 times the situation of described duration of ventilation length, all can obtain product in good condition.
The specific embodiment
Embodiment 1
To be 7mm with batch external diameter of 44M grade neodymium-iron-boron powder production, length is that the cylinder product of 25mm is divided into 6 parts, all adopt identical heating curve sintering, sintering temperature is 1060 ℃, the difference of each part product sintering process is listed in the table 1, and wherein " multiple " refers to length and the ratio of duration of ventilation length blanking time.After finishing, sintering according to same technique product is carried out 520 ℃ of heat treatments.Take a sample respectively for every part and survey product performance, the product performance measurement result is listed in the table 2.Adopt the product of technique sintering of the present invention to adopt density, remanent magnetism, the HCJ of the product of traditional high-vacuum sintering all to be improved, the oxygen content no significant difference, carbon content decreases.
Table 1:
Table 2:
Embodiment 2
To be 14.5mm with batch external diameter of 33EH grade neodymium-iron-boron powder production, length is that the cylinder product of 25mm is divided into 6 parts, all adopt identical heating curve sintering, sintering temperature is 1065 ℃, the difference of each part product sintering process is listed in the table 3, and wherein " multiple " refers to length and the ratio of duration of ventilation length blanking time.According to same technique product is carried out two levels of thermal after sintering is finished and process, first order heat treatment temperature is 900 ℃, and second level heat treatment temperature is 510 ℃.Take a sample respectively for every part and survey product performance, the product performance measurement result is listed in the table 4.Adopt the product of technique sintering of the present invention to adopt density, remanent magnetism, the HCJ of the product of traditional dividing potential drop sintering all to be improved, oxygen content, carbon content all decrease.
Table 3:
Table 4:
Claims (2)
1. the sintering process of a neodymium iron boron magnetic body is characterized in that in the process of whole intensification and insulation, according to periodically passing into argon gas cycle time in sintering furnace, comprises described cycle time:
1) blanking time, close the argon gas valve in blanking time, stop in sintering furnace, passing into argon gas;
2) open the argon gas valve in the duration of ventilation, duration of ventilation, in sintering furnace, pass into argon gas;
In described blanking time and duration of ventilation, continue the sintering body of heater is vacuumized.
2. the sintering process of neodymium iron boron magnetic body according to claim 1 is characterized in that be 22～330 seconds described cycle time, and described blanking time, length was 0.1～10 times of described duration of ventilation length.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2012101908861A CN103357872A (en) | 2012-06-12 | 2012-06-12 | Sintering technology of NdFeB (neodymium iron boron) magnet |
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| CN2012101908861A CN103357872A (en) | 2012-06-12 | 2012-06-12 | Sintering technology of NdFeB (neodymium iron boron) magnet |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105489368A (en) * | 2015-12-28 | 2016-04-13 | 徐力 | Preparation method of neodymium-iron-boron permanent magnet |
| CN108637249A (en) * | 2018-06-06 | 2018-10-12 | 山西大缙华磁性材料有限公司 | A kind of neodymium iron boron magnetic body sintering process |
| CN109411225A (en) * | 2018-09-07 | 2019-03-01 | 杭州永磁集团有限公司 | A kind of preparation process of samarium-cobalt magnet |
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| US20110025440A1 (en) * | 2008-03-31 | 2011-02-03 | Hitachi Metals, Ltd. | R-t-b-type sintered magnet and method for production thereof |
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| JPH0418441B2 (en) * | 1985-08-20 | 1992-03-27 | Tokyo Shibaura Electric Co | |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105489368A (en) * | 2015-12-28 | 2016-04-13 | 徐力 | Preparation method of neodymium-iron-boron permanent magnet |
| CN108637249A (en) * | 2018-06-06 | 2018-10-12 | 山西大缙华磁性材料有限公司 | A kind of neodymium iron boron magnetic body sintering process |
| CN109411225A (en) * | 2018-09-07 | 2019-03-01 | 杭州永磁集团有限公司 | A kind of preparation process of samarium-cobalt magnet |
| CN109411225B (en) * | 2018-09-07 | 2020-11-10 | 杭州永磁集团有限公司 | Preparation process of samarium cobalt magnet |
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Address after: 101300 Shunyi District Shun Road, Beijing, No. 31 Applicant after: JINGCI MATERIAL TECHNOLOGY CO., LTD. Address before: 101300 Shunyi District Shun Road, Beijing, No. 31 Applicant before: Beijing Jingci Magnet Co., Ltd. |
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Application publication date: 20131023 |