CN101685695A - Sintering method for mass big neodymium-iron-boron magnets - Google Patents
Sintering method for mass big neodymium-iron-boron magnets Download PDFInfo
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- CN101685695A CN101685695A CN200810223601A CN200810223601A CN101685695A CN 101685695 A CN101685695 A CN 101685695A CN 200810223601 A CN200810223601 A CN 200810223601A CN 200810223601 A CN200810223601 A CN 200810223601A CN 101685695 A CN101685695 A CN 101685695A
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Abstract
The invention provides a method for sintering mass big neodymium-iron-boron magnets, which sinters the neodymium-iron-boron magnets during the sintering by a symmetric-method process, wherein the sintering process thereof comprises three stages of temperature rise, heat preservation at constant temperature and temperature reduction; and the temperature rise rate in the temperature rise stage and the cooling rate in the temperature reduction stage are same in a relative same period of temperature. The method is particularly suitable for sintering the mass big neodymium-iron-boron magnets, can greatly improve the finished product ratio of the neodymium-iron-boron magnets, and reduce the cracking of products; and compared with the prior art, the method has the characteristics that the methodhas simple process and strong maneuverability, can reduce the waste and the cost, can be used for industrialized mass production and the like.
Description
Technical field
The present invention relates to a kind of sintering method that is used for mass big neodymium-iron-boron magnets, be specially adapted to the sintering of large scale neodymium iron boron magnetic body.
Background technology
Sintered Nd-Fe-B permanent magnetic material is since last century, the eighties was come out, it is the strongest to have become contemporary magnetic, the magnetic material that cost performance is the highest, it not only has excellent specific properties such as high remanent magnetism, high-coercive force, high energy product, and is processed into the magnet of different shape, specification easily.Therefore be widely used in the device and the equipment of permanent-magnetic fields such as electroacoustic telecommunication, motor, instrument, nulcear magnetic resonance (NMR), magnetic suspension and magnetic seal, be specially adapted to make various high-performance, complex-shaped product.
For many years, the sintering method of neodymium iron boron magnetic body all is to adopt the program control heating curve, make temperature be raised to a certain temperature between 1010 ℃～1160 ℃ and be incubated a period of time, program control finishes then, and heating stops, vacuum sintering furnace cools off automatically, close main valve, slightly take out valve, open charge valve, be inflated to Pressure gauge near switch closure, fan starting then is up to being cooled to come out of the stove behind the normal temperature state (process curve as shown in Figure 1).This sintering method is more suitable for the sintering of batch small neodymium iron boron magnetic body, and the product cracking is few, and efficient is also higher, and most of enterprises all adopt this sintering method.
But, in the development that science and technology is maked rapid progress, the application of neodymium iron boron magnetic body constantly enlarges, requirement to it also improves day by day, require the magnetic property of neodymium iron boron magnetic body higher, size is bigger, and shape is more complicated, and this just requires the compact dimensions of neodymium iron boron magnetic body bigger, the requirement of mass big neodymium-iron-boron magnets is just arranged in the production, come sintering with original method, showing the product cracking obviously increases, and rate of finished products is very low, sometimes even by the gross scrap, both incur loss through delay delivery just-in-time, improved production cost again, caused very big economic loss.
The product cracking just meaned scrapping of entire product after we knew the neodymium iron boron magnetic body sintering, the product cracking produces wherefrom, analyze reason, be because neodymium iron boron magnetic body in sintering process sintering and cooling procedure in produced internal stress, internal stress makes neodymium iron boron magnetic body produce cracking, we are through research, the reason that produces internal stress mainly is that intensification is bigger with the speed difference of cooling in the sintering process, as the speed that heats up greatly between 3～10 ℃/min, and the speed of cooling is greatly between 30～150 ℃/min, especially when just beginning to cool down, cooling rate is higher, can reach 150 ℃/min.
Summary of the invention
The object of the present invention is to provide a kind of technology simple, outstanding effect is used for the sintering method of mass big neodymium-iron-boron magnets, and it does not need existing equipment is transformed, and only needs the temp controlled meter of setting the sintering process curve is carried out program setting.
The invention provides a kind of sintering method that is used for mass big neodymium-iron-boron magnets, its sintering process comprises temperature rise period, constant temperature holding stage and temperature-fall period, it is characterized in that the programming rate in the temperature rise period is identical with cooling rate in the temperature-fall period in same relatively section temperature.
Wherein, the described temperature rise period comprises the process that intensification, constant temperature are incubated, heat up at least.Described temperature-fall period comprises the process that cooling, constant temperature are incubated, lower the temperature at least.
Wherein, the temperature-rise period in the temperature rise period and again the programming rate of temperature-rise period equate.Temperature-fall period in temperature-fall period and again the cooling rate of temperature-fall period equate.
Wherein, be that 30～1100 ℃ programming rate is 2～5 ℃/min in the temperature range of temperature rise period.Preferably, be that 30～1100 ℃ programming rate is 3 ℃/min in the temperature range of temperature rise period.
Wherein, be that 1100～30 ℃ cooling rate is 2～5 ℃/min in the temperature range of temperature-fall period.Preferably, be that 1100～30 ℃ cooling rate is 3 ℃/min in the temperature range of temperature-fall period.
Wherein, the temperature retention time at the constant temperature holding stage is 4 hours.Temperature retention time at the constant temperature insulating process of temperature rise period is 2～4 hours.Temperature retention time at the constant temperature insulating process of temperature-fall period is 2～4 hours.
Wherein, also be included in before the intensification, earlier vacuum degree be extracted into 1x10
-1～2x10
-1Pa.
Wherein, also be included in after the temperature rise period finishes the output that continues to keep heating current, voltage.
Wherein, the size of the output of heating current, voltage is adjusted immediately by computer program.
Wherein, after the constant temperature that also is included in temperature-fall period was incubated and finishes, working media adopted nitrogen, argon gas or vacuum.In addition, after sintering constant temperature holding stage finished, working media also can adopt nitrogen, argon gas or vacuum.
Technological principle of the present invention is: the sintering method that the present invention adopts is to adopt the technology of balanced method (or claiming low repetition system) to carry out sintering, a certain section which type of heating curve of temperature during intensification, same relatively section temperature is the identical cooling curve of usefulness of symmetry also, a promptly same relatively section temperature programming rate equates with cooling rate, give an example, as 850 ℃ to 1100 ℃ this section temperature, we are warmed up to 1100 ℃ with the programming rate of 3 ℃/min from 850 ℃, when beginning to cool down after 1100 ℃ of insulations finish, we use the cooling rate of 3 ℃/min to cool to 850 ℃ from 1100 ℃ equally.If at different temperature sections with different heating process curves, we also use identical cooling curve symmetrically during cooling, this process curve is that the mode with computer program pre-sets, whole process all is a computer PID s operation control, at any time adjust the output size of heating current, voltage, process curve can accurately be carried out with putting in place.In addition, neodymium iron boron magnetic body is after the constant temperature insulation of temperature-fall period finishes, or after sintering constant temperature holding stage finished, working media can adopt nitrogen, argon gas or vacuum etc., and they also can play the effect of regulating cooling rate.
The invention is characterized in: one, with common sintering process contrast, common sintering process is only controlled heating process curve, not the technology for controlled cooling curve; And the present invention not only controls heating process curve, and the technology for controlled cooling curve.Its two, common sintering process is after heating process curve finishes, the control switch of heating current, voltage all cuts out simultaneously, no longer includes the output of electric current, voltage; And the present invention is after heating process curve finishes, the control switch of heating current, voltage does not cut out, and continues to keep the output of heating current, voltage, according to computer PID computing, at any time adjust the output size of heating current, voltage, the process for cooling curve can accurately be carried out with putting in place.Feature of the present invention is included as " heating is arranged, and process curve is all pressed in the heating cooling " in cooling.
Description of drawings
Fig. 1 represents the sintering process curve of common prior art;
Fig. 2 represents sintering process curve of the present invention.
Embodiment
The present invention will be further described below with reference to embodiment, and embodiments of the invention only are used to technical scheme of the present invention is described, and non-limiting the present invention.
Embodiment 1
Sintering character is Φ 40*32 (being that diameter is the cylinder of the 40 length 32) product of N40, and we are extracted into 2*10 with vacuum degree earlier
-1Pa (2x10
-1Pa), begin heating then, setting programming rate is 5 ℃/min, is incubated 2 hours again after temperature is raised to 850 ℃, and the programming rate that insulation finishes to continue with 5 ℃/min is raised to 1100 ℃, be incubated 4 hours, cooling rate with 5 ℃/min after insulation finishes drops to 850 ℃, is incubated 2 hours, after insulation finishes, continuation drops to 30 ℃ with the cooling rate of 5 ℃/min, comes out of the stove.Its process curve as shown in Figure 2.With rate of finished products behind the sintering process curve sintering of the present invention is 93.2%, than improving 9.7% with rate of finished products behind the common sintering process curve sintering.Referring to table 1.
Embodiment 2
Sintering character is the Φ 60*32 product of N40, and we are extracted into 1.5*10 with vacuum degree earlier
-1Pa, begin heating then, setting programming rate is 4 ℃/min, after being raised to 850 ℃, temperature is incubated 3 hours again, insulation finishes, continuation is raised to 1100 ℃ with the programming rate of 4 ℃/min, is incubated 4 hours, after insulation finishes, do not close the control switch of heating current, voltage, continue to keep the output of heating current, voltage,, adjust the output size of heating current, voltage at any time according to computer PID computing, cooling rate with 4 ℃/min drops to 850 ℃, be incubated 3 hours, insulation finishes the back and continues to drop to 30 ℃ with the cooling rate of 4 ℃/min, comes out of the stove.Its process curve as shown in Figure 2.With rate of finished products behind the sintering process curve sintering of the present invention is 92.8%, than improving 16.2% with rate of finished products behind the common sintering process curve sintering.Referring to table 1.
Embodiment 3
Sintering character is the Φ 80*32 product of N40, and we are extracted into 1*10 with vacuum degree earlier
-1Pa, begin heating then, setting programming rate is 3 ℃/min, after being raised to 850 ℃, temperature is incubated 3 hours again, the programming rate that insulation finishes to continue with 3 ℃/min is raised to 1100 ℃, be incubated 4 hours, after insulation finishes, do not close the control switch of heating current, voltage, continue to keep the output of heating current, voltage, according to computer PID computing, at any time adjust the output size of heating current, voltage, drop to 850 ℃, be incubated 3 hours with the cooling rate of 3 ℃/min, insulation finishes the back and continues to drop to 30 ℃ with the cooling rate of 3 ℃/min, comes out of the stove.Its process curve as shown in Figure 2.With rate of finished products behind the sintering process curve sintering of the present invention is 91.6%, than improving 33.4% with rate of finished products behind the common sintering process curve sintering.Referring to table 1.
Embodiment 4
Sintering character is the Φ 100*32 product of N40, and we are extracted into 1*10 with vacuum degree earlier
-1Pa, begin heating then, setting programming rate is 2 ℃/min, after being raised to 850 ℃, temperature is incubated 4 hours again, the programming rate that insulation finishes to continue with 2 ℃/min is raised to 1100 ℃, be incubated 4 hours, the cooling rate with 2 ℃/min after insulation finishes drops to 850 ℃, is incubated 4 hours, after insulation finishes, add the working media argon gas, do not close heating current, the control switch of voltage continues to keep heating current, the output of voltage, according to computer PID computing, at any time adjust heating current, the output size of voltage continues to drop to 30 ℃ with the cooling rate of 2 ℃/min, comes out of the stove.Its process curve as shown in Figure 2.With rate of finished products behind the sintering process curve sintering of the present invention is 90.7%, than improving 46.4% with rate of finished products behind the common sintering process curve sintering.Referring to table 1.
Table 1 products of different specifications with common sintering process curve and sintering process curve sintering of the present invention after the rate of finished products contrast table
Can get according to data analysis in the table 1, sintering method of the present invention, under the situation that does not influence properties of product, to big product, its effect is obvious more, as to greater than the above product of Φ 40*32, rate of finished products can improve more than 10%, be that they have produced more internal stress in sintering process, eliminated well by internal stress of the present invention because of the big relative miscellaneous goods of part product, rate of finished products is largely increased, enterprise reduces cost, and the purpose that cuts the waste has reached, and benefit also can significantly promote.
Though introduce and described the specific embodiment of the present invention, the present invention is not limited thereto, but can also come specific implementation with the alternate manner in the scope that is in the technical scheme that defines in the claims.
Claims (10)
1, a kind of sintering method that is used for mass big neodymium-iron-boron magnets, its sintering process comprises temperature rise period, constant temperature holding stage and temperature-fall period, it is characterized in that the programming rate in the temperature rise period is identical with cooling rate in the temperature-fall period in same relatively section temperature.
2, sintering method as claimed in claim 1, wherein, the described temperature rise period comprises the process that intensification, constant temperature are incubated, heat up; Described temperature-fall period comprises the process that cooling, constant temperature are incubated, lower the temperature.
3, sintering method as claimed in claim 2, wherein, the temperature-rise period in the temperature rise period and again the programming rate of temperature-rise period equate; Temperature-fall period in temperature-fall period and again the cooling rate of temperature-fall period equate.
4,, wherein, be that 30～1100 ℃ programming rate is 2～5 ℃/min in the temperature range of temperature rise period as the arbitrary described sintering method of claim 1～3; In the temperature range of temperature-fall period is that 1100～30 ℃ cooling rate is 2～5 ℃/min.
5, sintering method as claimed in claim 1 wherein, is 4 hours in the temperature retention time of constant temperature holding stage.
6, sintering method as claimed in claim 2 wherein, is 2～4 hours in the temperature retention time of the constant temperature insulating process of temperature rise period; Temperature retention time at the constant temperature insulating process of temperature-fall period is 2～4 hours.
7, sintering method as claimed in claim 1 wherein, also is included in before the intensification, earlier vacuum degree is extracted into 1x10
-1～2x10
-1Pa.
8, sintering method as claimed in claim 1 wherein, also is included in after the temperature rise period finishes the output that continues to keep heating current, voltage.
9, sintering method as claimed in claim 8, wherein, the size of the output of heating current, voltage is adjusted immediately by computer program.
10, sintering method as claimed in claim 1, wherein, after the constant temperature that also is included in temperature-fall period was incubated and finishes, perhaps after sintering constant temperature holding stage finished, working media adopted nitrogen, argon gas or vacuum.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103594243A (en) * | 2013-11-20 | 2014-02-19 | 宁波科田磁业有限公司 | Manufacturing method capable of preventing sintered neodymium iron boron magnet from cracking |
| CN103620707A (en) * | 2011-05-25 | 2014-03-05 | Tdk株式会社 | Rare earth sintered magnet, method for manufacturing rare earth sintered magnet and rotary machine |
| CN103962555A (en) * | 2014-04-04 | 2014-08-06 | 徐州金石彭源稀土材料厂 | Method for sintering cylindrical or annular sintered NdFeB with height <= 30 mm |
| CN105895288A (en) * | 2016-06-23 | 2016-08-24 | 包头天石稀土新材料有限责任公司 | Neodymium iron boron magnet sintering method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1181503C (en) * | 2002-11-29 | 2004-12-22 | 北京工业大学 | Preparation method of rare earth-iron-boron permanent magnet material |
| CN101071667B (en) * | 2007-04-12 | 2010-11-24 | 北京中科三环高技术股份有限公司 | Gadolinium-containing Nd-Fe-B rare earth permanent magnetic material dn its manufacturing method |
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2008
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103620707A (en) * | 2011-05-25 | 2014-03-05 | Tdk株式会社 | Rare earth sintered magnet, method for manufacturing rare earth sintered magnet and rotary machine |
| US9177705B2 (en) | 2011-05-25 | 2015-11-03 | Tdk Corporation | Sintered rare earth magnet, method of producing the same, and rotating machine |
| CN103594243A (en) * | 2013-11-20 | 2014-02-19 | 宁波科田磁业有限公司 | Manufacturing method capable of preventing sintered neodymium iron boron magnet from cracking |
| CN103594243B (en) * | 2013-11-20 | 2016-03-30 | 宁波科田磁业有限公司 | Prevent the manufacture method that Sintered NdFeB magnet ftractures |
| CN103962555A (en) * | 2014-04-04 | 2014-08-06 | 徐州金石彭源稀土材料厂 | Method for sintering cylindrical or annular sintered NdFeB with height <= 30 mm |
| CN105895288A (en) * | 2016-06-23 | 2016-08-24 | 包头天石稀土新材料有限责任公司 | Neodymium iron boron magnet sintering method |
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| CN101685695B (en) | 2012-06-13 |
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