CN103962555B - Method for sintering cylindrical or annular sintered NdFeB with height ≤ 30 mm - Google Patents
Method for sintering cylindrical or annular sintered NdFeB with height ≤ 30 mm Download PDFInfo
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- CN103962555B CN103962555B CN201410134426.6A CN201410134426A CN103962555B CN 103962555 B CN103962555 B CN 103962555B CN 201410134426 A CN201410134426 A CN 201410134426A CN 103962555 B CN103962555 B CN 103962555B
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Abstract
The invention discloses a method for sintering cylindrical or annular sintered NdFeB with the height <= 30 mm. The method comprises the steps that the NdFeB is placed in a sintering furnace and is heated to be at the temperature of 1050 DEG C to 1115 DEG C under a vacuum state, then heat preservation is carried out, hygienic paper is laid between layers when the cylindrical NdFeB with the height <= 30 mm is placed before sintering, and the annular NdFeB with the height <= 30 mm is wrapped by the hygienic paper; in the sintering process, the temperature rise rate is four DEG C/minute at the stage with the indoor temperature of 300 DEG C to 380 DEG C, and the temperature rise rate is controlled within one DEG C/minute from the stage with the indoor temperature of 300 DEG C to 380 DEG C to the stage with the indoor temperature of 1050 DEG C to 1115 DEG C. The hygienic paper is added between the layers of the cylindrical product or the annular product is wrapped by the hygienic paper, the temperature rise rate is reduced, the problems of cracks, adhesion and air holes in the sintering process can be solved, the product percent of pass is improved, the furnace charge quantity is increased, the equipment utilization rate is greatly improved, high temperature resisting materials with the granularity of 10 microns to 60 microns cannot enter a vacuum system in the vacuum pumping process, a main valve, a rough suction valve and a valve sliding pump cylinder are prevented from being damaged, and the equipment service life is prolonged.
Description
Technical field
The present invention relates to a kind of sintering method of sintered NdFeB, more particularly to a kind of height≤30mm cylinder or ring-like
The sintering method of sintered NdFeB.
Background technology
The sintering of sintered NdFeB refers to the performance and usability in order to improve magnet further, improves the contact between powder
Property, improve intensity, make magnet have high performance microstructure characteristic, need by green compact be heated to powdered base phase fusing point with
Under temperature and the technique that is incubated a period of time.
Conventional vacuum-sintering flow process：Molding → isostatic pressed → exotic material is laid between two magnet contact faces
(be equivalent to compacting green product) → be placed in sintering magazine → filling with inert gas protect → enter stove → evacuation → heating →
Tempering.
By particle diameter in 10um～60um exotic material powder, such as graphite powder, alumina powder, magnesia powder or high temperature resistant
One of pottery, solves the problems, such as that product does not occur scorification in sintering process, but due to the high temperature resistant material of 10um～60um
Material granularity is thin, easily enters vacuum system during evacuation, and to main valve, the sliding pump cylinder of roughing valve, valve causes damage, and reduction equipment makes
Use the life-span.
The magazine size of sintered NdFeB is mostly 300mm*220mm*65mm or 320mm*240mm* (75～80) mm,
300 kilograms of sintering furnaces, the conventional Ф 9mm～Ф 33mm of preparation, during neodymium iron boron cylinder, magazine can put 40～45 boxes, and folding weighs about as 400
Kilogram, utilization rate of equipment and installations >=100%.
But, when sintering height is less than the small column of 30mm, taking Ф 9 (± 0.05) mm*30 (± 0.05) mm as a example,
Blank product Ф 9.6mm*31mm after sintering, compacting green compact size is Ф 11.5mm*42mm, using magazine 300mm*220mm*
65mm monolayer can fill this magnetic pole 306, and reduced mass is 16.8 grams/, i.e. 5.14 kilograms/box, 300 kilograms of sintering furnace charges
It is only 205.6 kilograms～231.3 kilograms；Preparation Ф 50mm～Ф 100mm cake, every box places two, 1.942 kilograms/；Often
Box-packed doses is 3.884 kilograms, and 300 kilograms of sintering furnace charges are only 155.36 kilograms～174.78 kilograms；As sintering (Ф
150mm～Ф 200mm) * 30mm when, every box is only capable of filling 1 disk, 3.974 kilograms/, and 300 kilograms of sintering furnace charges are only
158.96～178.83 kilograms, utilization rate of equipment and installations is reduced to 35.32%～37.35%, and, easily cause material between sequin
Material phase adhesion.Meanwhile, when the cake sintering diameter >=50mm or annulus neodymium iron boron, due to being to be placed directly in magazine bottom to burn
Knot, product is easily caused adhesion, causes product to ftracture with magazine when shrinking.
Content of the invention
It is an object of the invention to provide the sintering method of a kind of height≤30mm cylinder or ring-like sintered NdFeB, can solve
Cracking when certainly sintering and pore problem, improve conforming product rate.
For reaching above-mentioned purpose, the technical solution used in the present invention is：
A kind of height≤30mm the cylinder of the present invention or the sintering method of ring-like sintered NdFeB, are that neodymium iron boron is inserted burning
In freezing of a furnace, it is incubated after being heated to 1050～1115 DEG C under vacuum state, during sintering, heat up to (300～380) DEG C stage in room temperature
Speed is 4 DEG C/min, and (300～380) DEG C to (1050～1115) DEG C stage will heat up rate controlled at 1 DEG C/min.
Compared with vacuum sintering technology compare, the NbFeB sintered method of the present invention, using the technique of slow intensification, that is, burn
During knot, it is 4 DEG C/min in room temperature to (300～380) DEG C stage heating rate, (300～380) DEG C to (1050～1115) DEG C
Stage will heat up rate controlled at 1 DEG C/min, it can be avoided that cracking and pore, so that conforming product rate is greatly improved.
Brief description
Fig. 1 is the sintering operation schematic flow sheet of the present invention.
Specific embodiment
With reference to embodiment, the present invention will be described.
In the sintering process of green compact, a series of physicochemical change will occur.First, powder particle surface adsorbs
Gas (inclusion vapor) is excluded, Organic substance (antioxidant and the lubricant as the oil that may be stained with isostatic pressed or interpolation
Deng) evaporation and volatilization, the elimination of stress, the reduction of the oxide of powder particle surface, the reply and again of deformation powder particle
Crystallization.Secondly, atoms permeating, material transport, the contact between granule is changed to physical chemistry contact by Mechanical Contact, forms metal
Key and the combination of covalent bond.Finally, the contact surface between powder expands, and sintering neck, and big followed by sintering neck length, density carries
Height, crystal grain is grown up.The porosity of powder green compact is big, and surface area is also big, and therefore surface energy is also big, also has distortion of lattice simultaneously
Can, make powder green compact be in upper state on the whole.From the perspective of energy, this is unstable, has and spontaneously sinters
With the tendency being bonded to a DB and driving force.Therefore, under conditions of uniform temperature, the situation that is, kinetics allow
Under, the contact between powder particle will from point to surface, to reduce surface area and surface energy.Expansion with intergranular contact surface
Greatly, green compact start to shrink at and densification, finally become a sintered body.In short, sintering is exactly that powder consistency is become by green compact
Process for blank.
The sintering process process of the present invention：
(1) sinter annulus product, most of product substance in more than 1Kg, during sintering heating rate room temperature to (300～
380) DEG C stage is 4 DEG C/min；This stage discharges adsorbed gas and temperature rise period for product；Metal contact surface between powder particle
In the long-pending increase stage, be gas, the evaporation of Organic substance and volatilization in powder particle surface for the exclusion absorption at this stage first
(gasoline etc.), Main physical chemical process is that powder oxide on surface reduces, metal contact between the metal powder granulates in green compact
Area increases, and deforms reply (elimination of stress) and the recrystallization of powder particle；Sintering stage：Powder particle dissolution phase, its
Main process is that powder particle is mutually dissolved, the solid solution volume dispersion hardening of alloy composition, volumetric expansion.This is sintering process
Main Stage, 800～1000 DEG C of temperature range.
(2) holding stage：In the solid solution homogenization stage, the process at this moment occurring is solid solution homogenization and crystal grain is grown up,
Volume contraction, density improves and alloy merges, 1050～1115 DEG C of temperature range.
Alloying component is different, and the temperature range of three phases is also different, mainly has three temperature stage：
1. low-temperature space：Eliminate blank internal residual stress, the gas of exclusion absorption and volatility debris etc..
2. middle warm area：Blank starts to shrink at, and starts to spread and formed connection between metallic particles, continues the gas of exclusion absorption
Body.
3. high-temperature region：Blank shrinks rapidly, and space nodularization is reduced, and is coupled to interface between granule, and with temperature retention time
Extend crystal grain to grow up, ultimately form the sintered body of densification.
(3) each stage focuses on problem difference：Holding stage (1050～1115) DEG C now slows down heating rate, 1 DEG C/minute
Clock, small product size is shunk, and it is external heat that product is heated, and heat is by outer and interior, if heating rate is fast, inside product Outer shrink
Also not contracted, center can be caused to have pore, affect magnet overall performance, the technique of the present invention solves the problems, such as cracking and pore,
Substantially increase conforming product rate.
As a further improvement on the present invention, before sintering, when height≤30mm column type neodymium iron boron is put layer and layer it
Between place mat toilet paper, highly≤30mm ring-like neodymium iron boron toilet paper wraps up.As shown in figure 1, a kind of height of the present invention≤
30mm cylinder or the sintering method of ring-like sintered NdFeB, its operating process is：
Neodymium iron boron product can be bonded together in sintering process in extruding and superposition, has a strong impact on the qualified of product
Rate, height≤30mm column type neodymium iron boron is taken and is put after one layer of product by the present invention, and tile one layer of toilet paper, puts on top again
Put one layer of neodymium iron boron cylinder；All wrapped up with toilet paper to after height≤30mm ring products isostatic pressed, superposition is placed in magazine,
Remove toilet paper after sintering and carry out firsts and seconds tempering.So solve product adhesion problems it is ensured that conforming product rate, same
When, vacuum system is entered in evacuation using the exotic material that said method will not make 10um～60um granularity it is therefore prevented that
To main valve, the infringement of the sliding pump cylinder of roughing valve, valve, improve service life of equipment.
Claims (2)
1. the sintering method of a kind of height≤30mm cylinder or ring-like sintered NdFeB, neodymium iron boron is inserted in sintering furnace, vacuum
It is incubated after being heated to 1050 DEG C～1115 DEG C under state, it is characterized in that：During sintering, it is 4 in room temperature to 380 DEG C of stage heating rates
DEG C/min, more than 380 DEG C, extremely～1115 DEG C of stages will heat up rate controlled at 1 DEG C/min.
2. the sintering method of a kind of height≤30mm cylinder according to claim 1 or ring-like sintered NdFeB, its feature
It is：Before sintering, the place mat toilet paper between layers when height≤30mm column type neodymium iron boron is put, or height≤30mm ring
Type neodymium iron boron toilet paper wraps up.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410134426.6A CN103962555B (en) | 2014-04-04 | 2014-04-04 | Method for sintering cylindrical or annular sintered NdFeB with height ≤ 30 mm |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410134426.6A CN103962555B (en) | 2014-04-04 | 2014-04-04 | Method for sintering cylindrical or annular sintered NdFeB with height ≤ 30 mm |
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| Publication Number | Publication Date |
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| CN103962555A CN103962555A (en) | 2014-08-06 |
| CN103962555B true CN103962555B (en) | 2017-02-15 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105312564A (en) * | 2015-05-14 | 2016-02-10 | 洛阳名力科技开发有限公司 | Anti-sticking method for cemented carbide substrate sintering |
| CN108417375A (en) * | 2018-02-05 | 2018-08-17 | 宁波松科磁材有限公司 | A kind of preparation method without heavy rare earth sintered Nd-Fe-B permanent magnet |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101685695B (en) * | 2008-09-27 | 2012-06-13 | 宁波科宁达工业有限公司 | Sintering method for mass big neodymium-iron-boron magnets |
| US9082538B2 (en) * | 2008-12-01 | 2015-07-14 | Zhejiang University | Sintered Nd—Fe—B permanent magnet with high coercivity for high temperature applications |
| CN102107279A (en) * | 2009-12-25 | 2011-06-29 | 北京中科三环高技术股份有限公司 | Isostatic method for powder metallurgical process |
| CN202606851U (en) * | 2012-05-18 | 2012-12-19 | 常熟市双月机械有限公司 | Boat box for sintering copper leaching rings |
| CN102921950B (en) * | 2012-10-16 | 2015-09-23 | 山东依诺威强磁材料有限公司 | For producing the sintering aging technique of Nd-Fe-Bo permanent magnet material |
| CN103000363B (en) * | 2012-11-02 | 2015-08-19 | 宁波永久磁业有限公司 | The dividing potential drop sintering method of Sintered NdFeB magnet |
| 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 |
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