A kind of sintering Nd-Fe-B rare earth permanent magnetic alloy powder and sintering process
Technical field
The present invention relates to the technical field of rare earth permanent-magnetic material, a kind of sintering Nd-Fe-B rare earth permanent magnetic alloy powder and sintering process are particularly provided.
Background technology
Permanent magnetic material, as a kind of functional material be most widely used in modern industry and science and technology, mainly comprises Al-Ni-Co permanent magnet material, ferrite permanent-magnet materials, rare earth permanent-magnetic material and other permanent magnetic material etc.Wherein rare-earth permanent magnetic material is that the alloy that rare earth metal and transition metal are formed is made through certain technique, is the best class permanent magnetic material of current combination property.
And sintered Nd-Fe-B permanent magnetic material is as the representative of rare earth permanent-magnetic material, be with neodymium (Nd), iron (Fe), boron (B) for base stock, add other alloying elements a small amount of as required, a kind of iron-base permanent magnetic material that applied powder metallurgy technology manufactures.Because it is mainly formed by iron and relative low price, the neodymium of resource relative abundance, boron three kinds of element combinations, can relatively inexpensively prepare, also there is very excellent magnetic property simultaneously, there is high cost performance, be therefore widely used in the every field such as electronic equipment, composite power vapour motor for automobile and generator.
But existing sintered Nd-Fe-B permanent magnetic material also exists certain problem, be first that its Curie temperature is lower, be usually less than 300 DEG C, this makes its work serviceability temperature be subject to great restriction, thus constrains it to a great extent and apply more widely; Moreover it is typical hard brittle material, processing characteristics is poor, usually causes the destruction of material and the deterioration of magnetic property owing to needing Product processing to become given shape.
Summary of the invention
Namely object of the present invention is to provide a kind of novel Magnaglo for the preparation of sintered Nd-Fe-B system rare earth permanent-magnetic material, the present invention is chosen by suitable alloying element and the addition of the best, and the preparation technology matched with it, obtain the sintering Nd-Fe-Bo permanent magnet material powder of excellent performance.
The concrete preparation method of sintering Nd-Fe-B rare earth permanent magnetic alloy powder in the present invention is as follows:
One) pairing gold is got the raw materials ready: alloy one is by element Nd, Fe, B, Al, Co, Nb, Zr, Cu formed, alloy two is by element Dy, Fe, B, Al, Co, Nb, Zr, Cu formed, wherein except rare earth element, the content of all the other elements is identical with described Nd-Fe-B rare earth permanent magnetic alloy, with the ratio that the component meeting Nd-Fe-B rare earth permanent magnetic alloy is condition allotment alloy one and alloy two, the component of institute's Nd-Fe-B rare earth permanent magnetic alloy is: in atomic percentage conc, Nd15.0-18.0, B5.0-6.0, Al0.2-0.3, Co7.0-10.0, Nb0.5-0.8, Zr0.1-0.3, Cu0.2-0.4, Dy3.0-5.0, surplus is Fe and inevitable impurity.
Two) preparation of alloy one powder:
1) melting, alloy one raw material be equipped with is put into vacuum induction melting furnace, smelting furnace is evacuated to 15-20Pa and melting of heating until temperature is 0.1-0.3MPa to starting during 1000-1050 DEG C to be filled with argon gas to pressure, be warming up to 1200-1250 DEG C of refining 5-10 minute subsequently, insulation leaves standstill 1-2 minute;
2) pour into a mould, adopt the method for getting rid of Strip casting, chill roll diameter is 500mm, and controlled cooling model speed, at 2.7m/s-3m/s, obtains the slab that thickness is 0.2-0.4mm;
3) Mechanical Crushing, obtains by Mechanical Crushing the meal that particle diameter is 100-200 μm by slab;
4) hydrogen is quick-fried, be that meal Mechanical Crushing obtained under the condition of 1-2L/min is heated to 800-820 DEG C at hydrogen flowing quantity, after insulation 5-10min, increase hydrogen flowing quantity to keep to 3-4L/min, inhale hydrogen 2-3h, arrange hydrogen subsequently and be filled with argon gas, starting to vacuumize dehydrogenation when argon pressure reaches 0.8-1MPa, during to vacuum degree 2-4Pa, dehydrogenation terminates;
5) grind, adopt airflow milling to grind, specifically add the zinc stearate of 0.12-0.15wt%, in nitrogen atmosphere, be crushed to average grain diameter is 5-10 μm, obtains fine powder.
Three) preparation of alloy two powder:
1) melting, alloy two raw material be equipped with is put into vacuum induction melting furnace, smelting furnace is evacuated to 15-20Pa and melting of heating until temperature is 0.3-0.5MPa to starting during 1200-1250 DEG C to be filled with argon gas to pressure, be warming up to 1400-1450 DEG C of refining 3-5 minute subsequently, insulation leaves standstill 0.5-1 minute;
2) pour into a mould, adopt the method for getting rid of Strip casting, chill roll diameter is 500mm, and controlled cooling model speed, at 2.7m/s-3m/s, obtains the slab that thickness is 0.2-0.4mm;
3) Mechanical Crushing, obtains by Mechanical Crushing the meal that particle diameter is 100-200 μm by slab;
4) hydrogen is quick-fried, be that meal Mechanical Crushing obtained under the condition of 1-2L/min is heated to 820-850 DEG C at hydrogen flowing quantity, after insulation 5-10min, increase hydrogen flowing quantity to keep to 3-4L/min, inhale hydrogen 4-5h, arrange hydrogen subsequently and be filled with argon gas, starting to vacuumize dehydrogenation when argon pressure reaches 0.8-1MPa, during to vacuum degree 2-4Pa, dehydrogenation terminates;
5) inhale hydrogen process again, again pass into hydrogen with the flow of 3-5L/min at ambient temperature, and keep 0.5-1h;
6) grind, adopt airflow milling to grind, specifically add the zinc stearate of 0.08-0.1wt%, in argon gas atmosphere, be crushed to average grain diameter is 1-3 μm, obtains fine powder.
Four) pairing gold mixing: the fine powder ground is mixed under an argon atmosphere and obtains sintering Nd-Fe-Bo permanent magnet material powder of the present invention.
Preferably, described alloy powder is in atomic percentage conc, and Nd17.0, B5.5, Al0.25, Co9, Nb0.6, Zr0.2, Cu0.3, Dy4.0, surplus is Fe and inevitable impurity.
The sintering process of sintering Nd-Fe-Bo permanent magnet material powder of the present invention is specially, and sintering Nd-Fe-Bo permanent magnet material powder is carried out green compact compacting in magnetic field, sinters subsequently, carry out Ageing Treatment again after sintering.
As preferably, by sintering Nd-Fe-Bo permanent magnet material powder in the magnetic field of 1600kA/m, adopt the pressure at right angle of 200MPa that pressed by powder 15min is shaping, sintering condition is 0.5 × 10
-3under the vacuum condition of Pa, be warming up to temperature 580 DEG C with the heating rate of 40 DEG C/min, pressure 70MPa, sintering time is 13min, and be filled with after normal temperature argon gas is quickly cooled to room temperature and carry out timeliness, timeliness is by sintered alloy at 560 DEG C, insulation 3h.
The invention has the advantages that: (1) appropriate design composition of alloy, by rational proportion that is light, heavy rare earth, and the appropriateness of other alloying elements is added, and obtains and has optimum magnetic property rare earth permanent magnet alloy powder end; (2) take two alloy preparation technology, effectively avoid heavy rare earth element and add the hydraulic performance decline caused; (3) have employed suitable, obtain the powder with excellent sintering character for the different technique such as melting, pulverizing of pairing gold; (4) have employed advanced plasma discharge sintering process and prepare high performance RE permanent magnetic alloy.
Embodiment
Embodiment 1-4, and comparative example 1-9:
One) pairing gold is got the raw materials ready: alloy one is made up of element Nd, Fe, B, Al, Co, Nb, Zr, Cu, alloy two is made up of element Dy, Fe, B, Al, Co, Nb, Zr, Cu, wherein except rare earth element, the content of all the other elements is identical with described Nd-Fe-B rare earth permanent magnetic alloy (specifically see table 1), the ratio being condition allotment alloy one and alloy two with the component meeting described Nd-Fe-B rare earth permanent magnetic alloy.
Two) preparation of alloy one powder:
1) melting, alloy one raw material be equipped with is put into vacuum induction melting furnace, smelting furnace is evacuated to 18Pa and heat melting until temperature to 1050 DEG C time to start to be filled with argon gas to pressure be 0.2MPa, be warming up to 1200 DEG C of refinings 10 minutes subsequently, insulation leaves standstill 2 minutes;
2) pour into a mould, adopt the method for getting rid of Strip casting, chill roll diameter is 500mm, and controlled cooling model speed, at 2.8m/s, obtains the slab that thickness is 0.3mm;
3) Mechanical Crushing, obtains by Mechanical Crushing the meal that particle diameter is 100-200 μm by slab;
4) hydrogen is quick-fried, be that meal Mechanical Crushing obtained under the condition of 1L/min is heated to 820 DEG C at hydrogen flowing quantity, after insulation 10min, increase hydrogen flowing quantity to keep to 3L/min, inhale hydrogen 2h, arrange hydrogen subsequently and be filled with argon gas, starting to vacuumize dehydrogenation when argon pressure reaches 0.8MPa, during to vacuum degree 4Pa, dehydrogenation terminates;
5) grind, adopt airflow milling to grind, specifically add the zinc stearate of 0.14wt%, in nitrogen atmosphere, be crushed to average grain diameter is 5 μm, obtains fine powder.
Three) preparation of alloy two powder:
1) melting, alloy two raw material be equipped with is put into vacuum induction melting furnace, smelting furnace is evacuated to 20Pa and heat melting until temperature to 1250 DEG C time to start to be filled with argon gas to pressure be 0.4MPa, be warming up to 1400-1450 DEG C of refining 3 minutes subsequently, insulation leaves standstill 0.5 minute;
2) pour into a mould, adopt the method for getting rid of Strip casting, chill roll diameter is 500mm, and controlled cooling model speed, at 2.8m/s, obtains the slab that thickness is 0.3mm;
3) Mechanical Crushing, obtains by Mechanical Crushing the meal that particle diameter is 100-200 μm by slab;
4) hydrogen is quick-fried, be that meal Mechanical Crushing obtained under the condition of 2L/min is heated to 840 DEG C at hydrogen flowing quantity, after insulation 10min, increase hydrogen flowing quantity to keep to 4L/min, inhale hydrogen 4h, arrange hydrogen subsequently and be filled with argon gas, starting to vacuumize dehydrogenation when argon pressure reaches 0.8MPa, during to vacuum degree 3Pa, dehydrogenation terminates;
5) inhale hydrogen process again, again pass into hydrogen with the flow of 4L/min at ambient temperature, and keep 1h;
6) grind, adopt airflow milling to grind, specifically add the zinc stearate of 0.09wt%, in argon gas atmosphere, be crushed to average grain diameter is 1 μm, obtains fine powder.
Four) pairing gold mixing: the fine powder ground is mixed under an argon atmosphere.
Five) green compact compacting: by the alloy powder that mixes in the magnetic field of 1600kA/m, adopts the pressure at right angle of 200MPa that pressed by powder 15min is shaping.
Six) sinter: green compact are placed in vacuum tank, 0.5 × 10
-3under the vacuum condition of Pa, be warming up to 560 DEG C with the heating rate of 40 DEG C/min, then after plasma discharge sintering 10min, be filled with normal temperature argon gas and be quickly cooled to room temperature under the pressure of 60MPa.
Seven) timeliness: by sintered alloy at 560 DEG C, insulation 3h, thus obtain final Nd-Fe-B rare earth permanent magnetic alloy.
In described alloying element, Nd, Fe and B are the basic elements forming neodymium iron boron principal phase, must ensure that the content of Nd is more than 15.0, otherwise will be difficult to effectively form RE permanent magnetic alloy, but its content can not be too high, otherwise will the interpolation quantity of other elements be limited and affect the performance of alloy monolithic.B is also the basic composition element of principal phase, and its content should more than 5.0, but too much interpolation can cause the deterioration of magnetic property.
Aluminium element can play significantly and improve coercitive effect, useful effect is played for the processing characteristics improving alloy simultaneously, but excessive interpolation there is no benefit for coercitive raising, can cause the remarkable decline of remanent magnetism on the contrary, the Al in alloy system of the present invention should in the scope of 0.2-0.3.
Cobalt element obviously can improve the Curie temperature of alloy system, but the interpolation of cobalt obviously can cause the decline of the performance such as remanent magnetism, coercive force, therefore the addition of cobalt element must strictly be controlled, play for the enough raising effects of Curie temperature to make it, its addition at least should be 7.0, simultaneously in order to limit the side effect that it adds, its content should be controlled below 10.0.
Niobium and zirconium are all the elements of typical inhibiting grain growth, inhibiting grain growth can be played in alloy system, improve the effects such as squareness, its deficiency of adding content will cause alloy system to be difficult to adapt to corresponding plasma discharge sintering process, thus causes the remarkable decline sintering rear alloy system magnetic property.
Copper also can play the inhibitory action of grain growth in sintering and ag(e)ing process, avoid principal phase for the excessively solid solution mutually of rich neodymium simultaneously, thus significantly improve coercive force, but the interpolation of too much copper then can affect the level and smooth of main phase grain, thus low-alloyed magnetic property significantly falls.In addition, copper can also play the effect suppressing cobalt to worsen magnetic property to a certain extent.
The interpolation of heavy rare earth element dysprosium can improve the coercive force of alloy system significantly, but its too much interpolation can worsen the performances such as the remanent magnetism of alloy, and therefore limiting its addition is 3.0-5.0.
Table 1
RE permanent magnetic alloy system in the application, by the coordinative role between alloying element, the unforeseeable comprehensive magnetic energy obtaining excellence.
Embodiment 5-8, and comparative example 10-15, the chemical composition of alloy is identical with embodiment 3, and the advantage, particularly powder diameter of the two reasonable offer of paper examines are for the impact of alloy property.
Table 2
As can be seen from the result of table 2, the powder diameter of alloy one and alloy two has material impact for the performance of alloy, powder diameter is too small, to cause the hyperactivity of powder and be difficult to adapt to the temperature of plasma discharge sintering thus cause the growth of excessive grain and the dissolving for rich neodymium phase, the control simultaneously for oxidation also becomes the problem being not easy to solve.But the granularity of powder can not be excessive, excessive powder generates the institutional framework of needs by being difficult to effecting reaction under corresponding plasma discharge sintering condition.Meanwhile, the relative size of alloy one and alloy two powder diameter, the rare earth alloy for the partially outer enrichment of Dy needed for formation is significant.
The order tool knitting knot for powder that adds of zinc stearate has a significant effect, thus greatly enhance the remanent magnetism of alloy, in order to ensure its effect added, in two kinds of reasonable offer processes, certain lower limit should be kept to add, but can not excessively add, excessive interpolation can not obtain corresponding income, may cause coercitive decline on the contrary, and excessively add impurity elements such as will causing in alloy system C, O and be difficult to control, this is particularly evident in the preparation process of alloy two.
The preparation method of pairing gold is also obvious for the improvement of alloy system performance; Before grinding to inhale hydrogen treatment process more then obvious for the oxidation resistant control action of fine powder, and the oxidation controlling reasonable offer process undoubtedly for the condition and final alloy that reduce plasma discharge sintering performance all tool improve significantly.
Embodiment 9-11, and comparative example 10-12, the chemical composition of alloy is identical with embodiment 3, the paper examines impact of plasma discharge sintering process conditions for alloy property.
Table 2
Can find out, sintering temperature and pressure at least should at 560 DEG C, more than 60MPa, otherwise be difficult to effectively sintering reaction occur thus obtain required texture and corresponding magnetic property, but can not be too high, otherwise the excessive increase of the crystal grain of alloy system can be caused and reduce time performance significantly, being preferably 580 DEG C, 70MPa.Sintering time at least at more than 10min, otherwise is also difficult to effectively complete sintering reaction.Comparative example 13 is the high temperings adding 850 DEG C × 1h after the sintering, but the heat treatment of double tempering does not improve the performance of alloy significantly than lonneal, show that alloy system that the present invention prepares does not need deliberately to take twice or temper repeatedly.