New technology, new facility produces medium application in magnet of NdFeB rare earth -- the hydrogen of alloy explodes reach air current pink

  • (committee member of committee of 1.IEEETC-15 permanent magnetism, beijing 100081; 2. Limited company of trade of be in harmony of sea of Beijing fine Nuo, beijing 100029) emphasize uniformity of magnetic particle granuality, particle size distribution, granuality the importance of high-powered to preparation magnet. The hope borrows this to cause manufacturer of vast magnetic body to reach pair of attention that hardware equipment transforms to the control of craft principle.

    1 milling 1.1 hydrogen explode broken (HD) technical HD is to have substantially fasten the physico-chemical method at a mechanical and broken kind of broken material, it is special apply to the compound between the alloy that contains rare earth or metal, because this kind of material is had,suck hydrogenous character. Hydride is formed after NdFeB sucks hydrogen for example, the crystal lattice when be being generated as a result of hydride expands, the immense stress that produces makes a lot of micro-crack arise inside NdFeB crystal, material becomes loose and even become meal end, after taking off hydrogen treatment via heating subsequently, major advocate photograph hydride changes an original Nd2FeMB meal, and hydride of photograph of one part rich Nd still stays in stock. Want special those who point out is, borrowing HD to make the meal that give is not just by original ingot casting or fast coagulate casting piece (SC) the meal that become, a few hydride still remain in division of its magnetism material and parts of an apparatus, its chemistry component and magnetism changed, in the follow-up working procedure that this produce in NdFeB magnet must mature, make corresponding processing.

    HD smashs the law is applied to only can of the metal of hydrogenation or alloy thick broken, be in into makings dimension 1000.1mm. Granuality giving pink is 101000pm about, to Chu Qing alloy or place of Ni-HM batteries stuff need powder and character, this granuality already satisfied practical requirement, but for the preparation of boracic to neodymium iron magnet, pulverous granuality should be 0.7~7m, namely its are average granuality is 34m, criterion must farther fine grind ability to satisfy a requirement.

    The suction of NdFeB hydrogenous process metal or alloy suck hydrogen below certain condition or dehydrogenation is reversible, but forming hydride for the first time is to have certain condition and demand: Can of the compound between infiltration metal is pH indicator is not hydrogenous element, the dissociation need of hydrogenous element activations certainly can. In addition, the compound between the metal (alloy) the surface that the interface should be cleanness, the impurity that oxidation layer and other do not react with hydrogen will block up reacts undertake, undertake for this need " activation is handled " . From connect hydrogen to begin till reaction suction hydrogen, this paragraph of time makes incubation period. Sucking hydrogen is exothermic reaction, accompany calorific (hydride generates heat) , till saturation suction hydrogen, namely the course that hydride builds.

    The suction of NdFeB hydrogen can be divided for two paces, what suck hydrogen above all is the rich Nd photograph that is shown in the surface, its react as follows: It is next advocate photograph Nd2FeMB and H2 produce reaction: When hydride 2NdH2.7 by face heart cubic metre (Fcc) change 6 brilliant (Hcp) , crystal lattice constant greatens, bulk expands 20% . Hydride Nd2FeMBH5 crystal lattice also greatens, corresponding bulk expanded 4.5~5.0% , advocate the formation of photograph hydride is accompanying exothermic reaction, of this reaction generate hot A ugly =*57.2kJ/mol, total quantity of heat can make reactant temperature lifts from room temperature the saturated magnetization strength of ~300LNd2FeMBH5 is Ms=152A*m2/kg (300*K) , increase somewhat, and J of Qu, wind is acuteness drop, turn into soft magnetism photograph. Advocate the crystal lattice change when photograph hydrogen sulfide is shown at the watch 1. The name of crystal lattice change that expresses 1 Nd2FeMBH5 learns two paces. The first pace, crystal lattice of pH indicator infiltration, cause the change with crystal lattice little constant, if express the 1st place to show: Fl turns into by 0.877nm hydrogen, nd2FeMB structure did not produce change, only bulk increased 1.04% ; Nd2FeMB sucks hydrogen further, unripe chemistry of both finally hair reacts, generate hydride Nd2FeMBH5, bulk expanded 5.5% , crystal lattice great change is accompanying successive crackle news, at this moment hydric pressure not heighten, but temperature is elevatory, of hydride explode broken blast is cracked is microcosmic measure, it and hydric explosion have substaintial distinction. The place on put together is narrated can see, after neodymium iron boron is handled via HD, powder has produced qualitative change, if undertake dehydrogenation can make Nd2FeMBH5 part ground becomes original Nd2FeMB, but it is under firing temperature, the hydrogen in NdH2.7 is cannot be taken off clean.

    The process of dehydrogenation process dehydrogenation of NdFeB is decompose hydride, what dehydrogenation rate follows temperature, pressure is different and different, advocate the dehydrogenation rate rank of the photograph is expressed 2. Advocate photograph Nd2FeMB produces reaction to be decomposed completely with hydrogen below higher temperature, form the hydride NdH2 of neodymium and Fe2B: Watch 2 advocate the temperature of dehydrogenation of composition of hydride of different dehydrogenation rate that falls in different condition / C dehydrogenation pressure / MPa dehydrogenation is led / this kinds of % hydride and Fe2B change completely a Nd2FeMB advocate, below high temperature only dehydrogenation ability comes true: Medium H2 ability is complete eduction, but warm up when 650*C, rich Nd photograph already molten is fused, between brilliant fragile crack a phenomenon to may be changed, if continue to warm up again, be sure to produce HDDR reaction, be on the another direction that hydrogenation reacts apparently. Be based on afore-mentioned character of NdFeB and hydrogenous reaction, the optimal dehydrogenation temperature that uses now is 500C. Here the condition falls, advocate the hydrogen of photograph hydride is given off basically, ndH3 of hydride of rich neodymium photograph took off partial hydrogen to become NdH2 in 500C. The ability when the dehydrogenation of this one part hydride needs to stay in vacuum agglomeration undertakes.

    1.2HD smashs the advantage 1.2.1HD+JM of the law (air current is ground) tall milling efficiency as magnet of neodymium Tie Peng high-powered change, fusion casting piece change, rare earth content is reduced gradually, be close to Nd2FeMB advocate of the photograph distributing part (RE=11.76at% ) , talk with respect to mechanical function, this alloy hard pliable but strong (made of baked clay =530, bending strength 24~26kg/mm2) , with mechanical method milling, efficiency is low, and oxidation is serious. Smash with HD all problem all be readily solved. Crocus efficiency raises 23 times, the equipment with considerable amount be able to managing, crocus efficiency achieves 90100kg/h (former the oxidation rate that the milling of 1.2.2 oxygen content HD that reduce magnetic particle effectively can lower crocus workshop section effectively, pulverous oxygen content reduces 200800X10*6. There is hydrogen to exist in agglomeration process, but the oxide of reductive neodymium, purify crystal boundary, promote compact change, realize partial activated sintering.

    HD of craze of photograph of crystal boundary of HD pink much edge is broken it is preferential edge photograph of rich Nd crystal boundary or advocate the rich Nd inside photograph Nd2FeMB exceeds structural layer to undertake, criterion HD+JM pink bead all is single crystal grain, its dimension is close to 23m of optimal bead diameter, more important is every grain edge all has rich neodymium look, enhance correct dense power effectively thereby, function of correct HD magnetic particle mutates somewhat HD+JM powder because partial powder exists with hydride configuration (Nd2Fei4BHx, ndHx) , its magnetism shows certain variation: Ms slightly tall, qu zephyr J is reduced, present weak magnetism, the result makes drawing of patterns light, be helpful for mould pressing figuration, the outward appearance that controls base is orderly, pile up convenient.

    HD powder is had it is better to fight oxidisability HD+JM powder goodly to have fight oxidisability, save time longer, the powder that practice makes clear burns not easily in air, and the powder of mechanical legal system falls in this granuality, encounter air to burn immediately.

    The safe problem chemical industry of 1.3HD craft, metallurgy often should be used in manufacturing domain hydric, hydric can spontaneous combustion, mix by certain proportion with oxygen can explode, because this is relevant technological equipment must mature the requirement that eliminates generation explosion: Prevent leak, avoid hydrogen and oxygen to mix 2) prevent bright internal heat; (3) equipment place must consider to prevent hydrogenation with material, use the data that does not produce chemical reaction with hydrogen namely, for example stainless steel 1Cr18Ni9Ti fights hydrogenation material very well namely, chu Qing container and conduit choose 1Cr18Ni9Ti. 2 hydrogen explode the preparation that the current situation of broken milling equipment and Harris use HD technology successfully at NdFeB. 1988, old Yu Cai, Zhang Baicheng determined of NdFeB suck, dehydrogenation is characteristic, what use HD technology successfully at NdFeB alloy is broken. Of afterwards, development gave the NdFeBHD device of homebred 80kg class 1992. Why the thing lies between more than 10 years, the effect of this one technology just is shown come out, itself of the equipment that divide HD is not quite perfect outside needing a holiday to be improved with time, basically be right at that time the demand of high-grade magnet still not pressing. Well-known, if the preparation head of high-powered magnet assures low oxygen craft, the demand that is low oxygen environment promoted HD milling at an early date practical change, change character, HD technology equipment assures the core technology of low oxygen craft just about.

    The insular ferry HD of firm of ferry of island of Japan of 90 time end handles furnace to introduce Chinese market, later company of German POWDERTECHNOLOGY also is promoted in China 200 model HD equipment. They are with heat treatment furnace is basic structure, system of refrigeration of loop of system of structure of again add compression full H2, vacuumize, Ar, every furnace charge is 500kg and 200kg respectively. Construction of this kind of facility is more complex, treatment is excellent, but the price is high. Use effect is not ideal, put generally in following defect: (1) cold fast low, processing cycle is long, from ten arrive 30 hours; (2) it is difficult that magnetic particle is taken out below Ar or nitrogen protection; (3) working hydrogen atmospheric pressure is exorbitant (0.20.6MPa) .

    Be worth what carry was 2001 boracic hydrogen of iron of GS-1 of research and development of dominant of old Yu Cai neodymium explodes broken unit, be based on much work design thought, equipment structure is simple, on the safe side, but activity in series, use the computer to control, daily output (24h) 1600~1800kg. Facility cost is low.

    This equipment already used magnetic material division and parts of an apparatus at the product line of company of company of porcelain of constant of Shanxi carry city and Shanxi Jin Kaiyuan in December 2006.

    2.1HFS-1 hydrogen explodes the structure of broken equipment already developed brand-new hydrogen to explode broken unit, its core is retort of one stainless steel, if what the structure shows.

    HFS-1 hydrogen explodes structure of broken furnace retort its key component is the stainless steel retort with special structure, interior is not had identically by 9 length seam stainless steel to be in charge of composition, 3 a group, each other parallel discharges 3, inside the disc cover board that two end insert steel tube to have nine opening, canal and disc each other are sealed solder. Inside chamfer of form of one party of park of steel tube group, this chamfer has 3 sides only, all receive with disc close soldering and sealing. The end outside disc carries Gai Mi to seal connection with one metal each, an end lid submits funnel form, coping has valve, facilitate be mixed to uninstall by the prime of processing material; Charge valve and vacuum bleed valve were installed on another end lid. The stainless steel of park of alloy makings cent that is processed is in charge of inside.

    Resistor heater can insert stainless steel from the notch that open wide directly between the canal, be in charge of with heating effectively inside by processing material (see on the right side of) . When refrigeration, take out heater first, cooling water can enter retort directly outside inside groove, water floods steel tube (see left) , bottom land ministry installs valve of water having have diarrhoea outside. Apparent, of such design heat and cooling means, can rise effectively to heat and cool rate, make sure data processing cycle is the shortest thereby.

    After HD handles an end, retort perpendicular put stand, if what show, all alloy makings inside coal tub will reach valve through funnel batch can of successful infuse collect, already safety does not have any leak again, realize each requirement of low oxygen craft easily not only with this suit buy apparently, and safer, effective.

    2.3HFS-1 hydrogen explodes the hydrogenous atmospheric pressure inside the technical parameter retort of equipment is 0.01~0.2MPa; Retort is the biggest working temperature 500*C; The vacuum inside coal tub spends ~133Pa; The reaction time of every retort makes an appointment with 3h, add refrigeration to room temperature, make an appointment with 5.5h in all circularly every time; Every canister most high capacity makes an appointment with 100200kg; Every equipment matchs 3 retort, every canister is restricted to install 150kg, every day and night (24h) can handle 4 times, total treating capacity should be 1.8t; Every power that inserts type heater is 24kW (every retort needs two heater) ; Whole hydrogen explodes the process all is recorded with all craft parameter and show the indication screen at controlling ark to go up; Hydric conduit jacket has leak warning apparatus and 3 a powerful person; Will after retort is erect, in-house and all drossy and rapid and surely teem; Enter expecting is casting piece or casting board, dimension <30mm. 80 time China introduced grinder of 3 improved fluid-bed air current successfully type air current grinds German Alpine fluid-bed, undertook 1991 homebred change, a large number of at product line of neodymium iron boracic magnet using, promoted product quality and production efficiency greatly. Long-term since without person suspicion fluid-bed type air current is ground have what drawback. In recent years high-powered magnet (50MGOe) production, reach its to distributing to magnetic particle granuality raised strict with each passing day requirement. Japanese gold abundant studied the agglomeration NdFeB magnetic body that waits for preparation 2000, amount to year of Germany Rodewald to wait to innovate again tall, achieved 451kJ/m3 2004 year days this gold abundant treats wait to innovate again record: High-powered magnet divides 460kJ/m3 preparation high saturated magnetization strength (reach) evening is predicted, another key is how to retain power of tall correct dense (wind J) , had extensive and thorough research to this, discovery basically should control the micromechanism of magnetic body, make the grain of agglomeration magnet imperceptible, and dimension is even, this asks magnetic particle is extremely imperceptible, and particle size distribution cannot too dispersive, must center highly, the gold abundant of Japanese NEOMAX treats conclude: Magnetic particle granuality should be in 0.77pm, average size under 3pm, the magnetic body grain after agglomeration petty, dimension is even (4.8~6.0 clang) .

    Grain is imperceptible and will even requirement reach arrives milling phase, criterion average size should be magnetic particle 3m, curve of particle size distribution should very concentration, acerb, cannot too dispersive. Consider to make clear, the particle size distribution that new technology place makes magnetic particle is narrow (0.7~7) , and the particle size distribution that conventional technology place makes magnetic particle is very wide.

    The new technology magnetic particle that mentions here, SC+HD+JM applied to combine a technology when preparation, practice makes clear, use casting piece (SC) replace ingot casting, divide outside eliminating A-Fe effectively, with HD+JM milling efficiency tall, obtain the small white that 3~4 calls easily.

    Casting piece alloy and traditional casting alloy break with air current crocus, both smash the contrast of efficiency is shown at, the x-axis of this graph is average size (M) , cross axle is to feed makings speed (Kg/h) . If be raw material with casting alloy, when beforehand dimension exceeds broken ingot casting to be restricted and be fed when makings rate is too rapid, criterion magnetic particle granuality becomes bulky, if pursue medium,dotted line place is shown. On the other hand, if use casting piece alloy, although feed makings speed to be added by 20kg/h,come 40kg/h, magnetic particle granuality still maintains inside 3m limits, if pursue medium,solid line place is shown. See by the graph, if use ingot casting to be raw material, feed makings should very slow, grind the powdery size that give to coarsen otherwise. Air current grinds more comfortable Yu Zhu piece, crocus efficiency is extremely tall, feeding makings speed high to fall, still receive fine powder.

    Milling efficiency / 1 casting of Kgh ― piece comparative gold abundant treats the efficiency when with ingot casting two kinds of alloy break with air current crocus respectively put forward, magnetic particle is average granuality is 3m, 7m of the largest size. And grinder of our country's current and general fluid-bed air current achieves this requirement hard.

    The company of problem Germany Alpine that production of boracic magnet of 3.1 neodymium iron worries existence with air current developed fluid-bed successfully to be opposite fluid energy mill hitting formula, our country division amounted to a company to introduced the first above all 1986 rather, apply successfully on product line of neodymium iron boracic magnet. This machine is one of the most advanced type in fluid energy mill, after 1990 our country undertook batch is produced, it is the road principle graph that air current grinds. In smash inside antrum, if too big, density cannot present raw material grain greatly too,cannot smash when liquefaction condition. Grader lamina wears away serious, grinding super- when exceeding fine pink forcedly especially such.

    Circular water specific power consumption is low. Because much eject chew is bit righter resultant force of jet air stream is large, classification annulus make qualification fine pink is discharged in time, unqualified powder is returned to smash undertake 2 times smashing inside antrum, eject kinetic energy gets optimal use, reduce 3040 ° than specific power consumption of disc fluid energy mill % . Wear away with touch stick small. Because jet air stream and stock divide magnetic material division and road of parts of an apparatus to enter,smash room, avoided what particle midway arises to bump thereby, attrition and touch stick deposit, also prevented nozzle and pair of pipeline wear away.

    Grader can be adjusted independently, particle size distribution compares concentration.

    Automation operation, the structure is compact, wear away small, unpick and wash is more convenient.

    Construction of closed circuit type can antirust and pollution.

    Fluid-bed is right of fluid energy mill hitting formula smash room construction is shown at.

    Anyhow, homebred fluid-bed cannot satisfy boracic magnet of high-powered neodymium iron to produce craft demand to striking type fluid energy mill, develop new model to satisfy the requirement of this respect only.

    The neodymium iron boracic magnet with the defect long-term course of grinder of air current of 3.1.2 closed circuit produces practice, from high-powered magnet manufacturing technology asks to set out, observation considers to discover fluid-bed following to bumping into type fluid energy mill to exist issue.

    End pink problem. Fluid-bed is right of fluid energy mill hitting formula smash if what the room shows, what should defining above all is end pink. In smash stock of onefold breed, single component, the problem of nonexistent end pink when long-term serial production. However total presence of the milling in production of neodymium iron boracic magnet is different composition, different batch of makings, do not allow mutual and jumbly, for example 100kg raw material enters grinder, give powdery 88kg, still 12kg stops inside machine, makings of this 12kg pink is end pink (time spit makings) . Continue to join raw material ability to guide pink of this 12kg end only. The generation of end pink is too big, density cannot present liquefaction state greatly too and cannot smash as a result of raw material grain. But also may be contrary reason: Raw material grain is too little (but bigger than what divide class annulus requirement) , density is too small cannot present normal liquefaction state and smash efficiency is very low, cannot give pink. End pink is in to smash by hold back indoor empty revolve, go out not to come. This is the reason that end pink appears.

    Appear the reason of big grain tails. Derive the only way of end pink, stop to classification namely annulus rotational, let smash the air current of the room blows end pink, from tornado collect pink implement collect, collection end pink size is distinct, the amount is not large, bad to handle, deposit only, stay processing is centered again after waiting for. End pink is collected not complete, because this one pink shedding has a lot of big grain,meeting block stays in passes conduit, wait for the next time when grinder moves, new powerful pink sheds the pink of big grain end that may stay in before in conduit to coil to tornado collect pink implement in, the interfuse in new pink makings big grain, this is big grain " pollute " problem. A few factories to solve this problem, let worker of magnetic field figuration divide these big grain with bolt sieve.

    Go out, fluid energy mill sets two to give makings opening: Tornado collect pink implement it is powdery makings exit, it is below filter " exceed fine pink " exit, this kind of arrangement is extremely improper for production of boracic to neodymium iron magnet, because all powder needs, and should not abandon fine pink. Had had advanced round of type grader, set segregator of a tornado again " exceed fine pink " depart comes out, solid without necessary. What is more,the rather that " exceed fine pink " collect very hard, actually " exceed fine pink " the useless pink that had become oxidation.

    The issue that closed circuit system designs. The antirust on product line of low oxygen of neodymium iron boracic magnet is main task, crocus nitrogen 99.9995% in the system closed circuit circulates, present makings opening however, giving makings opening is not hermetically sealed design, entered oxygen basically relies on much nitrogen 99.9995% come attenuant, the effect is slow, and wasteful.

    Give powdery difficulty normally. In tornado segregator lower part till exit (include cone, valve, pipeline) the design is unreasonable, easy generation powder jams, touch add, stop wait for a phenomenon, because give powdery difficulty, jockey person must knock pipeline with ironware, rely on to shake a makings.

    The appearance that measure oxygen (zirconia probe) not accurate. Inchoate the used instrument that measure oxygen (zirconia probe) , once encounter hydric, firedamp to wait, the appearance that measure oxygen (zirconia probe) namely invalidation, the directive is 0.

    3.2 new-style fluid-bed are right fluid energy mill hitting formula boracic magnet of high-powered neodymium iron produces idea of 3.2.1 designs technology the new-style fluid-bed that craft asks is the low oxidation that should realize magnetic particle to striking type fluid energy mill, imperceptible change and change 3 ends equably. Devising an idea also is around move these 3 targets spread out.

    Systematic hermetically sealed, the former batch can that uses unified caliber and give batch can and machine sealed butt joint, remove the air in the machine with vacuum system, reoccupy tall purity nitrogen is rinsed, assure a machine to be made in low oxygen or come off work of the environment that do not have oxygen.

    Complete bead diameter reclaims pulverous, cancel tornado segregator, catch market greatly by implement collect powder of complete bead diameter.

    Change its course answers ending pink, in smash room lower part installs a butterfly a powerful person and powdery canister, the fluid energy mill of disc of end pink reoccupy of remove stage makeup and costume (the end pink that it machines is very few) undertake crocus, implementation of original lot number of end pink rejoin reclaims completely.

    Give pink to go to the lavatory, because used clip a powerful person, pneumatic knock hammer and optimal cone angle, when eliminating a pink, jam, the phenomenon that touch sluggish. A few 3.2.2 important parts (1) disc type fluid energy mill. If what show, by mouth of feed in raw material, advocate next annulus of gas entrance, eject, upper cover, lids and give makings mouth composition. There are 624 air currents to enter the mouth on eject annulus, air current entrance and fixed eject annulus form proper point of view, rotate disaster shedding makes generation of raw material particle collides, attrition, cut, can be in again the action make known to lower levels of centrifugal force arrives to classification correctly. Be smashed when particle classification when diameter is the following, break away from below the because of leaving mental efforts small action in afferent air current classification come back stream, by the center exit enters the system that catch market. In smash indoor because the heat insulation of jet air stream expands,action makes temperature drops. Some foreign magnet produce manufacturer to use milling of fluid energy mill of type of this kind of disc. Because jet air stream is fast, smash the room is little end pink is so little, solve fluid-bed with it the end pink problem to fluid energy mill.

    Graph of principle of disc type fluid energy mill places a powerful person and low oxygen canister. The valve that gives powdery mouth upper part to use to bumping into type fluid energy mill to go up in fluid-bed is pneumatic butterfly a powerful person or pilot valve, often fill in pink, sealed and difficult, increased to give powdery difficulty, the clip a powerful person that employs here its principle is very simple, it is chemical actually, jar upper part is clip a powerful person. At present general pulverous canister does not accord with the requirement of low oxidation mostly, its are as makings of pink of sealed, pass in and out, right as the machine receive, detect oxygen content put in the problem. The clip a powerful person that recommends here and low oxygen canister solved afore-mentioned problems.

    Type of compound pulse bag catchs market implement. Part of cone of its lower part by tornado segregator, clip a powerful person, give makings mouth composition, the property that establishs inside upper part drum raised taller requirement. It is garnet to YIG how utmost land increases data ask for Faraday to rotate originally function of light waiting for magnetism, in the meantime, the light that reduces material absorbs coefficient in order to improve performance of parts of an apparatus. Additional, because the YIG of garnet underlay is filmy existence and semiconductor light parts of an apparatus are incompatible problem, if where,the magnetism smooth film with the high grade preparation on semiconductor underlay also is the problem that deserves attention.