CN104843727A - Multi-component rare earth boride (LaxCe1-x)B6 solid solution polycrystalline cathode material and preparation method thereof - Google Patents

Multi-component rare earth boride (LaxCe1-x)B6 solid solution polycrystalline cathode material and preparation method thereof Download PDF

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CN104843727A
CN104843727A CN201510163304.4A CN201510163304A CN104843727A CN 104843727 A CN104843727 A CN 104843727A CN 201510163304 A CN201510163304 A CN 201510163304A CN 104843727 A CN104843727 A CN 104843727A
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powder
temperature rise
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ball milling
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CN104843727B (en
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周身林
叶子飘
罗回雨
余晓光
罗小兵
孙心瑗
陈明源
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Jinggangshan University
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Abstract

The invention provides a multi-component rare earth boride (LaxCe1-x)B6 solid solution polycrystalline cathode material and a preparation method thereof, and belongs to the technical field of rare earth boride cathode materials. The method adopting LaB6 and CeB6 powder as raw materials comprises the following steps: carrying out ball milling, and carrying out vacuum hot pressing sintering at a highest sintering temperature of 1700-1900DEG C to synthesize (LaxCe1-x)B6 solid solution polycrystals, wherein x is not smaller than 0.1 and not greater than 0.9. The method combines a powder synthesis process with a sintering densification process, so the method has the advantages of preparation flow simplification, purity and density increase, and production cost reduction, and is suitable for industrial production and application. The (LaxCe1-x)B6 solid solution polycrystalline cathode material obtained through the preparation method has the characteristics of single phase and high density, and can be used in plasma sources, electron beam welding machines, electron beam exposure machines and field emission arrays.

Description

Multicomponent rare earth boride (La xce 1-x) B 6sosoloid polycrystalline cathode material and preparation method thereof
Technical field
The invention belongs to rare-earth boride cathode material technical field, be specifically related to a kind of multicomponent rare earth boride (La xce 1-x) B 6sosoloid polycrystal and preparation method thereof.
Background technology
Negative electrode is the heart device of various Modern vacuum electronics, is all widely used at national defense industry, civil area.With lanthanum hexaborane (LaB 6) and six cerium boride (CeB 6) be the rare-earth hexboride compound (REB of representative 6), it is the hot-cathode of excellent performance, there is the features such as low work function, low-resistivity, low rate of evaporation, high-melting-point, long lifetime, be therefore widely used in the equipment such as all kinds of Electronic Speculum, plasma source, electron beam welding machine, electron beam exposure apparatus, field emission array.Special in some microfabrication equipments, need to obtain accurate controlled electron bundle, require the electron source of high-density, high brightness, LaB 6and CeB 6be desirable radiator, be successfully applied to the civilian industries such as automobile, electronics, motor.Recent studies have found that, will other REB appropriate 6with LaB 6doping solid solution is expected to reduce LaB 6negative electrode working temperature also significantly improves its hot-electron emission property, and therefore, Chinese scholars accelerates the research to multicomponent rare earth boride.At LaB 6other REB of middle solid solution 6except improving except emitting performance, significantly can also improve resistivity, contribute to the application of hexaboride negative electrode in heater cathode field.With LaB 6compare, CeB 6lower rate of evaporation and very strong anti-Prevent Carbon Contamination ability.Therefore have and compare LaB 6more wide application prospect.In addition, except outstanding emission properties, CeB 6also there is unusual transporting and magnetic property.Ce 3+in 4f electronics and 5d conduction band in the exchange of electronics cause it to have typical Kondo effect feature.Meanwhile, between the electronics of 4f and 5d track, very strong exchange interaction also makes CeB 6resistivity times over LaB 6, this just makes CeB 6likely be applied to heater cathode.Therefore, by solid solution CeB 6regulate and control LaB 6crystalline structure, the multicomponent rare earth boride (La of processability excellence xce 1-x) B 6sosoloid polycrystalline negative electrode, thus realize cathode material performance controlled, improve emission properties significant.
At present, the traditional preparation methods of multicomponent rare earth boride polycrystalline material, comprises sintering densification two processes of the synthesis of multicomponent rare earth boride polycrystal powder and powder.The synthetic method of multicomponent rare earth boride polycrystal powder mainly contains the hot method of boron, norbide reduction method, elementsynthesis, fused salt electrolysis process and magnesiothermy etc.These preparation methods have some shortcomings, and such as speed of response is slow.React fully, the general requirement reaction times, more than 10h, prepares some multielement rare earth hexaboride and even needs several days time.In addition, because the raw material preparing multielement rare earth hexaboride is all kinds of more, reaction is comparatively complicated, pilot process product is more, and the multielement rare earth hexaboride powder prepared often has dephasign, and purity is not high, this will make its work function increase, thus reduce emitting performance.The densification of multielement rare earth hexaboride powder mainly adopts cold-rolled sintered, hot pressed sintering or discharge plasma sintering (SPS) method.Cold-rolled sintered and hot pressed sintering prepares sintering temperature high (2000-2200 DEG C), product grains is thick, hole is many, density low (relative density is generally lower than 90%), affects mechanics and the emitting performance of material, causes product to be difficult to apply in the industrial production.SPS is a kind of Fast Sintering technology, but the method is high to equipment requirements, and productive rate is lower, is not too applicable to the industrialization of product.
Be disclose a kind of employing mechanical alloying in the Chinese patent application of 201110110277.6 to prepare nanometer LaB at publication number 6the method of powder, the method comprises the following steps: raw materials pretreatment: by La 2o 3powder and B powder respectively in vacuum drying oven in 100-150 DEG C of dry 8-10h, if B powder surface wetting caking, need to carry out processed in vacuum sintering furnace, dehydration temperaturre is at 1200-1400 DEG C, and dewatering time is 20-40min.Dress sample: by pretreated raw material according to reaction formula La 2o 3+ 12B+3Mg=3MgO+2LaB 6stoichiometric ratio mix; wherein 3% excessive Mg powder (mass percent); mixture is placed in 500mL stainless-steel grinding tank; select the Stainless Steel Ball of φ 20mm, φ 10mm and φ 6mm as grinding medium; add in mixture account for mixed powder total mass 1-3% stearic acid as process control agent, be then filled with high-purity Ar gas that purity reaches 99.99% as protection gas.Mechanical alloying: mixed powder is placed in planetary mills and carries out ball milling, the rotating speed of ball mill is 400-600r/min, ball milling 40-100h.Purify: by the powder absolute ethanol washing after mechanical alloying process, remove stearic acid wherein; Utilize mass concentration be the dilute hydrochloric acid of 18% as leaching agent, the product after alcohol wash is leached, leaches after 15-20h and filter, with deionized water circulation cleaning filtration product several, to washings is neutrality, at 80-100 DEG C, 6-8h is dried to filtration product, obtains the nanometer LaB that purity is higher 6powder.Be disclose a kind of high-purity CeB in the Chinese patent application of 201010233471.9 at publication number 6the preparation method of nano powder, carries out: according to the following steps 1) by CeO 2, B 2o 3with the mixing of magnesium powder, carry out high-energy ball milling process, be then pressed into blank; 2) blank is placed in self-propagating reaction stove, in air atmosphere, adds thermal initiation self-propagating reaction, obtain CeB 6the intermediate product of disperse in MgO matrix; Take dilute sulphuric acid as leaching agent, in airtight autoclave, intermediate product is leached, obtain and leach product filtration acquisition filter residue, through washing and the high-purity CeB of dry acquisition 6nano powder.The shortcomings such as it is loaded down with trivial details that above two kinds of rare-earth boride powder preparation methods all exist process, complex process, and technical requirements is high, if adopt these two kinds of methods to prepare (La xce 1-x) B 6powder, technique will be more complicated, and the purity of product is difficult to be guaranteed.
Be disclose a kind of multicomponent rare earth boride (La in the Chinese patent application of 200810225029 at publication number xrE 1-x) B 6cathode material and preparation method thereof, wherein RE is the second rare earth element (namely RE is any one element in Ce, Pr, Nd, Sm, Eu and Gd) in light rare earths except La.The method comprises the following steps: 1) respectively with simple substance rare earth lanthanum block and RE block for raw material, in hydrogen, argon atmospher, adopt DC arc-plasma evaporation condensation method, prepare LaH respectively 2nanometer powder and REH 2nanometer powder.2) by step 1) LaH for preparing 2nanometer powder, REH 2nanometer powder and raw material B nanometer powder are under hypoxemia ar gas environment, grinding is mixed and loads graphite jig, be placed in SPS sintering cavity, apply the axle pressure of 50MPa, sinter be better than the vacuum condition of 8Pa in argon gas atmosphere or vacuum tightness under, sintering temperature is 1300-1700 DEG C, cools to room temperature with the furnace after insulation 10min.The method preparation (La xrE 1-x) B 6polycrystalline needs two steps altogether: first adopt arc evaporation condensation method to prepare rare earth nano powder, then adopts SPS sintering densification to obtain polycrystalline bulk.Preparation process complex process, technical difficulty is large, apparatus expensive, and energy consumption is high, and raw material need use high purity elemental rare earth metal, and cost is high, output is little, and therefore distance industrial production is also far.
Summary of the invention
In order to solve existing rare-earth boride polycrystal preparation method complex process, technical difficulty is large, product purity and density lower, affect performance, and high in cost of production problem, the invention provides a kind of rare-earth boride (La xce 1-x) B 6sosoloid polycrystalline cathode material and preparation method thereof.Rare-earth boride sosoloid polycrystalline provided by the present invention consist of (La xce 1-x) B 6, wherein, 0.1≤x≤0.9.Method provided by the present invention is with two kinds of rare-earth boride LaB 6and CeB 6powder is raw material, adopts ball milling, vacuum heating-press sintering, most high sintering temperature 1700-1900 DEG C, synthesis (La xce 1-x) B 6sosoloid polycrystalline.The method is by (La xce 1-x) B 6powder synthesis and sintering densification two processes unite two into one, and simplify preparation flow, improve purity and density, and reduce production cost, are applicable to industrial production and application.According to (the La that preparation method provided by the invention obtains xce 1-x) B 6sosoloid polycrystal has feature that is single-phase, high-compactness, is conducive to the range of application expanding multicomponent rare earth boride polycrystalline material.
An aspect of of the present present invention there are provided a kind of multicomponent rare earth boride (La xce 1-x) B 6the multicrystal preparation method of sosoloid.These preparation method's concrete steps are as follows:
1) proportioning batch mixing, proportioning batch mixing has two kinds of modes can be optional: " mixed ball milling " or " classification ball milling+hand mixes ", wherein " mixed ball milling " is: will according to (La xce 1-x) B 6stoichiometric ratio, namely mol ratio is x:(1-x) weigh LaB respectively 6and CeB 6raw material powder is placed in stainless-steel grinding tank jointly, the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, the mass ratio of preferred Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1, and ball and powder quality are than being (10-20): 1; For preventing the boron pruinescence in mixed powder to be oxidized, above operation is all carried out in glove box, ball grinder is placed in high energy ball mill and carries out ball milling, and rotating speed is 500-700r/min, preserves sampling after ball milling 1-2h in glove box." classification ball milling+hand mixes " gets LaB 6and CeB 6raw material powder carries out ball milling respectively, and after weighing your ratio of the massage obtained after ball milling, hand mixes again, and wherein ball-milling technology is identical with above-mentioned " mixed ball milling ".In two kinds of modes that are mixed preferably " classification ball milling+hand mixes ".
2) shove charge, by step 1) LaB that is mixed evenly 6and CeB 6material loads graphite jig in glove box, is placed in by mould in hot-pressed sintering furnace;
3) heat up sintering, the first temperature rise period: room temperature is to 400-500 DEG C; Second temperature rise period: 400-500 DEG C from the first stage is warming up to 800-900 DEG C; 3rd temperature rise period: 800-900 DEG C from subordinate phase is warming up to 1200-1300 DEG C; 4th temperature rise period: 1200-1300 DEG C from the phase III is warming up to 1700-1800 DEG C; Wherein, the first temperature rise period applied axle pressure to powder, pressure range 10-20MPa to the 4th temperature rise period, and the first temperature rise period and the second temperature rise period apply identical axle pressure to powder, and then the axle pressure of per temperature rise period progressively increases; Preferably, the first temperature rise period and the second temperature rise period apply 10Mpa axle pressure to powder, and the 3rd temperature rise period applied 15Mpa axle pressure to powder; 4th temperature rise period applied 20Mpa axle pressure to powder;
4) be incubated, in step 3) fourth stage heat up after 1700-1900 DEG C of temperature 1.5-2h; And at insulating process, 30-40Mpa axle pressure is applied to powder;
5) lower the temperature, step 4) insulation end recession pressure, with the cold cooling of stove, obtain described (La xce 1-x) B 6sosoloid polycrystal.
Preferably, in step 1) described in raw material LaB 6and CeB 6the purity of powder reaches 99.99%, and particle size range is 1-40 μm.But the present invention is not limited to above-mentioned raw materials, the LaB of different-grain diameter 6and CeB 6and other rare-earth hexboride compound powder all may be used in the present invention.
Preferably, in step 1) and step 2) in, in described glove box in argon gas atmosphere oxygen level and vapour content all≤6ppm.
Preferably, in step 2) in, by described LaB 6and CeB 6material powders uses the inwall of graphite paper coating mould before loading graphite jig, also need to cover graphite paper with powder upper and lower surface contact position.
Preferably, step 3) described in the temperature rise rate of each temperature rise period be 5-15 DEG C/min, the temperature rise rate of the first temperature rise period and the second temperature rise period is identical or different.
Preferably, in step 3) in sintering before, in described hot pressing furnace, forvacuum is to air pressure≤1 × 10 -2pa.
Another aspect of the present invention there are provided a kind of high fine and close (La xce 1-x) B 6sosoloid polycrystal negative electrode, wherein, 0.1≤x≤0.9.This negative electrode comprises (La prepared by aforesaid method xce 1-x) B 6polycrystal, adopts method gained (La of the present invention xce 1-x) B 6sosoloid polycrystalline relative density is 98.14-99.78%, by this (La xce 1-x) B 6polycrystalline processing can obtain the negative electrode of desired shape and size.
Compared with prior art, the present invention has the following advantages:
1) the inventive method adopts hot pressed sintering by LaB 6and CeB 6solid solution forms (La xce 1-x) B 6polycrystalline, makes multicomponent rare earth boride powder synthesize and sintering densification two processes unite two into one.Simplify preparation flow, technique is simple, easy to operate.
2) LaB is used 6and CeB 6powder is raw material, reduces production cost, is applicable to industrial production and application, is conducive to expanding the Application Areas of rare-earth boride in cathode material.
3) (the La synthesized xce 1-x) B 6sosoloid polycrystalline has high purity and high-compactness.(the La of preparation xce 1-x) B 6be detected as single hexaboride phase through X-ray diffraction, relative density can reach 99.78%.
Accompanying drawing explanation
(the La of Fig. 1, embodiment 1 preparation 0.9ce 0.1) B 6the X-ray spectrogram of polycrystalline.
(the La of Fig. 2, embodiment 2 preparation 0.8ce 0.2) B 6the X-ray spectrogram of polycrystalline.
(the La of Fig. 3, embodiment 3 preparation 0.7ce 0.3) B 6the X-ray spectrogram of polycrystalline.
(the La of Fig. 4, embodiment 4 preparation 0.3ce 0.7) B 6the X-ray spectrogram of polycrystalline.
(the La of Fig. 5, embodiment 5 preparation 0.1ce 0.9) B 6the X-ray spectrogram of polycrystalline.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described, but protection scope of the present invention is not limited to following embodiment.Hereinafter describe the present invention in detail with reference to accompanying drawing, when not conflicting, the embodiment in the application and the feature in embodiment can combine mutually in conjunction with the embodiments.
Embodiment of the present invention Raw LaB 6and CeB 6the purity of powder is 99.99%, and the particle size range of raw material powder is 1-40 μm.
Embodiment 1
1) ball milling+hand of classifying mixes.By LaB 6and CeB 6the each 20g of raw material powder is placed in stainless-steel grinding tank respectively, the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, the mass ratio of preferred Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1, and ball and powder quality are than being 10:1.For preventing the boron pruinescence in mixed powder to be oxidized, above operation all oxygen level and vapour content all≤the argon gas atmosphere glove box of 0.5ppm in carry out.Ball grinder is placed in high energy ball mill and carries out ball milling, rotating speed is 500r/min, and after ball milling 2h, in glove box, sampling is preserved.The LaB in glove box, ball milling obtained 6and CeB 6massage that is than weighing respectively for 9:1, and powder total mass is 10g, by the LaB after weighing 6and CeB 6powder is placed in agate mortar to carry out underhand polish and is mixed.2) shove charge.Above-mentioned hybrid reaction material is loaded φ 20mm graphite jig in glove box, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 1 × 10 is evacuated in hot pressing furnace -2pa, sintering process is: pre-add 10Mpa axle pressure, rises to 500 DEG C with 10 DEG C/min temperature rise rate from room temperature.Then 900 DEG C are risen to 15 DEG C/min speed from 500 DEG C.Add axle pressure to 15Mpa, rise to 1300 DEG C with 10 DEG C/min speed from 900 DEG C.Add axle pressure again to 20Mpa, rise to 1900 DEG C with 10 DEG C/min speed from 1300 DEG C.4) be incubated.40Mpa is forced into, insulation 1.5h when temperature reaches 1900 DEG C.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La 0.9ce 0.1) B 6sosoloid polycrystal.
(La 0.9ce 0.1) B 6as shown in Figure 1, as we know from the figure, sample is that hexaboride is single-phase to multicrystal X-ray spectrogram, and diffraction peak intensity is high, well-crystallized.Electronics specific gravity balance is adopted to record (La 0.9ce 0.1) B 6multicrystal relative density is 99.72%.
Embodiment 2
1) ball milling+hand of classifying mixes.By LaB 6and CeB 6raw material powder is placed in stainless-steel grinding tank respectively, the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, the mass ratio of preferred Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1, and ball and powder quality are than being 20:1.For preventing the boron pruinescence in mixed powder to be oxidized, above operation all oxygen level and vapour content all≤the argon gas atmosphere glove box of 6ppm in carry out.Ball grinder is placed in high energy ball mill and carries out ball milling, rotating speed is 700r/min, and after ball milling 1h, in glove box, sampling is preserved.The LaB in glove box, ball milling obtained 6and CeB 6massage that is than weighing respectively for 4:1, and powder total mass is 10g, by the LaB after weighing 6and CeB 6powder is placed in agate mortar to carry out underhand polish and is mixed.2) shove charge.Above-mentioned hybrid reaction material is loaded φ 20mm graphite jig in glove box, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 8 × 10 is evacuated in hot pressing furnace -3pa, sintering process is: pre-add 10Mpa axle pressure, rises to 400 DEG C with 10 DEG C/min temperature rise rate from room temperature.Then 800 DEG C are risen to 15 DEG C/min speed from 400 DEG C.Add axle pressure to 15Mpa, rise to 1200 DEG C with 10 DEG C/min speed from 800 DEG C.Add axle pressure again to 20Mpa, rise to 1700 DEG C with 10 DEG C/min speed from 1200 DEG C.4) be incubated.40Mpa is forced into, insulation 2h when temperature reaches 1700 DEG C.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La 0.8ce 0.2) B 6sosoloid polycrystal.
(La 0.8ce 0.2) B 6as shown in Figure 2, as we know from the figure, sample is that hexaboride is single-phase to multicrystal X-ray spectrogram, and diffraction peak intensity is high, well-crystallized.Electronics specific gravity balance is adopted to record (La 0.8ce 0.2) B 6multicrystal relative density is 98.26%.
Embodiment 3
1) mixed ball milling.To be the LaB after 7:3 weighs respectively in molar ratio 6and CeB 6raw material powder is 20g altogether, with being placed in stainless-steel grinding tank, the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, and the mass ratio of preferred Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1, and ball and powder quality are than being 15:1; For preventing the boron pruinescence in mixed powder to be oxidized, above operation all oxygen level and vapour content all≤the argon gas atmosphere glove box of 1ppm in carry out.Ball grinder is placed in high energy ball mill and carries out ball milling, rotating speed is 600r/min, and after ball milling 1.5h, in glove box, sampling is preserved.2) shove charge.Above-mentioned hybrid reaction material is loaded φ 20mm graphite jig in glove box, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 8 × 10 is evacuated in hot pressing furnace -3pa, sintering process is: pre-add 10Mpa axle pressure, rises to 500 DEG C with 10 DEG C/min temperature rise rate from room temperature.Then 900 DEG C are risen to 15 DEG C/min speed from 500 DEG C.Add axle pressure to 15Mpa, rise to 1300 DEG C with 10 DEG C/min speed from 900 DEG C.Add axle pressure again to 20Mpa, rise to 1800 DEG C with 10 DEG C/min speed from 1300 DEG C.4) be incubated.30Mpa is forced into, insulation 1.5h when temperature reaches 1800 DEG C.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La 0.7ce 0.3) B 6sosoloid polycrystal.
(La 0.7ce 0.3) B 6as shown in Figure 3, as we know from the figure, sample is that hexaboride is single-phase to multicrystal X-ray spectrogram, and diffraction peak intensity is high, well-crystallized.Electronics specific gravity balance is adopted to record (La 0.7ce 0.3) B 6multicrystal relative density is 98.14%.
Embodiment 4
1) mixed ball milling.To be the LaB after 3:7 weighs respectively in molar ratio 6and CeB 6raw material powder is 20g altogether, with being placed in stainless-steel grinding tank, the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, and the mass ratio of preferred Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1, and ball and powder quality are than being 15:1; For preventing the boron pruinescence in mixed powder to be oxidized, above operation all oxygen level and vapour content all≤the argon gas atmosphere glove box of 0.3ppm in carry out.Ball grinder is placed in high energy ball mill and carries out ball milling, rotating speed is 500r/min, and after ball milling 2h, in glove box, sampling is preserved.2) shove charge.Above-mentioned hybrid reaction material is loaded φ 20mm graphite jig in glove box, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 9 × 10 is evacuated in hot pressing furnace -3pa, sintering process is: pre-add 10Mpa axle pressure, rises to 500 DEG C with 10 DEG C/min temperature rise rate from room temperature.Then 900 DEG C are risen to 15 DEG C/min speed from 500 DEG C.Add axle pressure to 15Mpa, rise to 1300 DEG C with 10 DEG C/min speed from 900 DEG C.Add axle pressure again to 20Mpa, rise to 1800 DEG C with 10 DEG C/min speed from 1300 DEG C.4) be incubated.40Mpa is forced into, insulation 2h when temperature reaches 1800 DEG C.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La 0.3ce 0.7) B 6sosoloid polycrystal.
(La 0.3ce 0.7) B 6as shown in Figure 4, as we know from the figure, sample is that hexaboride is single-phase to multicrystal X-ray spectrogram, and diffraction peak intensity is high, well-crystallized.Electronics specific gravity balance is adopted to record (La 0.3ce 0.7) B 6multicrystal relative density is 99.78%.
Embodiment 5
1) ball milling+hand of classifying mixes.By LaB 6and CeB 6raw material powder is placed in stainless-steel grinding tank respectively, the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, the mass ratio of preferred Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1, and ball and powder quality are than being 10:1.For preventing the boron pruinescence in mixed powder to be oxidized, above operation all oxygen level and vapour content all≤the argon gas atmosphere glove box of 0.3ppm in carry out.Ball grinder is placed in high energy ball mill and carries out ball milling, rotating speed is 500r/min, and after ball milling 2h, in glove box, sampling is preserved.The LaB in glove box, ball milling obtained 6and CeB 6massage that is than weighing respectively for 1:9, and powder total mass is 10g, by the LaB after weighing 6and CeB 6powder is placed in agate mortar to carry out underhand polish and is mixed.2) shove charge.Above-mentioned hybrid reaction material is loaded φ 20mm graphite jig in glove box, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 9 × 10 is evacuated in hot pressing furnace -3pa, sintering process is: pre-add 10Mpa axle pressure, rises to 500 DEG C with 10 DEG C/min temperature rise rate from room temperature.Then 900 DEG C are risen to 15 DEG C/min speed from 500 DEG C.Add axle pressure to 15Mpa, rise to 1300 DEG C with 10 DEG C/min speed from 900 DEG C.Add axle pressure again to 20Mpa, rise to 1800 DEG C with 10 DEG C/min speed from 1300 DEG C.4) be incubated.40Mpa is forced into, insulation 2h when temperature reaches 1800 DEG C.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La 0.1ce 0.9) B 6polycrystal.
(La 0.1ce 0.9) B 6as shown in Figure 5, as we know from the figure, sample is that hexaboride is single-phase to multicrystal X-ray spectrogram, and diffraction peak intensity is high, well-crystallized.Electronics specific gravity balance is adopted to record (La 0.1ce 0.9) B 6multicrystal relative density is 99.48%.

Claims (10)

1. a multicomponent rare earth boride (La xce 1-x) B 6the preparation method of sosoloid polycrystalline cathode material, is characterized in that, these preparation method's concrete steps comprise as follows:
1) proportioning batch mixing, proportioning batch mixing has two kinds of modes can be optional: " mixed ball milling " or " classification ball milling+hand mixes ";
Wherein " mixed ball milling " is: will according to (La xce 1-x) B 6stoichiometric ratio, namely mol ratio is x:(1-x) respectively weigh after LaB 6and CeB 6raw material powder is placed in stainless-steel grinding tank jointly, and the Stainless Steel Ball of selection φ 12mm, φ 10mm, φ 8mm and φ 6mm is as grinding medium, and ball and powder quality are than being (10-20): 1; For preventing the boron pruinescence in mixed powder to be oxidized, above operation is all carried out in glove box; Ball grinder is placed in high energy ball mill and carries out ball milling, rotating speed is 500-700r/min, preserves sampling after ball milling 1-2h in glove box;
" classification ball milling+hand mixes " gets LaB 6and CeB 6raw material powder carries out ball milling respectively, and after weighing your ratio of the massage obtained after ball milling, hand mixes again, and wherein ball-milling technology is identical with above-mentioned " mixed ball milling ";
2) shove charge, by step 1) LaB that is mixed evenly 6and CeB 6material loads graphite jig in glove box, is placed in by mould in hot-pressed sintering furnace;
3) heat up sintering, the first temperature rise period: room temperature is to 400-500 DEG C; Second temperature rise period: 400-500 DEG C from the first stage is warming up to 800-900 DEG C; 3rd temperature rise period: 800-900 DEG C from subordinate phase is warming up to 1200-1300 DEG C; 4th temperature rise period: 1200-1300 DEG C from the phase III is warming up to 1700-1800 DEG C; Wherein, the first temperature rise period to the 4th temperature rise period applies axle pressure to powder, pressure range 10-20MPa;
4) be incubated, in step 3) fourth stage heat up after 1700-1900 DEG C of temperature 1.5-2h; And at insulating process, 30-40Mpa axle pressure is applied to powder;
5) lower the temperature, step 4) insulation end recession pressure, with the cold cooling of stove, obtain described (La xce 1-x) B 6polycrystal.
2., according to the method for claim 1, it is characterized in that, step 1) described in raw material LaB 6and CeB 6the purity of powder reaches 99.99%, and particle size range is 1-40 μm;
In step 1) and step 2) in, in described glove box in argon gas atmosphere oxygen level and vapour content all≤6ppm.
3., according to the method for claim 1, it is characterized in that, step 2) in, by described LaB 6and CeB 6material powders uses the inwall of graphite paper coating mould before loading graphite jig, also need to cover graphite paper with powder upper and lower surface contact position.
4. according to the method for claim 1, it is characterized in that, the mass ratio of Stainless Steel Ball φ 12mm, φ 10mm, φ 8mm, φ 6mm is 1:2:2:1.
5., according to the method for claim 1, it is characterized in that, step 3) the first temperature rise period and the second temperature rise period apply identical axle pressure to powder, and then the axle pressure of per temperature rise period progressively increases.
6., according to the method for claim 1, it is characterized in that, step 3) the first temperature rise period and the second temperature rise period apply 10Mpa axle pressure to powder, and the 3rd temperature rise period applied 15Mpa axle pressure to powder; 4th temperature rise period applied 20Mpa axle pressure to powder.
7., according to the method for claim 1, it is characterized in that, step 3) described in the temperature rise rate of each temperature rise period be 5-15 DEG C/min, the temperature rise rate of the first temperature rise period and the second temperature rise period is identical or different.
8. according to the method for claim 1, it is characterized in that, in step 3) in sintering before, in described hot pressing furnace, forvacuum is to air pressure≤1 × 10 -2pa.
9. according to the (La that the either method of claim 1-8 prepares xce 1-x) B 6sosoloid polycrystal.
10. according to the (La that the either method of claim 1-8 prepares xce 1-x) B 6sosoloid polycrystal is as the application of cathode material.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108129153A (en) * 2017-12-28 2018-06-08 井冈山大学 A kind of multicomponent rare earth boride（LaxSr1-x）B6Polycrystalline cathode material and preparation method thereof
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CN111825463A (en) * 2020-06-29 2020-10-27 井冈山大学 LaB6-CrB2Composite cathode material and preparation method thereof
CN114920560A (en) * 2022-05-05 2022-08-19 兰州理工大学 LaB 6 Powder and method for producing sintered body thereof
CN115058775A (en) * 2022-06-07 2022-09-16 合肥工业大学 Large-size and high-performance ternary rare earth composite single crystal material and preparation method thereof
CN115058775B (en) * 2022-06-07 2024-03-19 合肥工业大学 Large-size high-performance ternary rare earth composite single crystal material and preparation method thereof

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