CN104843727B - 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 PDFInfo
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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
Technical field
The invention belongs to rare-earth boride cathode material technical field, and in particular to a kind of multicomponent rare earth boride
(LaxCe1-x)B6Solid solution polycrystal and preparation method thereof.
Background technology
Negative electrode is the heart device of various Modern vacuum electronic equipments, has in national defense industry, civil area and widely should
With.With lanthanum hexaboride (LaB6) and six cerium boride (CeB6) be representative rare-earth hexboride compound (REB6), it is that the heat of excellent performance is cloudy
Pole, the features such as with low work function, low-resistivity, low evaporation rate, high-melting-point, long-life, therefore is widely used in all kinds of electricity
In the equipment such as mirror, plasma source, electron-beam welder, electron beam exposure apparatus, field emission array.Especially set in some microfabrications
In standby, need to obtain accurate controllable electric beamlet, it is desirable to high density, the electron source of high brightness, LaB6And CeB6It is preferably transmitting
Body, has been successfully applied to the civilian industries such as automobile, electronics, motor.Recent studies have found that, will appropriate other REB6With LaB6Doping
Solid solution is expected to reduce LaB6Negative electrode operating temperature simultaneously greatly improves its hot-electron emission property, therefore, Chinese scholars are accelerated
Research to multicomponent rare earth boride.In LaB6Middle solid solution other REB6In addition to it can improve emitting performance, moreover it is possible to greatly improve
Resistivity, contributes to application of the hexaboride negative electrode in direct-heated cathode field.With LaB6Compare, CeB6Lower evaporation rate and
Very strong anti-carbon pollution capacity.Therefore have than LaB6Broader practice prospect.Additionally, except outstanding emission properties,
CeB6Also there is unusual transporting and magnetic property.Ce3+In 4f electronics cause it to have with exchanging for electronics in 5d conduction bands
Typical Kondo effect feature.Meanwhile, very strong exchange interaction also causes CeB between the electronics of 4f and 5d tracks6Resistivity it is several
Times LaB6, this allows for CeB6It is possible to be applied to direct-heated cathode.Therefore, by solid solution CeB6To regulate and control LaB6Crystal
Structure, the excellent multicomponent rare earth boride (La of processabilityxCe1-x)B6Solid solution polycrystalline negative electrode, so as to realize cathode material
The controllable of energy, raising emission properties are significant.
At present, the traditional preparation methods of multicomponent rare earth boride polycrystalline material, including multicomponent rare earth boride polycrystal powder
Synthesis and two processes of sintering densification of powder.The synthetic method of multicomponent rare earth boride polycrystal powder mainly have the hot method of boron,
Boron carbide reducing process, elementsynthesis, fused salt electrolysis process and magnesiothermy etc..These preparation methods have some shortcomings, for example instead
Answer speed slow.React fully, typically require the reaction time more than 10h, preparing some multielement rare earth hexaborides even needs
Take several days time.Further, since the raw material for preparing multielement rare earth hexaboride is all kinds of more, complex, pilot process is reacted
Product is more, and the multielement rare earth hexaboride powder for preparing often has dephasign, and purity is not high, and this will increase will its work function
Plus, so as to reduce emitting performance.The densification of multielement rare earth hexaboride powder mainly using cold-rolled sintered, hot pressed sintering or is put
Electric plasma agglomeration (SPS) method.Cold-rolled sintered and hot pressed sintering prepares sintering temperature height (2000-2200 DEG C), product grains
Thick, hole is more, consistency low (relative density is generally below 90%), affects the mechanics and emitting performance of material, causes product
It is difficult to apply in the industrial production.SPS is a kind of Fast Sintering technology, but the method is high to equipment requirement, and yield is relatively low,
Unsuitable for the industrialization of product.
Disclose a kind of using mechanical alloying preparation in the Chinese patent application of Publication No. 201110110277.6
Nanometer LaB6The method of powder, the method is comprised the following steps：Pretreatment of raw material：By La2O3Powder and B powder are dry in vacuum respectively
8-10h is dried in 100-150 DEG C in dry case, if B powder surface wetting caking, needs carry out processed in vacuum sintering furnace,
At 1200-1400 DEG C, dewatering time is 20-40min to dehydration temperaturre.Dress sample：By the raw material of pretreatment according to reaction equation La2O3+
12B+3Mg=3MgO+2LaB6Stoichiometric proportion mixed, wherein the Mg powder (mass percent) of 3% excess, mixture
In being placed in 500mL stainless-steel grinding tanks, φ 20mm, the stainless steel ball of φ 10mm and φ 6mm are selected as abrasive media, mixture
Middle addition accounts for the stearic acid of mixed-powder gross mass 1-3% as process control agent, be then charged with purity up to 99.99% it is high-purity
Ar gas is used as shielding gas.Mechanical alloying：Mixed powder is placed in planetary mills carries out ball milling, and the rotating speed of ball mill is 400-
600r/min, ball milling 40-100h.Purification：Powder absolute ethanol washing after mechanical alloying is processed, removes therein hard
Resin acid；By the use of the watery hydrochloric acid that mass concentration is 18% as leaching agent, the product after alcohol is washed is leached, after leaching 15-20h
Filter, deionized water circulation washing and filtering products several times, being in neutrality to cleaning solution, to filtration product in 80-100 DEG C of baking
Dry 6-8h, obtains higher nanometer LaB of purity6Powder.It is public in the Chinese patent application of Publication No. 201010233471.9
A kind of high-purity CeB is opened6The preparation method of nano powder, is carried out according to the following steps：1) by CeO2、B2O3With magnesium powder mixing, height is carried out
Energy ball-milling treatment, is then pressed into blank；2) blank is placed in self-propagating reaction stove, in air atmosphere plus thermal initiation is from climing
Prolong reaction, obtain CeB6Intermediate product of the disperse in MgO matrixes；With dilute sulfuric acid as leaching agent, will in closed autoclave
Intermediate product is leached, and is obtained to leach product and filter and is obtained filter residue, the scrubbed and high-purity CeB of dry acquisition6Nano powder.Both the above
It is loaded down with trivial details to there is process in rare-earth boride powder preparation method, complex process, the shortcomings of technical requirements are high, if using both
Method is preparing (LaxCe1-x)B6Powder, technique will be more complicated, and the purity of product hardly results in guarantee.
A kind of multicomponent rare earth boride is disclosed in the Chinese patent application of Publication No. 200810225029
(LaxRE1-x)B6Cathode material and preparation method thereof, wherein RE are second rare earth element in LREE in addition to La
(i.e. RE be Ce, any one element in Pr, Nd, Sm, Eu and Gd).The method is comprised the following steps：1) it is dilute with simple substance respectively
Earth metal lanthanum block and RE blocks are raw material, in hydrogen, argon atmospher, using DC arc-plasma evaporation condensation method, LaH are prepared respectively2Nanometer
Powder and REH2Nanometer powder.2) by step 1) LaH for preparing2Nanometer powder, REH2Nanometer powder and raw material B nano powders
Under hypoxemia ar gas environment, grinding is mixed and loads graphite jig at end, in being placed in SPS sintering cavities, applies the axial direction pressure of 50MPa
Power, sinters under the vacuum condition of argon gas atmosphere or vacuum better than 8Pa, and sintering temperature is 1300-1700 DEG C, is incubated 10min
After cool to room temperature with the furnace.The method prepares (LaxRE1-x)B6Polycrystalline needs two steps altogether：First condensed using arc evaporation
Method prepares rare earth nano powder, then obtains polycrystalline bulk using SPS sintering densifications.Preparation process complex process, technology is difficult
Degree is big, apparatus expensive, high energy consumption, and raw material need to use high purity elemental rare earth metal, and high cost, yield are little, therefore distance industry is raw
Produce also far.
The content of the invention
It is big in order to solve existing rare-earth boride polycrystalline preparation complex process, technical difficulty, product purity and cause
Density is relatively low, affects performance, and the problems such as high cost, the present invention provides a kind of rare-earth boride (LaxCe1-x)B6Solid solution polycrystalline
Cathode material and preparation method thereof.Rare-earth boride solid solution polycrystalline provided by the present invention consists of (LaxCe1-x)B6, its
In, 0.1≤x≤0.9.Method provided by the present invention is with two kinds of rare-earth boride LaB6And CeB6Powder is raw material, using ball
Mill, vacuum heating-press sintering, maximum sintering temperature 1700-1900 DEG C synthesizes (LaxCe1-x)B6Solid solution polycrystalline.The method will
(LaxCe1-x)B6Powder synthesizes and two processes of sintering densification unite two into one, and simplifies preparation flow, improves purity and consistency,
And production cost is reduced, it is adapted to industrial production and application.According to (the La that the preparation method that the present invention is provided is obtainedxCe1-x)B6Gu
The characteristics of solution polycrystal has single-phase, high-compactness, is conducive to expanding the range of application of multicomponent rare earth boride polycrystalline material.
It is an aspect of the invention to provide a kind of multicomponent rare earth boride (LaxCe1-x)B6The multicrystal system of solid solution
Preparation Method.The preparation method is comprised the following steps that：
1) proportioning batch mixing, proportioning batch mixing has two ways optional：" mixing ball milling " or " classification ball milling+hand is mixed ", wherein
" mixing ball milling " is：Will be according to (LaxCe1-x)B6Stoichiometric proportion, i.e., mol ratio be x:(1-x) LaB is weighed respectively6And CeB6
Material powder is collectively disposed in stainless-steel grinding tank, selects the stainless steel ball of φ 12mm, φ 10mm, φ 8mm and φ 6mm as grinding
Grinding media, preferred stainless steel ball φ 12mm, φ 10mm, φ 8mm, the mass ratio of φ 6mm are 1：2：2：1, ball and powder quality ratio
For (10-20)：1；To prevent from mixing the boron pruinescence oxidation in powder, above operation carries out in glove box, ball grinder is put
Ball milling is carried out in high energy ball mill, rotating speed is 500-700r/min, preserve in glove box after ball milling 1-2h and sample." classification
Ball milling+hand is mixed " it is to take LaB6And CeB6Material powder carries out respectively ball milling, after the massage that ratio to obtaining after ball milling is weighed
Again hand is mixed, and wherein ball-milling technology is identical with above-mentioned " mixing ball milling ".In two kinds of modes that are mixed preferably " classification ball milling+hand is mixed ".
2) shove charge, by step 1) LaB that is mixed evenly6And CeB6Material loads graphite jig in glove box, and mould is put
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：From the 400- of first stage
500 DEG C are warming up to 800-900 DEG C；3rd temperature rise period：1200-1300 DEG C is warming up to from 800-900 DEG C of second stage；4th
Temperature rise period：1700-1900 DEG C is warming up to from 1200-1300 DEG C of the phase III；Wherein, the first temperature rise period is to the 4th liter
Thermophase is applied to powder applying axial compressive force, pressure limit 10-20MPa, the first temperature rise period and the second temperature rise period to powder
Plus identical axial compressive force, then per the axial compressive force of temperature rise period is stepped up；It is preferred that, the first temperature rise period and second heats up
Stage applies 10Mpa axial compressive forces to powder, and the 3rd temperature rise period applied 15Mpa axial compressive forces to powder；4th temperature rise period
20Mpa axial compressive forces are applied to powder；
4) be incubated, in step 3) fourth stage heat up after 1700-1900 DEG C of temperature 1.5-2h；And in insulating process
30-40Mpa axial compressive forces are applied to powder；
5) lower the temperature, step 4) insulation end recession pressure, with the cold cooling of stove, obtain (the Lax
Ce1-x)B6Solid solution polycrystal.
Preferably, in step 1) described in raw material LaB6And CeB6Up to 99.99%, particle size range is 1-40 μ to the purity of powder
m.But the present invention is not limited to above-mentioned raw materials, the LaB of different-grain diameter6And CeB6And other rare-earth hexboride compound powder can be answered
In using the present invention.
Preferably, in step 1) and step 2) in, oxygen content and vapour content are equal in argon gas atmosphere in the glove box
≤6ppm。
Preferably, in step 2) in, by the LaB6And CeB6Coated with graphite paper before material powders loading graphite jig
The inwall of mould, also needs to cover graphite paper with powder upper and lower surface contact position.
Preferably, step 3) described in each temperature rise period heating rate be 5-15 DEG C/min, the first temperature rise period and
The heating rate of the second temperature rise period is identical or different.
Preferably, in step 3) in sintering before, forvacuum is to air pressure≤1 × 10 in the hot pressing furnace-2Pa。
It is another aspect of the invention to provide a kind of high densification (LaxCe1-x)B6Solid solution polycrystal negative electrode, wherein,
0.1≤x≤0.9.The negative electrode includes (La prepared by said methodxCe1-x)B6Polycrystal, using method of the present invention gained
(LaxCe1-x)B6Solid solution polycrystalline relative density is 98.14-99.78%, by this (LaxCe1-x)B6Polycrystalline processing can be obtained
The negative electrode of required form and size.
Compared with prior art, the present invention has advantages below：
1) the inventive method adopts hot pressed sintering by LaB6And CeB6Solid solution forms (LaxCe1-x)B6Polycrystalline, makes multielement rare earth
Boride powder synthesizes and two processes of sintering densification unite two into one.Preparation flow is simplified, process is simple is easy to operate.
2) LaB is used6And CeB6Powder is raw material, reduces production cost, is adapted to industrial production and application, is conducive to opening up
Application of the exhibition rare-earth boride in terms of cathode material.
3) (the La of synthesisxCe1-x)B6Solid solution polycrystalline has high-purity and high-compactness.(the La for preparingxCe1-x)B6Jing X
X ray diffraction is detected as single hexaboride phase, and relative density is up to 99.78%.
Description of the drawings
(La prepared by Fig. 1, embodiment 10.9Ce0.1)B6The X-ray spectrogram of polycrystalline.
(La prepared by Fig. 2, embodiment 20.8Ce0.2)B6The X-ray spectrogram of polycrystalline.
(La prepared by Fig. 3, embodiment 30.7Ce0.3)B6The X-ray spectrogram of polycrystalline.
(La prepared by Fig. 4, embodiment 40.3Ce0.7)B6The X-ray spectrogram of polycrystalline.
(La prepared by Fig. 5, embodiment 50.1Ce0.9)B6The X-ray spectrogram of polycrystalline.
Specific 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
It is limited to following embodiments.Below with reference to accompanying drawing in conjunction with the embodiments describing the present invention in detail, in the case where not conflicting, this
The feature in embodiment and embodiment in application can be mutually combined.
Raw material LaB in the embodiment of the present invention6And CeB6The purity of powder is 99.99%, and the particle size range of material powder is
1-40μm。
Embodiment 1
1) ball milling+hand of classifying is mixed.By LaB6And CeB6The each 20g of material powder is respectively placed in stainless-steel grinding tank, selects φ
The stainless steel ball of 12mm, φ 10mm, φ 8mm and φ 6mm as abrasive media, preferred stainless steel ball φ 12mm, φ 10mm, φ
The mass ratio of 8mm, φ 6mm is 1：2：2：1, ball is 10 with powder quality ratio：1.To prevent from mixing the boron pruinescence oxidation in powder,
More than operation oxygen content and vapour content≤the argon gas atmosphere glove box of 0.5ppm in carry out.Ball grinder is placed in into height
Ball milling can be carried out in ball mill, rotating speed is 500r/min, sampling is preserved in glove box after ball milling 2h.By ball milling in glove box
The LaB for obtaining6And CeB6Massage that is than being 9:1 weighs respectively, and powder gross mass is 10g, by the LaB after weighing6And CeB6
Powder is placed in agate mortar and carries out underhand polish and be mixed.2) shove charge.Above-mentioned hybrid reaction material is loaded into φ in glove box
20mm graphite jigs, 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 axial compressive force, 500 DEG C are risen to 10 DEG C/min heating rates from room temperature.Then with 15 DEG C/min
Speed rises to 900 DEG C from 500 DEG C.Plus axial compressive force rises to 1300 DEG C with 10 DEG C/min speed to 15Mpa from 900 DEG C.Again plus axle
To pressure to 20Mpa, 1900 DEG C are risen to from 1300 DEG C with 10 DEG C/min speed.4) it is incubated.Pressurize when temperature reaches 1900 DEG C
To 40Mpa, 1.5h is incubated.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La0.9Ce0.1)B6Gu
Solution polycrystal.
(La0.9Ce0.1)B6Multicrystal X-ray spectrogram as shown in figure 1, it can be seen that sample be hexaboride it is single-phase,
Diffraction peak intensity is high, well-crystallized.(La is measured using electronics specific gravity balance0.9Ce0.1)B6Multicrystal relative density is
99.72%.
Embodiment 2
1) ball milling+hand of classifying is mixed.By LaB6And CeB6Material powder is respectively placed in stainless-steel grinding tank, selection φ 12mm,
The stainless steel ball of φ 10mm, φ 8mm and φ 6mm as abrasive media, preferred stainless steel ball φ 12mm, φ 10mm, φ 8mm, φ
The mass ratio of 6mm is 1：2：2：1, ball is 20 with powder quality ratio：1.To prevent from mixing the boron pruinescence oxidation in powder, above behaviour
Make oxygen content and vapour content≤the argon gas atmosphere glove box of 6ppm in carry out.Ball grinder is placed in into high energy ball mill
In carry out ball milling, rotating speed is 700r/min, after ball milling 1h in glove box sampling preserve.Ball milling is obtained in glove box
LaB6And CeB6Massage that is than being 4:1 weighs respectively, and powder gross mass is 10g, by the LaB after weighing6And CeB6Powder is put
Carry out underhand polish in agate mortar to be mixed.2) shove charge.Above-mentioned hybrid reaction material is loaded into φ 20mm stones in glove box
Black mould, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 8 × 10 is evacuated in hot pressing furnace-3Pa, agglomerant
Skill is：Pre-add 10Mpa axial compressive force, 400 DEG C are risen to 10 DEG C/min heating rates from room temperature.Then with 15 DEG C/min speed from
400 DEG C rise to 800 DEG C.Plus axial compressive force rises to 1200 DEG C with 10 DEG C/min speed to 15Mpa from 800 DEG C.Again plus axial compressive force
To 20Mpa, 1700 DEG C are risen to from 1200 DEG C with 10 DEG C/min speed.4) it is incubated.It is forced into when temperature reaches 1700 DEG C
40Mpa, is incubated 2h.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La0.8Ce0.2)B6Solid solution
Polycrystal.
(La0.8Ce0.2)B6Multicrystal X-ray spectrogram as shown in Fig. 2 it can be seen that sample be hexaboride it is single-phase,
Diffraction peak intensity is high, well-crystallized.(La is measured using electronics specific gravity balance0.8Ce0.2)B6Multicrystal relative density is
98.26%.
Embodiment 3
1) ball milling is mixed.To be in molar ratio 7:3 respectively weigh after LaB6And CeB6The common 20g of material powder, it is same to be placed in not
In rust steel grinding pot, φ 12mm, φ 10mm, the stainless steel ball of φ 8mm and φ 6mm are selected as abrasive media, preferred stainless steel
Ball φ 12mm, φ 10mm, φ 8mm, the mass ratio of φ 6mm are 1：2：2：1, ball is 15 with powder quality ratio：1；To prevent from mixing
Boron pruinescence oxidation in powder, above operation oxygen content and vapour content≤the argon gas atmosphere glove box of 1ppm in enter
OK.Ball grinder is placed in high energy ball mill carries out ball milling, and rotating speed is 600r/min, and sampling is protected in glove box after ball milling 1.5h
Deposit.2) shove charge.Above-mentioned hybrid reaction material is loaded into φ 20mm graphite jigs in glove box, mould is placed in into hot-pressed sintering furnace
It is interior.3) heat up sintering.Air pressure 8 × 10 is evacuated in hot pressing furnace-3Pa, sintering process is：Pre-add 10Mpa axial compressive force, with 10
DEG C/min heating rates rise to 500 DEG C from room temperature.Then 900 DEG C are risen to from 500 DEG C with 15 DEG C/min speed.Plus axial compressive force is extremely
15Mpa, 1300 DEG C are risen to 10 DEG C/min speed from 900 DEG C.Again plus axial compressive force is to 20Mpa, with 10 DEG C/min speed from
1300 DEG C rise to 1800 DEG C.4) it is incubated.30Mpa is forced into when temperature reaches 1800 DEG C, 1.5h is incubated.5) lower the temperature.Insulation knot
Beam recession pressure, with the cold cooling of stove, obtains single-phase densification (La0.7Ce0.3)B6Solid solution polycrystal.
(La0.7Ce0.3)B6Multicrystal X-ray spectrogram as shown in figure 3, it can be seen that sample be hexaboride it is single-phase,
Diffraction peak intensity is high, well-crystallized.(La is measured using electronics specific gravity balance0.7Ce0.3)B6Multicrystal relative density is
98.14%.
Embodiment 4
1) ball milling is mixed.To be in molar ratio 3:7 respectively weigh after LaB6And CeB6The common 20g of material powder, it is same to be placed in not
In rust steel grinding pot, φ 12mm, φ 10mm, the stainless steel ball of φ 8mm and φ 6mm are selected as abrasive media, preferred stainless steel
Ball φ 12mm, φ 10mm, φ 8mm, the mass ratio of φ 6mm are 1：2：2：1, ball is 15 with powder quality ratio：1；To prevent from mixing
Boron pruinescence oxidation in powder, above operation oxygen content and vapour content≤the argon gas atmosphere glove box of 0.3ppm in
Carry out.Ball grinder is placed in high energy ball mill carries out ball milling, and rotating speed is 500r/min, and sampling is protected in glove box after ball milling 2h
Deposit.2) shove charge.Above-mentioned hybrid reaction material is loaded into φ 20mm graphite jigs in glove box, mould is placed in into hot-pressed sintering furnace
It is interior.3) heat up sintering.Air pressure 9 × 10 is evacuated in hot pressing furnace-3Pa, sintering process is：Pre-add 10Mpa axial compressive force, with 10
DEG C/min heating rates rise to 500 DEG C from room temperature.Then 900 DEG C are risen to from 500 DEG C with 15 DEG C/min speed.Plus axial compressive force is extremely
15Mpa, 1300 DEG C are risen to 10 DEG C/min speed from 900 DEG C.Again plus axial compressive force is to 20Mpa, with 10 DEG C/min speed from
1300 DEG C rise to 1800 DEG C.4) it is incubated.40Mpa is forced into when temperature reaches 1800 DEG C, 2h is incubated.5) lower the temperature.Insulation terminates
Recession pressure, with the cold cooling of stove, obtains single-phase densification (La0.3Ce0.7)B6Solid solution polycrystal.
(La0.3Ce0.7)B6Multicrystal X-ray spectrogram as shown in figure 4, it can be seen that sample be hexaboride it is single-phase,
Diffraction peak intensity is high, well-crystallized.(La is measured using electronics specific gravity balance0.3Ce0.7)B6Multicrystal relative density is
99.78%.
Embodiment 5
1) ball milling+hand of classifying is mixed.By LaB6And CeB6Material powder is respectively placed in stainless-steel grinding tank, selection φ 12mm,
The stainless steel ball of φ 10mm, φ 8mm and φ 6mm as abrasive media, preferred stainless steel ball φ 12mm, φ 10mm, φ 8mm, φ
The mass ratio of 6mm is 1：2：2：1, ball is 10 with powder quality ratio：1.To prevent from mixing the boron pruinescence oxidation in powder, above behaviour
Make oxygen content and vapour content≤the argon gas atmosphere glove box of 0.3ppm in carry out.Ball grinder is placed in into high-energy ball milling
Ball milling is carried out in machine, rotating speed is 500r/min, sampling is preserved in glove box after ball milling 2h.Ball milling is obtained in glove box
LaB6And CeB6Massage that is than being 1:9 weigh respectively, and powder gross mass is 10g, by the LaB after weighing6And CeB6Powder is put
Carry out underhand polish in agate mortar to be mixed.2) shove charge.Above-mentioned hybrid reaction material is loaded into φ 20mm stones in glove box
Black mould, mould is placed in hot-pressed sintering furnace.3) heat up sintering.Air pressure 9 × 10 is evacuated in hot pressing furnace-3Pa, agglomerant
Skill is：Pre-add 10Mpa axial compressive force, 500 DEG C are risen to 10 DEG C/min heating rates from room temperature.Then with 15 DEG C/min speed from
500 DEG C rise to 900 DEG C.Plus axial compressive force rises to 1300 DEG C with 10 DEG C/min speed to 15Mpa from 900 DEG C.Again plus axial compressive force
To 20Mpa, 1800 DEG C are risen to from 1300 DEG C with 10 DEG C/min speed.4) it is incubated.It is forced into when temperature reaches 1800 DEG C
40Mpa, is incubated 2h.5) lower the temperature.Insulation terminates recession pressure, with the cold cooling of stove, obtains single-phase densification (La0.1Ce0.9)B6Polycrystal.
(La0.1Ce0.9)B6Multicrystal X-ray spectrogram as shown in figure 5, it can be seen that sample be hexaboride it is single-phase,
Diffraction peak intensity is high, well-crystallized.(La is measured using electronics specific gravity balance0.1Ce0.9)B6Multicrystal relative density is
99.48%.
Claims (10)
1. a kind of multicomponent rare earth boride (LaxCe1-x)B6The preparation method of solid solution polycrystalline cathode material, 0.1≤x≤0.9, its
It is characterised by, the preparation method concrete steps include as follows：
1) proportioning batch mixing, proportioning batch mixing has two ways optional：" mixing ball milling " or " classification ball milling+hand is mixed "；
Wherein " mixing ball milling " is：Will be according to (LaxCe1-x)B6Stoichiometric proportion, i.e., mol ratio be x:(1-x) after weighing respectively
LaB6And CeB6Material powder is collectively disposed in stainless-steel grinding tank, selects φ 12mm, φ 10mm, φ 8mm and φ 6mm not
Rust steel ball is (10-20) with powder quality ratio as abrasive media, ball：1；To prevent from mixing the boron pruinescence oxidation in powder, with
Upper operation is carried out in glove box；Ball grinder is placed in high energy ball mill carries out ball milling, and rotating speed is 500-700r/min, ball
Preserve in glove box after mill 1-2h and sample；
" classification ball milling+hand is mixed " is to take LaB6And CeB6Material powder carries out respectively ball milling, to the massage that obtained after ball milling
Than again hand is mixed after weighing, wherein ball-milling technology is identical with above-mentioned " mixing ball milling "；
2) shove charge, by step 1) LaB that is mixed evenly6And CeB6Material loads graphite jig in glove box, and mould is placed in into heat
In pressure sintering furnace；
3) heat up sintering, the first temperature rise period：Room temperature is to 400-500 DEG C；Second temperature rise period：From the 400-500 of first stage
DEG C it is warming up to 800-900 DEG C；3rd temperature rise period：1200-1300 DEG C is warming up to from 800-900 DEG C of second stage；4th liter
Thermophase：1700-1900 DEG C is warming up to from 1200-1300 DEG C of the phase III；Wherein, the first temperature rise period is to the 4th intensification rank
Section applies axial compressive force, pressure limit 10-20MPa to powder；
4) be incubated, in step 3) fourth stage heat up after 1700-1900 DEG C of temperature 1.5-2h；And in insulating process to powder
End applies 30-40MPa axial compressive forces；
5) lower the temperature, step 4) insulation end recession pressure, with the cold cooling of stove, obtain (the LaxCe1-x)B6Polycrystal.
2. according to the method for claim 1, it is characterised in that step 1) described in raw material LaB6And CeB6The purity of powder reaches
99.99%, particle size range is 1-40 μm；
In step 1) and step 2) in, in the glove box in argon gas atmosphere oxygen content and vapour content≤6ppm.
3. according to the method for claim 1, it is characterised in that step 2) in, by the LaB6And CeB6Material powders load graphite
With the inwall of graphite paper coating mould before mould, also need to cover graphite paper with powder upper and lower surface contact position.
4. according to the method for claim 1, it is characterised in that stainless steel ball φ 12mm, φ 10mm, φ 8mm, the quality of φ 6mm
Than for 1：2：2：1.
5. according to the method for claim 1, it is characterised in that step 3) the first temperature rise period and the second temperature rise period apply to powder
Plus identical axial compressive force, then per the axial compressive force of temperature rise period is stepped up.
6. according to the method for claim 1, it is characterised in that step 3) the first temperature rise period and the second temperature rise period apply to powder
Plus 10MPa axial compressive forces, the 3rd temperature rise period is to powder applying 15MPa axial compressive forces；4th temperature rise period applied to powder
20MPa axial compressive forces.
7. according to the method for claim 1, it is characterised in that step 3) described in each temperature rise period heating rate be 5-15
DEG C/heating rate of min, 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 characterised in that in step 3) in sintering before, forvacuum in the hot pressing furnace
To air pressure≤1 × 10-2Pa。
9. (the La for preparing according to the either method of claim 1-8xCe1-x)B6Solid solution polycrystal.
10. (the La for preparing according to the either method of claim 1-8xCe1-x)B6Solid solution polycrystal is used as cathode material
Application.
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| CN111285380B (en) * | 2020-02-04 | 2022-12-16 | 天津包钢稀土研究院有限责任公司 | Preparation method and application of multi-rare earth co-doped boride and nano heat insulation powder thereof |
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