CN1274397C - Method for preparing cubic boron nitride by chemical reaction - Google Patents
Method for preparing cubic boron nitride by chemical reaction Download PDFInfo
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- CN1274397C CN1274397C CN 200410011085 CN200410011085A CN1274397C CN 1274397 C CN1274397 C CN 1274397C CN 200410011085 CN200410011085 CN 200410011085 CN 200410011085 A CN200410011085 A CN 200410011085A CN 1274397 C CN1274397 C CN 1274397C
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- boron nitride
- cubic boron
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Abstract
The present invention relates to a method of preparing cubic boron nitride by a chemical reaction, which belongs to a preparing method of superhard material. Simple substance boron or boron oxide and lithium nitride are mixed as reactants according to a proportion of mass ratio of B or B2O3: Li3N = 1: 0.8 to 1.3; cubic boron nitride crystals are generated by the reaction under the condition of high temperature and high pressure, the pressure is from 3.0 to 6.0 GPa, the temperature is from 1400 to 1700 DEG C, and the heating time is from 3 to 10 minutes. The generated cubic boron nitride crystals of the present invention are generated by the chemical reaction under relatively low pressure and low temperature, the cBN X-light diffraction spectrums of the generated cubic boron nitride crystals are relatively strong, and particle diameters are in a range of 20 to 400 micrometers. Because the technology is relatively simple, the synthesis pressure and the temperature are greatly reduced, and therefore, the present invention is suitable for large-scale industrial production.
Description
Technical field
The invention belongs to a kind of preparation method of superhard material, particularly a kind of method without catalyst synthesizing black cubic boron nitride monocrystal.
Background technology
Cubic boron nitride (cBN) hardness of crystals is only second to diamond, but different with diamond, and it and iron group metal are reactionless, is the excellent material of processing iron group metal and alloy thereof.Usually the cBN crystal has two kinds of preparation methods: a kind of is to make hexagonal boron nitride (hBN) be converted into cubic boron nitride under super-pressure (greater than 11.5GPa) high temperature (～1500 ℃), or makes hBN be converted into the method for cBN under the participations such as catalyst such as alkali metal alkaline earth metal and their nitride, boron nitride, boride under about 5Gpa, 1500 ℃ of conditions; Another is the method that obtains the cBN crystal under negative pressure with vapour deposition.Before add catalyst in the kind method method because its used pressure is low, output is high, crystal grain is thick, is fit to do industrial abrasive material and is widely adopted.CVD method is more suitable for preparing the cBN film.
The prior art close with the present invention is to be converted into the method for cBN by what people such as F.P.Budy made from hBN without catalyst.This method is recorded in exercise question in " hexagonal boron nitride is to the direct conversion of dense form " document, sees The Journal of Chemical Physical Volume38.Number5 (1962) 1144～1149.The used high temperature high pressure device of this method is top, " Belt-type " two sides, and used raw material is 1. commercial mold pressing hexagonal boron nitride, contains B
2O
3Reach 2.5%, or the 2. higher Powdered hexagonal boron nitride of purity, B in x-ray diffraction pattern, do not had
2O
3Be detected.Use raw material 1. at 14.0GPa, the product that obtains under the 4000K condition has the x-ray diffraction pattern of stronger cBN.Use raw material 2. at 11.3GPa, the product that obtains under the 2500K condition has the x-ray diffraction pattern of stronger cBN.
This method uses hexagonal boron nitride to be the directly synthetic cBN of raw material, though saved catalyst material, its synthesis condition is quite harsh, " changing required minimum pressure is 11.5GPa, minimum temperature 2000K ".Particularly the synthesis pressure of Shi Yonging is up to more than the 11.5Gpa, and this is unaffordable in actual production.And crystal structure is very little.Document is also pointed out, B in directly transforming
2O
3Existence, synthetic pressure and temperature has all been improved a lot, this to synthetic be very disadvantageous.
Summary of the invention
Cubic boron nitride is the tool materials of a kind of energy-efficient Precision Machining iron group metal and alloy, plays an important role in realizing the machining modernization.Reduce cubic boron nitride monocrystal synthesis pressure and temperature, simplifying synthetic method is the target that the researcher and the producer pursue all the time.The present invention adopts the method for chemical reaction, without catalyst, has synthesized the cubic boron nitride crystal of black under not too high high pressure, high temperature.This method is compared with traditional method, has overcome in the catalyst synthetic method catalyst and has prepared and prevent difficulty such as catalyst oxidation stain, has simplified technology; With direct conversion method is that non-catalyst method is compared, and pressure is reduced greatly, thereby has reduced the consumption of synthetic middle carbide alloy nail hammer, has reduced production cost, becomes the effective ways that are fit to large-scale industrial production.
Specific embodiment of the present invention is as described below.
With pure boron (B) or boron oxide (B
2O
3) and lithium nitride (Li
3N) be initial reactant, press mass ratio B or B
2O
3: Li
3N=1: 0.8～1.3 batching.Reactant grinds and to be pressed into behind the mixing cylindricly, in the graphite heating of packing into the container, is assembled into the synthetic piece of high pressure-temperature with pyrophillite, and reaction generates cubic boron nitride crystal under HTHP.The condition of reaction is: pressure: 3.0～6.0GPa; Temperature: 1400～1700 ℃; 3～10 minutes heat time heating times.Stop heated sample cooling back release and reclaim product.
After the product pulverizing that contains cubic boron nitride and impurity of reclaiming, remove impurity such as pyrophillite, graphite with conventional soda acid facture, obtain pure cubic boron nitride crystal.That is, can remove impurity such as pyrophillite, graphite with potassium hydroxide and nitric acid.
The present invention prepares the method for cubic boron nitride by chemical reaction, owing to use B or B
2O
3And Li
3N is a reactant, does not need catalyst, and under lower pressure and lower temperature, generates cubic boron nitride crystal by chemical reaction, and the product that obtains has the x-ray diffraction pattern of stronger cBN, and particle diameter is at 20～400 micrometer ranges.Because technology is fairly simple, compares with background technology and reduced pressure greatly, even use B
2O
3Make reactant, synthesis pressure and temperature also all reduce greatly, thereby are fit to technical scale production.
The specific embodiment
Embodiment 1:
This experiment be in finish on the homemade DSO29B swaging machine, this press high-pressure chamber is of a size of internal diameter φ 15.5 * 12mm.Before synthetic,, it is evenly mixed with the pure boron powder by 1: 0.9～1 mass ratio earlier with block lithium nitride grind into fine powder in agate mortar.Mixed powder is weighed by the capacity of high pressure chest carrying sample, depress to column at 8MPa pressure.The column that presses is packed in the graphite heating pipe of internal diameter φ 15.5 * 12mm, be assembled into synthetic piece with supporting pyrophillite.This piece is put into high-tension apparatus carry out high-temperature high-voltage reaction.Reaction condition is: pressure is 4.4～5.0Gpa; Temperature is 1450～1550 ℃; Be 4～6 minutes heat time heating time.Stop heating, after the cooling of chamber to be synthesized, lay down pressure and fetch synthetic product.After handling, conventional soda acid obtains the cubic boron nitride monocrystal body of black.
Embodiment 1 is a most preferred embodiment of the present invention, and the particle diameter maximum of the black cBN of generation can reach 400 microns.
Embodiment 2:
On embodiment 1 experiment condition basis, with pressure be reduced to original pressure about 70% (3.1～3.5GPa), still obtained cubic boron nitride crystal, but the granularity of cBN crystal product
Wanting of embodiment 1 is thin.
It is 6GPa that pressure is increased, and also can obtain the black cBN monocrystalline of coarsegrain.
Embodiment 3:
Change the reactant pure boron among the embodiment 1 into diboron trioxide, press mass ratio B
2O
3: Li
3N=1: 1.3 batchings, under the experiment condition identical, can obtain the cubic boron nitride monocrystal body of black equally with embodiment 1, particle diameter is thinner.
Embodiment 4:
Press reactant and proportioning, technical process and the experimental pressure condition of embodiment 1, reducing inversion temperature is 1400 ℃, but prolong heat time heating time to 10 minute accordingly, or the raising inversion temperature is 1700 ℃, corresponding shorten heat time heating time to 3 minute, the result of synthesis of cubic boron nitride monocrystal is not had too much influence.Temperature range in the best is 1450～1550 ℃, and be 4～6 minutes corresponding heat time heating time.
Claims (2)
1, a kind ofly preparing the method for cubic boron nitride by chemical reaction, it is characterized in that, is initial reactant with pure boron or boron oxide and lithium nitride, presses mass ratio B or B
2O
3: Li
3N=1: 0.8～1.3 batching; Reactant grinds and to be pressed into behind the mixing cylindricly, in the graphite heating of packing into the container, is assembled into the synthetic piece of high pressure-temperature with pyrophillite, and reaction generates cubic boron nitride crystal under HTHP; The condition of reaction is: pressure: 3.0～6.0GPa; Temperature: 1400～1700 ℃; 3～10 minutes heat time heating times.
2, prepare the method for cubic boron nitride according to claim 1 is described by chemical reaction, it is characterized in that, said high-temperature high-voltage reaction, reaction condition is: pressure is 4.4～5.0GPa; Temperature is 1450～1550 ℃; Be 4～6 minutes heat time heating time.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410011085 CN1274397C (en) | 2004-09-08 | 2004-09-08 | Method for preparing cubic boron nitride by chemical reaction |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410011085 CN1274397C (en) | 2004-09-08 | 2004-09-08 | Method for preparing cubic boron nitride by chemical reaction |
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|---|---|
| CN1605383A CN1605383A (en) | 2005-04-13 |
| CN1274397C true CN1274397C (en) | 2006-09-13 |
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| CN 200410011085 Expired - Fee Related CN1274397C (en) | 2004-09-08 | 2004-09-08 | Method for preparing cubic boron nitride by chemical reaction |
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