Claims
- 1. A process for producing amorphous boron nitride, substantially free from hexagonal system boron nitride and oxygen, which comprises heating a mixture consisting of a borohydride of an alkali metal and ammonium chloride at a temperature within a range of from 800.degree. to 1100.degree. C. in a non-oxidizing atmosphere.
- 2. The process for producing boron nitride according to claim 1, wherein said borohydride of alkali metal and ammonium chloride is mixed in such a ratio that nitrogen is in an equivalent or greater quantity in a molar ratio with respect to boron.
- 3. The process according to claim 1 wherein said alkali metal borohydride is LiBH.sub.4, NaBH.sub.4, or KBH.sub.4.
- 4. The process for producing amorphous boron nitride according to claim 1, wherein said non-oxidizing gas is nitrogen gas, ammonia gas or argon gas.
Priority Claims (1)
| Number |
Date |
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| 57-63067 |
Apr 1982 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 440,998, filed Nov. 12, 1982, now abandoned.
This invention is concerned with production of boron nitride.
For the process for producing an atmospheric pressure type boron nitride in an industrialized scale, there has so far been adopted a method, in which boric acid, boron oxide, or borate is reductively nitrized with an organic nitrogen compound such as, for example, urea, and so on. In boron nitride obtained by this method, there remains, as impurity, oxygen and carbon which are originally contained in raw material. For instance, amorphous boron nitride available in general market contains approximately 20% of oxygen, and even high purity boron nitride of hexagonal system contains approximately 0.5% of oxygen. Further, these types of boron nitride also contain carbon. When boron nitride containing therein a large quantity of oxygen is used as the raw material for producing cubic system boron nitride by the high pressure phase-transition, the rate of yield of such cubic system boron nitride lowers to an extreme degree. Also, boron nitride containing therein oxygen in a certain quantity reacts with metal material to become incapable of use. For example, boron nitride containing therein 2% of oxygen reacts with molybdenum at a temperature of 1800.degree. C. or below. Therefore, production of high purity boron nitride with less content of oxygen brings great benefit.
For production of the high purity boron nitride not containing oxygen, use of a raw material compound not containing therein oxygen is the best way.
For such production method, there has so far been known one, in which boron chloride gas or hydrogenated boron gas is mixed with ammonia, then the mixture is heated at a high temperature to deposit boron nitride from a gas phase. This method, however, has many shortcomings such that, since the raw material is highly toxic and corrosive, the material handling should be done with utmost of care, that the tubings in the production system tend to be readily clogged due to deposition of an intermediate reaction product, that boron nitride as produced is difficult to be captured, and others.
In view of the above mentioned disadvantages inherent in the known method for producing boron nitride, it is a primary object of the present invention to provide an improved method for production of boron nitride, from which all the shortcomings inherent in the conventional methods have been successfully eliminated, and which is capable of safely and readily producing boron nitride with less oxygen content.
With a view to attaining the above mentioned object, the present inventor has conducted strenuous research activities, as the result of which he has discovered a fact that boron nitride of high purity with less content of oxygen could be obtained when a mixture of borohydride of alkali metal such as Me(BH.sub.4), where Me denotes an alkali metal, and ammonium chloride is heated at a temperature range of from 800.degree. to 2200.degree. C. in a non-oxidizing atmosphere, on the basis of which finding the present invention has been completed.
According to the present invention, in general aspect thereof, there is provided a process for producing boron nitride, which comprises heating a mixture consisting of borohydride of alkali metal and ammonium chloride at a temperature range of from 800.degree. to 2200.degree. C. in a non-oxidizing atmosphere.
The foregoing object, other objects, as well as specific reaction mechanism of the present invention will become more apparent and understandable from the following detailed description thereof in connection with a few preferred embodiments and in reference to the accompanying drawing.
US Referenced Citations (5)
Non-Patent Literature Citations (4)
| Entry |
| H. Sumiya et al., "High Pressure Synthesis of Cubic Boron Nitride from Amorphous State", Mat. Res. Bull., vol. 18, pp. 1203-1207, (1983). |
| Chemical Abstracts, vol. 92, 1980, Abstract No. 149405t, Volkov, V. V. et al., "Borazole". |
| Gmelin Handbuch der Anorganischen Chemie, Springer Verlag, New York, 1983, p. 384. |
| Research Report No. 27 by National Institute for Researches in Inorganic Materials, 1981, "Study on Boron Nitride", Sections 2.1.2, 2.1.3 (part). |
Continuations (1)
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Number |
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| Parent |
440998 |
Nov 1982 |
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Patent Grant
4913887
