IE904431A1 - Monodisperse hexagonal boron nitride with a very high purity¹level with respect to metals and oxygen and its preparation¹process - Google Patents

Monodisperse hexagonal boron nitride with a very high purity¹level with respect to metals and oxygen and its preparation¹process

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Publication number
IE904431A1
IE904431A1 IE443190A IE443190A IE904431A1 IE 904431 A1 IE904431 A1 IE 904431A1 IE 443190 A IE443190 A IE 443190A IE 443190 A IE443190 A IE 443190A IE 904431 A1 IE904431 A1 IE 904431A1
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Prior art keywords
boron nitride
boron
calcination
platelets
oxygen
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IE443190A
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Rhone Poulenc Chimie
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Publication of IE904431A1 publication Critical patent/IE904431A1/en

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M103/00—Lubricating compositions characterised by the base-material being an inorganic material
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
    • C01B21/0643—Preparation from boron halides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/76—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by a space-group or by other symmetry indications
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/06—Metal compounds
    • C10M2201/061—Carbides; Hydrides; Nitrides
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/16—Carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/18—Ammonia

Abstract

Boron nitride consisting of platelets of hexagonal crystalline form of not more than 0.4 mu m, of a purity of at least 99 % and exhibiting a content of not more than 500 ppm of metal impurities and of silicon. This nitride is obtained by a process in which boron nitride originating from the gas-phase synthesis or originating from the reaction of liquid ammonia with a boron halide, is subjected to a double calcination; the first being carried out in a neutral and confined atmosphere, the second under vacuum.

Description

Monodisperse hexagonal boron nitride with a very high purity level with respect to metals and oxygen and its preparation process.
The present invention relates to the preparation of a boron nitride in the form of hexagonal monodisperse platelets of very high purity with respect to oxygen and metallic impurities, as well as the preparation of such a boron nitride.
Boron nitride has numerous industrial applications, being used as a refractory, an insulant and a lubricant.
In accordance with the envisaged application, namely when it is used as a lubricant, it is important to have a high purity boron nitride constituted by hexagonal platelets. It is also of interest to have a monodisperse, submicron product.
However, the boron nitride can also be in different forms as a function of the preparation procedure. Thus, for a boron nitride obtained from the gaseous phase reaction of ammonia on a boron halide or hydride, as well as for a boron nitride resulting from the liquid phase reaction of ammonia on a boron halide, it is in the form of amorphous spherical particles containing an excessive oxygen quantity and having a high reactivity with the atmosphere.
It is very difficult to crystallize and purify such a product. Thus, it is necessary for the particles to pass through a very poorly organized structure to a well ordered structure and in addition the oxygen has to be eliminated.
Therefore a first object of the invention is constituted by a high purity boron nitride resulting for exarrple from cne of the aforementioned syntheses and crystallized in the form of hexagonal platelets, λ second object is constituted by a boron nitride having moreover a fine microstructure.
Finally, a last object is the preparation of such a boron nitride.
To this end, the boron nitride according to the invention is constituted IE 904331 - 2 by hexagonal crystalline submicron platelets of at the most 0.4 μ».
Said boron nitride has a purity with respect to oxygen of at least 99% and a content of metallic impurities and silicon of at the most 500 ppm.
The preparation process of a boron nitride according to the invention is characterized in that the boron nitride resulting from gaseous phase synthesis or the reaction of liquid ammonia on a boron halide undergoes a double calcination, the first under a neutral and confined atmosphere and the second in vacuo.
Among other advantages, the process according to the invention has that of effectively controlling the crystallization of the boron nitride, whilst also giving a very pure product. It also makes it possible to prepare a monodisperse product and optionally limit the growth of the size of the particles, because the platelets constituting the end product can have a grain size of the same order of magnitude as the spheres of the initial product.
Other advantages and features of the invention can be more clearly gathered from reading the following description and the examples following the latter.
•Hie boron nitride according to the invention has a fine microstructure. Indeed it is constituted by hexagonal, crystalline, suhmicrcn platelets of at the most 0.4 ;m.
According to a preferred embodiment of the invention, the boron nitride has platelets with a size of at the most 0.3 pm and preferably between 0.2 and 0.15 μα, said sizes being determined by MEB. These platelets are also present in the form of monodisperse particles.
The boron nitride according to the invention is also characterized by its high purity with respect to oxygen, because the latter is at least 99% and preferably at least 99.3%.
IE 904331 - 3 Another feature of the boron nitride according to the invention is it» vary low content of silicon end aetallic iepurittes such as alkali metals and alkaline earth eetala. Thus, these impurities have a content of at the eoat 500 pp· and preferably at the aost 300 ppa and aore particularly at the aost 200 ppa.
Moreover, a boron nitride according to the invention la substantially carbon-free. The term carbon-free means a carbon content of at moat 300 ppn and more particularly of at most 100 fpm. Indeed, as said hereabove, the invention applies more particularly to a boron nitride obtained from the reaction of enrcnia in gaseous or liquid form with a boron halide. It is well known that such processes give a boron nitride substantially carbcn-free with the same sense as indicated hereinbefore.
Moreover, the boroo nitride platelets are characterised hy the Lc value, which corresponds to the aean distance perpendicular to the packing ails on which ao fault la found. It is aeasured hy s crystallographic study and hy measuring the width of tho line (002).
Thus, the hexagonal, crystalline boron nitride platelets havs a Lc value of at the aost 35θΙ.
Finally the boron nitride according to the invention presents a surface chemistry which can be called hydrophobic*. Such a product is essentially characterized by its pH-value, which can be measured in the following A water ethanol mixture is prepared in respective proportions of 30 ed 70» by volune. The pH-value of this mixture is adjusted to 7 2 1 by adding soda, This is followed by the introduction of O.3g of boron nitride into 20 cm3 of the mixture. The value of the pH is noted and 0.5 is added thereto, in order that the eitutaticn is the same as if the measurement was preformed in pure water. The wate-ethanol mixture le used because it is easier to disperse boron nitride therein than in pure water.
The boron nitride according to the invention has a pH, as determined in the above conditions, which is clearly basic. This is understood to mean a valu of at least 8 and preferable at least 8.5.
IE 904331 - 4 The boron nitride preparation process will now be described. As stated hereinbefore/ the process according to the invention starts from a boron nitride obtained from two synthesis types.
On the one hand, according to a first type, the syntheses are performed in the gaseous phase by reacting ammonia with a boron hydride or a boron halide. Preference is generally given to the use of a boron halide and more particularly boron trichloride.
It is also possible to use a liquid phase synthesis consisting of reacting the ammonia with a boron halide such as e.g. boron trichloride.
Generally the synthesis of the first type is performed by the action of ammonia on boron trichloride in the gaseous phase.
This leads to a amorphous boron nitride in the form of primary spherical particles.
Moreover, the boron nitride before being treated according to the invention, has to contain at least 5 % and preferably between 5 and 20 % by weight oxygen.
Preferably, the said oxygen has to be homogeneously distributed on the particles of boron nitride. Such a result can be obtained by an air oxidation of the boron nitride which can be spontaneous (for example an oxidation occurring during the storage of the boron nitride) or not, or by a gentle hydrolysis.
The first stage of the treatment consists of calcining boron nitride under a neutral, confined atmosphere. In this stage, the boron nitride is used in a form such that its apparent density is at least 0.1 g/cm3 and more particularly between 0.2 and 0.35 g/cm3. This apparent density is generally obtained by a prior compacting. Such an operation is of interest for several reasons.
IE 904331 - 4AOn the one hand it makes it possible to more easily handle the boron nitride powder. On the other hand, it contributes to increasing the productivity of the process by permitting the treatment in the furnace of larger product quantities.
The neutral atmosphere can be formed either by a rare gas, or by nitro gen. Normally a nitrogen atmosphere is used.
The term confined atmosphere is here understood to mean a slightly replenished atmosphere in which the release of volatile boron oxides is delayed. In other words, working takes place under conditions such that at the end of said first stage the oxygen content of the boron nitride does not significantly differ from that of the starting nitride that is of at most 10 %. In practice, an adequate confinement can be obtained by enclosing the boron nitride in a graphite container Finally, the treatment preferably takes place at a pressure close to atmospheric pressure.
The calcination temperature is generally above 1450°C. It can more particularly be between 1500 and 1800°C, more especially between 1500 and 1600° C. Below 1450°C, the energy is not sufficient to start the crystallization of the boron nitride, i.e. the transition between the amorphous structure of the particles resulting from the gaseous phase synthesis and the hexagonal platelet structure. However, beyond 1800°C, the elimination of boron oxides becomes excessive and consequently a poorly crystallized product is obtained at the end of the treatment.
The first stage lasts a few hours, e.g. roughly two hours, the treatment temperature the shorter this time.
The higher The second calcination is made of a dynamic vacuum. 10 and 500 Pa. performed in vacuo and preferably use is For example, the vacuum value is between IE 904331 The calcination temperature, which varies as a function of the vacuum, must be adequate to permit the elimination of the oxygen in this stage. Normally said temperature is at least 1500°C and is generally between 1500 and 22OO°C. Preferably, the second calcination is performed at between 1500 and 1800°C. This second stage takes a few hours and in particular approximately one hour. Hits time is also a function of the temperature.
According to a preferred embodiment, the two calcinations are carried out during the same thermal cycle by evacuating the nitrogen at the end of the first stage.
Specific, but non-limitative examples of the invention will now be given. For these examples, the dry compressed or tamped density is measured in the following way. A certain powder quantity is weighed and placed in a diameter 1 co and length 10 cm test tube. The latter is vibrated with an ultrasonic vibrator. The vibration is stopped when the powder has reached a minimum compression height. The determination of the volume occupied by the compressed powder gives the compressed density.
Example 1 The starting product is constituted by 400g of boron nitride obtained by the gaseous phase reaction of ammonia on boron trichloride. The borcn nitride contains approximately 9% by weight oxygen, resulting of the spontaneous oxidation during the storage in air of the said boron nitride.
Ihe boron nitride is previously compacted and is in the form of a powder of density 0.2 g/cm3. The boron nitride is calcined with the following heat cycle 2OO°C/h rise and then 2 hours at 1500°C in a confined nitroqen atmosphere (pN2 = 8.104 Pa).
A second calcination is preformed in vacuo and at the end of this the product has the following characteristics: IE 904331 morphology : hexagonal platelets of average size 0.15 jia (measured by scanning electron microscopy) Colour: White (meaning that the boron nitride is carbcn-free) oxygen content : 0.6X specific surface (BCT) : 32 m2/g dry compressed density : 0.27 g/ca Lc : 315 I La : 725 I The La value corresponds to the mean diameter of a graphite plane.
The product is monodisperse and has a variation coefficient (d^ dg^V^djo measured by 0.5 image analysis. dn is the diameter for which nX of the particles have a size below said diameter.
Comparative Example 2 The same boron nitride used as the starting product In Example 1 is used in the same quantity. It firstly undergoes the vacuum treatment and then the treataent under nitrogen under conditions identical to those of Example 1. Thia gives a turbostratlc product with an oxygen content of 2.5X.

Claims (16)

1. Boron nitride constituted by hexagonal, crystalline platelets of at the most 0.4 |im, a purity of at least 99% and a content of metallic impurities and silicon of at the most 500 ppm.
2. Boron nitride according to claim 1, characterized in that the size of the platelets is at the most 0.3 pm and is preferably between 0.2 and 0.15 pm.
3. Boron nitride according to one of the preceding claims, characterized in that the oxygen purity is at least 99.3%.
4. Boron nitride according to one of the preceding claims, characterized in that the content of metallic impurities and silicon is at the most 300 ppm and more particularly at the most 200 ppm.
5. Boron nitride according to one of the preceding claims, characterized in that the platelets have a Lc-value of at the most 350 X.
6. Boron nitride according to one of the preceding claims, characterized in that the platelets are monodisperse.
7. Process for the preparation of a boron nitride according to one of the claims 1 to 6, characterized in that the boron nitride obtained from gaseous phase synthesis or the reaction of liquid ammonia on a boron hydride undergoes a double calcination, the first taking place in a neutral, confined atmosphere and the second in vacuo.
8. Process according to claim 7, characterized in that the neutral, confined atmospohere is a nitrogen atmosphere.
9. Process according to one of the claims 7 or 8, characterized in that the first calcination is performed at a temperature above 1450°C.
10. Process according to one of the claims 7 to 9, characterized in that the first calcination takes place at a temperature between 1500 and 1800°C.
11. Process according to one of the claims 7 to 10, characterized in that the second calcination is performed at a temperature of at least 1500°C.
12. Process according to one of the claims 7 to 11, characterized in that the second calcination is performed at a temperature between 1500 and 2000°C.
13. Process according to one of the claims 7 to 12, characterized in that a boron nitride obtained by gaseous phase reaction of ammonia on a boron halide undergoes said double calcination.
14. Boron nitride according to claim 1, substantially as hereinbefore described and exemplified.
15. A process for the preparation of boron nitride according to claim 1, substantially as hereinbefore described and exemplified.
16. Boron nitride according to claim 1, whenever prepared by a process claimed in a preceding claim.
IE443190A 1989-12-08 1990-12-07 Monodisperse hexagonal boron nitride with a very high purity¹level with respect to metals and oxygen and its preparation¹process IE904431A1 (en)

Applications Claiming Priority (1)

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FR8916243A FR2655638A1 (en) 1989-12-08 1989-12-08 HIGH PURITY MONODISPERSE HEXAGON BORON NITRIDE AGAINST METALS AND OXYGEN AND PROCESS FOR PREPARING THE SAME

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JP (1) JPH0578106A (en)
AU (1) AU6772790A (en)
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CA (1) CA2031834A1 (en)
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JP3316590B2 (en) * 1992-01-08 2002-08-19 川崎製鉄株式会社 Hexagonal boron nitride powder and method for producing the same
JP3460746B2 (en) * 1995-02-23 2003-10-27 電気化学工業株式会社 Method for producing hexagonal boron nitride powder
EP0918039A4 (en) * 1996-08-06 1999-10-27 Otsuka Kagaku Kk Boron nitride and process for preparing the same
US6660241B2 (en) 2000-05-01 2003-12-09 Saint-Gobain Ceramics & Plastics, Inc. Highly delaminated hexagonal boron nitride powders, process for making, and uses thereof
US6794435B2 (en) * 2000-05-18 2004-09-21 Saint Gobain Ceramics & Plastics, Inc. Agglomerated hexagonal boron nitride powders, method of making, and uses thereof
US6764975B1 (en) 2000-11-28 2004-07-20 Saint-Gobain Ceramics & Plastics, Inc. Method for making high thermal diffusivity boron nitride powders
CA2445555C (en) 2001-04-30 2010-11-23 Saint-Gobain Ceramics & Plastics, Inc. Polymer processing aid and method for processing polymers
US6645612B2 (en) 2001-08-07 2003-11-11 Saint-Gobain Ceramics & Plastics, Inc. High solids hBN slurry, hBN paste, spherical hBN powder, and methods of making and using them
US7494635B2 (en) 2003-08-21 2009-02-24 Saint-Gobain Ceramics & Plastics, Inc. Boron nitride agglomerated powder
JP4307451B2 (en) * 2006-01-18 2009-08-05 電気化学工業株式会社 Boron nitride powder, production method and use thereof
JP5081488B2 (en) * 2006-04-20 2012-11-28 Ｊｆｅスチール株式会社 Hexagonal boron nitride powder
JP2008174448A (en) * 2008-04-08 2008-07-31 Osamu Yamamoto Crystalline turbostratically structured boron nitride
JP5065198B2 (en) * 2008-08-04 2012-10-31 株式会社カネカ Method for producing hexagonal boron nitride
JP2010042963A (en) * 2008-08-18 2010-02-25 Kaneka Corp Manufacture method of hexagonal boron nitride
CN102398897B (en) * 2011-11-07 2013-04-24 北京航空航天大学 Method for preparing two-dimensional nano boron nitride with jet flow cavitation technology

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JPS60151202A (en) * 1983-08-25 1985-08-09 Yuka Meramin Kk Manufacture of boron nitride
CA1260671A (en) * 1984-06-07 1989-09-26 Takahisa Koshida High-purity powder of hexagonal boron nitride and a method for the preparation thereof
US4544535A (en) * 1985-03-22 1985-10-01 The United States Of America As Represented By The Secretary Of The Army Method or preparing nonlaminating anisotropic boron nitride
JPS61256905A (en) * 1985-05-10 1986-11-14 Kawasaki Steel Corp Fine hexagonal boron nitride power having high purity and its preparation
JPS62100404A (en) * 1985-10-28 1987-05-09 Kawasaki Steel Corp Production of pulverous hexagonal boron nitride having high purity
JPH01184033A (en) * 1988-01-19 1989-07-21 Natl Inst For Res In Inorg Mater Production of cubic boron nitride

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FI906048A (en) 1991-06-09
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JPH0578106A (en) 1993-03-30
EP0432007A1 (en) 1991-06-12
NO905289D0 (en) 1990-12-06
BR9006359A (en) 1991-09-24
FR2655638A1 (en) 1991-06-14
CA2031834A1 (en) 1991-06-09
PT96113A (en) 1991-09-30

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