JPS6339885A - Production of silicon nitride precursor and silicon nitride powder - Google Patents

Abstract

PURPOSE:To obtain the titled powder for high temperature structural materials, etc., containing no needle crystal and having high purity alpha type isometric system with a particle size of submicron order, by reacting specific amines with a halosilane and then reacting the reaction product with ammonia. CONSTITUTION:A primary or secondary amine (e.g. aniline, etc.) expressed by formula I (R is aliphatic or aromatic residue; l is an integer of 1<=l<=4; r is 1-2, provided that in the case of a cyclic nitrogen compound, l is 2 when r is 1) is reacted with a halosilane (e.g. tetrahalogenosilane, etc.) expressed by formula II [X is halogen; m is an integer of 0<=m<=2p+2 (pis 1 or 2); n is an integer of 0<=n<=2p+2; m+n is an integer of 0<=m+n<2p+2] at a ratio of numbers of Si atoms to C atoms within the range of 1-100 to partially form a silane or organoaminosilane, which is then reacted with ammonia to afford the aimed compound powder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing silicon nitride precursors and silicon nitride powders.

[Conventional technology]

Silicon nitride sintered bodies have excellent high-temperature strength, thermal shock resistance, and oxidation resistance, so they can be used as high-temperature structural materials for gas turbines, diesel engines, etc., or as cutting tools, making a great contribution to energy and resource conservation. It is important as one of the possible high-performance materials.

Conventionally, the following four methods are known as methods for manufacturing silicon nitride.

■ Metallic silicon powder in a nitrogen or ammonia stream,
A silicon direct nitriding method in which silicon is directly nitrided by heating at 1300°C to 1500°C.

(2) A silica reduction method in which silica or a silica-containing substance is heated together with carbon in a nitrogen atmosphere, or silica is reduced with urea, and the generated silicon reacts with nitrogen.

■ A gas phase synthesis method in which silicon tetrachloride and ammonia are directly reacted at high temperatures.

■ An imide amide thermal decomposition method in which silicon nitride is obtained by heating silicon imide or silicon amide obtained by ammonolysis of silicon tetrachloride in a non-oxidizing atmosphere.

[Problem that the invention seeks to solve]

It has been pointed out that the above-mentioned conventional method has the following problems in boat fishing.

In other words, in the case of method (■) above, the reaction time is long;
The heating process is complicated, and the silicon nitride obtained is mainly β-type silicon nitride, which is coarse and contains many impurities.In the case of method (2), not only is it difficult to purify the raw material, but the reaction time is long. , the product obtained is a mixed system of α-type silicon nitride and β-type silicon nitride, and in the case of method 2, the silicon nitride produced is generally amorphous, so it is further crystallized (α phase formation). Not only is the step (2) required, but the treatment of chlorine generated during high-temperature heating is complicated. However, when synthesizing silicon imide or silicon amide, the reactor tubes are easily clogged, and since this reaction is rapidly exothermic, it is difficult to control the reaction, and furthermore, it is difficult to manufacture sintered bodies. generates needle-like crystals that become an obstacle. However, with respect to method (2), the present inventors included a step of reacting halosilane with a base to produce an adduct and a step of reacting the adduct with ammonia, thereby controlling the rapid exothermic reaction and achieving high purity. We have already proposed a method for synthesizing silicon nitride powder (Japanese Unexamined Patent Publication No. 1983-1999).
-260406).

An object of the present invention is to eliminate the drawback that a large amount of needle-shaped crystals are produced in such an imidoamide thermal decomposition method, which hinders the production of a fired product.

[Means for solving problems]

The present inventors have discovered that in the process of investigating methods for eliminating the drawback of the above-mentioned imidoamide pyrolysis method, in which a large amount of needle-shaped crystals are produced, which is a major hindrance in producing sintered bodies, In the present invention, a mixture of (organo-amino)silane and halosilane obtained by reacting an amine with a halosilane is reacted with ammonia to produce silicon imide or silicon amide, and when this is heat-treated, it contains almost all needle crystals. First, silicon imide or silicon amide, which is a precursor for silicon nitride production, is produced. In this method for producing a precursor, formula (I): R, N, II□r++
-t(r) (wherein R represents an aliphatic residue or an aromatic residue, l is an integer of 15.f<4,
r is 1 or 2. However, in the case of cyclic nitrogen compounds, r
=1, l becomes 2. ) and at least one primary or secondary amine represented by the formula (II): RJI, IS'ipX (211,2-<m*n++
(II) (wherein R is an aliphatic residue or an aromatic residue, X is a halogen atom, and m is 05m<2p+
2, n is an integer of 0≦n<2p+2, p is 1 or 2, and m + n is an integer of 0≦m+n<2p+2. ) at least one type of halosilane represented by
A silicon nitride precursor is produced by reacting at a certain ratio within the range of (organoamino)silane to partially produce (organoamino)silane, and then reacting the reaction mixture consisting of (organoamino)silane and halosilane with ammonia. Produces silicon amide or silicon amide. In this case, the halosilane represented by formula (II) is treated with a base that does not react with it other than to form an adduct, and the resulting adduct is converted into the Si / By reacting with an amine represented by formula (I) in a proportion in which the C atomic ratio is within the range of 1 to 100 to produce an adduct mixture, and then reacting with ammonia, or by reacting with ammonia After reacting the amine with the halosilane represented by formula (II) at a Si/C atomic ratio within the range of 1 to 100, the reaction product is reacted with the halosilane represented by formula (n). Silicon imide or silicon amide, which is a precursor that can be suitably used in the production of silicon nitride, can be produced by reacting a base that does not perform reactions other than those that form adducts and reacting the resulting adduct mixture with ammonia.

The primary or secondary amine represented by formula (1) is represented by formula (n)
This amine is used to introduce an organic carbon atom into silicon imide or silicon amide by reacting with a halosilane represented by Must. The organic group containing a carbon atom is not particularly limited, but aliphatic residues and aromatic residues, particularly aromatic hydrocarbon groups, are preferred. Examples of such primary or secondary amines represented by formula (I) include monoalkylamine, monoallylamine, dialkylamine, diallylamine, alkylarylamine, monoalkyldiamine, dialkyldiamine, trialkyldiamine, monoallyldiamine, Diallyldiamine, triallyldiamine, monoalkyldiallyldiamine, dialkylmonoallyldiamine, monoalkylhydrazine, dialkylhydrazine, trialkylhydrazine, monoallylhydrazine, diallylhydrazine, triallylhydrazine,
monoalkyldiallylhydrazine, dialkylmonoallylhydrazine, cyclic nitrogen compound (at least one N-
Examples include compounds having an H bond, such as pyrroles, indoles, carbazoles, imidazoles, piperidines, azepines, etc.

Halosilane represented by II (II) is a main component that reacts with ammonia to produce silicon imide or silicon amide, and has at least one halogen group to react with ammonia or the amine represented by formula (I). should exist. Further, in order to polymerize the silicon imide or silicon amide produced by reacting with ammonia or amine, the halosilane is preferably dihalosilane, more preferably trihalosilane or tetrahalosilane. Furthermore, this halosilane can also have an organic group, and this organic group can be the same as the organic group of the above-mentioned amine, but in terms of -i, those with aliphatic groups are easily available. Examples of the halosilane represented by formula (II) include tetrahalogenosilane, trihalogenosilane, dihalogenosilane, heptanohalogenosilane, monoalkyltrihalogenosilane, monoalkyldihalogenosilane, monoalkylmonohalogenosilane, and monohalogenosilane. trihalogenosilane, mono-dihalogenosilane, mono-dihalogenosilane, dialkyldihalogenosilane, dialkylmonohalogenosilane, diallyldihalogenosilane, diallylmonohalogenosilane, trialkylmonohalogenosilane, tri-monohalogenosilane , monoalkyl monohalogenosilane, monoalkyl monohalogenosilane, dialkyl monoallyl monohalogenosilane, monoalkyl diallyl monohalogenosilane, hexahalogenodisilane, pentahalogenodisilane, hexahalogenodisilane, trihalogenodisilane, At least one type of halogenosilane selected from halogenodisilane, monohalogenodisilane, alkyl and/or allyl substituted products of these halogenodisilanes, etc. can be mentioned. However, examples of halogen include chlorine, bromine, fluorine, and iodine.

The amine represented by (I) and the halosilane represented by formula (n) are S i / C in the whole of these components.
The reaction is carried out at an atomic ratio within the range of 1 to 100. In the above, if the St/C atomic ratio is less than 1, there will be too much carbon in the silicon nitride precursor produced after reacting with ammonia, and if the S i /C atomic ratio is less than 1.
If it is larger than 00, the amount of carbon in the silicon nitride precursor to be produced will be small, and the effect of suppressing the formation of needle-shaped crystals will not be sufficiently exhibited when the precursor is heat-treated to produce silicon nitride powder.

In a preferred embodiment of the method of the present invention, if an adduct is created by reacting halosilane with a base, the adduct exists stably in the solvent, making it easy to control the reaction with ammonia, and furthermore, yielding high yields. It also has the advantage of being able to obtain high molecular weight products.

The base that can be used in the present invention is a base that does not react with halosilane other than the reaction that forms an adduct,
Examples of such bases include Lewis bases, tertiary amines (trialkylamines, pyridine, picoline, and derivatives thereof), secondary amines having sterically hindered groups, phosphine, stibine, arsine, and derivatives thereof. (e.g. trimethylphosphine, dimethylethylphosphine, methyldiethylphosphine, triethylphosphine, trimethylarsine, trimethylstipine, trimethylamine, triethylamine, thiophene, furan, dioxane, selenophene, ■-methylphosphine, etc.) Among them, bases with low boiling points and less basicity than ammonia (e.g. pyridine, picoline, trimethylphosphine, dimethylethylphosphine, methyldiethylphosphine, triethylphosphine, thiophene, furan, dioxane,
Selenophene and 1-methylphosphool are preferred;
Pyridine and picoline are particularly preferred from the viewpoint of handling and economy. The amount of the base used does not need to be particularly strict; it is sufficient that the base, including the amine in the adduct, is present in a stoichiometric amount relative to the halosilane, ie, in excess of amine:silane=2=1.

The halosilane adduct produced in the reaction process of the present invention only needs to be substantially produced as a reaction intermediate, and may or may not actually be separated as a halosilane adduct.

The reaction conditions for the synthesis of silicon imide or silicon amide of the present invention are not particularly limited in terms of reaction time or reaction pressure, as long as the reaction temperature is 178°C to 100°C, since the reaction rate is high.

The complex formation reaction between (organoamino)silane, which is a reaction product of halosilane and amine, and an organic base is preferably carried out at a temperature below the boiling point of halosilane, and the subsequent ammonolysis reaction of the complex is mild. Therefore, it is not necessary to carry out the process at a low temperature, and it is preferable to carry out the process at a temperature of 0°C to 50°C.

On the other hand, the reaction between (organoamino)silane, which is a reaction product of halosilane and amine, and ammonia is a violent reaction, so it must be carried out at a low temperature. It is preferable to carry out the reaction in a temperature range.

Further, the synthesis reaction of silicon imide or silicon amide is preferably carried out under an inert gas atmosphere, and nitrogen or argon is preferably used as the inert gas.

The thus obtained silicon imide or silicon amide is heated to remove the solvent under reduced pressure, and then the by-product ammonium chloride is removed by washing and filtration in a pressure container in the temperature range of -80 to 50°C or at a temperature/pressure that allows sublimation. By this,
A suitable chlorine-free silicon nitride powder precursor is obtained. In general, the sublimation method raises the temperature, so amide decomposes into imide, and there are reports that some chlorine is also taken into the interior, so cleaning with liquid ammonia is preferable.

The silicon imide or silicon amide produced by the method of the present invention can be considered to be one in which an amine residue is bonded to the silicon atom of the silazane produced by the reaction of halosilane and ammonia.

This silazane has a linear, cyclic, composite structure, or crosslinked structure having 5t-N bonds, 5i-N-N bonds, etc. in the main chain, and the amine residue has a 5t-N bond as a side group.
It can also be present in the main skeleton. In the method of the present invention, at least the amine residue is accompanied by an organic group, so that the silicon imide or silicon amide forming the obtained silicon nitride precursor contains a predetermined ratio (St/C ratio of 1 to 100) of organic groups. . Furthermore, the molecular weight of silicon imide or silicon amide varies over a wide range depending on the type of starting materials and reaction conditions, ranging from low molecular weight to very high molecular weight fi.
(For example, as calculated from the results of electron microscopic observation of the product, there are various types, including those with a three-dimensional irregular network structure of 3.8 million or more).

Regarding silicon nitride precursors that do not contain (organoamino)silane, the applicant has disclosed Japanese Patent Application Laid-Open No. 60-145903.
No. 60-260406 and patent application No. 60-2
57824 and other documents disclose its manufacturing method or product. Also, regarding the product of the analogue, R, R,
Wills, R.A., Markle, and S.P.
, Mukherie et al.
etin Vol, 62. Fish 8. pages 904-915 (1
983) describes the chemical structure.

The silicon imide or silicon amide thus synthesized by the method of the present invention is a suitable precursor for the production of silicon nitride, and is carried out at temperatures ranging from 600°C to 1300°C under an atmosphere of inert gas or reducing gas or a mixture of both. If the temperature is raised to 1,300° C. to 1,700° C. for firing, and the temperature is further raised to a temperature in the range of 1,300° C. to 1,700° C. for crystallization, an isotropic silicon nitride powder containing almost no needle crystals can be obtained.

Nitrogen, argon, etc. can be used as the inert gas, and hydrogen, ammonia, carbon oxide, etc. can be used as the reducing gas.

In the heat treatment, the temperature is first raised to a temperature in the range of 600 to 1300° C. to scatter organic groups, halogen atoms, etc. from silicon imide or silicon amide, and mainly produce amorphous silicon nitride.

When the temperature is then raised to a temperature in the range of 1300 to 1700°C, crystalline silicon nitride powder can be obtained.

Silicon nitride as the raw material powder for the silicon nitride sintered body is generally highly pure and preferably has an α-type crystal structure. This is because when α-phase is used as a raw material, a transition from α-phase to β-phase occurs during the sintering process, resulting in improved sinterability and development of a fibrous structure, resulting in high-strength silicon nitride. This is because a sintered body of

In order to obtain a silicon nitride powder in which 90% or more is α-type and has extremely excellent sinterability using the silicon imide or silicon amide produced according to the present invention in a high yield, it is necessary to °C preferably 9
The temperature is raised to 00 to 1200°C and held for 30 minutes or more to scatter organic groups, halogen atoms, etc., and mainly produce amorphous silicon nitride. Next, the temperature is raised to 1300 to 1700°C, preferably 1450 to 1650°C (preferably at a temperature increase rate of 15°/1 Ilin or more), and the temperature is increased to 1450°C.
℃ for more than 2 hours, 1650℃ for less than 10 minutes, 145
By holding the temperature in the temperature range of 0° C. to 1650° C. for a period of 1 minute or more and 3 hours or less, an isotropic crystalline silicon nitride powder containing no needle crystals can be obtained.

[For production]

1 used in the present invention in the process of synthesizing silicon imide or silicon amide, which is a precursor of silicon nitride.
(Organoamino)silanes, which are the reaction products of primary or secondary amines and halosilanes, also serve as a carbon source and are homogeneously distributed in the precursor during the heating process to form crystal growth inhibitors and Acts as an oxidation inhibitor. It is believed that this made it possible to produce isotropic silicon nitride powder containing almost no acicular crystals.

〔Example〕

Force j-8iCI Anilin・Si/C=10/1)
(1) Inner volume of precursor synthesis for producing silicon nitride: 50
A gas blowing tube, a mechanical stirrer, a dewar condenser, and a dropping funnel were installed in a 0 ml four-bottomed flask, and after the reaction system was replaced with nitrogen, 20 ml (174 mmol!) of silicon tetrachloride and 220 ml of dry toluene were placed in the four-bottom flask. was added and kept at ice temperature. When a mixed solution of 40 mf of dry pyridine and 200 mβ of dry toluene was dropped into the mixture from the dropping funnel, a white complex slurry of silicon tetrachloride and pyridine was produced. Next, 0.25 ml (2.74 m
A mixture of mol) and 10 ml of dry toluene was added dropwise from the dropping funnel.

Next, 84 g of ammonia was mixed with nitrogen and blown into the reaction product over a period of 5 hours while the reaction product was kept at 15 to 25°C and stirred vigorously. After the reaction was completed, pyridine and the solvent were removed under reduced pressure (15 mmHg; 60°C) to yield a solid product of 47.3
g was obtained. This is a yield of 99.4 based on silicon tetrachloride.
Corresponds to %. No pine dew was produced during the entire reaction, and there were no blockages in the gas flow path or ammonia supply port.

22.2g of dried reaction product with an internal volume of 200mj! The mixture was transferred to a liquid ammonia cleaning device in a nitrogen bag and washed five times with 110 mf of liquid ammonia to remove by-product ammonium chloride to obtain 3.88 g of a precursor for producing silicon nitride.

(2) Transfer 1.65 g of the firing precursor in a nitrogen bag to a carbon firing boat, and the furnace tube is made of high-purity aluminum → Inside the tubular furnace under nitrogen flow (21/m1n), temperature increase at 600°C/hr. The temperature was raised to 1000°C at a rapid rate and left for 3 hours. The product obtained after cooling to room temperature was a white powder with a nitrogen content of 37.9%.
According to powder X-ray diffraction and infrared spectroscopic analysis, 1.22 g of amorphous silicon nitride was recovered.

Next, this amorphous silicon nitride powder 1. The OOg was transferred to a carbon boat made of the same material, and heated to 1480°C at a heating rate of 3000°C/hr under a nitrogen stream in a Tammann furnace.
It was left for 1 minute. After cooling to room temperature, 0.90 g of white silicon nitride powder as shown in Table 1 was obtained.

When this powder was observed using an electron microscope, isotropic particles with a diameter of approximately 1 μm were mainly observed.

--2SiC1 Aniline: 5iC=21) 20 ml (174 mmol) of silicon tetrachloride and 1 ml (11 mmol) of aniline as a -class amine were used as raw materials, and the ratio of silicon to carbon was 2 (St/C・2 /1) Synthesis and firing were performed in the same manner as in Example-1,
The obtained amorphous silicon nitride powder was heated to 1500°C at a temperature increase rate of 6000°C/hr under a nitrogen stream in a Tammann furnace and held for 20 minutes. After cooling to room temperature, 0.90 g of yellowish white powder was obtained.

Table 1 shows the X-ray diffraction results and the elemental analysis results for N, C, and 0. Observation of this powder using an electron microscope shows that
Isotropic silicon nitride particles with a diameter of about 1 μm were obtained.

'l 3 5tC1a error: Si/C=5
0/1) A gas blowing tube, a mechanical stirrer, a dewar condenser, and a dropping funnel were installed in a four-loaf flask with an internal volume of sooml, and the inside of the reaction system was replaced with nitrogen.
20 ml of silicon tetrachloride (174 mm
ol) and 220 ml of dry toluene were added and kept at ice temperature. Here, 0.05 m of dry aniline was added from the dropping funnel so that the ratio of silicon in the raw material silicon halide to carbon in the amine was 50 (Si/C = 50).
When a mixture of 1 (0.55 mmol) and 5 mA of dry toluene was added dropwise from the dropping funnel, the solution became slightly cloudy and (organoamine)silane was produced. From the dropping funnel, add 40 ml of dry pyridine and 2 ml of dry toluene.
When the mixture with 00 m 6 was added dropwise, a white complex slurry of silicon tetrachloride and pyridine was produced. Thereafter, a silicon nitride production precursor was obtained in the same manner as in Example-1.

The obtained silicon nitride precursor was heated in a Tammann furnace under a nitrogen stream for 6 hours.
Raise the temperature to 600°C at a heating rate of 00°C/hr, hold for 3 hours, then raise the temperature to 1650°C at a heating rate of 6000°C/hr.
After raising the temperature to
．． 63g was obtained.

When this powder was observed under an electron microscope, it was found that about 10% of the isotropic particles with a diameter of about 1 μm were mixed with needle-shaped crystals with a diameter of about 0.5 μm and a length of about 20 μm.

・Method 1 4 (SiCI4/(CzH5)JH:
Si/C=10/1) silicon tetrachloride 20 ml (17
4m mol) and diethylamine as secondary amine 0
．． Using 33mβ (3.2m mol) as a raw material, synthesis and firing were performed in the same manner as in Example-1 so that the ratio of silicon to carbon was 10 (Si/C = 10/1), and the obtained Amorphous silicon nitride powder was heated in a Tammann furnace under a nitrogen stream for 60 minutes.
The temperature was raised to 1600°C at a heating rate of 00°C/hr, and
Hold for minutes. After cooling to room temperature, 0.29 g of a pale powder was obtained. Table 1 shows the X-ray diffraction results and the elemental analysis results for N, C, and 0.

Observation of this powder using an electron microscope shows a diameter of approximately 1 μm.
Isotropic silicon nitride particles with a diameter of about 0.3 μm and a length of 10~
Approximately 20% of needle crystals with a diameter of 20 μm were present.

1 5 (SiHCI Ayun 1: SiC・12/1
20 ml (198 m mol) of silicon trichloride and 0.25 mj of aniline as a -grade amine! (2,74m
mol) as the raw material, and the ratio of silicon to carbon is 12
(SiC14/1) was obtained by repeating the same operation as in Example 1 to obtain 0.192 g of a white-yellow powder as shown in Table 1.

Observation of this powder using an electron microscope shows a diameter of approximately 1 μm.
Isotropic silicon nitride particles were mainly observed.

-6(SiC14/n-propylamine・S
i/C=1/1) 20 ml (174 mmol) of silicon tetrachloride and 4.7 ml (6 ml) of n-propylamine as a -class amine.
The same operation as in Example 4 was repeated except that 1m mol) was used as the raw material and the reaction was carried out so that the ratio of silicon to carbon was 1 (Si/C = 1/1). 1.92 g of white-yellow powder was obtained as shown.

Observation of this powder using an electron microscope shows that isotropic silicon nitride particles with a diameter of approximately 1 μm have a diameter of approximately 0.5 μm and a length of 20 to 30 μm.
Approximately 5% of μm needle crystals were present.

? I-7 (SiHCI 50) SiHC1 (
50)/Ayun: St/C・10/1) Silicon trichloride 10 m/ (Loom mat), silicon dichloride 8.5 ml (100 m mol) and -
0.36 mJ (4 m
mol) as the raw material, and the ratio of silicon to carbon is 1.
0 (S i/C = 10/1), and the resulting amorphous chamber silicon nitride powder was heated at 3000'C/1 in a nitrogen stream in a Tammann furnace.
The temperature was raised to 1400°C at a heating rate of hr and held for 30 minutes. After cooling to room temperature, 0.57 g of white silicon nitride powder as shown in Table 1 was obtained.

When this powder was observed using an electron microscope, isotropic particles with a diameter of approximately 1 μm were mainly observed.

--85iC1, 5iCHC1 Ayun.

20 ml (174 m mol) of silicon tetrachloride, 1 ml (5.2 m mol) of methyltrichlorosilane and 0.22 mj of dry aniline as -grade amine! (
The silicon nitride precursor obtained was synthesized in the same manner as in Example-1 using 2.5 mmol) as a raw material and the ratio of silicon to carbon was 10 (Si/C 10/1). 1 at a heating rate of 600°C/hr in a tube furnace under nitrogen flow.
The temperature was raised to 300°C, held for 3 hours, and then transferred to a Tamman furnace.
The temperature was raised to 1600° C. by 6000° C./hrO boundary temperature increase, held for 5 minutes, and then allowed to cool to room temperature, yielding 0.37 g of silicon nitride powder with colors as shown in Table 1.

When this powder was observed using an electron microscope, isotropic particles with a diameter of about 1 μm were observed.

-1l 9 (SiCIm/Ani1in, Ayu/C・1
0/1) A gas blowing tube, a mechanical stirrer, a dewar condenser, and a dropping funnel were installed in a four-loaf flask with an internal volume of 300 ml, and after purging the reaction system with nitrogen, 20 ml of silicon tetrachloride was placed in the four-loaf flask (
174 mmol) and 220 rrl of dry toluene were added, and this was kept at ice temperature. From the dropping funnel, add 0.25 ml (2.74 m mol
) and 10 ml of dry toluene was added dropwise from the dropping funnel.

Next, while keeping the reaction product at ice temperature and stirring vigorously, 75 g of ammonia was mixed with nitrogen and blown in over 4.5 hours. At that time, many plumes were generated and a lot of white product was deposited in the downstream line. Thereafter, cleaning and firing were performed in the same manner as in Example-1, and the obtained amorphous silicon nitride was heated at a heating rate of 6000°C/hr in a Tammann furnace under a nitrogen stream.
The temperature was raised to 500°C and left for 5 minutes. After cooling to room temperature, white silicon nitride powder 0.2 as shown in Table 1 was added.
5g was obtained.

When this powder was observed under an electron microscope, isotropic particles with a diameter of about 1 μm were mainly produced.

' l 1 (SiC1t) (1) Inner volume of precursor synthesis for producing silicon nitride 1
A gas blowing tube, a mechanical stirrer, a dewar condenser, and a dropping funnel were installed in a 000 ml four-bottle flask, and after purging the reaction system with nitrogen, 35 ml (305 m mol) of silicon tetrachloride was placed in the four-bottom flask.
, 385 ml of dry toluene was added, and this was kept at ice temperature. Next, a mixture of 7Qml of dry pyridine and 350ml of dry toluene was added dropwise from the dropping funnel.
A white complex slurry of silicon tetrachloride and pyridine was produced.

Next, 90.5 g of ammonia was mixed with nitrogen and blown into the reaction product over a period of 5 hours while the reaction product was kept at 15 to 25°C and stirred vigorously. After the reaction, pyridine and the solvent were removed under reduced pressure (15 mmt (g 60°C)) to give a solid product of 82.
3g was obtained. This is a yield of 99.99% based on silicon tetrachloride.
This corresponds to 3%. No pine dew was produced during the entire reaction, and there were no blockages in the gas flow path or ammonia supply port.

32.5 g of the dried reaction product was placed in an inner volume of 200 m/
The mixture was transferred to a liquid ammonia cleaning device in a nitrogen bag and washed five times with 160 ml of liquid ammonia to remove by-product ammonium chloride to obtain 5.19 g of a precursor for producing silicon nitride.

(2) 1.34 g of the calcined precursor was transferred to a carbon boat in a nitrogen bag, and the furnace tube was heated to 1000°C at a heating rate of 600°C/hr under nitrogen flow in a high-purity alumina tubular furnace. death,
It was left for 3 hours. After cooling to room temperature, the obtained product was a white powder with a nitrogen content of 33.5% and 0.8% of amorphous silicon nitride according to powder X-ray diffraction and infrared spectroscopy.
5g was recovered.

Next, 2.20 g of this amorphous silicon nitride powder was transferred to the same carbon firing boat and heated in a Tammann furnace under a nitrogen stream for 3
The temperature was raised to 1500°C at a heating rate of 000"C/hr,
It was left for 20 ml. After cooling to room temperature, 1.61 g of crystalline silicon nitride powder as shown in Table 1 was obtained.

When observed using an electron microscope, this powder has a diameter of approximately 0.8 μm.
Acicular crystals with a length of 10 to 20 μm were mainly observed.

In-mold I 2 (SiHClz) The same operation as in Comparative Example-1 was repeated except that 38 ml (370 mmol) of silicon trichloride was used as the raw material, and a mixture of white silicon nitride precursor and ammonium chloride 76 was obtained as a reaction product. .5 g was obtained. This corresponds to a yield of 97.7% based on silicon trichloride. No pine dew was produced during the entire reaction, and there were no blockages in the gas flow path or ammonia supply port.

The dried reaction product was washed with liquid ammonia, and the silicon nitride precursor from which by-produced ammonium chloride was removed was fired in the same manner as in Comparative Example-1. 3000℃ in the Tammann furnace
The temperature was raised to 1600° C. at a heating rate of /hrO, and after cooling to room temperature without any holding time, 1.03 g of crystalline silicon nitride powder as shown in Table 1 was obtained.

When observed using an electron microscope, this powder has a diameter of approximately 0.8 μm.
Acicular crystals with a length of 10 to 30 μm were mainly observed.

Margin below [Effects of the Invention] As is clear from the above description, the present invention provides the following effects.

(a) Since the carbon source is uniformly mixed into silicon imide or silicon amide, which is a silicon nitride precursor,
By heating, highly purified α-type equiaxed silicon nitride powder containing almost no needle crystals and having a particle size on the order of submicrons can be easily obtained at a high yield.

(0) Even if the silicon nitride powder accidentally comes into contact with oxygen before or after heating, the amount of oxygen in the silicon nitride powder will not increase.

(c) Primary or secondary amines used as carbon sources are cheap, so they have little impact on production costs.

Claims (1)

[Claims] 1. Formula (I): R_lN_rH_2_r_+_1_-_l (I) (wherein R represents an aliphatic residue or an aromatic residue, and l is 1≦l)
It is an integer of ≦4, and r is 1 or 2. However, in the case of a cyclic nitrogen compound, l is 2 for r=1. ) at least one primary or secondary amine represented by the formula (II): R_mH_nSi_pX_(_2_p_+_2_-_(
_m_+_m_)_)(II) (wherein, R is an aliphatic residue or an aromatic residue, X is a halogen atom, and m is 0≦m
n is an integer such that 0≦n<2p+2, p is 1 or 2, and m+ n is an integer such that 0≦m+n<2p+2. ) is reacted with at least one type of halosilane represented by (1) at a ratio of silicon atoms to carbon atoms in a certain ratio within the range of 1 to 100 to partially produce (organoamino)silane,
A method for producing silicon imide or silicon amide, which comprises subsequently reacting the reaction mixture consisting of the (organoamino)silane and the halosilane with ammonia. 2. Before or after reacting the at least one halosilane with the at least one primary or secondary amine, the at least one halosilane or the at least one halosilane and the at least one halosilane produced in part by the reaction. 2. The method according to claim 1, further comprising the step of reacting said (organoamino)silane with a base that does not react with it other than to form an adduct to produce a mixture of these adducts. 3. Formula (I): R_lN_rH_2_r_+_1_-_l(I) (wherein, R represents an aliphatic residue or an aromatic residue, and l is 1≦
l is an integer of 4, and r is 1 or 2. However, in the case of a cyclic nitrogen compound, l is 2 for r=1. ) and at least one primary or secondary amine of the formula (II): R_mH_nSi_pX_(_2_p_+_2_-_(
_m_+_n_)_)(II) (wherein, R is an aliphatic residue or an aromatic residue, X is a halogen atom, and m is 0≦m
n is an integer such that 0≦n<2p+2, p is 1 or 2, and m+ n is an integer such that 0≦m+n<2p+2. ) is reacted with at least one type of halosilane represented by (2) at a ratio in which the atomic ratio of silicon atoms to carbon atoms is within the range of 1 to 100 to partially produce (organoamino)silane,
Production of silicon nitride powder, characterized in that a reaction mixture consisting of the (organoamino)silane and the halosilane is reacted with ammonia to obtain silicon imide or silicon amide, and the purified and recovered silicon imide or silicon amide is heat treated. Method. 4. Before or after reacting the at least one halosilane with the at least one primary or secondary amine, the at least one halosilane or the at least one halosilane and the at least one halosilane formed in part by the reaction. 4. The method according to claim 3, further comprising the step of producing adducts by reacting said (organoamino)silane with a base that does not react with any reaction other than to form adducts. 5. In order to obtain silicon nitride powder from the silicon imide or silicon amide, silicon imide or silicon amide is first calcined at a temperature of 600 to 1300°C in an atmosphere of an inert gas, a reducing gas, or a mixed gas of both. to obtain amorphous silicon nitride, then 1300
4. The method according to claim 3, wherein crystalline silicon nitride is obtained by firing at a temperature of ~1700<0>C.