JPH0613439B2 - Silicon carbide whisker manufacturing method and manufacturing apparatus thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a silicon carbide whisker, and more particularly to a method for manufacturing a highly efficient silicon carbide whisker that can be mass-produced at low cost.

The second aspect of the present invention relates to a manufacturing apparatus capable of implementing the method for manufacturing a silicon carbide whisker.

[Prior Art] The following three methods are mainly known as conventional methods for manufacturing silicon carbide whiskers. The first method is a method in which silicon dioxide (silica gel) and charcoal (furnace carbon black) are reacted in the presence of salt or the like to synthesize (JP-A-58-145700). As the second method, there is known a synthetic method in which organic silicon produced by the reaction of silicon tetrachloride or the like with a hydrocarbon is thermally decomposed (Japanese Patent Laid-Open No. Sho 5).
7-123813). A third method is known in which metallic silicon, hydrogen sulfide, sulfur, and hydrocarbons such as propane are reacted in a reaction furnace to synthesize them (Showa 61).
Annual Ceramic Society Annual Meeting Proceedings P. 21).

[Problems to be Solved by the Invention] The first manufacturing method is not suitable for mass production because it consumes a large amount of electric power. Further, the second method is not suitable for mass production because the raw material cost is high. Although the third method is relatively advantageous in terms of cost, it is known that silicon carbide whiskers cannot be produced unless hydrogen sulfide and sulfur are used without fail. Therefore, it is not preferable to use this hydrogen sulfide as a raw material because a harmful raw material is used. Further, hydrogen sulfide and sulfur gas are generated in the exhaust gas, which is not preferable, and since two kinds of sulfur sources are required as raw materials, a manufacturing apparatus is required. It is not preferable because it becomes complicated.

The first invention and the second invention overcome the above-mentioned drawbacks, respectively, and provide a method for manufacturing a silicon carbide whisker and a manufacturing apparatus therefor, which can be manufactured at low cost by using an inexpensive raw material source and the like. The purpose is to do.

[Means for Solving the Problems] In the method for manufacturing a silicon carbide whisker of the first aspect of the present invention, the first step of heating the sulfur to generate sulfur vapor and supplying a carrier gas to the sulfur vapor and the carrier gas is performed. A first step of producing a raw material gas; and a second raw material gas containing silicon sulfide gas by supplying the first raw material gas while heating silicon metal to react the silicon metal with the sulfur vapor in the first raw material And a second raw material gas and a third raw material gas containing a hydrocarbon are mixed to react the silicon sulfide gas with the hydrocarbon to produce silicon carbide and a silicon carbide whisker is produced. And a process.

The first step is a step of producing a first source gas of sulfur vapor and carrier gas. Various sulfur can be used as the sulfur raw material. Further, the temperature at which the sulfur vapor is generated is sufficient if it is the temperature at which the sulfur vapor is generated, and is usually higher than the temperature near the melting point of sulfur. This temperature is 100 ~
The temperature is preferably about 500 ° C. The temperature above 100 ° C is to generate necessary sulfur gas, and 500 ° C
The following is to suppress the generation of excessive sulfur gas. A non-oxidizing gas can be used as the carrier gas, and an inert gas such as argon or helium, a reducing gas such as hydrogen, or a mixed gas thereof can be used as the non-oxidizing gas. Further, exhaust gas containing an inert gas or the like can be used as the carrier gas.

The second step is a step of producing a second raw material gas containing silicon sulfide gas. The form of this silicon metal is not particularly limited, and a powdery one is usually used, but a square blocky one or the like may be used. The temperature at which the silicon metal is heated may be any temperature at which the metal can be activated and reacted with sulfur vapor. Usually this temperature is 800-1200
C is preferred. At this temperature, grain growth of the silicon powder is less likely to occur, the activity of the powder surface can be increased, and the silicon sulfide produced can be easily sublimated and continuously proceed to the next step. . If the temperature is lower than 800 ° C., the deep inside of silicon is not sufficiently activated, and if the temperature exceeds 1200 ° C., grain growth is not preferable.

The third step is a step of making a silicon carbide whisker. The third source gas is a gas containing hydrocarbon. This gas may be a hydrocarbon alone or may contain a carrier gas such as an inert gas. As this hydrocarbon, methane, ethane, propane, butane, etc. are used,
Any hydrocarbon can be used as long as it becomes a gas under the reaction conditions. The nucleus for growing the silicon carbide whiskers may be a substrate made of alumina, zirconia, or the like, or a fine metal or metal compound may be arranged on the substrate. It may be particles suspended inside. Usually, a metal chloride or the like is used as the material of this core.

It is preferable to carry out the first step, the second step and the third step continuously.

Further, it is preferable to continuously use, as the carrier gas in the first step, the exhaust gas containing the sulfur vapor and the carrier gas which are continuously discharged after the third step. this is,
Although it can be applied to the case where the first step, the second step and the third step are discontinuous, it is preferable to apply them when these steps are continuous. In this case, it is possible to prevent the effective use of raw materials and the emission of sulfur which is a pollution source. In this case, the recycled exhaust gas is kept at a temperature above its boiling point so that the sulfur does not solidify. When only the non-oxidizing gas or the like as the carrier gas is reused, the recovered gas after cooling to remove sulfur can be reused.

After the third step, it is preferable to have a sulfur separation step of cooling to below the melting point of the exhaust gas discharged from the third step and solidifying and separating sulfur. If other sulfur compound gas is generated, it can be removed as a solid such as sulfur. This is because it is preferable to remove sulfur or the like, which is a pollution source.

An apparatus for manufacturing a silicon carbide whisker according to the second aspect of the present invention has a heating means, a carrier gas inlet, and a first source gas outlet for outlet of a first source gas containing sulfur vapor. A first source gas generator for heating to generate sulfur vapor to produce the first source gas; heating means; a first source gas inlet connected to the first source gas outlet; and a silicon sulfide gas A second raw material gas outlet for leading out a second raw material gas, and heats the silicon metal powder disposed inside, and reacts the sulfur vapor in the first raw material gas with the heated silicon metal. A second raw material gas generator for synthesizing silicon sulfide to produce a second raw material gas, heating means, a second raw material gas inlet connected to the second raw material gas outlet, and an exhaust gas containing sulfur or the like Of the exhaust gas that leads to the And a third raw material gas containing the hydrocarbon, and the silicon sulfide gas and the hydrocarbon are reacted with each other to form silicon carbide and a silicon carbide whisker. And a silicon carbide whisker synthesizing device for making the same.

This manufacturing apparatus is for carrying out the method for manufacturing a silicon carbide whisker of the first invention. This manufacturing device is the first
As shown in the figure, it has a first source gas generator 1, a second source gas generator 2 and a silicon carbide whisker synthesizer 3. In the following description, the device will be mainly described,
The conditions for carrying out this device are the same as those described for the above manufacturing method.

The first raw material gas generator is an apparatus that heats sulfur to generate sulfur vapor and introduces a carrier gas to produce a first raw material gas. A Kanthal wire heater can be used as the sulfur heating means. Further, this apparatus is made of a corrosion-resistant and heat-resistant material such as a corrosion-resistant alloy.

The second raw material gas generation device is a device for producing a second raw material gas by reacting sulfur vapor with heated and activated silicon metal to synthesize silicon sulfide. As a heating means for heating the silicon metal, a Kanthal wire heater can be used. A high-purity alumina tube or the like can be used as the material of this device.

The silicon carbide whisker synthesizing apparatus described above uses the second source gas and the third source gas
This is an apparatus for mixing a raw material gas and reacting a silicon sulfide gas with a hydrocarbon to produce silicon carbide, and at the same time, producing a silicon carbide whisker. A Kanthal wire heater can be used as a heating means for heating the synthesizer. Further, this manufacturing apparatus has means for disposing a predetermined nucleus for manufacturing silicon carbide whiskers in advance.

In the present manufacturing apparatus, the first raw material generator, the second raw material gas generator, and the silicon carbide whisker synthesizer may not be continuous, but are preferably continuous.
In particular, it is more preferable that the second source gas generator and the silicon carbide whisker synthesizer are continuous. Further, it is preferable that the second raw material gas generation container and the whisker synthesis container are integrated.

As shown in FIG. 2, the present manufacturing apparatus is equipped with a cooling device for cooling the exhaust gas containing the sulfur vapor and the carrier gas discharged from the whisker manufacturing apparatus 3 to the melting point of sulfur or lower, and solidifying the sulfur vapor. It is possible to have a sulfur separator 4 that cools and solidifies the sulfur vapor to separate it. Further, in this manufacturing apparatus, an exhaust gas reuse apparatus 5 for returning exhaust gas containing sulfur vapor, carrier gas, etc., continuously discharged from the whisker manufacturing apparatus 3 to the first raw material gas generation apparatus 1
Can have Further, the exhaust gas re-use device may be a device that returns the exhaust gas after sulfur removal generated via the sulfur separation device to the first raw material gas generation device. In this case, exhaust gas containing mainly non-oxidizing gas after sulfur removal is effectively reused. This exhaust gas reuse device is, for example, as shown in FIG.
And a pipe 51 communicating with the exhaust gas outlet 33 and the carrier gas inlet 12 of the first raw material generator 1;
And a fan 52 disposed in the middle of.

This manufacturing apparatus may have a carrier gas supply device 6 for supplying a carrier gas into the first raw material gas generation device 1 as shown in FIG. Similarly, a hydrocarbon feed device 7 for feeding hydrocarbons into the silicon carbide whisker synthesizer 3 may be provided.

[Effects of the Invention] The method for producing a silicon carbide whisker of the present invention comprises:
Since silicon metal and hydrocarbon are used as raw materials, silicon carbide whiskers can be manufactured inexpensively and in large quantities. According to this manufacturing method, an inexpensive silicon carbide whisker can be manufactured.
It is extremely useful for manufacturing silicon carbide whiskers for C (fiber reinforced ceramics) and the like.

Further, when the reaction temperature for synthesizing silicon sulfide in the present production method is 800 to 1200 ° C., the produced silicon sulfide is sublimated one after another and can be easily transported to the next step. The second step and the third step can be easily carried out continuously, and when they are carried out continuously, the silicon oxide whiskers can be manufactured at extremely low cost and with high efficiency.

Further, in the case where the present manufacturing method has the sulfur separation step or the exhaust gas reusing step, or both of these steps, since the sulfur component is basically not contained in the final exhaust gas discharged to the atmosphere, there is no pollution carbonization. Since it is a method for producing silicon whiskers and sulfur or carrier gas can be reused, raw materials and exhaust heat can be effectively used.

A manufacturing apparatus of the second invention is a first raw material gas generator, a second raw material gas generator, a silicon carbide whisker synthesizer,
Therefore, the manufacturing method of the first invention can be carried out by using the imaging device of the present invention. Therefore, the present manufacturing apparatus is a useful apparatus that enables inexpensive and large-scale production of silicon carbide whiskers.

Further, when the present manufacturing apparatus has a sulfur separation apparatus or an exhaust gas reusing apparatus capable of reusing sulfur gas or ha carrier gas, a pollution-free apparatus that eliminates sulfur emission or a manufacturing method that effectively uses sulfur or carrier gas Can be said to be a device that provides.

In the present manufacturing apparatus, when the silicon sulfide synthesis container forming the second raw material gas generator and the whisker synthesis container forming the whisker synthesizer are partitioned by a partition wall, contact between metallic silicon and hydrocarbon is avoided. Since the carbonization of metallic silicon can be eliminated and the metallic silicon can be effectively converted into silicon carbide whiskers, the present production method is a highly useful method with extremely high reaction efficiency of silicon.

[Examples] Hereinafter, the first invention and the second invention will be described by examples.

A schematic explanatory view of the apparatus used in this example is shown in FIG. This apparatus comprises a first source gas generator 1, a carrier gas supply unit 6, a second source gas generator 2, a silicon carbide whisker synthesizer 3, a hydrocarbon supply unit 7, and a sulfur separator 4. The exhaust gas recycling device 5 is included.

The first source gas generator 1 includes a sulfur generating container (made of stainless steel) 11 and a non-oxidizing gas inlet 12.
, First raw material gas outlet 13, and heating means (heater) 1
Have 4.

The carrier gas supply device 6 has a hydrogen supply source 61 and an argon supply source 64. These supply sources 61 and 64 are composed of needle valves 63 and 66 for adjusting the flow rate and pipes 62 and 65 leading to the inlet of the sulfur generator.

The second source gas generator is a heating means (heater) 24,
It has a silicon sulfide synthesis container (made of an alumina tube) 21, a first raw material gas inlet 22 at one end, and a second raw material gas outlet 23 at the other end. Also, an alumina board 2 for arranging silicon metal powder 25 therein
Have six.

The silicon carbide whisker synthesizing apparatus has a heater 34 and a whisker synthesizing vessel 31, an inlet 32 connected to the second raw material gas outlet 23 at one end, and an exhaust gas outlet 33 at the other end, and another. It has a hydrocarbon (third source gas) inlet 37 at one end. This whisker synthesis container 31 is the second
It is integrated with the source gas generation container 21 and made of the same material, and a partition wall 27 is provided between the two containers 21 and 31. An alumina substrate 36 is placed in this container 31.

The hydrocarbon supply device 7 has a hydrocarbon (propylene) supply source 71, a flow rate adjusting needle valve 73 attached to the tip thereof, and an inlet 37 of a silicon carbide whisker synthesizer attached to the outflow side of the bubble. The hydrocarbon outlet 71 is connected.

The sulfur separator 4 has an exhaust gas inlet 42 connected to the exhaust gas outlet 33 of the silicon carbide whisker synthesizer 3 at one end, and an exhaust gas outlet 43 for discharging to the atmosphere.
And the needle valve 43 following this and the exhaust pump 4
Have six.

The exhaust gas re-use device 5 is provided in the middle of the pipe connecting the silicon carbide whisker production device 3 and the sulfur separation device 4,
It has a pipe 51 connecting the source gas generator 1 and the hydrogen supply source 61, a pipe 51 connecting the same, and a fan 52 provided in the middle of the pipe 51.

Silicon carbide whiskers were manufactured by the following method using the above manufacturing apparatus. First, a sulfur generating container 1 made of a corrosion resistant alloy
A sulfur block 15 was placed in the reactor 1, and an alumina board was placed in a silicon sulfide synthesis container 21 composed of an alumina tube. 1 to 5 g of silicon metal powder 25 having an average particle size of about 100 μm was put into this alumina board. Further, an alumina substrate 36 was placed in the whisker synthesizing container 31.

After that, the air inside the series of devices was purged with argon gas and replaced with argon gas.

Using the heater 14 of the first raw material generator, the sulfur 1
5 was heated to 450 ° C. At the same time, the heaters 24 of the first raw material generating device 2 and the silicon carbide whisker manufacturing device 3,
34 was used to raise the temperature of the silicon metal powder 25 to 1200 ° C. and the temperature in the whisker synthesizing vessel 31 to 1300 ° C. or higher. After that, the argon gas is stopped and the needle valve 6 of the hydrogen supply source 61
3 was opened and hydrogen was allowed to flow out at a rate of 100 ml / min. The heated gas was circulated in the system through the fan 52.

Sulfur vapor generated in the sulfur generation container 11 is transported by hydrogen into the silicon sulfide synthesis container 21, and the sulfur vapor reacts with the silicon on the surface of the activated silicon metal powder 25 in the container 21 to generate silicon sulfide gas. Was generated.

At this time, propylene gas was caused to flow into the whisker synthesis vessel 31 through the hydrocarbon inlet 37 at a rate of about 5 to 10 ml / min. The propylene that has flowed in is reacted with the silicon sulfide gas that has been carried by the carrier gas and has flowed into the whisker synthesizing container 31 to generate silicon carbide, and silicon carbide grows based on the nuclei on the substrate 36, resulting in silicon carbide whiskers. Three
5 was synthesized.

A partition wall 27 was provided between the silicon sulfide synthesis container 21 and the whisker synthesis container 31 to prevent carbonization of the silicon powder.

It was returned to the first source gas generator 1 again through the pipe 51 heated at 500 ° C., and the sulfur, hydrogen, etc. were reused.

In addition, since only the amount of hydrogen obtained by decomposition from propylene in the exhaust gas is excess hydrogen in the system, about 15 to 30 ml / min of this exhaust gas was discharged through the fan 46. Cooling was performed to separate and recover sulfur in the gas at this time. Therefore, the final exhaust gas 48 is discharged through the cooling means 4. Cooling water is circulated in the cooling means 4.

After reacting for about 3 hours using the above-mentioned manufacturing apparatus, these apparatuses were cooled and the synthesis state of silicon carbide whiskers was examined.

Most of the metallic silicon powder 25 was consumed, and whitish silicon carbide whiskers 35 were densely formed on the substrate 36 in the whisker synthesizing container 31.

However, when the hydrogen gas is introduced by the hydrogen supply source 61 and the exhaust gas 48 is discharged by the exhaust gas fan 46, most of the sulfur 45 can be collected on the cooling surface of the sulfur separation device 4. .

According to the above manufacturing method using this manufacturing apparatus, whitish silicon carbide whiskers can be manufactured at a low cost, and most of the sulfur can be recovered by the cooling device, and the exhaust gas discharged to the atmosphere contains sulfur. Contains almost no ingredients. Therefore, according to these, the silicon carbide whiskers can be manufactured inexpensively and in large quantities, and there is no fear of pollution. Further, since most of the heat quantity is recovered by the exhaust gas reusing device, the exhaust heat can be effectively used and the energy cost can be reduced. Further, since a partition wall was provided between the whisker manufacturing container and the silicon sulfide synthesis container, it was possible to avoid contact between silicon powder and propane, so that carbonization of silicon could be eliminated and silicon could be effectively converted into whiskers. It was Further, since the manufacturing method using this manufacturing apparatus is continuous iron transportation, a large amount of silicon carbide whiskers can be continuously manufactured with high efficiency.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a silicon carbide whisker manufacturing apparatus including a first source gas generator, a second source gas generator, and a silicon carbide whisker synthesizer. FIG. 2 is an explanatory view of a silicon carbide whisker manufacturing apparatus which is obtained by adding a sulfur separator and an exhaust gas reusing apparatus to each apparatus shown in FIG. Third
The figure is an explanatory view of a silicon carbide whisker manufacturing apparatus in which a carrier gas supply apparatus and a hydrocarbon supply apparatus are added to each apparatus shown in FIG. FIG. 4 is a schematic explanatory view of a silicon carbide whisker manufacturing apparatus used in the examples. 1 ... First raw material gas generator 2 ... Second raw material gas generator 3 ... Silicon carbide whisker synthesizer 4 ... Sulfur separator 5 ... Exhaust gas reuse device 6 ... Carrier gas supply device 7 ... Carbonization Silicon supply device 14, 24, 34 ... Heating means (heater) 15 ... Sulfur 25 ... Silicon powder 27 ... Partition wall 35 ... Silicon carbide whisker 36 ... Alumina substrate 44 ... Cooling means 45 ... Recovered sulfur 61 ...... Hydrogen supply source 64 ...... Argon supply source

Claims (10)

[Claims] 1. A first step of heating sulfur to generate sulfur vapor and supplying a carrier gas to produce a first raw material gas of the sulfur vapor and the carrier gas; and a first step of heating silicon metal. A second step of supplying a source gas to react the silicon metal with the sulfur vapor in the first source to produce a second source gas containing a silicon sulfide gas; and a second step containing the second source gas and a hydrocarbon. 3. A method for producing a silicon carbide whisker, which comprises: mixing a raw material gas 3 and reacting the silicon sulfide gas with the hydrocarbon to form silicon carbide and producing a silicon carbide whisker. 2. The reaction temperature in the second step is 800-12.
The method for producing a silicon carbide whisker according to claim 1, wherein the temperature is 00 ° C. 3. The method according to claim 1, further comprising a fourth step of cooling the exhaust gas discharged from the third step below the melting point (113 ° C.) and solidifying and separating the sulfur after the third step. Manufacturing method of silicon carbide whiskers. 4. The method for manufacturing a silicon carbide whisker according to claim 2, wherein the first step, the second step and the third step are continuously carried out. 5. The method for producing whiskers according to claim 4, wherein the exhaust gas continuously discharged from the third step is continuously used as the carrier gas in the first step. 6. A heating means, a carrier gas inlet, and a first raw material gas outlet for discharging a first raw material gas containing sulfur vapor, which heats the sulfur arranged inside to generate sulfur vapor. A first raw material gas generator for producing the first raw material gas, heating means, a first raw material gas inlet connected to the first raw material gas outlet, and a second raw material gas containing silicon sulfide gas And a second source gas outlet port for heating the silicon metal powder disposed inside, and reacting the sulfur vapor in the first source gas with the heated silicon metal to generate silicon sulfide. A second raw material gas generator that synthesizes the second raw material gas, a heating means, a second raw material gas inlet connected to the second raw material gas outlet, and an exhaust gas that exhausts an exhaust gas containing sulfur or the like And a hydrocarbon introduction port for introducing hydrocarbons. A silicon carbide whisker synthesizing apparatus for mixing a source gas and a third source gas containing the hydrocarbon to react the silicon sulfide gas with the hydrocarbon to form silicon carbide and to produce a silicon carbide whisker. Characteristic silicon carbide whisker manufacturing equipment. 7. A sulfur separator provided with a cooling means for cooling the exhaust gas discharged from the silicon carbide whisker manufacturing apparatus to a melting point (113 ° C.) or less and for solidifying and separating the sulfur vapor. A method for producing a silicon carbide whisker according to item 6. 8. The production of a silicon carbide whisker according to claim 6, further comprising an exhaust gas re-use device for returning exhaust gas continuously discharged from the silicon carbide whisker production device to the first raw material gas generation device. apparatus. 9. The apparatus for manufacturing a silicon carbide whisker according to claim 6, further comprising a carrier gas supply device for supplying a carrier gas into the first source gas generation device. 10. The apparatus for manufacturing a silicon carbide whisker according to claim 6, further comprising a hydrocarbon supply device for supplying a hydrocarbon into the silicon carbide whisker synthesizer.