JPS61219800A - Production of silicon carbide whisker - Google Patents

Abstract

PURPOSE:To obtain the titled whisker large in the aspect ratio at the low reaction temp. by charging both the sulfide grains of Si and the sulfide grains of Al in a specified reaction vessel and feeding a gaseous mixture of H2 and gaseous hydrocarbon under the heating. CONSTITUTION:After charging the spherical sulfide grains 4 of Si having 0.2-0.5mm diameter and the spherical sulfide grains 5 of Al having 0.2-0.5mm diameter so that the height ratio of the grains 4 and the grains 5 is regulated to about 50:1 in a reaction vessel 1 which is provided with a perforated plate 2 having plural gas blow-off ports 3 of about 0.1mm diameter to a base part, these are heated at 1,100-1,500 deg.C and held and a gaseous mixture of >=90% H2 and <=10% gaseous hydrocarbon (e.g. propylene) is fed in about 500cm<3>/min flow velocity through the gas blow-off port 3, and the SiC whiskers 6 are deposited and grown on the upper part of the sulfide grains 4 of Si and the sulfide grains 5 of Al.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing silicon carbide whiskers, and more specifically, to a method for producing silicon carbide whiskers, and more specifically, to a method for producing silicon carbide whiskers.
The present invention relates to a method for producing silicon carbide whiskers that can be suitably applied as reinforcing fibers in FRC, etc.).

[Conventional technology]

The basic technology for producing whiskers, which are single-crystal fibers, is based on a chemical reaction between a gas phase and a gas phase containing chemical species consisting of constituent elements that form the whisker.

Specifically, in the case of manufacturing conventional silicon carbide whiskers, there are two methods:
No. 00125, JP-A-57-101000, etc.).

That is, at a high temperature of 1350 to 1600°C, gaseous SiO and CO generated from the mixture of the above components produce the following: SiO* + CO= SiO+ COaS
I O+ 3 CO-S i C+ 2 COt3G+
A method for producing silicon carbide whiskers by precipitating and growing silicon carbide whiskers through a second step reaction based on the chemical reaction shown by 3CO2=6CO ・■ CHtSiCl
A method for producing silicon carbide whiskers by thermal decomposition of an organosilicon compound such as

■ By silicon tetrachloride, carbon tetrachloride and hydrogen, 5iC1
, +cC14+4H2=sic+8C1 A method for producing silicon carbide whiskers by a gas phase reaction of halide and hydrogen or hydrocarbon gas (for example, JP-A-58-49697, etc.).

The following methods have been adopted.

[Problem that the invention seeks to solve]

In view of the current state of the conventional technology as described above, the problem that the present invention attempts to solve is that in the conventional method for producing silicon carbide whiskers, not only the reaction temperature for producing silicon carbide whiskers is high; It has been difficult to mass-produce silicon carbide whiskers with a large length-to-diameter ratio, or so-called aspect ratio.

Therefore, the technical problem of the present invention is to heat and maintain a reaction vessel loaded with silicon sulfide particles and aluminum sulfide particles at 1100 to 1500°C, and to By supplying a mixed gas of hydrogen and hydrocarbon gas from multiple gas outlets,
This is because not only can the reaction temperature be lowered compared to conventional silicon carbide whisker manufacturing methods, but also mass production is possible, and moreover, it is possible to efficiently manufacture silicon carbide whiskers with a large aspect ratio. It is in.

[Means for solving problems]

In view of such problems in the conventional technology, the present invention provides a means for solving the problems in the conventional technology by using a porous bottom part of a reaction vessel in which a perforated plate having a large number of gas outlets is disposed at the bottom part. A step of loading silicon sulfide particles on a plate and loading and arranging aluminum sulfide particles on the upper layer thereof, and a reaction vessel loaded with silicon sulfide particles and aluminum sulfide particles as described above. , 1100-150
It consists of a step of heating and holding at 0°C and feeding a mixed gas of hydrogen and hydrocarbon gas from a large number of gas outlets bored in the perforated plate, and silicon sulfide particles and aluminum sulfide particles are removed. This method consists of producing silicon carbide whiskers, which is characterized by precipitating and growing silicon carbide whiskers above a layer loaded with particles.

[Effect]

Hereinafter, the effects of the present invention will be explained.

In the method for producing silicon carbide whiskers of the present invention, silicon sulfide particles and aluminum sulfide particles are used as vapor phase generating components for producing silicon carbide whiskers because the vapor pressure of the sulfide This is to increase the concentration of silicon vapor species for producing silicon carbide whiskers by taking advantage of the fact that is higher than the vapor pressure of the oxide.

Further, in the method for producing silicon carbide whiskers of the present invention, a reaction vessel loaded with silicon sulfide particles and aluminum sulfide particles is heated and held at 1100 to 1500°C, and the perforated plate is bored. The mixed gas of hydrogen and hydrocarbon gas is supplied from a large number of gas outlets.Silicon sulfide particles are vaporized at high temperature and the hydrogen and hydrocarbon gas undergo a chemical reaction. By using aluminum as a growth promoter for silicon whiskers, not only can the reaction temperature be lowered compared to conventional methods, but also mass production is possible, and moreover, silicon carbide whiskers with a large aspect ratio can be efficiently grown. This is to enable manufacturing.

In addition, in the method for producing silicon carbide whiskers of the present invention, silicon sulfide particles are first loaded into the reaction vessel, and aluminum sulfide particles are loaded and arranged in the upper layer because the chemical reaction gas is By including aluminum in the phase, a part of β-3iC (cubic crystal) that would grow in the absence of aluminum is converted into hexagonal crystal (2
This is to make it easier to maintain the shape of silicon carbide whiskers and to allow them to grow into very long whiskers.

Further, in the method for producing silicon carbide whiskers of the present invention, the reaction temperature for producing silicon carbide whiskers is set to 11
The temperature is set at 00-1500°C because the reaction rate is slow below 1100°C, and when it exceeds 1500°C, aluminum sulfide particles sublime and disappear, which is not desirable.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

The figure shows a situation in which silicon carbide whiskers are manufactured by the method of the present invention.

First, silicon sulfide particles 4 having a diameter of 0.2 to 0.51 mm are obtained by granulating silicon sulfide particles with an average particle size of 15 μm, and the diameter is as shown in FIG. 80 cranes were loaded into a silicon carbide reaction vessel 1 with a height of 400 m,
Aluminum sulfide particles with an average particle size of 4 μm are granulated in the upper layer of the silicon sulfide spherical particles 4 to have a diameter of 0.2 to 0.0 μm.
5 Aluminum sulfide spherical particles 5 having the size of a fin,
Silicon sulfide spherical particles 4 and aluminum sulfide spherical particles 5
The layers were loaded and arranged at a layer height ratio of 50:1.

Then, on the perforated plate 2 arranged at the bottom of the reaction vessel l,
It has a large number of gas outlets 3 with a diameter of 0.1 tar, and only hydrogen is supplied to the inside of the reaction vessel l via the gas outlets 3 until the reaction temperature in the reaction vessel 1 reaches 1100°C. After the reaction temperature reached the above reaction temperature, a mixed gas of hydrogen and hydrocarbon gas was fed.

As the hydrocarbon gas, methane, propane, propylene, acetylene, benzene, toluene, methyl ethyl ketone, etc. can be suitably used, but among the above hydrocarbon gases, when propylene and benzene are used, silicon carbide The whisker yield was excellent.

Further, the concentration of hydrocarbon gas relative to hydrogen is preferably 10% or less, and as the concentration of hydrocarbon gas becomes higher, soot becomes mixed.

In the case of acetylene, it was effective at low concentrations.The gas flow rate was 500 c4/min and the temperature was 13.
The silicon carbide whiskers 6 produced under the conditions of 0Q"C, propylene and 7% have a diameter of 5 to 10 μ and a length on the order of several CnI, and are silicon carbide whiskers produced by the usual conventional method G. Compared to those of several hundred microns,
Silicon carbide whiskers with a significantly large aspect ratio could be produced.

[Effects of the Invention] As is clear from the above, according to the method for producing silicon carbide whiskers according to the present invention, a reaction vessel loaded with silicon sulfide particles and aluminum sulfide particles is heated to 11
．． By heating and holding at 00 to 1,500°C and supplying a mixed gas of hydrogen and hydrocarbon gas from a large number of gas outlets provided in the perforated plate, the conventional method for producing silicon carbide whiskers can be applied. In comparison, not only can the reaction temperature be lowered, but also mass production is possible.
Moreover, there is an advantage that silicon carbide whiskers with a large aspect ratio can be efficiently produced.

[Brief explanation of drawings]

The figure shows a situation in which silicon carbide whiskers are manufactured by the method of the present invention. 1-・-・-Reaction container. 2.---perforated plate. 3------Gas outlet. 4-...Silicon sulfide spherical particles. 5.----mono-aluminum sulfide spherical particles. 6-------Silicon carbide whiskers. Applicant: Toyota Motor Corporation 1 - Container 2 - Paste plate 3 - η Also air outlet 4 - Raw 41 group monster ball F4 large vertical 2 ± 5-7 Luminous two i - Calm itm Tamara Deshaku〕iΣ Chiro J I Otsuji Bag Tsu Inuka-

Claims (1)

[Scope of Claims] 1. Silicon sulfide particles are loaded onto the bottom perforated plate of a reaction vessel in which a perforated plate having a large number of gas outlets is disposed at the bottom, and aluminum sulfide particles are loaded onto the bottom perforated plate. The reaction vessel loaded with silicon sulfide particles and aluminum sulfide particles as described above is heated and held at 1100 to 1500°C, and a large number of holes bored in the perforated plate are The process consists of feeding a mixed gas of hydrogen and hydrocarbon gas from the gas outlet, and silicon carbide whiskers are precipitated and grown on the upper part of the layer loaded with silicon sulfide particles and aluminum sulfide particles. A method for producing silicon carbide whiskers, the method comprising: