JPS5941772B2 - Ultrafine powder synthesis furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrafine powder synthesis furnace using a novel high frequency induction thermal plasma method.

In the conventional powder synthesis furnace using the high-frequency induction plasma method, a gas flow mainly composed of argon is used as thermal plasma, raw materials are introduced into this plasma flame, vaporization reaction takes place, and fine powder precipitated in the downstream region is collected. There is.

However, in the conventional method, the particle size of the powder obtained is 0.3~0.
It was difficult to obtain finer powder with a good yield of about 5 μm.

On the other hand, there is a strong need for ultrafine powder, and the development of highly efficient synthesis methods is strongly desired.

An object of the present invention is to provide an ultrafine powder synthesis furnace using a high-frequency induction thermal plasma method that can obtain powder with a particle size of 0.08 μm or less at a high yield.

The present invention provides a high-frequency induction heating coil, a nozzle for supplying gas to the inside of the coil, and a metal powder and a chemical substance formed between the metal powder and the metal powder during a plasma flame of the gas formed at the tip of the nozzle by heating by the coil. A device comprising a nozzle for supplying a reactive gas to be reacted and a container for collecting inorganic fine powder formed by a chemical reaction between the metal powder and the reactive gas, which corresponds to a tail frame portion of the plasma flame of the container. The ultrafine powder synthesis furnace is characterized in that a cooling gas introduction chamber is provided at a position where cooling gas is ejected to cool the plasma flame.

The present invention was made as a result of various experimental studies focusing on the fact that the size of powder particles formed in a powder synthesis furnace is easily controlled by the temperature gradient after the gas flow containing the raw material passes through the plasma. It has been discovered that ultrafine powder can be obtained by blowing cooling gas onto the tail frame portion of the frame.

The embodiment diagram is a cross-sectional configuration diagram showing an example of the ultrafine powder synthesis furnace of the present invention.

Argon is introduced into the plasma torch 2 from the introduction pipe 8, and
A thermal plasma flame 16 is generated at the bottom of the torch 2 using an induction coil 3 connected to a high frequency power source of MHz.

Hydrogen gas is introduced from the introduction pipe 9 for the purpose of preventing deposition of reactants on the inner wall of the torch 2.

Methane is introduced from the introduction pipe 7 into the raw material feeder 1 containing 325 meshes of silicon powder 18, and a mixture of the silicon powder 18 and methane is supplied into the thermal plasma flame 16.

A water-cooled metal tube 5 is installed in the container 6 downstream of the tail frame portion 17 of the plasma flame 16, and precipitates 19 are deposited on the upper end of the water-cooled metal tube 5 as shown in the figure.

The particle size of the precipitated powder when the conventional tail frame part 17 is not provided with the cooling gas introduction chamber 4 is 0.3 to 0.5μ.
It is a mixture of silicon carbide and carbon.

On the other hand, the tail frame portion 1 of the plasma flame 16
According to the present invention, the particle size of the precipitates is 0.08μ. The particle size of the precipitate can be controlled by further adjusting the supply amount of the quenching gas.

As a result of various studies, the inventors have found that the amount of quenching gas introduced is related to the amount of argon gas introduced from the introduction pipe 8.

That is, if the flow rate ratio of cooling gas and argon is less than 0.3/1, the pulverization effect will be small, and if it is less than 15/l, the plasma flame 16 will become unstable and it will be difficult to continue the synthesis reaction continuously.

Further, the cooling gas introduction chamber 4 is provided in the tail frame portion 1γ of the plasma flame 16, and is provided in the tail frame portion 1γ of the plasma flame 16.
It is necessary to provide it downstream from /2.

That is, if it is provided closer to the induction coil, thermal plasma is more likely to disappear, making it impossible to synthesize fine powder.

An example of synthesis of silicon carbide is shown below, but the resulting powder,
The raw material 2 reaction and cooling gas are not limited to this example, but can be applied to the synthesis of fine powders of oxides, nitrides, carbides, borides, etc.

According to the present invention, fine powder of 0.1 μm or less can be easily obtained, which has the effect of promoting the development of new materials for functional sintered bodies.

[Brief explanation of the drawing]

The figure is a schematic diagram illustrating the basic configuration of the present invention. 1... Raw material feeder, 2... Plasma torch, 3...
...Induction heating coil, 4...Cooling gas introduction chamber, 5.
...Water-cooled metal tube, 619. container, 710. Gas introduction pipe (
methane), 8, gas introduction pipe (argon), 9, 1
0. ...Gas introduction pipe (hydrogen), 11, 12.・・Water inlet pipe, 13° 14・・Drainage pipe, 15・Exhaust, 16・
...Plasma flame, 17. ,, tail frame part,
18..., metal powder.

Claims (1)

[Claims] 1 A high-frequency induction heating coil, a nozzle that supplies gas to the inside of the coil, a metal powder and a chemical reaction with the metal powder during a plasma flame of the gas formed at the tip of the nozzle by heating by the coil. A device comprising a nozzle for supplying gas and a container for collecting inorganic fine powder formed by a chemical reaction between the metal powder and the reaction gas, wherein the container is located at a position corresponding to the tail frame portion of the plasma flame. An ultrafine powder synthesis furnace characterized in that a cooling gas introduction chamber is provided for blowing out a cooling gas for cooling the plasma flame.