JPS62102827A - Production of metallic or ceramic fine grain - Google Patents

Abstract

PURPOSE:To continuously produce a metallic or ceramic fine grain having uniform grain size by introducing vapor of a metallic compd. or a gas reactive with this vapor into low-temp. plasma of gaseous atmosphere having specified pressure, decomposing and allowing it to react each other. CONSTITUTION:One or more of electrodes 2, 3 are provided to the inside of a reaction vessel 1 and a high frequency electric power source 4 is connected thereto and low-temp. plasma 5 is generated between the electrodes. The electrode 3 is connected to the reaction vessel 1 and furthermore grounded. A reaction gas 7 consisting of vapor of a metallic compd. [e.g. metallic carbonyl of Fe(CO)5] or a mixed gas of a gas 8 (e.g. O2 and NH3, etc.) reactive therewith is introduced into the inside of the reaction vessel 1 through the nozzles 6. Simultaneously it is exhausted by a vacuum pump 9 to maintain the pressure of the inside of the reaction vessel 1 in 10<-4>-50Torr. Thereby the reaction gas 7 is decomposed by plasma or allowed to react with the reactive gas 8 and associated and a metallic fine grain or a ceramic fine grain is accumulated to the grounded electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing metal, ceramic, or cus fine particles. More specifically, the present invention relates to a method for producing metal or ceramic particles using low-volume plasma.

Conventional technology Metal or ceramic using conventional plasma.

The manufacturing method of the gas particles is as follows: (1) Metal is heated and evaporated in a nitrogen atmosphere to generate metal particles, and then the metal particles are introduced into a low nitrogen plasma atmosphere of several Torr to nitride the metal particles. and a method for producing metal nitride fine particles.

(2) Several 1000 Torr of gas
A method that generates high-temperature plasma at temperatures above ℃ and causes metals to evaporate and react.

It has been known.

However, in method (1), the generated particles are fused by radiant heat from the evaporation heat source, making it difficult to control the particle size, resulting in a wide particle size distribution, the equipment being complex, and the continuous supply of raw materials being impossible. , it has the disadvantage of poor productivity. Furthermore, method (2) has the drawback that the generated particles are fused by the heat of the high-temperature plasma, making it difficult to control the particle size and resulting in a wide particle size distribution. Furthermore, both methods (1) and (2) have the disadvantage of requiring large amounts of power.

Purpose of the Invention The present invention has been made to overcome the drawbacks of conventional methods, and its purpose is to continuously produce fine particles of uniform particle size without requiring a large amount of electric power and without using a heat source to generate fine particles. An object of the present invention is to provide a method for manufacturing metals or ceramics using low-volume plasma.

Structure of the Invention As a result of research to achieve the above object, the present inventor found that when vapor of a metal compound that can be vaporized is introduced into a gas plasma at a specific pressure, fine metal particles can be easily obtained. It was found that fine ceramic particles could be obtained by incorporating a reactive gas. The present invention was completed based on this knowledge.

The gist of the present invention is to introduce the vapor of a vaporizable metal compound or the vapor and other reactive gas into a low-volume plasma of a low-pressure atmospheric gas of 10-' to 50'-50' ro r r. This refers to a method for producing metal or ceramic fine particles, which is characterized by subjecting compound vapor to plasma decomposition.

The pressure of the atmospheric gas for generating plasma in the method of the present invention needs to be in the range of io-' to 50 T'orr.If the pressure is lower than 10-4+llo r, it is difficult to generate plasma. < , 50'I
When the pressure is higher than 'orr, the temperature of the plasma becomes high and the generated particles fuse, making it difficult to control the fine particles and widening the particle size distribution.

The metal compound that can be vaporized in the method of the present invention includes:
For example, Pc(Go), , o2(Co), , N1(0
0),,A0 V(C!0),,C! r(00),, Mn2(CO
)6, m(Co), , W(C!0'), .

Metal sulfonyl such as FLe(CO)6, 5it(4, A
, N3, metal hydrides such as PH8, GaC11, In(
j13,BBr3,AlCl,,F e CI z,F
eC! metal halides such as Al(CH3)3,
I n (CH3), 5n (CI-I,), Zn
Examples include organometallic compounds such as (CH3)2, Zn(02H,), and the like.

However, any metal compound that can be vaporized may be used. Among these, metal carbonyl is preferred from the operational point of view.

The atmospheric gas is a gas that generates plasma, such as N2, N
2, NH3,02, ArXCo, 002, H, 01H
e.

If Ne is oxidized and this gas is a gas that reacts with generated metal atoms, for example, if it is 02, metal oxides, NT, T
3, a metal nitride is obtained.

Next, an embodiment of the method of the present invention will be explained based on FIG. One or more pairs of opposing electrodes 2.3 are provided inside the reaction vessel 1, and a high frequency power source 4 is connected to these electrodes 1 to generate a low amount of plasma 5 between the two electrodes. In addition, one of the electrodes 3 is connected to the reaction vessel 1 7 and further grounded, so that both are at zero potential, the electrode 3 on the ground side is cooled with water, for example, and the electrode 2 that is not grounded is provided with a nozzle 6. Through this, a metal compound (hereinafter referred to as reaction gas) 7 that can be vaporized together with the atmospheric gas inside the reaction vessel 1, such as Fe (C!
O) 5 and, if necessary, a reactive gas 8 are introduced.

Note that as long as a small amount of plasma can be generated in the reaction vessel 1, an induction coil may be used instead of the electrode, and instead of introducing high frequency waves, for example, microwaves or laser light may be used.

Further, the gas inlet may be provided anywhere as long as the gas directly contacts the plasma.

Reactive gas Fe(00), 7 or this and reactive gas 8
is introduced into the reaction vessel 1, and at the same time, it is evacuated by the vacuum pump 9 to maintain the inside of the reaction vessel 1 at 10'' to 50 TOrr K.

The introduced Fe((:30)s is decomposed by the plasma, generates Fe atoms, reacts with the reactive gas 8, and then assembles to deposit iron particles or ceramic particles on the ground electrode. In this case, providing the cooling pipe 10 at the ground electrode is effective for depositing fine particles there.Of course, it is also possible to cool parts other than the ground electrode and deposit fine particles there. .

Example 1 The tube shown in Fig. 1 was used, a pair of vertically opposed discs with a diameter of 100 cm was used as the electrodes, and the distance between the electrodes was set at 70 mm.
The lower electrode of m+ was connected to the reaction vessel and grounded at the same time. In addition, a copper tube was installed on the lower electrode, and the electrode surface was cooled with water so that fine particles could be collected.Many small holes were made on the upper electrode, through which the reactive gas and reactive gas were allowed to react. It was introduced into the container. Using Fe(00) and steam as the reaction gas, H, 40r
c/min, N26 occ/min was introduced into the reaction vessel. On the other hand, the reaction vessel was evacuated using a vacuum pump, and the internal pressure was maintained at a low pressure of 1 mHg. A high frequency voltage of 1156 MHz frequency was applied between the upper and lower electrodes to generate plasma. The power effectively absorbed by the plasma was about too. As a result, the F
e Fine particles were deposited. Its average particle size was about 10OA.

Example 2 Instead of N2 gas in Example 1, 0□ gas was used at 6 oc.
c, iron oxide fine particles were obtained in 7 minutes. The average particle size of the fine particles was about 10OA.

Example 3゜60CC of NH3 gas instead of 02 gas in Example 2
Fine particles of iron (Fe, N) (x=about 4) were obtained in the same manner by supplying Z component. Its average particle size was about 20OA.

Example 4 E” e (CO)s and N i (C
These vapors were introduced into the reaction vessel in a ratio of 1=1 using O)s. The rest was the same as in Example 1, about 80 parts Nl.
-Fe alloy fine particles were placed. Its thousand force particle size is about 10
It was OA.

Effects of the Invention According to the method of the present invention, since the amount of plasma used is low and near room temperature, fusion of the generated particles does not occur, so fine particles of uniform particle size can be obtained, and the pressure inside the reaction vessel can be adjusted. By doing so, it is also possible to control the particle size.

Furthermore, since the raw materials can be continuously supplied, large quantities can be produced, low power consumption is required, and productivity is high, resulting in low cost. Furthermore, in addition to metals, alloys and ceramics can also be easily manufactured using the same reaction apparatus, and other excellent effects can be achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the method of the present invention 1-Reaction vessel 2: Upper electrode 3; Lower electric body 4, high frequency power source 5; Plasma 6 Nozzle 7: Reactant gas
8: Reactive gas and atmospheric gas 9° nine air pump [0:
Cooling tube patent applicant Ryu Kawa, Director, Metal Materials Technology Research Institute, Science and Technology Agency - 1st T1

Claims (1)

[Claims] 1) Introducing the vapor of a evaporable metal compound or the vapor and other reactive gas into a low-volume plasma of a low-pressure gas atmosphere of 10^-^4 to 50 Torr, A method for producing metal or ceramic fine particles, which is characterized by generating fine particles by plasma decomposition or reaction of steam. 2) The method for producing metal or ceramic fine particles according to claim 1, wherein the vaporizable metal compound is a metal carbonyl. 3) The method for producing ceramic fine particles according to claim 1, wherein the reactive gas is NH_3.