JPH0867503A - Production of hydrogenated titanium superfine particle - Google Patents

Abstract

PURPOSE: To obtain superfine particles of hydrogenated titanium free from contamination due to impurities without a powdering step by reacting high- temperature hydrogen plasma with titanium, melting and evaporating titanium and simultaneously carrying out formation of superfine particles and hydrogenation reaction of the titanium. CONSTITUTION: This method for producing hydrogenated titanium superfine particles are to heat, melt and evaporate titanium using DC arc discharge, DC plasma jet and RF plasma as a plasma source and hydrogen-argon mixed gas as a plasma gas, respectively and simultaneously carry out formation of superfine titanium particles having <=1μm diameter and hydrogenation reaction of titanium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ultrafine titanium hydride particles by an evaporation method using hydrogen plasma. The titanium hydride ultrafine particles are directly used for powder metallurgy, or dehydrogenated in vacuum to be used as titanium ultrafine particles. In the former case, when mixed with metal powder and sintered, a dense sintered body is obtained due to the reducing action of titanium hydride. The latter is used for getter materials, bonding materials, sintered solid titanium capacitors, powder metallurgy and the like.

[0002]

2. Description of the Related Art As prior art, the purity is 99.9%, 10
Titanium sponge below mesh is 800 ℃, 10-5m
After degassing with mHg, a method of producing titanium hydride by reacting with high-purity hydrogen at 400 ° C. or higher,
There is a method of producing titanium hydride by reducing with calcium hydride at 00 to 1000 ° C., further reacting with hydrogen, and removing calcium oxide by-produced with hydrochloric acid. In this case, the hydrogen to be reacted must have a purity of 99.999% or more, and the hydrogen can be passed through the palladium alloy film or at 850 ° C.
A dew-point humidity of about −70 ° C. is used in which oxygen, nitrogen and water are removed by passing through a titanium sponge layer which has been heated. The titanium hydride thus produced is mechanically crushed to obtain a titanium hydride powder having a desired particle size.
The particle size in this case is usually 10 to 100 μm. (Titanium Roundtable, Metals such as titanium and their compounds, p. 3
09 (published by Agne)

[0003]

In the prior art, as mentioned above, the production of titanium hydride powder requires two steps of hydrogenation reaction and pulverization. In the hydrogenation reaction, pretreatment is performed in high vacuum, degassing at 800 ° C., and then hydrogenation in 400 ° C. high-purity hydrogen.
High-purity hydrogen is required. Also, in the crushing process, mixing of impurities from the crusher is unavoidable, and the particle size is tens of μm.
m is common, and it is very difficult to obtain a powder having a particle size of 10 μm or less due to a method of pulverization, and it is impossible to produce a powder having a particle size of 1 μm or less.

[0004]

The present invention provides a method for producing ultrafine titanium hydride particles of 1 μm or less in which the number of steps is simplified, the reaction time is shortened, high vacuum and high purity hydrogen are unnecessary, and impurities are not mixed. It is a proposal. The method is characterized in that a high-temperature hydrogen plasma is applied to titanium to cause ultrafine particles by evaporation and condensation of titanium and a hydrogenation reaction to occur simultaneously.

DC arc discharge, DC plasma jet, or RF plasma is used as the plasma source. In any case, the device is composed of an ultrafine particle generation container for generating plasma (arc discharge) for hydrogenation and ultrafine particle formation of titanium, an ultrafine particle collector for collecting the generated ultrafine particles, and equipment attached thereto. . A water-cooled container having excellent airtightness is used as the ultrafine particle generation container, and a cyclone or a filter is used as the ultrafine particle recovery device. The incidental equipment consists of a plasma power supply, a powder carrier gas supply system, and a device cooling water circulation system.

When using DC arc discharge, the atmosphere in the apparatus is first replaced with a hydrogen-argon mixed atmosphere. Next, when the bulk titanium as a raw material is melted by an arc, titanium evaporates from the vicinity of the arc and reacts with hydrogen in the atmosphere to form titanium hydride ultrafine particles. The ultrafine particles are transported by gas and recovered by an ultrafine particle collector.

When using a DC plasma jet, DC
Similar to arc discharge, a method of melting massive titanium to generate titanium hydride ultrafine particles, and hydrogen as plasma gas
There is a method in which argon gas is flown from a torch to generate plasma, and titanium powder is fed into the plasma to cause vaporization and hydrogenation of titanium powder in the plasma.

When RF plasma is used, hydrogen-argon gas is flown as a plasma gas from the upper part of the torch to generate high frequency plasma, and titanium powder is fed into the thermal plasma reaction part to cause evaporation and hydrogenation of titanium powder. It is a method to let.

[0009]

This method makes it possible to produce spherical and high-purity titanium hydride ultrafine particles of 1 μm or less, which cannot be obtained by the conventional method. That is, in the conventional method, since the powder is pulverized, the powder shape is indefinite and only the particle size of 1 μm or more can be produced. Further, although there is a drawback that impurities are easily mixed in, since this method is an evaporation method, it is possible to produce ultrafine powder having a particle size of 1 μm or less, most of which is 0.1 μm or less. Impurities are not easily mixed in because hydrogen plasma is applied to titanium in a closed container to cause evaporation and hydrogenation reaction at the same time.

[0010]

【Example】

Example 1 Titanium hydride ultrafine particles were produced by the DC arc discharge device shown in FIG. This equipment has an arc discharge electrode and a water-cooled sample stand installed in an ultrafine powder generation container, puts massive titanium on the water-cooled sample stand, first evacuates the atmosphere in the equipment to 1 Pa with a rotary pump, and then hydrogen-argon mixing Gas was introduced and the pressure was adjusted to 0.1 MPa. When lumpy titanium was melted by an arc, titanium hydride ultrafine particles were generated from the surface of the sample, which was transported to the ultrafine particle collector by a carrier gas and collected.

FIG. 2 shows the relationship between the hydrogen concentration in the atmosphere and the amount of titanium hydride ultrafine particles generated. The condition of arc discharge is 1
It is 50A and 40V. The hydrogen concentration in the atmosphere can be arbitrarily selected, but if the hydrogen concentration is 40% or less, the amount of hydrogen generated is extremely small, which is not practical.

FIG. 3 shows the DSC curve. 4 from this figure
It can be seen that dehydrogenation begins at 15 ° C.

The condition of arc discharge during the production of ultrafine powder is 150
A and 40 V, the atmosphere was 60% hydrogen-40% argon, and the results of TEM photographs and X-ray diffraction of the ultrafine titanium hydride powder were shown in FIGS. 4 and 5. From these figures, the grain size and generation phase can be seen. In other words, the particle size is large, 0.3 μm and mostly 0.1 μm, which are almost spherical ultrafine particles, and the production phase is titanium hydride of TiH1.9.

Example 2 Titanium hydride ultrafine particles were produced by a DC plasma jet apparatus as shown in FIG.
In this device, a DC plasma jet torch is installed in an ultrafine particle generating container. The torch is shown in FIG. In the operation, first, the apparatus was evacuated to 1 Pa by a rotary pump, and then argon was introduced to make the pressure 0.1 MPa. As the plasma gas, 30 l / min of 10% hydrogen-90% argon was flown from the torch nozzle to ignite the DC plasma. After the plasma was stabilized, when titanium powder (<45 μm) was introduced from a powder feeder with a carrier gas of 5 l / min, melting, evaporation and hydrogenation occurred in the plasma, and titanium hydride ultrafine particles were obtained. Plasma output is MAX 3k
It uses a W power source and uses it at a regular 2 kW. If the titanium input amount is 3 g / min or less, the plasma is stable and the generation of ultrafine particles is good. .. An SEM image of titanium hydride ultrafine particles produced by this method is shown in FIG.

Example 3 Titanium hydride ultrafine particles were produced by the high frequency plasma apparatus shown in FIG. In this device, a high-frequency plasma torch is installed above the ultrafine particle generation container. The frequency of the high frequency is 4 MHz. First, the apparatus was evacuated to 1 Pa by a rotary pump, and then argon was introduced to adjust the pressure to 0.1 MPa. As the plasma gas, argon was flown from the upper part of the torch to ignite the high frequency plasma, and then hydrogen was introduced so that the plasma gas became 10% to 20% hydrogen-argon. Plasma output is MAX 50k
Although it was W, it was normally used at 35-40 kW. From the top of the plasma, add 1 titanium powder with a powder feeder.
When charged at g / min, melting, evaporation and hydrogenation occurred in plasma, and titanium hydride ultrafine particles were obtained. From the particle size distribution shown in FIG. 10, it can be seen that the particles are ultrafine particles of 1 μm or less.

[0016]

The present invention relates to a method for easily producing ultrafine titanium hydride particles using titanium as a raw material by utilizing hydrogen plasma. By this method, it is possible to produce spherical titanium hydride ultrafine particles of 1 μm or less in which no impurities are mixed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a DC arc discharge device.

[Fig. 2] Relationship between hydrogen concentration in atmosphere and generation amount of titanium hydride ultrafine particles

FIG. 3 DSC measurement results of titanium hydride ultrafine particles

FIG. 4 is a TEM image of titanium hydride ultrafine particles prepared by a DC arc discharge method.

FIG. 5: X-ray diffraction results of titanium hydride ultrafine particles

FIG. 6 is a schematic diagram of a DC plasma jet device.

FIG. 7 is a schematic diagram of a DC plasma jet torch.

FIG. 8 is an SEM image of titanium hydride ultrafine particles prepared by a DC plasma jet.

FIG. 9 Overview of high-frequency plasma device

FIG. 10: Particle size distribution of titanium hydride ultrafine particles prepared by the high frequency plasma method

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihiko Iwasaki, 1 Nisshin Steel Co., Ltd., New Materials Research Center, 7-7 Takaya Shinmachi, Ichikawa City, Chiba Prefecture

Claims (3)

[Claims] 1. A method for producing titanium hydride ultrafine particles, which comprises melting and evaporating titanium by heating and melting it with hydrogen plasma to form ultrafine particles having a particle size of 1 μm or less and at the same time causing a hydrogenation reaction. . 2. The method for producing ultrafine titanium hydride particles according to claim 1, wherein the bulk titanium is heated and melted in a hydrogen or hydrogen-argon mixed atmosphere using a DC arc discharge or a DC plasma jet as a hydrogen plasma source. 3. The production of titanium hydride ultrafine particles according to claim 1, wherein DC plasma jet or RF plasma is used as a hydrogen plasma source, and hydrogen-argon mixed gas is used as a plasma gas to introduce titanium powder into the plasma. Method.