JPH05345904A - Production of titanium powder - Google Patents

Abstract

PURPOSE:To provide the process for production of titanium powder by efficiently hydrogenating raw materials without restriction in the shapes thereof in a hydrogenation treatment for producing the titanium powder by a hydrogenation and dehydrogenation method. CONSTITUTION:The delta phase of the surface layer for rate determination of hydrogenation is removed by the collision of the titanium which is the raw material and the wall of a rotary furnace or the collision of the titanium against each other and the hydrogenation is accelerated by executing the hydrogenation treatment of the titanium in this furnace. Ordinary titanium ingots and titanium scrap are heretofore used as the raw materials by machining and thinning the ingots and scrap with a planing machine, etc., with the conventional static type hydrogenation furnace, but there is no need for machining according to this process and the straight use of various kinds of the scrap which cannot heretofore be machined to a smaller thickness is possible. The effects of reducing the cost of machining, improving the productivity, enabling the use of the inexpensive raw materials, etc., are thus obtd.

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 titanium powder as a raw material for powder metallurgy by a hydrodehydrogenation method (hereinafter referred to as HDH method).

[0002]

2. Description of the Related Art Titanium alloy has a high specific strength and excellent heat resistance and corrosion resistance, and has ideal characteristics as a material for aircraft and the like, but has a difficulty in workability such as melting, forging and cutting. is there. Therefore, the powder metallurgy method is promising as a technique for directly manufacturing a semi-finished product having a final shape from the viewpoint of reducing the processing cost and improving the yield.

When a titanium alloy is produced by powder metallurgy, there are two methods: a method using a mixed powder of pure titanium powder and a titanium master alloy powder as a raw material and a method using a titanium alloy powder. The former method is considered to be advantageous because alloys of various compositions can be manufactured at low cost by changing the mixing ratio of both powders.

As a method of producing pure titanium powder, there is a method of mechanically pulverizing sponge titanium, which is generally obtained as metallic titanium, into a powder. However, since sponge titanium is rich in spreadability, it is directly pulverized and finely divided. It is difficult to obtain a powder, and since it contains a large amount of chlorine, it is a low grade product for powder metallurgy.

Therefore, in general, there is an atomizing method in which molten titanium is blown off with a gas to produce powder, or a rotating electrode method in which a titanium electrode is rotated and the electrode is melted by plasma or the like and blown away by centrifugal force to produce powder. is there. According to this method, a titanium powder having a relatively high purity can be obtained, but there are drawbacks in the powder shape, particle size, cost and the like.

For this reason, titanium is hydrotreated to form a brittle titanium hydride, which is mechanically crushed into powder and then dehydrogenated by vacuum heating or the like to obtain titanium powder H
The method based on the DH method is generally adopted.

[0007]

In the conventional HDH method, as disclosed in JP-A-56-20103, a method of hydrogenating titanium to obtain brittle titanium hydride is usually a titanium ingot, titanium scrap, etc. The titanium raw material is cut by a machine such as a planing machine, thinned, and charged into a static hydrogenation furnace.

This is a hydrotreating process in which titanium is charged into a static hydrogenation furnace and then the furnace is evacuated and hydrogen is supplied to heat the furnace. Hydrogen is absorbed and a δ phase with a high hydrogen content (3 wt% or more) is formed on the surface layer, which becomes a resistance against hydrogen intrusion inside, and if it is thick titanium such as ingot, scrap, etc., it will completely penetrate to the inside. There is a problem that cannot be embrittled. Therefore, conventionally, in order to hydrogenate the raw material, a method of cutting the raw material with a machine such as a planing machine, thinning it, and charging it into a static hydrogenation furnace has been adopted. However, in the hydrotreatment method using a static hydrogenation furnace, the δ phase formed in the surface layer is the rate-determining factor for hydrogen absorption,
There is a problem that it takes a long time to perform the hydrotreatment and the efficiency is low. Further, in the method of hydrotreating titanium thinned by cutting, there are problems that the raw material titanium has a shape that can be cut and that the cost required for cutting is high.

A first object of the present invention is to completely hydrogen embrittle (into the δ phase) even in the inside in a short time even if the raw material is a thick material such as titanium ingot or titanium scrap or titanium scrap having an uncut shape. The present invention is to provide a method for hydrotreating titanium in the HDH method, which is capable of eliminating raw material restrictions and cutting costs.

The second purpose is to significantly reduce the hydrogenation treatment time (δ-phase conversion required time) of raw materials obtained by cutting titanium ingot, titanium scrap and the like.
It is to provide a method for hydrotreating titanium in the DH method.

[0011]

The present invention is characterized in that in the method for producing titanium powder by the hydrodehydrogenation method, titanium is hydrogenated in a rotary furnace. Rotation of this hydrogenation furnace is performed by rotating the furnace to collide the δ phase having a high hydrogen content (3% by weight or more) formed in the surface layer with titanium as a raw material on the furnace wall, or between titanium. Is to be made to collide and to be removed by the collision force at that time. As the direction of rotating the hydrogenation furnace, it is possible to rotate vertically or horizontally, but in order to make the raw material titanium collide with the furnace wall or collide titanium with each other, it must be rotated vertically. Is desirable. Also,
The operation of the hydrogenation furnace can remove the δ phase formed in the surface layer by rotating the furnace under either batch processing or continuous processing operation conditions.

[0012]

[Function] In the hydrotreating process in which titanium of the HDH method is charged into the hydrogenation furnace, the inside of the furnace is evacuated, and hydrogen is supplied to heat the furnace, the progress of hydrogenation causes the β phase and the β + δ phase to change to δ The hydrogen absorption amount of the δ phase is 3% by weight or more. Titanium is hydrogenated because hydrogen is absorbed from the surface layer and changes from β phase and β + δ phase to δ phase, but when it becomes δ phase, hydrogen absorption is significantly reduced as compared with β phase and β + δ phase. Therefore, when the titanium material as a raw material becomes thicker, the δ phase in the surface layer becomes the rate-determining factor for hydrogen absorption, and it takes a long time for the whole to become the δ phase. Further, the β phase and the β + δ phase become the α + δ phase in the normal temperature region, and are harder than the δ phase, and the pulverization is somewhat difficult.

Therefore, as a means for promoting hydrogenation, attention has been paid to promoting hydrogenation by removing the δ phase in the surface layer. The δ phase is extremely brittle and can be easily crushed by hand, and the δ phase in the surface layer can be removed by applying an impact. As a method of removing the δ phase of this surface layer,
By rotating the furnace, the raw material titanium rotates and collides,
If the δ phase in the surface layer is removed by the impact at that time, the titanium surface is always exposed and hydrogenation is promoted. The rotation of this furnace requires that the raw material titanium collide with the furnace wall or the titanium collides with each other, and the number of revolutions of the furnace varies depending on the size of the furnace, the amount of raw material charged, the raw material shape, etc. Generally, 10 rpm or more is sufficient.

[0014]

Example 1 A rotor re-kiln type rotary hydrogenation furnace was used as a hydrogenation furnace, and titanium scrap of 100 mm × 100 × 50 mm thickness was used as a raw material for hydrogenation. First, after loading titanium scrap into a rotor re-kiln type rotary hydrogenation furnace, the furnace pressure was evacuated to 10 ^-3 torr, hydrogen was added, and the furnace pressure was added to atmospheric pressure. Rotated. The rotation speed of the furnace is 60 rpm, and the furnace is 600
It was heated to ℃ and retained. Since the furnace pressure decreases as titanium absorbs hydrogen, the furnace pressure was controlled by supplying hydrogen so that the furnace pressure became atmospheric pressure.

FIG. 1 shows the relationship between the resulting hydrogenation time and the δ phase thickness of the surface layer. The δ-phase thickness of the surface layer indicates the δ-phase thickness removed. In the conventional static hydrogenation furnace in which hydrogenation was carried out under the same conditions as in the rotor re-kiln type rotary hydrogenation furnace, the δ phase thickness removed was 5 mm when the hydrogenation time was 3 hours. The same hydrogenation time is 3 hours and δ phase thickness is 20
mm, the hydrogenation processing time and efficiency have been greatly reduced and improved.

Further, in the present invention, titanium which is hydrogenated by collision between titanium as a raw material and the furnace wall or collision between titanium is crushed by the rotation of the furnace and coarsely crushed. In the conventional static hydrogenation furnace, after the hydrogenation was completed, it was necessary to perform coarse pulverization before it was subjected to the pulverizer, but in the present invention, it was found that this is not necessary.

Further, in the conventional static hydrogenation furnace, if the material titanium is thick, the δ phase thickness does not increase due to the influence of the δ phase in the surface layer even if the hydrogenation time is lengthened, but in the present invention, the rate of hydrogen absorption is rate-determining. Since the δ phase in the surface layer is removed, titanium is converted to the δ phase almost in proportion to the hydrogenation time.

[0018]

Example 2 Titanium scrap was mechanically cut and thinned in the same manner as in the prior art, and hydrogenated using a rotor re-kiln type rotary hydrogenation furnace as a hydrogenation furnace. Hydrogenation was carried out with two types of machine-cut material thicknesses of 0.5 mm and 1.0 mm. In the hydrogenation, after the cut raw material was charged into the hydrogenation furnace, the pressure inside the furnace was evacuated to 10 ⁻³ torr, hydrogen was added, and the furnace was rotated. The rotation speed of the furnace was 30 rpm, and the furnace was heated to 600 ° C. and held. Since the furnace pressure decreases as titanium absorbs hydrogen, the furnace pressure was controlled by supplying hydrogen so that the furnace pressure became atmospheric pressure.

Table 1 shows the required hydrotreatment time as a result. The time required for titanium to absorb hydrogen to form the δ phase was 5 minutes at a material thickness of 0.5 mm and 10 minutes at a thickness of 1.0 mm. This is because the time required for titanium to absorb hydrogen into the δ phase in a conventional static hydrogenation furnace that has been hydrogenated under similar hydrogenation conditions is 12 minutes when the material thickness is 0.5 mm. ,
The hydrogenation treatment time was significantly shortened, while it was 25 minutes at 1.0 mm.

[0020]

[Table 1]

[0021]

EFFECTS OF THE INVENTION In the conventional static hydrogenation furnace, a method of cutting the titanium raw material such as titanium ingot and titanium scrap as a raw material by a machine such as a planing machine to thin the raw material is used. Increase, and that the target materials are limited, that the material is bulky and does not increase productivity because it is thinned by cutting, and the δ phase formed in the surface layer is the rate-determining factor for hydrogen absorption, There was a problem that processing took time and was inefficient.

However, according to the present invention, since the δ phase in the surface layer, which is the rate-determining factor for hydrogenation, is always removed by rotating the furnace, it is not necessary to cut the raw material titanium thinly.
Therefore, cutting costs can be reduced and productivity can be increased by promoting hydrogenation. In addition, various scraps that could not be thinly cut in the past can be used as they are, and it is possible to use inexpensive raw materials. Thus, it is possible to significantly reduce costs and improve productivity. On the other hand, according to the present invention, hydrogenation is promoted even if a conventional raw material is cut and thinned and used, so that the hydrogenation time can be shortened and the efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a hydrogenation time and a hydrogen embrittlement phase thickness in an example of the present invention in comparison with a conventional method.

Claims (1)

[Claims] 1. A method for producing titanium powder by a hydrodehydrogenation method, wherein the hydrogenation treatment of titanium is performed in a rotary furnace.