JP3459342B2 - Method for producing titanium-based powder - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a titanium-based powder comprising titanium hydride powder (including titanium hydride alloy powder, the same applies hereinafter) and titanium powder (including titanium alloy powder, apply the same below). In particular, it relates to a method for producing a titanium-based powder that is preferably used as a raw material for producing a sintered titanium product by a powder metallurgy method.

[0002]

2. Description of the Related Art Recently, sintered titanium or sintered titanium alloy products manufactured by powder metallurgy have come to be used in various fields including heat-resistant members, and their applications have been expanded. There is. As the raw material, use of titanium powder and titanium hydride powder by the hydrodehydrogenation method, which are of high quality and excellent in formability, has been attempted. Excellent mechanical properties are required for this sintered titanium or sintered titanium alloy member, but the oxygen content greatly affects its strength, and the oxygen content in the titanium-based sintered member is 0.3% by weight. It is known that the mechanical properties such as elongation decrease remarkably when the content exceeds 100% (Toyota Central Research Institute R & D Review, 26-1 (1991),
44.). Considering unavoidable oxygen contamination in the sintering process, it is desirable to maintain the oxygen content of the titanium-based powder as a raw material at 0.15 wt% or less.

Among the titanium hydride powder and the method for producing the titanium powder, the hydrogen embrittlement of titanium or a titanium alloy is utilized to hydrogenate the titanium or the titanium alloy and then pulverize the titanium or the titanium alloy to an arbitrary particle size to obtain a titanium hydride powder. The hydrodehydrogenation method, in which the material is dehydrogenated by heating under vacuum and converted into titanium powder, makes it possible to obtain high-quality powder by improving the quality of the raw material, and to easily make the particle diameter of the powder. It has attracted attention as a method for producing a titanium hydride powder and a titanium powder because it has the advantage of being adjustable.

Specifically, this method is a hydrogenation step of hydrogenating a titanium or titanium alloy raw material in a hydrogen gas atmosphere at a high temperature, and a pulverization step of pulverizing the obtained titanium hydride agglomerates to a predetermined particle size. To produce titanium hydride powder,
The titanium-based powder is manufactured through a dehydrogenation step of dehydrogenating the pulverized titanium hydride powder in a vacuum at a high temperature and a crushing step of crushing a titanium agglomerate sintered during dehydrogenation.

In the titanium-based powder, the oxygen content of the entire powder increases as the amount of fine powder having a smaller particle size increases.
As a method for reducing the oxygen content in the powder, for example, the particle size distribution of the titanium hydride powder is adjusted by particle size adjustment by removing the particles with a particle size of 63 μm or less in advance to limit the particle size to 63% or less, and then dehydration A method has been proposed in which elemental treatment is performed to obtain titanium powder. (Japanese Patent Laid-Open No. 5-247503)
However, this method has a drawback in that most of the fine-grained powder is removed, so that the product yield is greatly reduced and the manufacturing cost is increased.

On the other hand, since fluidity and moldability are important for titanium hydride powder and titanium powder for powder metallurgy raw materials, these characteristics must be satisfied, and fine particle properties and fluidity are required. As a titanium powder with excellent properties, the particle size range is 5 to 74 μm, and the average particle size is 20 μm.
Those having the following particle properties have been proposed (JP-A-7-278601), but in this titanium powder, there is a limit to the reduction of the oxygen content because the particle size is fine,
For example, oxygen content 2000-3000ppm (0.2-0.3wt
%) You can only get something like this.

Further, when titanium sponge produced by the Kroll method is used as the titanium material to be subjected to the hydrogenation step, since it contains magnesium chloride produced as a by-product in the titanium sponge production step, it is usually about 0.08% by weight of chlorine. It is included. This chlorine remains as an impurity element also in the titanium powder after hydrodehydrogenation, and it is avoided as a cause of expanding and increasing the pores of the sintered titanium member which is the final product, and causing a decrease in fatigue strength. Therefore, a low chlorine titanium powder is desired, and as a means therefor, a method of removing residual chlorine by washing the titanium powder after hydrodehydrogenation with water has been proposed (JP-A-1-139706).

However, the water used for washing is required to be ion-exchanged water containing substantially no chlorine, and further oxygen contamination during washing cannot be ignored, and a perfect drying means for avoiding it. Will become an indispensable requirement, so new challenges will arise in terms of resource and energy costs.

As a result of various studies to solve the problems remaining in the above-mentioned prior art, the present inventors have found that the content of titanium hydride powder in the titanium hydride powder can be adjusted by adjusting the powder ratio of fine powder having a particle size of 10 μm or less. It was found that the amount of oxygen can be controlled to an allowable range of 0.15% by weight or less, and that chlorine as an impurity is biasedly contained in fine powder having a particle size of 10 μm or less, and the above particle size adjustment is performed. It was confirmed that the chlorine content in the titanium-based powder can also be reduced by the above, and the powder characteristics such as fluidity and moldability of the titanium-based powder can be significantly improved, and the present invention has been completed. .

[0010]

That is, the object of the present invention is to provide a raw material for producing a sintered titanium product by powder metallurgy, which has reduced oxygen content and chlorine content, excellent flowability and moldability. It is an object of the present invention to provide a titanium hydride powder and a titanium powder which can be suitably used as a titanium hydride powder and a titanium powder having a high product yield, and a method for producing the titanium powder.

[0011]

The method for producing a titanium hydride powder or a titanium hydride alloy powder according to the present invention for achieving the above object comprises a hydrogen produced by hydrogen embrittlement of titanium or a titanium alloy. After crushing a lump of titanium hydride or titanium hydride alloy by mechanical means, selectively obtain fine powder having a particle size of 10 μm or less from titanium hydride powder having a maximum particle size of substantially 150 μm or less. It is characterized in that the content of the powder having a particle diameter of 10 μm or less is adjusted to more than 0.9% by weight and 8 % by weight or less by removing.

Further, in the method for producing titanium powder of titanium powder according to the present invention, the titanium hydride powder obtained by the above method is further heated in vacuum for dehydrogenation, then crushed, and then the particle size is adjusted. As a result, the maximum particle size is substantially 150μ
The characteristic feature of the constitution is that the proportion of powder having m or less and particle diameter of 10 μm or less is 5% by weight or less.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The titanium hydride powder obtained by the method of the present invention has a maximum particle size of substantially 150 obtained through a hydrogenation step of hydrogen embrittlement of a titanium or titanium alloy raw material.
It is less than μm. Substantially 150 μm or less means
There may be some powder remaining on the 150 μm mesh during sieving, but it also accounts for less than 1% of the total powder,
99% or more means 150 μm or less. The average particle size of the titanium hydride powder is preferably 100 μm or less in order to maintain fluidity and moldability during powder molding.

The titanium hydride powder obtained by the method of the present invention has an oxygen content of 0.15% by weight or less and a chlorine content of 0. Since it is limited to 06% by weight or less, when used as a raw material for powder metallurgy, the oxygen content and chlorine content of the titanium-based sintered member to be the final product are sufficiently reduced.
Further, by setting the proportion of powder having a particle size of 10 μm or less to 8% by weight or less, the fluidity required in powder metallurgy is secured, and fine powder having a high oxygen content and poor compression moldability is removed. As a result, a titanium hydride powder having satisfactory moldability can be obtained. When the proportion of powder having a particle size of less than 10 μm exceeds 8% by weight, the proportion of fine powder increases, the oxygen content and chlorine content relatively increase, and the fluidity and moldability also decrease. An oxygen content of 0.15% or less is an oxygen content within a range where mechanical properties such as elongation of a sintered titanium product or a sintered titanium alloy product manufactured by powder metallurgy using the powder as a raw material can be sufficiently satisfied. Further, the chlorine content of 0.06% by weight or less is an allowable range for satisfying the fatigue strength and the like of the titanium-based sintered member which is the final product. In order to secure the desired oxygen content and chlorine content, the proportion of powder with a particle size of 10 μm or less is
It is appropriately adjusted in the range of 8% by weight or less in accordance with the powder properties required for the desired sintered product and the product cost set, and it is also preferable to set it to 5% by weight or less.

The titanium powder obtained by the method of the present invention is obtained by subjecting the above-mentioned titanium hydride powder of the present invention to heating in a vacuum for dehydrogenation, crushing, and then adjusting the particle size to obtain the maximum grain size. Diameter is substantially less than 150 μm,
An essential requirement is that the proportion of powder having a particle size of 10 μm or less is 5% by weight or less.

The titanium powder obtained by the method of the present invention having the above requirements has an oxygen content of 0.15% by weight or less and a chlorine content of 0.04% by weight or less, and is a raw material for powder metallurgy. When it is used as a steel sheet, it is reduced to such an extent that it does not adversely affect the mechanical properties of the titanium-based sintered member that is the final product. Further, by reducing the content of the fine powder, the fluidity during powder molding is maintained good, the oxygen content is high, by removing the fine powder having poor compression moldability as much as possible, Formability when used for powder metallurgy is also effectively secured.

The titanium hydride powder obtained by the method of the present invention is a hydrogenated material that can be vacuum-replaced with a raw material such as a titanium sponge ingot, titanium or titanium alloy ingot cutting scraps, scrap scraps, and scraps generated during processing. Charge into the furnace, 1
Hydrogen embrittlement was performed in a hydrogen gas atmosphere at a high temperature of 000 ° C. or lower to perform a hydrogenation treatment to obtain a titanium hydride agglomerate containing 3.5 to 4.5 wt% of hydrogen. Grind by mechanical means to form titanium hydride powder with a maximum particle size of substantially 150 μm or less, then classify and screen to remove fine powder, and adjust the proportion of powder with a particle size of 10 μm or less to 8% by weight or less. To do. A crushing device such as a ball mill or a vibration mill can be used for mechanical crushing, and a sieving device such as a circular vibrating sieve or an air stream classifier is used for classification. Oxygen contained in the obtained titanium hydride powder is limited to 0.15 wt% or less, and chlorine is limited to 0.06 wt% or less.

The titanium powder is produced by filling the above-mentioned titanium hydride powder in a container and charging it in a vacuum heating type dehydrogenation furnace, for example, in a vacuum of 10 ^-3 Torr or less and 500 to 900.
It is carried out by heating to a temperature of about ℃ to dehydrogenate, mechanically crushing the obtained titanium agglomerates, and then adjusting the particle size. The resulting titanium powder has a maximum particle size of substantially 150 μm or less, a powder ratio of 10 μm or less is 5% by weight or less, and the oxygen content is 0.15% or less, which is the same as the titanium hydride powder, Chlorine content is 0.0
It is limited to 4% by weight or less.

The titanium hydride powder and titanium powder obtained by the method of the present invention can be reduced in oxygen content and chlorine content by adjusting the ratio of the powder in a specific particle size range to the whole powder, and can be flowed. It also has excellent moldability and moldability, and can function as a high-quality raw material for powder metallurgy that is well-balanced in terms of required properties and setting costs.

[0020]

EXAMPLES The present invention will be described below in comparison with Comparative Examples with reference to Examples. Examples 1 to 2 Titanium sponge having a particle size of ½ mesh or less was charged into a hydrogenation furnace to be hydrogenated to produce hydrogenated sponge titanium having a hydrogen content of 4%. The lumps are crushed with a ball mill and the maximum particle size is 150
Titanium hydride powder having a particle size of not more than μm was used.

Then, using an air stream classifier, the proportions of powders having a particle size of 10 μm or less contained in the titanium hydride powder are 1.6% by weight (Example 1) and 7.3% by weight (Example 2), respectively. To remove the fine powder. Table 1 shows the evaluation results of the oxygen content, chlorine content, fluidity and moldability of the obtained titanium hydride powder.

For comparison, titanium hydride powder (Comparative Example 1) in which fine powder having a particle size of 10 μm or less was not removed,
The oxygen content and the chlorine content of the titanium hydride powder ( Comparative Example 2 ) in which the powder ratio with the particle size of 10 μm or less was further reduced were also evaluated to evaluate the fluidity and the moldability.
The results are also shown in Table 1.

The proportion of powder having a particle size of 10 μm or less was measured by a laser diffraction method, the fluidity was measured according to JIS Z 2505, and a needle was used if necessary. Moldability is JS
According to PM4-69 (Rutler test), the powder is 3 tons / cm ²
It was evaluated by the weight reduction rate of the pellet-shaped molded product pressed at the molding pressure of.

As shown in Table 1, the titanium hydride powder according to the present invention has a low oxygen content, is excellent in fluidity, and has been proved to have excellent formability in the formability test by the Ratler test. There is. On the other hand, the powder of Comparative Example 1 containing the fine powder has an oxygen content exceeding 0.15% by weight, a chlorine content as high as 0.08% by weight, and has a fluidity that cannot be practically used. Is. In Comparative Example 2 , the oxygen content was even lower and the flowability and moldability were good, but
The product yield of the titanium hydride powder according to the present invention (Examples 1 and 2) was 90% or more, whereas the product yield of the titanium hydride powder of Comparative Example 2 was 60% or less, and the raw material unit Rose 1.5 times.

[0025]

[Table 1]

Examples 3, 4 Titanium hydride powders of Examples 1 and 2 are charged into a dehydrogenation furnace and heated to 500 to 900 ° C under a vacuum of 10 ^-3 Torr or less for dehydrogenation. The agglomerates of titanium produced by the above method were crushed by a ball mill to obtain titanium powder having a maximum particle size of 150 μm or less. Example 1 of the obtained titanium powder
The oxygen content was measured by the same method as in. The results are summarized in Table 2. Here, Examples 3 and 4 mean titanium powders obtained by using the titanium hydride powders obtained in Examples 1 and 2 of Table 1 as raw materials. Also, a comparative example
3 means titanium powder obtained by using the titanium hydride powder obtained in Comparative Example 1 in Table 1 as a raw material. The oxygen contents of Examples 3 and 4 in which the proportion of powder having a particle size of 10 μm or less was adjusted to 5% by weight or less were 0.12% by weight and 0.15% by weight, respectively. % By weight) or less. On the other hand, in Comparative Example 3 in which the proportion of powder of 10 μm or less exceeds 5% by weight, the oxygen content is also 0.15% by weight.
And is not suitable as a raw material for powder metallurgy.

[0027]

[Table 2]

[0028]

INDUSTRIAL APPLICABILITY According to the present invention, titanium hydride powder and titanium powder having reduced oxygen content and chlorine content, excellent flowability and moldability are provided by a simple operation at low cost, And the product yield rate is high, the powder is
It can be suitably used as a powder raw material for producing sintered titanium or titanium alloy products by the powder metallurgy method.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-247503 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22F 9/04

Claims (2)

(57) [Claims] 1. A lump of titanium hydride or a titanium hydride alloy produced by hydrogen embrittlement of titanium or a titanium alloy is pulverized by mechanical means, and the obtained maximum particle size is substantially the same. By selectively removing fine powder having a particle size of 10 μm or less from titanium hydride powder having a particle size of 150 μm or less, the powder ratio of the particle size of 10 μm or less can be reduced.
A method for producing titanium hydride powder or titanium hydride alloy powder, which comprises adjusting the content to exceed 0.9% by weight and 8 % by weight or less. 2. The titanium hydride powder or titanium hydride alloy powder obtained by the method according to claim 1, is further heated in vacuum for dehydrogenation treatment, crushed, and then subjected to particle size adjustment. A method for producing titanium powder or titanium alloy powder, characterized in that the proportion of powder having a maximum particle size of substantially 150 μm or less and a particle size of 10 μm or less is 5% by weight or less.