JP2006022377A - Dendritic titanium powder and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide titanium powder excellent in compactibility, sinterability and production cost, and to provide a production method therefor. <P>SOLUTION: The dendritic titanium powder contains dendritically branched bar-shaped grains having a mean length of ≤10 mm and a mean diameter of ≤1 of the smallest circles surrounding the cross-sections. The production method for the dendritic titanium powder is characterized in that molten magnesium chloride in which lower titanium chloride is dissolved is charged with a solid reducing agent, and the lower titanium chloride is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing metal titanium, and more particularly, to a method for producing metal powder using a metal lower chloride as a starting material.

  Titanium metal is lightweight and has characteristics such as excellent strength, corrosion resistance, and workability, and is widely used for machine parts, engine parts, filters, sports equipment, and the like. Since these titanium products are manufactured by molding and sintering titanium powder, titanium powder having excellent moldability and sinterability is considered preferable.

  As such titanium powder, the titanium material is hydrogenated and embrittled, then crushed and pulverized to a predetermined size, and then dehydrogenated (for example, see Patent Document 1), the titanium mass is melted Atomized powder obtained by atomization (for example, refer to Patent Document 2), PREP powder (for example, refer to Patent Document 3) obtained by irradiating plasma on a titanium block and melting it by centrifugal force is disclosed. Yes.

  While spherical powder such as atomized powder or PREP powder is excellent in fluidity, there is a problem that moldability and sinterability are very poor. In addition, since the HDH powder has a relatively square shape, the moldability and sintering properties are improved as compared with the atomized powder and PREP powder, but the production cost is high.

  The demand for improved performance for titanium products is increasing day by day, and there is no titanium powder that is currently produced in this way that satisfies the moldability, sinterability, and manufacturing cost, and titanium powder that combines these characteristics is desirable. It is rare.

JP-A-10-096003 JP-A-08-199207 Japanese Patent Laid-Open No. 02-088707

  The present invention has been made in view of the above circumstances, and an object thereof is to provide titanium powder and a titanium powder manufacturing method that are excellent in terms of formability, sinterability, and manufacturing cost.

  The present invention has been made by intensive studies in view of such circumstances, and the dendritic titanium powder of the present invention has an average length of 10 mm or less and an average diameter of a minimum circle surrounding the cross section of 1 mm or less. It has a certain rod shape and is characterized by containing dendritic particles.

  In the dendritic titanium powder of the present invention, the particles of the titanium powder are intertwined with each other, so that the particles can be fixed to each other with a pressure smaller than the conventional one, and have excellent moldability and sinterability. Yes.

  The method for producing dendritic titanium powder of the present invention is characterized in that a solid reducing agent is introduced into molten magnesium chloride in which titanium lower chloride is dissolved to reduce titanium lower chloride.

  According to such a manufacturing method, since the charged solid reducing agent is sequentially dissolved in the molten salt to reduce the titanium lower chloride, the titanium produced is unlikely to be spongy and the particles grow in a dendritic shape. Thus, the dendritic titanium powder of the present invention can be produced efficiently.

  The best embodiment of the present invention will be described below with reference to the drawings. In this embodiment, first, the manufacturing method of the dendritic titanium powder of the present invention will be described, and then the characteristics of the obtained titanium powder will be described.

  FIG. 1 shows an apparatus configuration used for dissolving lower chloride of titanium used for carrying out the present invention in magnesium chloride. Reference numeral 1 denotes a reaction vessel. After charging solid magnesium chloride into the reaction vessel 1, the entire reaction vessel 1 is heated to a temperature equal to or higher than the melting point of magnesium chloride to melt the magnesium chloride to form a salt bath 2. .

When the temperature of the salt bath 2 is stabilized, the tub 4 holding the titanium material 3 is immersed in the salt bath 2, and titanium tetrachloride is placed at the bottom of the tub 4 from the titanium tetrachloride supply pipe 5 immersed in the vicinity thereof. Supply towards. The supplied titanium tetrachloride is immediately gasified and reacts with the titanium material 3 to mainly generate titanium dichloride (lower chloride) (Ti + TiCl ₄ → 2TiCl ₂ ). At this time, titanium trichloride may be generated at the same time depending on the conditions. The produced lower chloride is dissolved in the salt bath 2 to form a mixed salt bath of magnesium chloride and titanium chloride.

  In the above step, the temperature of the salt bath 2 may be such that the salt bath is maintained in a molten state and evaporation loss is suppressed. As such a temperature range, when the salt bath 2 is magnesium chloride, since the melting point is 714 ° C., it is preferably maintained at 750 to 950 ° C., more preferably 800 to 900 ° C. .

  As the titanium material 3, titanium of any shape such as sponge titanium and titanium scrap can be used. Impurity oxygen and nitride in the titanium material hardly react in the above-described lower chloride formation process, so that sponge titanium having a high oxygen or nitrogen concentration can also be used.

  Any material can be used as the cage 4 for storing the titanium material 3, but it is preferable to use carbon steel or stainless steel, more preferably nickel, in consideration of corrosion resistance against a high-temperature salt bath.

  When titanium sponge and titanium tetrachloride are reacted in magnesium chloride, lower chloride of titanium is formed and simultaneously dissolved in magnesium chloride. Titanium lower chloride with respect to magnesium chloride near 800 to 900 ° C. has a solubility in the range of 8 mol% to 33 mol%. Therefore, it is preferable to supply titanium tetrachloride within a range not exceeding this range. However, when high purity is not required, titanium tetrachloride may be supplied beyond this range. Titanium lower chloride that cannot be dissolved in magnesium chloride precipitates in a solid state in the salt bath 2 and can be used as a titanium source by being transferred to the reduction vessel together with the salt bath 2.

  FIG. 2 shows an apparatus structure for producing the titanium powder of the present invention. The salt bath 12 in which the titanium lower chloride dissolved in the apparatus shown in FIG. 1 is charged into the reaction vessel 11, heated and maintained at a predetermined temperature, and after the temperature is stabilized, the solid reducing metal 6 . This reducible metal 6 reduces the lower chloride of titanium while being dissolved in the salt bath 12 to produce a reductive metal chloride as well as metallic titanium. Titanium produced in this process grows in a dendritic shape.

  The charging of the reducing metal 6 is continued, and the dendritic titanium powder generated in the reaction vessel 11 settles in the salt bath 12 and deposits at the bottom. Some deposits on the inner wall of the reaction vessel 11. After the reduction reaction is completed, the salt bath 12 is withdrawn from the reaction vessel 11, cooled to room temperature, diluted acid is poured into the reaction vessel 11, and the magnesium chloride remaining between the dendritic titanium particles is removed. Reach (wash). By repeating the water injection operation a plurality of times, the magnesium chloride remaining in the dendritic titanium is removed and further dried to produce the dendritic titanium powder of the present invention.

  In the reduction step, it is preferable to use a solid reducing agent, and it is preferable to intermittently add it. It is preferable that the solid reducing metal is introduced at a rate after one reducing agent introduced into the salt bath 12 is completely consumed and then the next reducing agent is introduced. By selecting such a charging speed, dendritic titanium powder can be obtained efficiently.

The particle size of the solid reducing metal used in the present invention is preferably in the range of 1 mm to 10 mm in a small-scale facility. However, it is preferable to use an ingot of about 200 mm × 700 mm × 60 mm, for example, in actual equipment.
As the solid reducing metal, metallic magnesium, metallic calcium, or metallic sodium can be used.

  Note that it is preferable to perform all the steps described above under an inert atmosphere of argon gas. By performing the reaction in an argon gas atmosphere, contamination of the dendritic titanium powder with moisture and oxygen can be suppressed.

  When the titanium powder produced in the salt bath 2 is washed, it is preferable that the dendritic titanium powder is taken out from the reaction vessel and pulverized into small lumps and then leached with water or dilute acid.

  FIG. 3 shows an SEM photograph of the dendritic titanium powder of the present invention produced as described above. The dendritic titanium powder is entangled in a mesh form. Individual titanium is branched in a dendritic shape, and its length is 10 mm or less. The cross section is rectangular or circular, and the diameter of the minimum circle surrounding the cross section is in the range of 1 mm or less. This dendritic titanium is characterized by its uniform length and uniformity. Furthermore, the dendritic titanium powder obtained by the present invention has a high purity and an oxygen concentration in the range of 0.20 wt% or less.

  Moreover, since the atomized powder conventionally used is spherical, a sintering step is required after molding. In the dendritic titanium powder of the present invention, individual dendritic titanium particles are fixed to each other. Since there are many things, it can be used as it is as a filter, for example, as it is or just by molding.

  In addition, after leaching with water as described above and drying, dendritic titanium powder having a low impurity concentration can be produced by vacuum separation at high temperature under reduced pressure. In this method, the produced titanium powders are sintered together, so that they can function effectively as a precision filter.

  In addition, taking advantage of the dendritic feature of the titanium powder of the present invention, it functions as a fiber reinforcing filler material for the purpose of fiber reinforcement of FRM (fiber reinforced metal), FRP (fiber reinforced plastic), or sintered parts. Can also be used as a raw material.

After the lower chloride of titanium was dissolved in molten magnesium chloride using the apparatus shown in FIG. 1, solid magnesium was added using the apparatus shown in FIG. 2 to obtain dendritic titanium powder. Reaction conditions and physical properties of the obtained dendritic titanium are as follows.
1) Reaction conditions Titanium lower chloride concentration in magnesium chloride: 7 wt%
Solid Mg particle size: 5-10mm
Reaction temperature: 900 ° C
2) Reaching condition Reaching solution: 5% HCl-1% HNO ₃
Cleaning liquid: water + acetone 3) Drying conditions Temperature: 65 ° C
Pressure: Atmospheric pressure 4) Crushing equipment: Ball mill 5) Physical properties of dendritic titanium powder Specific surface area: 0.4 g / m ²
Aspect ratio: 6 (average value), 2 to 16 (range)

  Using the obtained titanium powder, the moldability by the Rattler test was examined. As shown in Table 1, it was confirmed that the titanium powder of the present invention was superior to the conventional titanium powder obtained by the hydrodehydrogenation method in terms of formability at low pressure molding and production cost. . Here, the numerical values in Table 1 represent relative values based on the comparative example. In addition, it means that a molded object is hard to break, so that the numerical value of a moldability is small.

  According to the dendritic titanium powder of the present invention, a fiber reinforcing material, a filter, and a sintered part having excellent performance can be obtained.

It is a schematic diagram which shows the melt | dissolution process of the titanium lower chloride in the manufacturing method of the dendritic titanium powder of this invention. It is a schematic diagram which shows the reduction | restoration process of titanium in the manufacturing method of the dendritic titanium powder of this invention. It is a SEM photograph of the dendritic titanium powder of the present invention.

Explanation of symbols

1 Reaction vessel 2 Salt bath 3 Titanium material 4 籠 5 Titanium tetrachloride supply pipe 6 Solid reducing agent 11 Reduction vessel 12 Mixed salt bath

Claims (9)

  A dendritic titanium powder comprising rod-like particles having an average length of 10 mm or less and an average diameter of a minimum circle surrounding a cross-section of 1 mm or less and branched into a dendritic shape.   The dendritic titanium powder according to claim 1, wherein a cross section of the dendritic titanium powder is rectangular or circular.   The dendritic titanium powder according to claim 1 or 2, wherein an oxygen content in the dendritic titanium powder is 0.20 wt% or less.   The dendritic structure according to any one of claims 1 to 3, which is obtained by charging a solid reducing agent into molten magnesium chloride in which titanium lower chloride is dissolved and reducing the titanium lower chloride. Titanium powder.   The dendritic titanium powder according to claim 4, wherein the solid reducing agent is metallic magnesium, metallic calcium or metallic sodium.   A method for producing a dendritic titanium powder, wherein a solid reducing agent is introduced into molten magnesium chloride in which titanium lower chloride is dissolved to reduce the titanium lower chloride.   The method for producing dendritic titanium powder according to claim 6, wherein the titanium lower chloride concentration in the molten magnesium chloride is 10 wt% to 60 wt%.   The method for producing a dendritic titanium powder according to claim 6 or 7, wherein the temperature of the molten magnesium chloride is set to 750C to 950C.   The method for producing dendritic titanium powder according to any one of claims 6 to 8, wherein the solid reducing agent is metallic magnesium, metallic calcium or metallic sodium.

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