Titanium hydride powder and active metal brazing filler metal

Abstract

To provide titanium hydride powder which can be suitably used for an active metal brazing filler metal and the active metal brazing filler metal.SOLUTION: The titanium hydride powder of the present invention contains TiH2 and is used for an active metal brazing filler metal, and when analyzed by an image analysis method, the average particle diameter D50 is within the range of 0.1 μm to 10.0 μm, and the number ratio of particles having a particle diameter of 15 μm or more is 15% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] This invention relates to titanium hydride powder containing TiH2 and to an active metal braze material. [Background technology]

[0002] For example, small nodules generated during the crushing of sponge blocks obtained by the reduction of titanium tetrachloride with metallic magnesium, and cutting chips and other scrap generated during the cutting of ingots or slabs made by melting and casting the crushed titanium sponge, may be subjected to the hydrodehydrogenation process (the so-called HDH process).

[0003] In the hydrogenation-dehydrogenation method, the small pieces or scraps are heated in a hydrogen gas atmosphere to be hydrogenated and embrittled, and then crushed to a specified particle size to produce titanium hydride powder. The titanium hydride powder is then heated in a vacuum as a dehydrogenation process to produce titanium powder (pure titanium powder).

[0004] The titanium hydride powder obtained before the dehydrogenation treatment in the hydrogenation-dehydrogenation method contains TiH2, which is a metal hydride, and can be used for various purposes other than the production of titanium powder by the hydrogenation-dehydrogenation method described above.

[0005] As a related technology, Patent Document 1 describes "a method for producing titanium powder by hydrogenation-dehydrogenation, characterized in that titanium hydride is pulverized to an average particle size of 10 μm or less and the dehydrogenation temperature is set to 300 to 600°."

[0006] Patent Document 2 also describes "a titanium-based powder obtained by a hydrogenation-dehydrogenation method, characterized in that the particle size range is 5 to 74 μm, the average particle size is 20 μm or less, and the flow characteristic is a flow rate of less than 100 sec / 50 g." Patent Document 2 also describes that "the particle size adjustment step of the present invention is an operation step in which the above-mentioned hydrogenated titanium powder or hydrogenated titanium alloy powder pulverized after the hydrogenation step is mechanically pulverized and classified to adjust the particle size range to 5 to 74 μm and the average particle size to 20 μm or less."

[0007] Both the "titanium hydride" described in Patent Document 1 and the "titanium hydride powder" described in Patent Document 2 are recognized as being used for producing titanium powder by a hydrogenation-dehydrogenation method.

[0008] Patent Document 3 states that "the titanium-based powder for paste according to the present invention has an average particle size of 20 μm or less, a d90 of 22.50 μm or less, and the parameters α and β related to the particle size distribution satisfy the following relational expression: 0.6<β / α<1.0···(1) where α=(d90-d50) / d50 and β=(d50-d10) / d50, and d10, d50, and d90 mean particle sizes corresponding to 10%, 50%, and 90% of the integrated weight in the cumulative frequency distribution of the titanium-based powder." It also states that "the titanium-based powder for paste according to the present invention is preferably a titanium hydride powder produced by a hydrogenation crushing method or a metallic titanium powder produced using this as a raw material." Patent Document 3 states that "the present invention has the effect of being suitable for use as a paste for producing titanium sheets suitable for use as electrodes for dye-sensitized solar cells and secondary batteries." [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 3-122205 [Patent Document 2] Japanese Patent Application Publication No. 7-278601 [Patent Document 3] Patent No. 5898761 Summary of the Invention [Problem to be solved by the invention]

[0010] Incidentally, active metal brazing filler metals used for joining ceramic materials and metal materials, which are difficult to join with ordinary brazing filler metals, may contain Ti, and titanium hydride powder may be used for these.

[0011] In this case, the titanium hydride powder is required to improve the reactivity of Ti in the active metal brazing material with the joined material such as ceramic materials, and to improve the wettability between the active metal brazing material and the joined material. Patent Documents 1 to 3 do not pay any attention to such uses and aspects of the titanium hydride powder.

[0012] An object of the present invention is to provide a titanium hydride powder that can be suitably used in an active metal brazing material, and an active metal brazing material. [Means for solving the problem]

[0013] As a result of extensive research, the inventors have found that when titanium hydride powder having a specific particle size or particle size distribution is used in an active metal brazing material, compounds are formed almost uniformly at the bonding interface between the Ti in the active metal brazing material and the materials to be bonded. The inventors believe that this is achieved because, by adjusting the particle size as described above, the number of powder particles in a unit volume of the brazing material is increased compared to conventional methods, the powder density difference in the brazing material is reduced, and, in addition, the particle size difference is small and the specific surface area is large, so that compounds with a relatively uniform size are formed uniformly and homogeneously in the reaction process.

[0014] The titanium hydride powder of the present invention contains TiH2 and is used in active metal brazing materials, and when analyzed by image analysis, has an average particle size D50 in the range of 0.1 μm to 10.0 μm, and the proportion of particles having a particle size of 15 μm or more is 15% or less.

[0015] It is preferable that the titanium hydride powder has a particle diameter of 15 μm or more of 10% or less when analyzed by image analysis.

[0016] The titanium hydride powder preferably has a maximum particle size of 50 μm or less as measured by image analysis.

[0017] The titanium hydride powder preferably has a maximum particle size of 35 μm or less as measured by image analysis.

[0018] When the titanium hydride powder is analyzed by image analysis, it is preferable that the larger of the difference between the average particle size D50 and the 10% particle size D10 and the difference between the 90% particle size D90 and the average particle size D50 is 10 μm or less.

[0019] When the titanium hydride powder is analyzed by image analysis, it is preferable that the larger of the difference between the average particle size D50 and the 10% particle size D10 and the difference between the 90% particle size D90 and the average particle size D50 is 8 μm or less.

[0020] The titanium hydride powder is particularly suitable for use in active metal brazing materials used to join ceramic materials and metal materials.

[0021] The active metal brazing material of the present invention contains any one of the titanium hydride powders described above. Effect of the Invention

[0022] The titanium hydride powder of the present invention can be suitably used for active metal brazing materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail.

[0024] (Titanium hydride powder) The titanium hydride powder according to one embodiment of the present invention contains TiH2 and is used in active metal brazing materials.

[0025] Active metal brazing using an active metal brazing material is often applied to joining ceramic materials together or ceramic materials and metal materials, and may also be called the active metal method. In active metal brazing, Ti contained in the titanium hydride powder in the active metal brazing material reacts with the materials to be joined, improving the wettability between the active metal brazing material and the materials to be joined, so that it can be applied to materials that are difficult to join with ordinary brazing materials.

[0026] On the other hand, the properties of titanium hydride powder that can increase the reactivity between Ti in the active brazing material and the materials to be joined have not been fully studied. In response to this, the inventors have newly discovered that if the titanium hydride powder has a relatively small particle size and relatively few particles with a predetermined large particle size, when used in an active brazing material, compounds are uniformly formed at the bonding interface between Ti and the materials to be joined. The inventors believe that this is achieved because the above-mentioned predetermined particle size adjustment increases the number of powder particles in a unit volume of the brazing material compared to the conventional method, reducing the powder density difference in the brazing material, and because the particle size difference is small and the specific surface area is large, compounds with a relatively uniform size are uniformly formed in the reaction process.

[0027] Based on this knowledge, the titanium hydride powder of this embodiment has an average particle size D50 within the range of 0.1 μm to 10.0 μm, and the proportion of particles having a particle size of 15 μm or more is 15% or less.

[0028] If the average particle size D50 is larger than 10.0 μm, the specific surface area will be small, resulting in insufficient reactivity with the workpiece during active metal brazing. On the other hand, if the average particle size D50 is smaller than 0.1 μm, handling in the air will be difficult due to the risk of fire, making it impractical. From this perspective, the average particle size D50 of the titanium hydride powder is preferably 0.1 μm to 10.0 μm, and more preferably 5.0 μm to 8.0 μm.

[0029] In addition, if the number ratio of particles having a particle diameter of 15 μm or more is more than 15%, the possibility of generating coarse particles during active metal brazing increases, which inevitably leads to a decrease in reactivity with the joined materials. In this case, for example, there is a concern that the overall or partial thickness of the joining layer formed by the active metal brazing material between circuit boards of ceramic materials or metal materials, etc., joined using the active metal brazing material will increase due to the generation of the coarse particles. For this reason, it is desirable that the number of particles having a particle diameter of 15 μm or more is small, and the number ratio is preferably 13% or less, and more preferably 10% or less.

[0030] The maximum particle size of the titanium hydride powder is preferably 50 μm or less, more preferably 35 μm or less. If the maximum particle size is small, the generation of coarse particles during active metal brazing is suppressed, and mechanical properties such as the joining strength after joining are stabilized. The maximum particle size of the titanium hydride powder may be, for example, 50 μm or more, typically 60 μm or more.

[0031] The titanium hydride powder is preferably such that the larger of the difference between the average particle size D50 and the 10% particle size D10 (D50-D10) and the difference between the 90% particle size D90 and the average particle size D50 (D90-D50) is 10 μm or less, and more preferably 8 μm or less. A small difference between the average particle size D50 and the 10% particle size D10 or the difference between the 90% particle size D90 and the average particle size D50 means that the particle size distribution of the titanium hydride powder is sharp. When the larger of these differences is small as described above, it is believed that relatively small particles are generated uniformly during active metal brazing, and the mechanical properties are further stabilized.

[0032] The above-mentioned average particle diameter D50, 10% particle diameter D10, and 90% particle diameter D90, as well as the number ratio of particles with a given particle diameter, are each determined by analysis using an image analysis method. More specifically, an image containing projected images of 5000 or more particles of titanium hydride powder is obtained using a particle shape image analyzer PITA-04 (manufactured by Seishin Enterprise Co., Ltd., conditions: dispersion medium: IPA, pump speed: 2000 Hz), and the particle diameter is calculated as a sphere with an area equal to the projected area of ​​each particle in the image. This allows a cumulative distribution based on the number to be obtained on a graph with the particle diameter on the horizontal axis and the cumulative frequency of the number of particles (number) on the vertical axis. The average particle diameter D50, 10% particle diameter D10, and 90% particle diameter D90 respectively mean particle diameters at which the cumulative frequency based on the number in the above cumulative distribution is 50%, 10%, or 90%. The number ratio of particles with a particle diameter of 15 μm or more can also be determined from the above cumulative distribution. The maximum particle size means the particle size of the particle having the largest particle size among the above 5,000 particles.

[0033] In addition, titanium hydride powder has a specific surface area of ​​0.6 to 3.0 m 2 / g, and further 1.0 to 2.0 m 2 / g is preferable. This is because a larger specific surface area is expected to further improve reactivity due to an increased contact area with the materials to be joined. The specific surface area is measured by the BET method using N2 gas.

[0034] Titanium hydride powder contains TiH2, and typically consists mostly of TiH2. The hydrogen concentration in TiH2 is a maximum of 4 mass%, and the fact that titanium hydride powder contains TiH2 can be confirmed by analyzing the hydrogen concentration using an inert gas fusion-thermal conductivity method.

[0035] Titanium hydride powder may contain Fe, Si, Mn, Mg, Cl, N and / or O as impurities at a content of 0.1 mass% or less. It may also contain other impurities at amounts less than the detection limit. The presence or absence and content of impurities can be confirmed by ICP emission spectroscopy (Fe, Si, Mn, Mg), silver nitrate titration (Cl), ammonia distillation separation amidosulfuric acid titration (N), and inert gas fusion-infrared absorption spectroscopy (O).

[0036] (Manufacturing method) The titanium hydride powder as described above can be produced, for example, by carrying out the steps before the dehydrogenation treatment of the titanium raw material in the hydrodehydrogenation method under predetermined conditions. In other words, the titanium hydride powder is obtained before the dehydrogenation step during the hydrodehydrogenation method under predetermined conditions.

[0037] In the hydrodehydrogenation process, first, a hydrogenation process is performed on the titanium raw material. The titanium raw material can be small pieces generated when crushing titanium sponge blocks, cutting powder or chips generated when cutting an ingot or slab produced by melting and casting the titanium sponge obtained by crushing, or other scraps. The above-mentioned titanium sponge blocks are produced by reducing titanium tetrachloride with metallic magnesium, and are mainly composed of Ti.

[0038] In the hydrogenation process, the titanium raw material may be heated to a temperature of, for example, 500°C or higher and hydrogen gas may be supplied to the titanium raw material, causing the titanium raw material to absorb hydrogen and generate TiH2, which becomes the hydrogenated raw material.

[0039] Thereafter, the hydrogenation raw material is subjected to a pulverization process and a classification process. At this time, a pulverization device equipped with an impact type pulverization rotor and an air classifier equipped with a classification rotor may be used. Air classification can classify powder in a relatively fine range, and can also finely adjust the classification point, so it can be suitably used for producing the titanium hydride powder of the above-mentioned embodiment. By adjusting the rotation speed of the impact type pulverization rotor and the classification rotor, etc., it is possible to obtain titanium hydride powder having a predetermined particle size and particle size distribution. On the other hand, when titanium powder is produced, the titanium hydride powder is recovered and then subjected to a dehydrogenation process.

[0040] The titanium hydride powder produced as described above is often polygonal rather than spherical because of the pulverization. It is believed that the titanium hydride powder has a significantly increased reactivity with the materials to be joined when used in an active brazing material. The titanium powder obtained after the dehydrogenation step tends to have a large particle size as a result of the promotion of sintering during the dehydrogenation treatment, and therefore may not become fine titanium hydride powder as in this embodiment even if it is further subjected to hydrogenation. The "fine titanium hydride powder" here means a powder having an average particle size D50 in the range of 0.1 μm to 10.0 μm and a number ratio (cumulative distribution based on number) of particles having a particle size of 15 μm or more when analyzed by the above-mentioned image analysis method.

[0041] (Active metal brazing material) The titanium hydride powder described above is used in an active metal brazing material for use in active metal brazing. At least a part of the active metal brazing material may contain the titanium hydride powder.

[0042] The active metal brazing material can be typically used for joining ceramic materials such as circuit boards to metal materials by active metal brazing. Examples of the ceramic material include oxide-based, nitride-based, or carbide-based ceramics, specifically Al2O3, SiC, Si3N4, AlN, ZrO2, etc. Examples of the metal material include Cu.

[0043] The active metal brazing material may be in the form of a powder, a sheet, or a paste. For example, a paste-type active metal brazing material may contain an organic substance such as an organic solvent in addition to the titanium hydride powder, and may be a powder containing titanium hydride powder dispersed in an organic solvent. Examples of powders other than the titanium hydride powder contained in the active metal brazing material include silver powder and copper powder. The titanium hydride powder may be mixed into such powders as an additive.

[0044] In active metal brazing, an active metal brazing material is placed on one of the materials to be joined by coating or the like, and the active metal brazing material is sandwiched between the one and the other materials to be joined, and then the materials are heated. At this time, the organic solvent in the paste-like active metal brazing material evaporates, other powders melt, and Ti reacts with the components of the materials to be joined (Al2O3, etc.) to form compounds (Al-Ti-O, etc.), and the active metal brazing material and the materials to be joined are chemically bonded. In the case of the active metal brazing material containing titanium hydride powder of the above-mentioned embodiment, the titanium hydride powder distributed relatively uniformly and densely on the target surface uniformly and uniformly forms compounds of the same size. This increases the substantial reactivity between Ti and the materials to be joined, and it is considered that the bonding strength between the materials to be joined by the active metal brazing material can be improved. EXAMPLES

[0045] Next, a titanium hydride powder according to the present invention was produced as a prototype, which will be described below, although the description here is merely for illustrative purposes and is not intended to be limiting.

[0046] (Examples 1 to 4) The cutting chips generated during the machining of titanium ingots were subjected to a hydrogenation process using a hydrogenation-dehydrogenation method, a crushing process, and a classification process to produce hydrogenated titanium powder. In the hydrogenation process, the cutting chips were heated to over 600°C and hydrogen gas was supplied to create a hydrogen gas atmosphere, obtaining the hydrogenation raw material.

[0047] In the subsequent pulverization and classification processes, the pulverization and classification conditions were finely adjusted at a classification point of around 10 μm, and the fine powder was collected to obtain titanium hydride powders with different particle size distributions.

[0048] (Comparative Examples 1 to 4) The coarse powders collected in Examples 1 to 4 were further air-classified to obtain titanium hydride powders with different particle size distributions. The classification point of Comparative Example 1 was 20 μm, and the classification points of Comparative Examples 2 to 4 were 45 μm. In Comparative Examples 1, 2, and 4, a dehydrogenation treatment was performed by heating to a temperature of 500° C. or higher in a vacuum. Titanium powder (pure titanium) was thus obtained.

[0049] (Evaluation 1: Particle size distribution measurement) For each of the titanium hydride powders and titanium powders in Examples 1 to 4 and Comparative Examples 1 to 4, the average particle size D50, 10% particle size D10, 90% particle size D90, maximum particle size, and the number ratio of particles with a particle size of 15 μm or more were measured according to the methods described above. The results are shown in Tables 1 and 2.

[0050] (Evaluation 2: Alumina plate bonding test) For each of the titanium hydride powders and each of the titanium powders (hereinafter referred to as "test powders") in Examples 1 to 4 and Comparative Examples 1 to 4, an alumina plate bonding test was carried out according to the procedure described below. The results are shown in Table 2. (1) Approximately 1 g of the test powder was spread on an alumina plate measuring 15 x 15 x 1.5 mmt placed on a SUS tray. (2) An alumina plate of the same size as (1) was placed on top of the alumina plate on which the test powder was spread, and a quartz plate was placed on top of that. (3) Several quartz plates for height adjustment were stacked on top of the quartz plate, and a titanium plate weighing approximately 130 g was placed on top of them as a weight to obtain a test sample. (4) The obtained test samples were subjected to a heat treatment at 800° C. for 90 minutes in a vacuum atmosphere of 10 Pa or less. (5) After the heat treatment, the test samples were checked to see whether the alumina plates could be joined together. (6) Regarding the bonding of the test samples after the heat treatment, a shear test was performed in which one end face of the stacked alumina plates was fixed, and a 5 kg weight was placed on the other end face (area: 15 mm x 1.5 mm), and a shear load was applied horizontally to the bonded surfaces to check for damage. If the bonded alumina plates peeled off or the solidified test powder was damaged and could not be used for the thermal conductivity measurement described later, the result was judged as "no."

[0051] (Evaluation 3: Thermal conductivity measurement) For each of the titanium hydride powders and titanium powders (hereinafter referred to as "test powders") in Examples 1 to 4 and Comparative Examples 1 to 4, test samples were prepared in the same manner as in the alumina plate bonding test in Evaluation 2, and thermal conductivity was measured in accordance with the US standard "ASTM E 1530." The results are shown in Table 2. The measurement device used was a steady-state thermal conductivity measurement device (GH-1, manufactured by Advance Riko Co., Ltd.) The test sample was prepared using an alumina plate of 25 × 25 × 1.5 mmt, and the amount of the test powder used was approximately 0.1 g.

[0052] [Table 1]

[0053] [Table 2]

Claims

1. T.I.H. 2 A titanium hydride powder for use in an active metal brazing material, comprising: A titanium hydride powder having an average particle size D50 in the range of 0.1 μm to 10.0 μm, and a ratio of particles having a particle size of 15 μm or more to the number of particles of 15% or less, when analyzed by image analysis.

2. 2. The titanium hydride powder according to claim 1, wherein when analyzed by image analysis, the proportion of particles having a particle diameter of 15 μm or more is 10% or less.

3. 2. The titanium hydride powder according to claim 1, wherein the maximum particle size measured by an image analysis method is 50 μm or less.

4. 4. The titanium hydride powder according to claim 3, wherein the maximum particle size measured by an image analysis method is 35 μm or less.

5. 2. The titanium hydride powder according to claim 1, wherein, when analyzed by image analysis, the larger of the difference between the average particle diameter D50 and the 10% particle diameter D10 and the difference between the 90% particle diameter D90 and the average particle diameter D50 is 10 μm or less.

6. 6. The titanium hydride powder according to claim 5, wherein, when analyzed by image analysis, the larger of the difference between the average particle diameter D50 and the 10% particle diameter D10 and the difference between the 90% particle diameter D90 and the average particle diameter D50 is 8 μm or less.

7. 2. The titanium hydride powder according to claim 1, wherein the active metal brazing material is used for joining a ceramic material to a metal material.

8. An active metal brazing material comprising the titanium hydride powder according to any one of claims 1 to 7.

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