Titanium hydride powder and active metal solder

Abstract

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

Description

Technical Field

[0001] This invention relates to a titanium hydride powder containing TiH2, and to an active metal solder. Prior Technology

[0002] For example, small pieces produced during the crushing of sponge blocks obtained by reducing titanium tetrachloride with metallic magnesium, or ingots made by melting and casting the crushed sponge titanium, or cutting discs and other waste materials produced during the machining of thick plates are sometimes supplied to the hydrogenation dehydrogenation process (so-called HDH (Hydride-Dehydride) process).

[0003] In the hydrogenation-dehydrogenation process, the aforementioned small pieces or waste materials are subjected to hydrogenation treatment and embrittled by heating in a hydrogen atmosphere, and then crushed into a predetermined particle size to produce titanium hydride powder. The titanium hydride powder is then heated in a vacuum (as a dehydrogenation treatment) to become titanium powder (pure titanium powder).

[0004] The titanium hydride powder obtained before the dehydrogenation treatment in the hydrogenation-dehydrogenation process contains TiH2, which is a metal hydride. In addition to manufacturing titanium powder using the above-mentioned hydrogenation-dehydrogenation process, it can also be used for various other applications.

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

[0006] Furthermore, Patent Document 2 describes "a titanium-based powder obtained by a hydrogenation-dehydrogenation method, characterized in that it has a particle size range of 5 μm to 74 μm and an average particle size of less than 20 μm, and possesses a flow characteristic with a flowability of less than 100 sec / 50 g". Patent Document 2 further states that "the particle size adjustment step of the present invention is an operational stage after the hydrogenation step in which the pulverized titanium hydride powder or titanium hydride alloy powder is mechanically pulverized and classified to adjust the particle size range to 5 μm to 74 μm and an average particle size of less than 20 μm."

[0007] The "titanium hydride" described in Patent Document 1 and the "titanium hydride powder" described in Patent Document 2 are both considered to be used for the manufacture of titanium powder obtained by the hydrogenation dehydrogenation method.

[0008] Patent Document 3 states, "That is, the titanium-based powder for paste of the present invention is characterized by: 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 relationship: 0.6 < β / α < 1.0･･･(1); where α = (d90 - d50) / d50, β = (d50 - d10) / d50. And d10, d50, and d90 refer to the particle size corresponding to 10%, 50%, and 90% of the cumulative weight of the titanium-based powder relative to the cumulative frequency distribution." It also states, "Furthermore, the titanium-based powder for paste of the present invention is preferably titanium hydride powder manufactured by hydrogenation pulverization, or metallic titanium powder manufactured using this titanium hydride powder as a raw material." Patent Document 3 states, "The present invention can achieve the following effect: it is suitable for use as a paste for manufacturing titanium sheets suitable for electrodes of pigment-sensitized solar cells and secondary batteries." [Previous Technical Documents] [Patent Literature]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 3-122205. [Patent Document 2] Japanese Patent Application Publication No. 7-278601. [Patent Document 3] Japanese Patent No. 5898761. Summary of the Invention

[0010] [The problem that the invention aims to solve] Incidentally, active metal solders used for joining ceramic and metal materials that are difficult to join with conventional solders sometimes contain Ti, and sometimes titanium hydride powder is used in these solders.

[0011] In this context, titanium hydride powder is required to improve the reactivity of Ti in active metal solders with the bonded materials such as ceramics, and to improve the wettability of the active metal solder and the bonded materials. Patent documents 1 to 3 completely fail to address this application or aspect of titanium hydride powder.

[0012] The purpose of this invention is to provide a titanium hydride powder suitable for use in active metal soldering materials, and the active metal soldering materials themselves. [Methods used to solve problems]

[0013] The inventors' research revealed that when titanium hydride powder with a predetermined particle size or particle size distribution is used in active metal brazing materials, the compound at the interface between the Ti in the brazing material and the bonded material is formed almost uniformly. The inventors believe this is achieved by adjusting the predetermined particle size, resulting in a greater number of powder particles per unit volume of the brazing material compared to previous methods, a smaller density difference among the powder particles, a smaller particle size difference, and a larger specific surface area. Therefore, during the reaction steps, a more uniformly sized compound is formed.

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

[0015] The titanium hydride powder is preferably analyzed by image analysis method, in which the proportion of particles with a diameter of 15 μm or larger is less than 10%.

[0016] The maximum particle size of the aforementioned titanium hydride powder, according to image analysis, is preferably below 50 μm.

[0017] The maximum particle size of the aforementioned titanium hydride powder, according to image analysis, is preferably below 35 μm.

[0018] The titanium hydride powder described above is preferably characterized by having a larger value of less than 10 μm when analyzed by image analysis, which is 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.

[0019] The titanium hydride powder described above is preferably characterized by having a larger value of less than 8 μm when analyzed by image analysis, which is 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.

[0020] The aforementioned titanium hydride powder is particularly suitable for use as an active metal brazing material for bonding ceramic and metallic materials.

[0021] The active metal solder of the present invention comprises any of the above-mentioned titanium hydride powders. [Invention Benefits]

[0022] The titanium hydride powder of the present invention can be suitably used in active metal soldering materials. Implementation

[0023] The embodiments of the present invention will now be described in detail.

[0024] (Titanium hydride powder) One embodiment of the present invention contains titanium hydride powder containing TiH2 and is used in active metal soldering materials.

[0025] Active-metal brazing, using active metal brazing materials, is often used for joining ceramic materials to each other or ceramic materials to metal materials; it is also known as the active-metal method. In active-metal brazing, the Ti contained in the titanium hydride powder in the active-metal brazing material reacts with the materials being joined, improving the wettability of the active-metal brazing material and the materials being joined. Therefore, it can also be used for joining materials that are difficult to join with conventional brazing materials.

[0026] On the other hand, the properties of titanium hydride powder, which can improve the reactivity between Ti and the bonded material in active metal solders, have not been fully explored to date. In contrast, the inventors have discovered that when titanium hydride powder with a sufficiently small particle size and a small number of predetermined large-particle-size particles is used in active metal solders, a compound is uniformly formed at the interface between Ti and the bonded material. The inventors believe that this is achieved by adjusting the predetermined particle size, resulting in a greater number of powder particles per unit volume of the solder compared to the past, a smaller density difference among the powder particles within the solder, a smaller particle size difference, and a larger specific surface area. Therefore, during the reaction step, a more uniformly sized compound is formed.

[0027] Based on this understanding, the titanium hydride powder system of this embodiment has an average particle size D50 in the range of 0.1 μm to 10.0 μm, and the proportion of particles with a particle size of 15 μm or larger is set to less than 15%.

[0028] When the average particle size D50 is greater than 10.0 μm, the reactivity between the active metal and the bonded material becomes insufficient due to the reduced specific surface area. On the other hand, when the average particle size D50 is less than 0.1 μm, it becomes difficult to handle in the atmosphere due to the risk of ignition, making it impractical. From this perspective, the average particle size D50 of titanium hydride powder is preferably between 0.1 μm and 10.0 μm, and more preferably between 5.0 μm and 8.0 μm.

[0029] Furthermore, if the proportion of particles with a diameter of 15 μm or larger exceeds 15%, the likelihood of generating coarse particles during active metal soldering increases, potentially leading to reduced reactivity with the bonded materials. In this case, there are concerns, for example, that the generation of these coarse particles could increase the overall or partial thickness of the bonding layer formed by the active metal solder between ceramic, metal, and other circuit substrates bonded using active metal solder. Therefore, it is ideal for particles with a diameter of 15 μm or larger to be present in small quantities, with a suitable proportion of 13% or less, and more preferably 10% or less.

[0030] The maximum particle size of titanium hydride powder is preferably less than 50 μm, and more preferably less than 35 μm. This small maximum particle size suppresses the formation of coarse particles during active metal brazing, stabilizing mechanical properties such as bond strength after bonding. The maximum particle size of titanium hydride powder is, for example, greater than 50 μm, and typically sometimes greater than 60 μm.

[0031] 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 preferably less than 10 μm, and more preferably less than 8 μm. Small differences between the average particle size D50 and the 10% particle size D10, and between the 90% particle size D90 and the average particle size D50, indicate a sharp particle size distribution in the titanium hydride powder. When the larger of these differences is as small as described above, it is considered that smaller particles are uniformly generated during active metal hard soldering, thus stabilizing the mechanical properties.

[0032] The average particle size D50, 10% particle size D10, and 90% particle size D90, as well as the ratio of the number of particles of the predetermined particle size, are each determined by analysis using image analysis. More specifically, using a particle shape image analysis device PITA-04 (manufactured by SEISHIN Enterprise Co., Ltd.: conditions: dispersion medium: IPA (isopropyl alcohol); pump speed: 2000Hz), an image of a titanium hydride powder containing more than 5000 particles is obtained, and the particle size is calculated by using a sphere with an area equal to the projected area of ​​each particle in the image. The cumulative distribution based on the number of particles is then obtained on a graph (with particle size on the horizontal axis and cumulative frequency of particle count on the vertical axis). The average particle size D50, 10% particle size D10, and 90% particle size D90 each refer to the particle size at which the cumulative frequency of the number of particles in the above cumulative distribution is 50%, 10%, or 90%. Furthermore, the percentage of particles with a diameter of 15 μm or larger can be determined from the cumulative distribution described above. The maximum particle size refers to the particle with the largest diameter among the aforementioned 5000 particles.

[0033] Furthermore, the specific surface area of ​​the titanium hydride powder is from 0.6 m² / g to 3.0 m² / g, and more preferably from 1.0 m² / g to 2.0 m² / g. This is because a larger specific surface area can be expected to increase reactivity by increasing the contact area with the bonded material. The specific surface area is determined by the BET (Brunauer-Emmett-Teller) method using N₂ gas.

[0034] Titanium hydride powder contains TiH₂, typically consisting mostly of TiH₂. The hydrogen concentration in TiH₂ is at most 4% by mass, and its hydrogen concentration can be analyzed using the inert gas melting-thermal conductivity method to confirm the presence of TiH₂ in titanium hydride powder.

[0035] Titanium hydride powder sometimes contains Fe, Si, Mn, Mg, Cl, N, and / or O as impurities at a concentration of less than 0.1% by mass. It may also contain other impurities in amounts below the detection limit. The presence and content of impurities can be confirmed by ICP (inductively coupled plasma) emission spectrometry (Fe, Si, Mn, Mg), silver nitrate titration (Cl), ammonia distillation separation followed by acetylene sulfate titration (N), and inert gas melting-infrared absorption spectrometry (O).

[0036] (Manufacturing method) As with the titanium hydride powder described above, it can be manufactured, for example, by performing the steps in a hydrogenation-dehydrogenation process under predetermined conditions up to the point where the titanium raw material is subjected to dehydrogenation treatment. In other words, titanium hydride powder can be obtained before the dehydrogenation step in a hydrogenation-dehydrogenation process under predetermined conditions.

[0037] In the hydrogenation-dehydrogenation process, the titanium raw material is first subjected to a hydrogenation step. The titanium raw material can be: small pieces produced when sponge titanium blocks are crushed, or ingots made from the crushed sponge titanium through melting and casting, or cutting powder or chips and other waste materials generated during the cutting of thick plates. Furthermore, the aforementioned sponge titanium blocks are generated by reducing titanium tetrachloride with metallic magnesium and are primarily composed of Ti.

[0038] In the hydrogenation step, for example, the titanium raw material is sometimes heated to a temperature above 500°C, and hydrogen gas is supplied at this temperature. In this way, the titanium raw material absorbs hydrogen and generates TiH₂, which becomes the hydrogenation feedstock.

[0039] Next, the hydrogenated raw material undergoes a pulverization and classification step. At this time, a pulverizing device equipped with an impact-type pulverizing rotor and an air classifier equipped with a classifying rotor can also be used. Air classification not only classifies finer areas of powder but also allows for fine adjustment of the classification points, thus making it suitable for producing the titanium hydride powder described above. By adjusting the rotation speed of the impact-type pulverizing rotor and the classifying rotor, titanium hydride powder with a predetermined particle size and particle size distribution can be produced. Alternatively, when producing titanium powder, the titanium hydride powder can be recovered and then fed into the dehydrogenation step.

[0040] Titanium hydride powder manufactured in the manner described above, due to being pulverized, generally results in polygonal rather than spherical particles. This is believed to significantly enhance the reactivity of the titanium hydride powder with the bonded material when used in active metal solders. Furthermore, the titanium powder obtained after the dehydrogenation step tends to have a larger particle size due to the sintering effect promoted during the dehydrogenation process; therefore, even with further hydrogenation treatment, it may not always become the fine titanium hydride powder as described in this embodiment. Moreover, the term "fine titanium hydride powder" here refers to powder with an average particle size D50 in the range of 0.1 μm to 10.0 μm when analyzed using the aforementioned image analysis method, and a particle size ratio (cumulative distribution based on number) of 15% or less for particles with a diameter of 15 μm or larger.

[0041] (Active metal soldering material) The titanium hydride powder described above is an active metal soldering material used for active metal soldering. It is sufficient that at least a portion of the active metal soldering material contains titanium hydride powder.

[0042] Active metal soldering materials are typically used for bonding ceramic and metal materials in circuit boards and other applications via active metal soldering. Examples of ceramic materials include oxide ceramics, nitride ceramics, and carbide ceramics, specifically Al₂O₃, SiC, Si₃N₄, AlN, and ZrO₂. Examples of metal materials include Cu.

[0043] Examples of active metal soldering materials include powders, flakes, and pastes. For instance, paste-like active metal soldering materials, in addition to the aforementioned titanium hydride powder, may also contain organic substances such as organic solvents; for example, they are sometimes made by dispersing a powder containing titanium hydride powder in an organic solvent. Other powders included in active metal soldering materials besides titanium hydride powder include silver powder and copper powder. Sometimes titanium hydride powder is mixed into these powders as an additive.

[0044] In active metal brazing, an active metal brazing material is applied to one of the substrates by coating or other methods, and then heated while the active metal brazing material is sandwiched between the two substrates. During this process, in the paste-like active metal brazing material, the organic solvent evaporates and other powders melt, and Ti reacts with components of the substrates (such as Al₂O₃) to form compounds (Al-Ti-O, etc.), thus chemically bonding the active metal brazing material to the substrates. In the case of an active metal brazing material containing titanium hydride powder as described above, the titanium hydride powder is evenly and densely distributed on the target surface, forming compounds of equal size. It is believed that by this, the substantial reactivity of Ti with the substrates is increased, thereby enhancing the bonding strength between the substrates achieved by the active metal brazing material. [Example]

[0045] Subsequently, the titanium hydride powder of the present invention was prepared and will be described below. However, the description herein is for illustrative purposes only and is not intended to be limiting.

[0046] (Examples 1 to 4) Titanium hydride powder is produced by hydrogenating, pulverizing, and classifying the chips generated from the machining of titanium ingots using a hydrogenation-dehydrogenation process. In the hydrogenation step, the chips are heated to above 600°C while being placed in a hydrogen atmosphere supplied with hydrogen gas to obtain the hydrogenated raw material.

[0047] Subsequently, in the pulverization and classification steps, the pulverization and classification conditions are finely adjusted near the classification point of 10 μm, and the micro powder is recovered, thereby obtaining titanium hydride powder with different particle size distributions.

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

[0049] (Evaluation 1; Particle size distribution determination) For each titanium hydride powder and each titanium powder of 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 ratio of particles with a particle size of 15 μm or more were measured according to the aforementioned method. The results are shown in Tables 1 and 2.

[0050] (Evaluation 2; Alumina Plate Bonding Test) For each titanium hydride powder and each titanium powder (hereinafter referred to as "test powder") of Examples 1 to 4 and Comparative Examples 1 to 4, an alumina plate bonding test was performed according to the procedure shown below. The results are shown in Table 2. (1) Apply approximately 1g of the test powder to a 15×15×1.5mm alumina plate placed on a SUS (stainless steel) tray. (2) Overlap an alumina plate of the same size as (1) on an alumina plate covered with the test powder, and place a quartz plate on it. (3) Several quartz plates for height adjustment are stacked on a quartz plate, and a titanium plate of about 130g is placed on it as a weight to obtain a test sample. (4) The obtained test samples were subjected to heat treatment at 800°C for 90 minutes in a vacuum atmosphere below 10 Pa. (5) For the test samples after heat treatment, confirm whether the alumina plates can be joined together. (6) A shear test is performed on the joint of the heat-treated test samples. The shear test is conducted by fixing one end face of the overlapping alumina plates and placing a 5kg weight on the other end face (area: 15mm × 1.5mm) and applying a shear load in the horizontal direction of the joint surface to check for breakage. In this case, if the joined alumina plates are peeled off or the cured test powder is broken and cannot be used for the thermal conductivity measurement described later, it is marked as "No".

[0051] (Evaluation 3; Thermal conductivity measurement) For each titanium hydride powder and each titanium powder (hereinafter referred to as "test powder") of Examples 1 to 4 and Comparative Examples 1 to 4, the same test samples as those used in the alumina plate bonding test of Evaluation 2 were prepared, and the thermal conductivity was measured in accordance with the American standard "ASTM E 1530". The results are shown in Table 2. Furthermore, the measuring apparatus used was a steady-state thermal conductivity measuring device (GH-1; manufactured by ADVANCE RIKO Co., Ltd.). Also, when preparing the test sample, an alumina plate measuring 25×25×1.5 mm was used, and the amount of test powder used was approximately 0.1 g.

[0052] [Table 1] Material Number of observed particles (individuals) D10 D50 D90 Maximum particle size D50-D10 D90-D50 (μm) Example 1 TiH 2 5103 3.35 6.42 10.89 20.1 3.1 4.5 Example 2 TiH 2 5000 2.79 5.36 9.24 18.7 2.6 3.9 Example 3 TiH 2 5000 3.87 6.74 11.07 22.4 2.9 4.3 Example 4 TiH 2 5000 4.03 7.21 11.47 25.8 3.2 4.3 Comparative Example 1 Ti 5009 9.03 14.08 19.31 32.0 5.0 5.2 Comparative Example 2 Ti 5001 11.33 18.94 32.90 61.4 7.6 14.0 Comparative Example 3 TiH 2 5005 13.60 22.64 37.97 61.4 9.0 15.3 Comparative Example 4 Ti 5000 14.86 25.60 38.88 50.9 10.7 13.3

[0053] [Table 2] Cumulative ratio (%) of particles larger than 15 μm Number of particles larger than 15μm Can the aluminum oxide plates be joined? Thermal conductivity measurement of alumina plate bonded samples (Wm -1K -1) Example 1 3.5 181 Can 3.52 Example 2 2.6 130 Can 3.79 Example 3 7.4 370 Can 3.41 Example 4 9.3 465 Can 3.23 Comparative Example 1 52.4 2625 Can 0.90 Comparative Example 2 79.1 3958 no - Comparative Example 3 89.3 4468 no - Comparative Example 4 92.5 4626 No -

Claims

1. A titanium hydride powder containing TiH2 and used in active metal brazing materials; when analyzed by image analysis, the average particle size D50 is in the range of 0.1 μm to 10.0 μm, and the percentage of particles with a particle size of 15 μm or larger is more than 2.6% and less than 15%.

2. The titanium hydride powder as described in claim 1, wherein when analyzed by image analysis, the percentage of particles with a diameter of 15 μm or larger is less than 10%.

3. The titanium hydride powder as described in claim 1, wherein the maximum particle size according to image analysis is less than 50 μm.

4. The titanium hydride powder as described in claim 3, wherein the aforementioned maximum particle size according to image analysis is 35 μm or less.

5. The titanium hydride powder as described in claim 1, wherein when analyzed by image analysis, 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 less than 10 μm.

6. The titanium hydride powder as described in claim 5, wherein when analyzed by image analysis, 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.

7. The titanium hydride powder as described in claim 1, wherein the aforementioned active metal solder is used to bond ceramic materials and metal materials.

8. An active metal solder comprising titanium hydride powder as described in any one of claims 1 to 7.