Titanium hydride powder and reactive metal solder

Abstract

The titanium hydride powder according to the present invention contains TiH2, is used in an active metal brazing filler metal, and when analyzed by image analysis, has an average particle diameter D50 in the range of 0.1-10.0 [mu] m, and has a number ratio of 15% or less of particles having a particle diameter of 15 [mu] m or more.

Description

Technical Field

[0001] This invention relates to titanium hydride powder containing TiH2 and active metal solder. Background Technology

[0002] For example, small pieces produced during the crushing of sponge titanium blocks obtained by reducing titanium tetrachloride with metallic magnesium, and cutting discs and other scraps produced during the machining of ingots or slabs formed by melting and casting the crushed sponge titanium are sometimes used in the hydrodehydrogenation process (so-called HDH process).

[0003] In the hydrodehydrogenation process, after the aforementioned small pieces or waste materials are heated in a hydrogen atmosphere to undergo hydrogenation treatment and become embrittled, they are pulverized into a specified particle size to produce titanium hydride powder. Subsequently, the titanium hydride powder is heated in a vacuum as a dehydrogenation treatment to become titanium powder (pure titanium powder).

[0004] The titanium hydride powder obtained before dehydrogenation in the hydrodehydrogenation process contains TiH2 as a metal hydride. In addition to manufacturing titanium powder using the above-mentioned hydrodehydrogenation 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 hydrodehydrogenation, titanium hydride is pulverized to an average particle size of less than 10 μm, and the dehydrogenation temperature is set to 300 to 600°C."

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

[0007] It can be assumed that the "titanium hydride" described in Patent Document 1 and the "titanium hydride powder" described in Patent Document 2 are both used to manufacture titanium powder using the hydrodehydrogenation method.

[0008] Patent Document 3 states: "That is, the titanium-based powder for paste of the present invention is characterized by having 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 satisfying the following relationship: 0.6 < β / α < 1.0 (1). Here, α = (d90 - d50) / d50, β = (d50 - d10) / d50, and d10, d50, and d90 refer to the particle sizes of the titanium-based powder corresponding to 10%, 50%, and 90% of the cumulative weight relative to the cumulative frequency distribution."; and, "Furthermore, the titanium-based powder for paste of the present invention refers to titanium hydride powder manufactured by hydrogenation pulverization or metallic titanium powder manufactured using this as a raw material, which is a preferred embodiment." Patent Document 3 states: "The present invention achieves the effect of being preferably used as a paste for manufacturing titanium sheets suitable for electrodes of dye-sensitized solar cells and secondary batteries."

[0009] Existing technical documents Patent documents 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 Furthermore, active metal solders used for joining ceramic and metal materials, which are difficult to join using conventional solders, sometimes contain Ti, and titanium hydride powder is sometimes used for such active metal solders.

[0011] In this case, titanium hydride powder is required to improve the reactivity of Ti in the active metal solder with the bonded parts such as ceramic materials, and to improve the wettability of the active metal solder with the bonded parts. Patent documents 1 to 3 do not focus on the above-mentioned uses or aspects of titanium hydride powder.

[0012] The purpose of this invention is to provide titanium hydride powder and active metal solder that are suitable for use in active metal solders.

[0013] Solution for solving the problem The inventors conducted in-depth research and discovered that when titanium hydride powder with a specified particle size or particle size distribution is used in active metal solder, the compound at the interface between the Ti in the active metal solder and the bonded parts is formed approximately uniformly. The inventors believe that by adjusting the specified particle size, the number of powder particles per unit volume of the solder increases, the density difference of the powder within the solder decreases, and the small particle size difference combined with a large specific surface area results in the consistent and uniform formation of compounds of relatively uniform size during the reaction process, thereby achieving the aforementioned effect.

[0014] The titanium hydride powder of the present invention contains TiH2 and is used in active metal solders. 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 larger is less than 15%.

[0015] Preferably, when the titanium hydride powder described above is analyzed using image analysis, the proportion of particles with a particle size of 15 μm or larger is less than 10%.

[0016] Preferably, the maximum particle size of the titanium hydride powder described above, as measured by image analysis, is less than 50 μm.

[0017] Preferably, the maximum particle size of the titanium hydride powder described above, as measured by image analysis, is less than 35 μm.

[0018] Preferably, when the titanium hydride powder described above is analyzed using 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.

[0019] Preferably, when the above-mentioned titanium hydride powder is 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.

[0020] The aforementioned titanium hydride powder is particularly preferred for use as an active metal solder in the bonding of ceramic and metallic materials.

[0021] The active metal solder of the present invention comprises titanium hydride powder as described in any one of the above-mentioned methods.

[0022] Invention Effects The titanium hydride powder of the present invention is suitable for use in active metal solders. Detailed Implementation

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

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

[0025] Active metal brazing, using active metal solders, is primarily used for joining ceramic materials or ceramic materials with 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 solder reacts with the workpiece, improving the wettability between the active metal solder and the workpiece. Therefore, it can also be used for joining workpieces that are difficult to join using conventional solders.

[0026] On the other hand, the properties of titanium hydride powder, which can improve the reactivity of Ti in active metal solders with the bonded component, have not been sufficiently studied until now. In contrast, the inventors have made a new discovery: when titanium hydride powder has a sufficiently small particle size and a limited number of particles with a specified large particle size, a compound is uniformly formed at the bonding interface between Ti and the bonded component when used in active metal solders. The inventors believe that by adjusting the specified particle size as described above, the number of powder particles per unit volume of the solder increases compared to the past, the density difference of the powder within the solder decreases, and the small particle size difference and large specific surface area result in the consistent and uniform formation of compounds of relatively uniform size during the reaction process, thereby achieving the aforementioned effect.

[0027] Based on this understanding, for the titanium hydride powder of this embodiment, the average particle size D50 is set to be 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 set to 15% or less.

[0028] When the average particle size D50 is greater than 10.0 μm, the smaller specific surface area leads to insufficient reactivity with the joined parts during active metal brazing. On the other hand, when the average particle size D50 is less than 0.1 μm, it is difficult to operate in the atmosphere due to the possibility of ignition, making it impractical. From this perspective, the average particle size D50 of titanium hydride powder is preferably 0.1 μm to 10.0 μm, and more preferably 5.0 μm to 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 brazing increases, and the resulting decrease in reactivity with the bonded components cannot be ruled out. In addition, in this case, there is concern that, for example, between circuit boards made of ceramic or metal materials bonded using active metal solder, the overall or local thickness of the bonding layer formed by the active metal solder may increase due to the generation of the aforementioned coarse particles. Therefore, it is ideal to have fewer particles with a diameter of 15 μm or larger, preferably 13% or less, and more preferably 10% or less.

[0030] The maximum particle size of titanium hydride powder is preferably 50 μm or less, more preferably 35 μm or less. This smaller maximum particle size suppresses the generation 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 sometimes, for example, 50 μm or more, typically 60 μm or more.

[0031] For titanium hydride powder, the larger of the difference between the average particle size D50 and 10% of the particle size D10 (D50 - D10), and the difference between 90% of the particle size D90 and the average particle size D50 (D90 - D50), is preferably 10 μm or less, and more preferably 8 μm or less. A smaller difference between the average particle size D50 and 10% of the particle size D10, and a smaller difference between 90% of the particle size D90 and the average particle size D50, indicates a sharper particle size distribution in the titanium hydride powder. When the larger of these differences is smaller than described above, it is believed that smaller particles will be generated more uniformly during active metal brazing, further stabilizing the mechanical properties.

[0032] The average particle size D50, 10% particle size D10, and 90% particle size D90, as well as the proportion of particles of the specified particle size, were determined by image analysis. More specifically, using a particle shape image analysis device PITA-04 (manufactured by SEISHIN ENTERPRISE CO., LTD., with IPA as the dispersion medium and a pump speed of 2000 Hz), an image containing more than 5000 particles of titanium hydride powder was obtained. The particle size was calculated using a sphere with an area equal to the projected area of ​​each particle in the image. Thus, a cumulative distribution based on the number of particles was obtained on a graph where the horizontal axis was set to particle size and the vertical axis to the cumulative frequency of the number of particles. The average particle size D50, 10% particle size D10, and 90% particle size D90 refer to the particle sizes where the cumulative frequency based on the number of particles in the aforementioned cumulative distribution is 50%, 10%, or 90%, respectively. Furthermore, based on the cumulative distribution described above, the proportion of particles with a diameter of 15 μm or larger can also be determined. The maximum particle size refers to the particle size with the largest diameter among the aforementioned 5000 particles.

[0033] Furthermore, the specific surface area of ​​the titanium hydride powder is preferably 0.6–3.0 m². 2 / g, more preferably 1.0 to 2.0m 2 / g. The reason is that if the specific surface area is larger, a further increase in reactivity can be expected due to the increased contact area with the bonded component. The specific surface area is determined using the BET method with N2 gas.

[0034] Titanium hydride powder contains TiH2, and typically, it is mostly formed from TiH2. The hydrogen concentration in TiH2 is at most 4% by mass. The presence of TiH2 in titanium hydride powder can be confirmed by analyzing its hydrogen concentration using an inert gas melting-thermal conductivity method.

[0035] Titanium hydride powder sometimes contains Fe, Si, Mn, Mg, Cl, N, and / or O as impurities at a content of less than 0.1% by mass. In addition, other impurities may sometimes be present in amounts less than the detection limit. The presence and content of impurities can be confirmed by ICP emission spectroscopy (Fe, Si, Mn, Mg), silver nitrate titration (Cl), ammonia distillation followed by aminosulfonic acid titration (N), and inert gas melting-infrared absorption (O).

[0036] (Manufacturing method) The titanium hydride powder described above can be manufactured, for example, by performing a process on titanium raw material under specified conditions prior to the dehydrogenation treatment in a hydrodehydrogenation process. In other words, titanium hydride powder is obtained before the dehydrogenation step in a hydrodehydrogenation process under specified conditions.

[0037] In the hydrodehydrogenation process, the titanium raw material is first subjected to a hydrogenation process. The titanium raw material can be small pieces generated during the crushing of sponge titanium blocks, cutting powder or chips generated during the cutting of ingots or slabs made from the sponge titanium obtained through melting and casting, and other waste materials. It should be noted that the aforementioned sponge titanium blocks are produced by reducing titanium tetrachloride with metallic magnesium and are mainly composed of Ti.

[0038] In the hydrogenation process, the titanium feedstock is heated to a temperature of, for example, above 500°C, and sometimes hydrogen is supplied to it. As a result, the titanium feedstock absorbs hydrogen and produces TiH2, which becomes the hydrogenation feedstock.

[0039] Next, the hydrogenation feedstock undergoes a pulverization and classification process. At this time, a pulverizing device equipped with an impact-type pulverizing rotor and an air classifier equipped with a classifying rotor can be used. Air classification can classify powders in finer regions and allows for fine adjustment of the classification points, thus it is preferably used to produce the titanium hydride powder described in the above embodiment. By adjusting the rotational speed of the impact-type pulverizing rotor and the classifying rotor, titanium hydride powder with a specified particle size and particle size distribution can be produced. On the other hand, in the case of producing titanium powder, after recovering the titanium hydride powder, it is supplied to the dehydrogenation process.

[0040] The titanium hydride powder manufactured as described above is pulverized, resulting in particles that are mostly polygonal rather than spherical. Therefore, when used with active metal solders, this titanium hydride powder is considered to have significantly improved reactivity with the bonded component. It should be noted that the titanium powder obtained after the dehydrogenation process is promoted to sinter during dehydrogenation treatment, resulting in a tendency for the particle size to increase. Therefore, even with further hydrogenation treatment, it may not become the fine titanium hydride powder of this embodiment. It should be noted that "fine titanium hydride powder" as used here refers to a particle size distribution (cumulative distribution based on the number of particles) with a diameter of 15 μm or larger within the range of an average particle size D50 of 0.1 μm to 10.0 μm, as analyzed using the image analysis method described above.

[0041] (Active metal brazing filler metal) The titanium hydride powder described above is used in active metal brazing filler metals. At least a portion of the active metal brazing filler metal must contain titanium hydride powder.

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

[0043] Active metal solders can be in powder, flake, or paste form. For example, paste-form active metal solders, in addition to the aforementioned titanium hydride powder, may also contain organic substances such as organic solvents. Sometimes, they are formulated by dispersing a powder containing titanium hydride powder in an organic solvent. Other powders besides titanium hydride powder included in active metal solders include silver powder and copper powder. Titanium hydride powder is sometimes mixed into the powder as an additive.

[0044] Active metal brazing is sometimes performed by applying an active metal filler metal to one of the workpieces to be bonded using a coating or similar method, and then heating the workpieces while the active metal filler metal is sandwiched between them. During this process, the organic solvent in the paste-like active metal filler metal evaporates, other powders melt, and Ti reacts with the components of the workpieces (such as Al₂O₃) to form compounds (Al-Ti-O, etc.), thus chemically bonding the active metal filler metal to the workpieces. In the case of an active metal filler metal containing titanium hydride powder as described in the above embodiment, the titanium hydride powder, which is relatively uniformly and densely distributed on the target surface, forms compounds of equal size. This increases the substantial reactivity of Ti with the workpieces, and therefore is considered to improve the bonding strength between the workpieces resulting from the active metal filler metal.

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

[0046] (Examples 1-4) The chips generated during the machining of titanium ingots undergo a hydrogenation process, a crushing process, and a classification process using a hydrodehydrogenation method to produce titanium hydride powder. In the hydrogenation process, the chips are heated to above 600°C while being placed in a hydrogen atmosphere supplied with hydrogen gas, thus obtaining the hydrogenated feedstock.

[0047] Subsequently, in the pulverization and classification processes, the pulverization and classification conditions were finely adjusted near the 10μm classification point to recover the micro powder side, thereby obtaining titanium hydride powders with different particle size distributions.

[0048] (Comparative Examples 1-4) The coarse powder recovered in Examples 1-4 was further classified by airflow to obtain titanium hydride powders with different particle size distributions. In this case, the classification point for Comparative Example 1 was set to 20 μm, and the classification points for Comparative Examples 2-4 were set to 45 μm, respectively. 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. As a result, titanium powder (pure titanium) was obtained.

[0049] (Evaluation 1; Particle size distribution determination) For each titanium hydride powder and each titanium powder of Examples 1-4 and Comparative Examples 1-4, the average particle size D50, 10% particle size D10, 90% particle size D90, maximum particle size, and the proportion of particles with a particle size of 15 μm or larger were determined according to the method described above. 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 1-4 and Comparative Examples 1-4, an alumina plate bonding test was performed according to the steps shown below. The results are shown in Table 2.

[0051] (1) On a 15×15×1.5mm alumina plate placed on a SUS tray, about 1g of the test powder is spread.

[0052] (2) Stack an alumina plate of the same size as (1) on an alumina plate on which the test powder is laid, and place a quartz plate on it.

[0053] (3) Several quartz plates for height adjustment were stacked on a quartz plate, and a titanium plate of about 130g was placed on it as a counterweight to obtain the test sample.

[0054] (4) The obtained test samples were heat-treated at 800°C for 90 minutes in a vacuum atmosphere below 10 Pa.

[0055] (5) For the test samples after heat treatment, confirm whether the alumina plates can be joined together.

[0056] (6) Regarding the joining of the test samples after heat treatment, the following shear test is performed: fix one end face of the stacked alumina plates, and place a 5kg weight on the other end face (area: 15mm × 1.5mm). Under the condition that a shear load is applied in the horizontal direction of the joint surface, confirm whether there is any breakage. At this time, if the test powder peels off or is cured from the joined alumina plates and is therefore unable to be used for the thermal conductivity measurement described later, it is set as "No".

[0057] (Evaluation 3; Thermal conductivity measurement) For each titanium hydride powder and each titanium powder (hereinafter referred to as "test powder") of Examples 1-4 and Comparative Examples 1-4, the same test samples as those used in the alumina plate bonding test of Evaluation 2 were prepared, and the thermal conductivity was determined according to the American standard "ASTM E 1530". The results are shown in Table 2.

[0058] It should be noted that the steady-state thermal conductivity measuring apparatus (GH-1, manufactured by ADVANCE RIKO, Inc.) was used as the measuring device. Furthermore, when preparing the test sample, an alumina plate measuring 25×25×1.5 mm was used, and the amount of test powder used was set to approximately 0.1 g.

Claims

1. A titanium hydride powder containing TiH2, used in active metal solders. When using 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 diameter of 15 μm or larger is less than 15%.

2. The titanium hydride powder according to claim 1, wherein, When using image analysis, the proportion of particles with a diameter of 15 μm or larger is less than 10%.

3. The titanium hydride powder according to claim 1, wherein, The maximum particle size measured by image analysis was less than 50 μm.

4. The titanium hydride powder according to claim 3, wherein, The maximum particle size, as determined by image analysis, is less than 35 μm.

5. The titanium hydride powder according to claim 1, wherein, When using 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 according to claim 5, wherein, When analyzed using 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 8 μm.

7. The titanium hydride powder according to claim 1, wherein, The active metal solder is used for bonding ceramic materials to metal materials.

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

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