Brazing paste

Abstract

To provide a paste-like brazing material which can achieve high workability.SOLUTION: A brazing material paste contains 80 mass% or more and 95 mass% or less of a brazing material, and 5 mass% or more and 20 mass% or less of a binder. The brazing material contains 2 mass% or more and 5 mass% or less of a flux. The binder contains two or more hydroxyl groups, a solid solvent having 8 to 10 carbon atoms, and a liquid solvent. (1) When the binder does not contain a thixotropic material, 68 mass% or more of the liquid solvent is contained with respect to the whole binder, and (2) when the binder contains the thixotropic material, 11 mass% or less of the thixotropic material is contained with respect to the whole binder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present embodiment relates to a brazing paste. [Background technology]

[0002] Brazing filler metals have traditionally been used to join components, particularly metal components. For example, Patent Document 1 discloses a configuration in which a tubular component is joined to a joint body by brazing using nickel brazing, silver brazing, or the like, with its end inserted into an opening of a joint body. Patent Document 1 discloses that brazing is performed along the boundary between the opening and the outer peripheral surface of the tubular component on the end face of the joint body, and the melted, liquid brazing material penetrates into the small gap between the inner peripheral surface of the opening and the outer peripheral surface of the tubular component by capillary action, where the temperature of the brazing material that has penetrated drops and hardens, thereby joining the end of the tubular component to the joint body by brazing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-76224 Summary of the Invention [Problem to be solved by the invention]

[0004] Brazing material bonding is generally performed using pellet-shaped brazing material. However, since pellet-shaped brazing material is not easy to work with, its use has been limited. When using pellet-shaped brazing material, it is also necessary to provide a recess for placing the pellet-shaped brazing material.

[0005] In order to improve this situation, the present invention provides a paste-like brazing material that can achieve high workability. [Means for solving the problem]

[0006] [Concept 1] The brazing paste of the present invention is Contains 80% by mass or more and 95% by mass or less of a brazing material and 5% by mass or more and 20% by mass or less of a binder, The brazing material contains 2% by mass or more and 5% by mass or less of flux, The binder includes a solid solvent having two or more hydroxyl groups and 8 to 10 carbon atoms, and a liquid solvent, (1) When the binder does not contain a thixotropic material, the binder contains a liquid solvent in an amount of 68% by mass or more based on the total amount of the binder; (2) When the binder contains a thixotropic material, the thixotropic material may be contained in an amount of 11% by mass or less based on the total mass of the binder.

[0007] [Concept 2] The brazing paste of Concept 1 is When measured under the condition of a temperature rise rate of 10°C / min from 25°C to 450°C, the amount of TG remaining at 250°C may be 0% by mass or more and 1% by mass or less.

[0008] [Concept 3] In the brazing paste of concept 1 or 2, The binder may contain a solid solvent that does not have an endothermic effect on the flux.

[0009] [Concept 4] In any one of the brazing pastes of concepts 1 to 3, The brazing material may contain a metal and either or both of boric acid and borax.

[0010] [Concept 5] The brazing paste of any one of concepts 1 to 4, The binder may contain 2,5-dimethyl-2,5-hexanediol as a solid solvent.

[0011] [Concept 6] The brazing paste of any one of concepts 1 to 5, The binder may contain one or more of isobornylcyclohexanol, terpineol, and isooctadecanol as a liquid solvent. [Effects of the Invention]

[0012] According to the present invention, a paste-like brazing material that can achieve sufficient bonding and has high workability is provided. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a side view showing a mode in which metal parts are joined together using the brazing paste according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] A preferred embodiment of this invention will be described in detail below. In this invention, "or" is a concept that includes "and," and A or B means either A, B, or both A and B.

[0015] The brazing paste of this embodiment may contain a brazing material and a binder. The brazing material may contain a metal and boric acid or borax as a flux. The binder may contain a solid solvent and a liquid solvent, and may further contain a thixotropic material. In this embodiment, tobox may be used as the material containing boric acid and borax.

[0016] This embodiment provides a brazing paste. By using this brazing paste, it can be applied directly to the joint, ensuring wetting and achieving stable joint quality. Furthermore, molded parts can be made smaller and simpler, improving processing accuracy and yield per part. Furthermore, the adhesive strength of the brazing paste makes it easier to join smaller parts by stacking them like bricks, enabling various applications in mass production. As an example, the brazing paste 50 of this embodiment is used to join metal parts 10, 20 to another metal part 30, as shown in FIG. 1 . For example, the brazing paste is spread on the surfaces of the metal parts 10, 20 and used to join the metal parts 10, 20 to the other metal part 30. This joining is performed at temperatures of 450°C or higher, typically 900 to 1000°C. As an example, the brazing paste 50 may be used to join components of an automatic transmission.

[0017] The brazing paste may contain 80% to 95% by mass of brazing material, and 5% to 20% by mass of binder. As described below, the binder evaporates and disappears during joining, so the ratio of brazing material to binder is not particularly limited. However, a high binder content reduces viscosity and workability, so the upper limit of the binder content is preferably 20% by mass, more preferably 15% by mass, and even more preferably 10% by mass. Furthermore, a low binder content increases viscosity, also reducing workability, so the lower limit of the binder content is preferably 5% by mass, more preferably 7% by mass, and even more preferably 8% by mass.

[0018] As the solid solvent for the binder, it is preferable to use one that contains two or more hydroxyl groups, has 8 to 10 carbon atoms, and is solid at 25° C., and for example, 2,5-dimethyl-2,5-hexanediol or the like may be used.

[0019] As the liquid solvent for the binder, a liquid solvent with a low boiling point may be used, and as an example, isobornylcyclohexanol, terpineol, or isooctadecanol may be used. As the terpineol, α-terpineol, β-terpineol, γ-terpineol, δ-terpineol, or the like may be used. In this embodiment, the liquid solvent refers to a solvent that is in a liquid state at 25°C, and the solid solvent refers to a solvent that is in a solid state at 25°C. Note that the boiling point of α-terpineol is 217°C, and it is characterized by not being water-soluble.

[0020] The metal of the brazing material may be added as a metal powder and mixed with other components to form a paste. Because it is in this paste form, the metal powder cannot be recognized as a powder with the naked eye in the brazing material paste. The metal may be an alloy powder, a metal powder, or a mixture of an alloy powder and a metal powder. The metal contained in the brazing material is not particularly limited, and any type of metal can be used. The metal contained in the brazing material may be appropriately changed depending on the material of the metal parts to be joined. For example, a Cu-based alloy powder and an Fe-based metal powder may be used. More specifically, a CuNiMnSiB alloy powder and an Fe powder may be used. The CuNiMnSiB alloy powder may contain 38.0 to 41.0 mass% Cu, 40.0 to 43.0 mass% Ni, 14.0 to 16.0 mass% Mn, 1.6 to 2.0 mass% Si, 1.3 to 1.7 mass% B, and 1.0 mass% or less of other components. Typically, the alloy powder is the main component of the joint, and the metal powder is added to ensure wettability. When using Fe sheet metal, the Fe powder can ensure wettability to the Fe sheet metal.

[0021] Typically, the brazing filler metal components include alloy powder, metal powder, boric acid, and borax. The brazing filler metal components (100% by mass) may contain 70-90% by mass of alloy powder, 10-20% by mass of metal powder, and 1-10% by mass of flux. The ratio of boric acid to borax in the flux may be 1:5 to 5:1. Boric acid and borax are fluxes that function as reducing agents for the alloy powder and metal powder. For example, when Cu is used as the metal or elemental metal in the alloy, boric acid functions as a reducing agent, and when Fe is used as the metal or elemental metal in the alloy, borax functions as a reducing agent. Fluxes containing boric acid and borax exhibit a reducing effect over a wide temperature range, from around 170°C to high temperatures.

[0022] The binder of this embodiment may be selected from those that do not inhibit the reduction effect of boric acid and borax. When such a binder is used, this embodiment is extremely beneficial for brazing filler metals containing boric acid or borax. While boric acid or borax is preferably used as a reducing agent for the metal powder contained in the brazing filler metal, the binder of this embodiment allows for the provision of a paste-like brazing filler metal paste while utilizing boric acid or borax. Therefore, this embodiment exhibits outstanding advantages in enabling a wide variety of applications. The inventors of this application have confirmed that if the solid and liquid solvents are not appropriate, the binder will remain when joining metal parts at high temperatures of approximately 900 to 1000°C. If the binder remains, it will inhibit the reduction effect of the boric acid or borax contained in the brazing filler metal, preventing the brazing filler metal from functioning as a joining material. Since the binder is expected to eventually evaporate and disappear, as mentioned above, the metal contained in the brazing filler metal is not particularly limited.

[0023] The binder may contain a thixotropic material. As the thixotropic material, an amide component may be used, and examples thereof include stearic acid amide, toluamide, lauric acid amide, myristic acid amide, and palmitic acid amide.

[0024] As an example, the binder component may include a solid solvent such as 2,5-dimethyl-2,5-hexanediol, a liquid solvent such as terpineol, isobornylcyclohexanol, or isooctadecanol, and a thixotropic material such as stearic acid amide or toluamide.

[0025] For example, the brazing paste may contain 80% by mass to 95% by mass of brazing material and 5% by mass to 20% by mass of binder, the brazing material containing 2% by mass to 5% by mass of flux, and the binder containing a solid solvent having two or more hydroxyl groups, having 8 to 10 carbon atoms, and solidifying at 25°C, and a liquid solvent. If the binder does not contain a thixotropic material, the liquid solvent may be contained in an amount of 68% by mass or more relative to the total binder. Alternatively, if the binder contains a thixotropic material, the thixotropic material may be contained in an amount of 11% by mass or less relative to the total binder. The brazing paste may contain other components.

[0026] A solid solvent that does not cause an endothermic reaction with the flux may be selected. For example, 2,5-dimethyl-2,5-hexanediol does not cause an endothermic reaction with a flux containing boric acid or borax. Therefore, when a flux containing boric acid or borax is used, 2,5-dimethyl-2,5-hexanediol may be selected as the solid solvent. Note that, in this embodiment, an endothermic reaction refers to a chemical reaction that absorbs heat from the outside.

[0027] The binder component may contain 10 to 60% by mass of the solid solvent and 10 to 90% by mass of the liquid solvent. For example, (1) if the binder does not contain a thixotropic agent, the binder may contain 68% by mass or more of a liquid solvent containing one or more of terpineol, isooctadecanol, and isobornylcyclohexanol, based on the total weight of the binder. (2) If the binder contains a thixotropic agent, the binder may contain 10 to 90% by mass of the liquid solvent containing one or more of terpineol, isooctadecanol, and isobornylcyclohexanol, based on the total weight of the binder, and the binder may contain 11% by mass or less of the thixotropic agent.

[0028] When terpineol is used as the sole liquid solvent, 2,5-dimethyl-2,5-hexanediol is used as the solid solvent, and the binder does not contain a thixotropic agent, the upper limit of the terpineol content relative to the entire binder is preferably 64% by mass or less, and more preferably 60% by mass or less. In this case, the lower limit of the terpineol content relative to the entire binder is preferably 35% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. Under these conditions, a high terpineol content can cause paste separation and deteriorate paste storage performance. On the other hand, a low terpineol content can deteriorate binder properties.

[0029] When 2,5-dimethyl-2,5-hexanediol is used as the solid solvent, in order to achieve optimal softness and optimal tackiness (above 0.6) as a paste, the lower limit of 2,5-dimethyl-2,5-hexanediol in the binder component (out of 100% by mass) is preferably 25% by mass, more preferably 30% by mass, and the upper limit of 2,5-dimethyl-2,5-hexanediol in the binder component is preferably 65% ​​by mass, more preferably 50% by mass, and even more preferably 40% by mass.

[0030] When 2,5-dimethyl-2,5-hexanediol is used as the solid solvent and one or more of terpineol, isooctadecanol, and isobornylcyclohexanol are used as the liquid solvent, in order to achieve optimal softness and optimal tackiness (a tackiness of 0.6 or more) as a paste, the lower limit of the total amount of terpineol, isooctadecanol, and isobornylcyclohexanol in the binder component (100% by mass) (including cases where any of terpineol, isooctadecanol, and isobornylcyclohexanol is not present and is 0) is preferably 45% by mass, more preferably 50% by mass. Also, the upper limit of the total amount of terpineol, isooctadecanol, and isobornylcyclohexanol in the binder component is preferably 75% by mass, more preferably 70% by mass.

[0031] From the viewpoint of more reliably suppressing binder residue when joining metal parts together, it is preferable that the binder component be contained in an amount of 10 mass% or less, more preferably 6 mass% or less, and even more preferably 2 mass% or less, based on the total binder components. [Example]

[0032] The alloy powder used was a CuNiMnSiB alloy powder with a particle size distribution of 22 μm to 44 μm and a D50 of 33 μm. The CuNiMnSiB alloy powder contained 38.0 to 41.0 mass% Cu, 40.0 to 43.0 mass% Ni, 14.0 to 16.0 mass% Mn, 1.6 to 2.0 mass% Si, and 1.3 to 1.7 mass% and 1.0 mass% or less B. As the metal powder, Fe powder was used, and the powder had a particle size distribution of 75 μm or less and a D50 of 33 μm. A flux containing boric acid and borax in a ratio of 4:1 was used. The brazing material contained 100 mass % of CuNiMnSiB alloy powder, 82 mass % of Fe powder, and 3 mass % of flux.

[0033] The 175°C TG remaining amount % was measured using a thermogravimetric differential thermal analyzer (TG-DTA) manufactured by Hitachi High-Tech Science Corporation, under the condition of a heating rate of 10°C / min from 25°C to 450°C. The TG remaining amount % affects the bonding strength. The % shown in the table is the value at 175°C TG remaining amount. If the 175°C TG remaining amount % was less than 1 mass%, it was marked as "Good", and if it was 1 mass% or more, it was marked as "Poor". The flux reactivity was judged visually after the paste was prepared. When no reaction with boric acid or borax was observed by visual observation, it was marked as "Good", and when a reaction with boric acid or borax was observed by visual observation, it was marked as "Poor". Pasting was confirmed by viscosity according to JIS standards and visual inspection. If the viscosity was 50-160 Pa s and no separation was visible, it was marked "Good." If the viscosity was outside the range of 50-160 Pa s or separation was visible, it was marked "Poor." The strength was measured using a DFH210 static torsion tester manufactured by Saginomiya Seisakusho Co., Ltd. Weak strength indicates that the material does not function as a joining material. Strengths of 7900 Nm or greater were marked "Good," while strengths below 7900 Nm were marked "Poor." It is presumed that a high TG balance at 175°C inhibits the reduction effect of the flux, resulting in weak strength. While the values ​​at 175°C are used in this example, values ​​higher than 175°C may be used for the evaluation. Alternatively, a material with a TG balance of less than 1% by mass at 220°C or less than 1% by mass at 250°C may be selected. However, in terms of effectiveness, a TG balance of less than 1% by mass at 250°C is preferred, a TG balance of less than 1% by mass at 220°C is more preferred, and a TG balance of less than 1% by mass at 175°C is even more preferred.

[0034] Binder components consisting of each of Examples 1 to 9 in Table 1 were prepared. Next, 91% by mass of the brazing filler component was mixed with 9% by mass of the binder component, and then measurements were made of the 175°C TG residual %, flux reactivity, pasting, and strength. As mentioned above, the brazing filler component (100% by mass) was a mixture of 82% by mass of CuNiMnSiB alloy powder, 15% by mass of Fe powder, and 3% by mass of flux, and this is also true for Comparative Examples 1 to 14 described below.

[0035] [Table 1]

[0036] As shown in Table 1, all of Examples 1 to 9 showed excellent results in terms of TG, flux reactivity, pasting, and strength. Note that when the TG residual percentage at 175°C is evaluated as "Good," the TG residual percentage at 250°C is naturally also 1 mass% or less.

[0037] Binder components consisting of each of Comparative Examples 1 to 7 in Table 2 were prepared. The TG, flux reactivity, pasting, and strength were evaluated in the same manner as in the examples. In Comparative Example 1, in which no solid solvent was used, favorable results were not obtained in terms of TG and strength. In Comparative Examples 2 to 7, in which no solid solvent containing two or more hydroxyl groups and consisting of 8 to 10 carbon atoms was used, favorable results were not obtained in terms of flux reactivity, pasting, and strength. [Table 2]

[0038] Binder components consisting of each of Comparative Examples 8 to 14 in Table 3 were prepared. The TG, flux reactivity, pasting, and strength were evaluated in the same manner as in Examples 1 to 7. As in Comparative Examples 2 to 7, in Comparative Examples 8 and 9, which did not use a solid solvent containing two or more hydroxyl groups and having 8 to 10 carbon atoms, favorable results could not be obtained in terms of flux reactivity, pasting, and strength. In Comparative Examples 10 to 12, in which 2,5-dimethyl-2,5-hexanediol was used as the solid solvent but no thixotropic agent was contained and the liquid solvent was contained in an amount of 65 mass% or less relative to the entire binder, favorable results were not obtained in terms of strength. Furthermore, in Comparative Examples 10 and 11, in which α-terpineol was used as the liquid solvent, favorable results were not obtained in terms of pasting. Furthermore, in Comparative Example 12, in which isooctadecanol was used as the liquid solvent, favorable results were not obtained in terms of TG. In Comparative Examples 13 and 14, in which 2,5-dimethyl-2,5-hexanediol was used as the solid solvent and the content of the thixotropic material was 15 mass % or more, favorable results could not be obtained in terms of either TG or strength. [Table 3]

[0039] Furthermore, when the deposition properties for 30 mass% 2,5-dimethyl-2,5-hexanediol were confirmed, it was confirmed that the deposition properties of 2,5-dimethyl-2,5-hexanediol were extremely superior to those of α-terpineol, and it was also confirmed that it is beneficial to use α-terpineol when using 2,5-dimethyl-2,5-hexanediol. [Explanation of symbols]

[0040] 10, 20, 30 Metal parts 50 Brazing paste

Claims

1. Contains 80% by mass or more and 95% by mass or less of a brazing material and 5% by mass or more and 20% by mass or less of a binder, The brazing material contains 2% by mass or more and 5% by mass or less of flux, The binder includes a solid solvent having two or more hydroxyl groups and 8 to 10 carbon atoms, which is in a solid state at 25°C, and a liquid solvent which is in a liquid state at 25°C, (1) When the binder does not contain a thixotropic material, the liquid solvent is contained in an amount of 68% by mass or more relative to the entire binder, and the solid solvent is contained in an amount of 10% by mass or more relative to the entire binder; (2) When the binder contains a thixotropic material, the thixotropic material is contained in an amount of 2% by mass or more and 11% by mass or less based on the total amount of the binder, and the solid solvent is contained in an amount of 10% by mass or more based on the total amount of the binder. Brazing paste.

2. 2. The brazing paste according to claim 1, wherein the TG residual amount at 250 ° C. is 0% by mass or more and 1% by mass or less when measured under the condition of a temperature increase rate of 10 ° C. / min from 25 ° C. to 450 ° C. The brazing paste according to claim 1, wherein the TG residual amount at 250 ° C. is 0% by mass or more and 1% by mass or less.

3. 3. The brazing paste according to claim 1, wherein the binder contains a solid solvent that does not cause an endothermic reaction with the flux.

4. The brazing paste according to claim 1 or 2, wherein the brazing material contains a metal and either one or both of boric acid and borax.

5. The brazing paste according to claim 1 or 2, which contains 2,5-dimethyl-2,5-hexanediol as a solid solvent for the binder.

6. 3. The brazing paste according to claim 1, further comprising at least one of isobornylcyclohexanol, terpineol, and isooctadecanol as a liquid solvent for the binder.

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