Mixed powder for paste brazing materials, and paste brazing material using same

Abstract

The present invention provides: a mixed powder for paste brazing materials; a paste brazing material which is produced using this powder; and a method for producing a paste brazing material.　A paste brazing material according to the present invention is able to be produced by mixing 8.0 parts by mass to 22.0 parts by mass of an aqueous solution that contains an organic solvent or the like into 100 parts by mass of a mixed powder for paste brazing materials, wherein the mass ratio of a brazing filler material powder to a resin powder, which serves as a water-soluble thickening agent, is 99.88-97.90:0.12-2.10. It is preferable that the resin powder is composed of a cellulose-based material; and it is particularly preferable that the resin powder is composed of one or two materials selected from among methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropylmethyl cellulose.

Description

Mixed powder for paste brazing and paste brazing using the same

[0001] The present invention relates to raw material powder for a brazing paste used for joining stainless steel and the like, and to a brazing paste produced using the raw material powder.

[0002] Conventionally, when joining stainless steel, particularly when corrosion resistance is required, brazing filler metals containing nickel, iron, and cobalt as the main components are used, and joining is performed by furnace brazing. The brazing filler metal is applied by methods such as placing an amorphous foil, applying a paste brazing filler metal with a dispenser, screen printing, or sprinkle printing, and in particular, applying a paste brazing filler metal is used to reduce the amount of brazing filler metal applied.

[0003] This paste brazing material is obtained by kneading a brazing material powder with a binder, which requires three steps: production of the brazing material powder, production of the binder, and production of the paste. For example, the paste brazing material is disclosed in Patent Document 1.

[0004] Patent No. 3228849

[0005] While hydrophobic (oil-based) and water-soluble binders are used for paste wax, water-soluble binders are preferable because they have a lower environmental impact and do not require a working environment or explosion-proof facilities. However, during the water-soluble binder manufacturing process, when the water-soluble resin used as the thickener is dissolved in an aqueous solution, lumps called "mamako" (agglomerates formed when only the outer surfaces of powder particles or their aggregates hydrate, forming a viscous gel layer that prevents water from penetrating into the interior) form. This requires strong stirring, prolonged stirring, or a long dispersion period to stabilize the water-soluble binder, limiting the rate of paste wax manufacturing. Furthermore, the formation of lumps and the evaporation of water during manufacturing can lead to problems such as unstable binder viscosity.

[0006] The present inventor has developed a new brazing paste that can suppress the generation of loose particles and eliminate the binder manufacturing process, as well as a mixed powder for the brazing paste used therein.

[0007] Specifically, the mixed powder for paste brazing of the present invention contains a brazing material powder and a resin powder which is a water-soluble thickener, and is characterized in that the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10.

[0008] The resin powder serving as the thickener is preferably a cellulose-based resin, and the resin powder is characterized by being one or two types selected from methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and the like.

[0009] The paste wax of the present invention can be obtained by blending 8.0 to 26.6 parts by mass of water with 100 parts by mass of the mixed powder for the paste wax.

[0010] The paste wax of the present invention can also be obtained by kneading 100 parts by mass of the paste wax mixed powder with 7.8 parts by mass or less of a total of one to three organic solvents selected from acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin (hereinafter referred to as organic solvents) (excluding cases where the total amount of organic solvents is 0 parts by mass), and 2.0 to 20.0 parts by mass of water, in which case the total amount of water and organic solvents is 8.0 to 22.0 parts by mass.

[0011] Alternatively, the paste wax of the present invention can also be obtained by kneading 100 parts by mass of the paste wax mixed powder with water and one or two water-soluble resins selected from polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate in a total amount of 1.0 part by mass or less (excluding cases where the total is 0 part by mass), in which case the total amount of water and the water-soluble resin is 8.0 to 22.0 parts by mass.

[0012] The paste wax of the present invention contains, per 100 parts by mass of the paste wax mixed powder, one to three organic solvents selected from acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin in a total amount of 7.8 parts by mass or less (except when the total amount of the organic solvents is 0 parts by mass), and one or two water-soluble resins selected from polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate in a total amount of 1.0 part by mass or less (except when the total amount is 0 parts by mass), with the remainder being water, and the total amount of water, organic solvent, and water-soluble resin being 8.0 to 22.0 parts by mass. The remaining amount of water is preferably 2.0 to 20.0 parts by mass.

[0013] When producing the paste wax of the present invention, it is preferable to use the polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate in aqueous solution form by diluting them with water rather than using solid forms. Examples of such aqueous solutions include solutions with a solid content of 50% by mass or less, such as polyvinyl alcohol with a solid content of about 10% by mass, urethane resin with a solid content of about 30% by mass, and vinyl acetate with a solid content of about 40% by mass.

[0014] Since the brazing paste of the present invention is a brazing material used for furnace brazing of stainless steel, the brazing material powder is preferably a brazing material containing nickel, iron, or cobalt as a main component.

[0015] Furthermore, the brazing material powder contained in the mixed powder for paste brazing of the present invention is preferably an alloy powder produced by an atomization method, and the particle size thereof is preferably 250 μm or less.

[0016] In order to prevent the brazing material powder in the brazing paste of the present invention from settling, the particle size of the brazing material powder is preferably 150 μm or less, more preferably 63 μm or less.

[0017] Next, the reasons for limiting the components and blending ratios of the mixed powder for paste brazing according to the present invention and the paste brazing using the same will be described.

[0018] The water-soluble thickener in the paste braze mixed powder of the present invention has the function of suppressing settling and separation of the brazing powder, but if the amount is less than 0.12 parts by mass per 100 parts by mass of the paste braze mixed powder, the thickening effect is weak and the brazing powder will settle, while if the amount is more than 2.10 parts by mass, the viscosity of the paste braze will increase, impairing application workability and generating a large amount of decomposition gas from the resin during the brazing process, causing brazing defects, so the amount of water-soluble thickener added is limited to the range of 0.12 to 2.10 parts by mass.

[0019] The water-soluble thickener is preferably a cellulose-based thickener that inhibits settling and separation of the brazing powder, although any water-soluble powder thickener other than a cellulose-based thickener may also be used.

[0020] When preparing a paste braze by adding only water to the mixed powder for paste braze of the present invention, if the amount of water added is less than 8.0 parts by mass per 100 parts by mass of the mixed powder for paste braze, the viscosity of the paste braze becomes high and application workability is impaired. On the other hand, if the amount of water added exceeds 26.6 parts by mass, the viscosity of the paste braze becomes low, the brazing material powder is likely to settle, and application workability is impaired. Therefore, the amount of water in the paste braze is limited to the range of 8.0 to 26.6 parts by mass.

[0021] The addition of an organic solvent not only improves compatibility with the stainless steel base material even when oils and greases adhere to it, but also provides antiseptic properties for the paste and allows for adjustment of the drying speed (fast or slow). Because the thickener is water-soluble, water-soluble organic solvents can be selected, including one to three selected from acetone, methyl alcohol (methanol), ethyl alcohol (ethanol), n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin. When an organic solvent is added to the paste, as described above, the total amount of water and organic solvent is preferably in the range of 8.0 to 22.0 parts by mass per 100 parts by mass of the paste brazing mixture powder. In this case, if the amount of water added is less than 2.0 parts by mass or the total amount of organic solvent exceeds 7.8 parts by mass, the amount of water reacting with the water-soluble thickener is reduced, resulting in an unstable viscosity of the paste brazing material, which can lead to precipitation of the brazing material powder and impaired application workability. Therefore, the amount of water added is limited to the range of 2.0 to 20.0 parts by mass, and the total amount of organic solvent added is limited to 7.8 parts by mass or less.

[0022] Furthermore, the brazing paste of the present invention can contain one or two water-soluble additives selected from water-soluble polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate to inhibit the settling and separation of the brazing powder and improve adhesion to the stainless steel base material. However, adding more than 1.0 part by mass to the paste increases the amount of decomposition gas generated during the brazing process, causing brazing defects. Therefore, the amount added to the paste is limited to 1.0 part by mass or less. When a water-soluble resin is added to the paste, the total amount of water and water-soluble resin is preferably in the range of 8.0 to 22.0 parts by mass per 100 parts by mass of the paste brazing mixture powder. In the case of a brazing paste containing water, an organic solvent, and a water-soluble resin, the total amount of water, organic solvent, and water-soluble resin is preferably in the range of 8.0 to 22.0 parts by mass, as described above.

[0023] The present invention can be obtained by homogeneously mixing a brazing powder produced by atomization and adjusted to a predetermined particle size, such as BNi-1 to BNi-13, or BCo-1 as specified in "JIS Z 3265 Nickel Brazing Filler Metals" or "AWS A5.8 Specification for Filler Metals for Brazing and Braze Welding," or the developed materials specified in Japanese Patent Nos. 3,354,922, 5,269,888, 5,783,641, and 5,858,512, with a water-soluble thickener in a predetermined ratio using a V-type mixer or the like. The present invention is preferably based on the Ni-based heat-resistant brazing filler powder described in Japanese Patent No. 3,354,922, which contains, by weight, 25 to 35% Cr, 4 to 8% P, 3 to 6% Si, a total of 9 to 11.5% P and Si, with the balance being Ni and unavoidable impurities.

[0024] Furthermore, a predetermined amount of a solution containing water, an organic solvent, etc. can be added to the paste braze mixed powder and kneaded using a kneader (mixer), etc. to obtain a paste braze using the paste braze mixed powder of the present invention.

[0025] By adjusting the amount of water-soluble thickener in the paste wax mixed powder and the amount of water or solution in the paste wax produced using it, it is possible to obtain a paste wax viscosity suitable for the intended application method, and the paste wax can be used for dispenser application, screen printing, metal masking, dipping, etc. In particular, by adjusting the viscosity of the paste wax to 100 to 1500 dPa·s, good application workability can be obtained.

[0026] Brazing filler metal pastes were prepared according to the above procedure so as to have the blending ratios shown in Table 1. After mixing, the pastes were placed in a sealed container and stored at 25°C for 12 hours. The viscosity of the pastes was then confirmed using a Viscotester VT-06 (using a No. 2 rotor, rotor rotation speed 62.5 rpm) manufactured by Rion Co., Ltd. It was also confirmed whether or not the brazing filler metal powder had settled in the sealed container.

[0027] Taking into consideration the ease of application, a paste viscosity in the range of 100 to 1500 dPa·s was deemed acceptable, and furthermore, no precipitation of brazing powder 12 hours after the paste preparation was deemed acceptable.

[0028] The mixing ratios, paste viscosities, and precipitation states of the brazing powder for the examples and comparative examples are shown in Table 1. The brazing powder used was Ni-29Cr-6P-4Si alloy powder described in Japanese Patent No. 3354922.

[0029]

[0030] In Examples 1 to 11, the paste viscosity was in the range of 100 to 1500 dPa·s, and no precipitation of brazing filler powder was observed. On the other hand, in Comparative Example 12, the amount of thickener was less than 0.12 parts by mass, in Comparative Example 13, the amount of thickener exceeded 2.10 parts by mass, in Comparative Example 14, the amount of organic solvent exceeded 7.8 parts by mass, and in Comparative Example 15, the amount of vinyl acetate exceeded 1.0 part by mass. These results indicate that the paste viscosity fell outside the target range of 100 to 1500 dPa·s, or that precipitation of brazing filler powder was observed. In all of the Examples and Comparative Examples of the pastes prepared using the present invention, no precipitation of brazing filler powder was observed.

[0031] The production procedure of the present invention was also evaluated for its effect on suppressing the occurrence of mold and the number of days required for production of the paste wax. The results are shown in Table 2.

[0032]

[0033] Example No. A shows the manufacturing details of Example No. 2 described in Table 1, and in addition to the manufacturing and adjustment of the mixed powder for paste brazing (Step I), the manufacturing process of the paste (Steps II and III) required one day.

[0034] In contrast, in Comparative Example No. B, which had the same ingredients as Example No. 2 but added a thickener to the paste wax powder but did not mix it, the paste production process (steps II and III combined) required only one day, as in Example No. A. However, loose particles occurred in step III of the paste production, rendering the product unusable as a paste wax. In Comparative Examples C and D, which use a typical paste wax production process, Comparative Example No. C, which required a long stirring time in step II of the binder production, required a total of three days for the paste production process (steps II and III combined), longer than the production time of the present invention. Furthermore, it was confirmed that the viscosity of the paste wax also tends to increase as the moisture in the binder evaporates in step II, resulting in an unstable paste viscosity. Therefore, Comparative Example No. D, which required a short stirring time to suppress moisture evaporation in step II of the binder production, generated loose particles in step II of the binder production, and it took five days for the particles to disperse. The viscosity of the paste wax was equivalent to that of Example No. A, but the number of days required for the paste production process (the total of Steps II and III) was a long 7 days in total.

[0035] In other words, the method for producing paste wax of the present invention is more effective than the current method for producing paste wax in terms of the occurrence of lumps, the number of days required for production, and the viscosity stability of the paste wax.

[0036] As described above, the mixed powder for paste brazing according to the present invention and the paste brazing using the same have a viscosity suitable for application of the paste brazing, are free from the settling of the brazing powder, and can provide a paste brazing that is excellent in application workability. Furthermore, in the production of paste brazing, this method is expected to be a new paste production method that can simplify the binder production process.

Claims

1. The present invention comprises a brazing material powder and a resin powder which is a water-soluble thickener, and a mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, 2. A mixed powder for paste brazing, wherein the brazing powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component.

2. 2. The mixed powder for paste braze according to claim 1, wherein the resin powder is a cellulose-based powder.

3. 3. The mixed powder for paste braze according to claim 1 or 2, wherein the resin powder is one or two types selected from the group consisting of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose.

4. A composition comprising a brazing filler powder and a resin powder which is a water-soluble thickener, wherein the mass ratio of the brazing filler powder to the resin powder is 99.88-97.90:0.12-2.10, 10. A paste wax mixture powder comprising one or two resin powders selected from the group consisting of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose.

5. 5. The mixed powder for paste brazing according to claim 1, wherein the grain size of the brazing powder is 250 μm or less.

6. A paste wax comprising 8.0 to 26.6 parts by mass of water blended with 100 parts by mass of the paste wax mixed powder according to claim 1 or 4.

7. A paste wax comprising, relative to 100 parts by mass of the paste wax mixed powder according to claim 1 or 4, 1 to 3 organic solvents selected from acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin in a total amount of 7.8 parts by mass or less (excluding cases where the total amount of the organic solvents is 0 parts by mass), and 2.0 to 20.0 parts by mass of water, the total amount of the water and the organic solvent being 8.0 to 22.0 parts by mass.

8. A paste wax comprising, per 100 parts by mass of a paste wax mixed powder, one or two water-soluble resins selected from polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate in a total amount of 1.0 part by mass or less (excluding cases where the total is 0 part by mass), the remainder being water, and the total amount of water and the water-soluble resin being 8.0 to 22.0 parts by mass, The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, or The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, and the brazing material powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component. Let's paste.

9. A paste wax comprising, per 100 parts by mass of a paste wax mixed powder, one to three organic solvents selected from acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin in a total amount of 7.8 parts by mass or less (excluding cases where the total of the organic solvents is 0 parts by mass), and one or two water-soluble resins selected from polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate in a total amount of 1.0 part by mass or less (excluding cases where the total of the water and the organic solvent and the water-soluble resin is 0 parts by mass), with the remainder being water, and the total of the water, the organic solvent, and the water-soluble resin being 8.0 to 22.0 parts by mass, The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, or The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, and the brazing material powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component. Let's paste.

10. A method for producing a paste wax, comprising the step of mixing 8.0 to 26.6 parts by mass of water with 100 parts by mass of a paste wax mixed powder, The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, or The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, and the brazing material powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component. A method for producing a paste wax.

11. A method for producing a paste wax, comprising the step of mixing 7.8 parts by mass or less of one to three organic solvents selected from acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin in total (excluding cases where the total of the organic solvents is 0 parts by mass) with 2.0 to 20.0 parts by mass of water per 100 parts by mass of a paste wax mixed powder, wherein the total of the water and the organic solvent is 8.0 to 22.0 parts by mass, The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, or The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, and the brazing material powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component. A method for producing a paste wax.

12. A method for producing a paste wax, comprising the step of mixing 1.0 part by mass or less (excluding the case where the total is 0 part by mass) of one or two water-soluble resins selected from polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate with 100 parts by mass of paste wax mixed powder, wherein the total of the water and the water-soluble resin is 8.0 to 22.0 parts by mass, The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, or The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, and the brazing material powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component. A method for producing a paste wax.

13. A method for producing a paste wax, comprising the step of mixing, relative to 100 parts by mass of a paste wax mixed powder, one to three organic solvents selected from acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin in a total amount of 7.8 parts by mass or less (excluding the case where the total of the organic solvents is 0 parts by mass), one or two water-soluble resins selected from polyvinyl alcohol, urethane resin, acrylic resin, and vinyl acetate in a total amount of 1.0 part by mass or less (excluding the case where the total is 0 parts by mass), and water, wherein the total of the water, organic solvent, and water-soluble resin is 8.0 to 22.0 parts by mass, The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, or The paste brazing mixed powder contains a brazing material powder and a resin powder which is a water-soluble thickener, and the mass ratio of the brazing material powder to the resin powder is 99.88 to 97.90:0.12 to 2.10, and the brazing material powder is an alloy powder produced by an atomization method, the alloy powder containing nickel, iron, or cobalt as a main component. A method for producing a paste wax.