PASTE COMPOSITION FOR ALUMINUM BRAZING

• US 20090165893A1
• Filed: 12/19/2008
• Published: 07/02/2009
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation, Harima Chemicals Incorporated
• Original Assignee: DENSO Corporation, Harima Chemicals Incorporated
• Inventors: Itoh, Akira, Muto, Ken, Teshima, Shoei, Teruse, Masaki, Taninaka, Ichiro, Yamamoto, Kinya, AKAZAWA, Tomoaki
• Granted Patent: US 8,075,706 B2
• Time in Patent Office: Days
• US Class Current: 148/24
• CPC Class Codes: B23K 35/0244 Powders, particles or spheres; Preforms made therefrom
• CPC Class Codes: B23K 35/025 Pastes, creams, slurries
• CPC Class Codes: B23K 35/22 characterised by the composition or nature of the material
• CPC Class Codes: B23K 35/286 Al as the principal constituent
• CPC Class Codes: B23K 35/361 Alumina or aluminates
• CPC Class Codes: B23K 35/3613 Polymers, e.g. resins
• CPC Class Codes: B23K 35/362 Selection of compositions of fluxes B23K35/365, B23K35/368 take precedence

Abstract

A paste composition for aluminum brazing of the invention contains 40 to 65% by weight of a metal powder for brazing (a), 5 to 35% by weight of a fluoride type flux (b), 1 to 10% by weight of a methacrylic acid ester type polymer (c), and 10 to 40% by weight of an organic solvent (d); and the component (d) is a hydrocarbon type organic solvent having no aromatic ring and no hydroxyl group and the composition is in a paste-like state having a viscosity of 6,000 to 200,000 mPa·s at 23° C. and accordingly, the storage stability and applicability (practically, discharge property and pressure stability by using a dispenser) and brazing property can be improved in good balance.

Claims

1. A paste composition for aluminum brazing comprisingto 65% by weight of a metal powder for brazing (a),

5 to 35% by weight of a fluoride type flux (b),

1 to 10% by weight of a methacrylic acid ester type polymer (c), and

to 40% by weight of an organic solvent (d),

wherein the component (d) is a hydrocarbon type organic solvent having no aromatic ring and no hydroxyl group and the composition is a paste-like state having a viscosity of 6,000 to 200,000 mPa·

s at 23°

C.

2. The paste composition for aluminum brazing according to claim 1, wherein the weight average molecular weight of the methacrylic acid ester type polymer (c) is 500,000 to 2,000,000.

3. The paste composition for aluminum brazing according to claim 1, wherein the methacrylic acid ester type polymer (c) is a polymer selected from the group consisting of homopolymers of C₁ to C₁₈ alkyl esters of methacrylic acid and copolymers of C₁ to C₁₈ alkyl esters of methacrylic acid and hydroxyl group-containing methacrylic acid esters.

4. The paste composition for aluminum brazing according to claim 1, further comprising a thickener.

5. The paste composition for aluminum brazing according to claim 4, wherein the thickener is at least one selected from the group consisting of a fatty acid amide type thickener and a hardened caster oil type thickener.

6. The paste composition for aluminum brazing according to claim 4, wherein the content of the thickener is 0.1 to 5% by weight in the composition.

7. The paste composition for aluminum brazing according to claim 1, wherein the metal powder for brazing (a) is at least one selected from a group consisting of metal silicon, a silicon-aluminum alloy, a silicon-zinc alloy, a silicon-aluminum-zinc alloy, a silicon-magnesium alloy, a silicon-aluminum-magnesium alloy, a silicon-copper alloy, a silicon-aluminum-copper alloy, and aluminum-zinc alloy.

8. The paste composition for aluminum brazing according to claim 1, wherein the fluoride type flux (b) is at least one selected from the group consisting of potassium fluoroaluminate, potassium fluoride, aluminum fluoride, lithium fluoride, sodium fluoride, potassium fluoroaluminate-cesium complex, cesium fluoroaluminate, potassium fluorozincate, and cesium fluorozincate.

9. The paste composition for aluminum brazing according to claim 1, wherein the hydrocarbon type organic solvent having no aromatic ring and no hydroxyl group has a boiling point of 150°

C. or higher.

10. A method for brazing a member made of aluminum, comprising applying the paste composition for aluminum brazing according to any one of claims 1 to 9 to the member and heating the member in a state that the member is assembled in a prescribed structure.