HEAT EXCHANGER TUBE PRECURSOR AND METHOD OF PRODUCING THE SAME

• US 20140186560A1
• Filed: 12/27/2013
• Published: 07/03/2014
• Est. Priority Date: 05/06/2003
• Status: Active Grant

• Current Assignee: MA Aluminum Corporation (Altemira Company Limited)
• Original Assignee: Mitsubishi Aluminum Company Limited (Mitsubishi Materials Corporation)
• Inventors: KATSUMATA, Masaya, Hyogo, Yasunori
• Granted Patent: US 9,283,633 B2
• Time in Patent Office: Days
• US Class Current: 428/34.1
• CPC Class Codes: B23K 1/0012 Brazing heat exchangers
• CPC Class Codes: B23K 1/008 Soldering within a furnace B23K1/012 takes precedence
• CPC Class Codes: B23K 1/012 Soldering with the use of hot gas
• CPC Class Codes: B23K 1/203 Fluxing, i.e. applying flux onto surfaces
• CPC Class Codes: B23K 2101/06 Tubes
• CPC Class Codes: B23K 2101/14 Heat exchangers
• CPC Class Codes: B23K 2101/34 Coated articles , e.g. plated or painted; Surface treated articles
• CPC Class Codes: B23K 2103/10 Aluminium or alloys thereof
• CPC Class Codes: B23K 35/0222 for use in soldering, brazing B23K35/0205 takes precedence
• CPC Class Codes: B23K 35/0238 layered
• CPC Class Codes: B23K 35/0244 Powders, particles or spheres; Preforms made therefrom
• CPC Class Codes: B23K 35/24 Selection of soldering or welding materials proper B23K35/34 takes precedence
• CPC Class Codes: B23K 35/28 with the principal constituent melting at less than 950 degrees C
• CPC Class Codes: B23K 35/282 Zn as the principal constituent
• CPC Class Codes: B23K 35/286 Al as the principal constituent
• CPC Class Codes: B23K 35/36 Selection of non-metallic compositions, e.g. coatings, fluxes B23K35/34 takes precedence; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest selection of soldering or welding materials proper B23K35/24
• CPC Class Codes: B23K 35/3603 Halide salts
• CPC Class Codes: B23K 35/3605 Fluorides
• CPC Class Codes: B23K 35/3612 with organic compounds as principal constituents
• 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
• CPC Class Codes: B32B 15/017 : one layer being formed of aluminium or an aluminium alloy, another layer being formed of an alloy based on a non ferrous metal other than aluminium
• CPC Class Codes: C23C 4/12 : characterised by the method of spraying
• CPC Class Codes: F28F 19/02 : by using coatings, e.g. vitreous or enamel coatings
• CPC Class Codes: F28F 19/06 : of metal
• CPC Class Codes: F28F 21/084 : from aluminium or aluminium alloys
• CPC Class Codes: F28F 2255/16 : extruded
• CPC Class Codes: Y10T 428/13 : Hollow or container type article [e.g., tube, vase, etc.]

Abstract

A heat exchanger tube precursor that allows manufacturing a heat exchanger having high corrosion resistance after brazing treatment is provided. The heat exchanger tube precursor includes: an Al alloy tube; and a flux layer including a Si powder, a Zn-containing flux, a Zn-free flux, and a binder, the flux layer being formed on an outer surface of the Al alloy tube.

Claims

1. A heat exchanger tube precursor comprising:

an Al alloy tube; and

a flux layer including a Si powder, a Zn-containing flux, a Zn-free flux, and a binder, the flux layer being formed on an outer surface of the Al alloy tube.

2. The heat exchanger tube precursor according to claim 1, wherein

an amount of the Si powder applied on the Al alloy tube is in a range of 1 g/m² to 5 g/m², and

an amount of the Zn-containing flux applied on the Al alloy tube is in a range of 3 g/m² to 20 g/m².

3. The heat exchanger tube precursor according to claim 1, wherein

the Si powder has a particle diameter distribution such that 99% particle diameter (D₉₉) is 5 μ

m or more and 20 μ

m or less, and an amount of coarse particles having diameters of not smaller than 5 times (D₉₉) is less than 1 ppm by volume, wherein

(D₉₉) denotes a critical diameter defined such that cumulative volume of particles not larger than (D₉₉) constitute 99% by volume of all the particles.

4. The heat exchanger tube precursor according to claim 1, whereinparticle diameter (D₅₀) of the Si powder is (D₉₉)×

0.05 or more and (D₉₉)×

0.7 or less, wherein

(D₉₉) denotes a critical diameter defined such that cumulative volume of particles not larger than (D₉₉) constitute 99% by volume of all the particles, and

(D₅₀) denotes a critical diameter defined such that cumulative volume of particles not larger than (D₅₀) constitute 50% by volume of all the particles.

5. The heat exchanger tube precursor according to claim 1, wherein the Zn-containing flux contains at least one selected from ZnF₂, ZnCl₂, and KZnF₃.

6. The heat exchanger tube precursor according to claim 1, wherein the Zn-free flux contains at least one selected from LiF, KF, CaF₂, AlF₃, SiF₄, KAlF₄, and KAlF₃.

7. The heat exchanger tube precursor according to claim 1, wherein

the Al alloy tube is constituted of an alloy containing Si of 0.05% or more and 1.0% or less by weight, Mn of 0.05% or more and 1.2% or less by weight, and the balance being consisting of Al and inevitable impurities.

8. A method of producing a heat exchanger tube precursor, the method comprising the steps of:

classifying a pre-classification Si powder to obtain a post-classification Si powder in which 99% particle diameter (D₉₉) is 5 μ

m or more and 20 μ

m or less, an amount of coarse particles having diameters of not smaller than 5 times (D₉₉) is less than 1 ppm by volume, and 50% particle diameter (D₅₀) of the Si powder is (D₉₉)×

0.05 or more and (D₉₉)×

0.7 or less;

preparing a coating material including the post-classification Si powder, a Zn-containing flux, a Zn-free flux, and a binder; and

applying the coating material on an Al alloy tube, wherein

an amount of the Si powder applied on the Al alloy tube is in a range of 1 g/m² to 5 g/m²,

an amount of the Zn-containing flux applied on the Al alloy tube is in a range of 3 g/m² to 20 g/m²,

(D₉₉) denotes a critical diameter defined such that cumulative volume of particles not larger than (D₉₉) constitute 99% by volume of all the particles, and

(D₅₀) denotes a critical diameter defined such that cumulative volume of particles not larger than (D₅₀) constitute 50% by volume of all the particles.

9. The method of producing a heat exchanger tube precursor according to claim 8, wherein the Zn-containing flux contains at least one selected from ZnF₂, ZnCl₂, and KZnF₃.

10. The method of producing a heat exchanger tube precursor according to claim 8, wherein the Zn-free flux contains at least one selected from LiF, KF, CaF₂, AlF₃, SiF₄, KAlF₄, and KAlF₃.