JPH0142793B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a serpentine heat exchanger in which the fins are used as sacrificial anode fins to protect the working fluid passage from corrosion, and particularly to a serpentine heat exchanger in which the fins and the working fluid passage are joined by vacuum brazing. The present invention relates to a method for manufacturing a core of an exchanger. [Prior Art] Conventionally, the core of a serpentine-type aluminum alloy heat exchanger obtained by bonding a sacrificial anode fin and a working fluid using a vacuum brazing method has been made by bonding an Al--Zn based, Brazing sheets and fins are used with Al-Sn or Al-In alloy as the core material. [Problems to be solved by the invention] Al--Zn brazing sheet fins used as sacrificial anode fins in the production of serpentine-type aluminum alloy heat exchanger cores obtained by conventional vacuum brazing methods. Because evaporation of Zn during vacuum brazing is unavoidable,
The amount of Zn added to the core material is increased to take advantage of the sacrificial anode effect caused by residual Zn after evaporation. However, vapor deposition
There is an increase in the frequency of furnace repairs due to Zn adhesion inside the furnace.
Furthermore, this brazing sheet/fin is not necessarily satisfactory because the effect of residual Zn is insufficient. On the other hand, in brazing sheets and fins whose core material is Al-Sn alloy, since Sn is a low melting point element, there is a problem of cracks occurring in the material during fin manufacturing, resulting in poor manufacturing yields and high costs. Become something. In addition, although the sacrificial anode effect of added In has long been known for Al-In alloys as core materials, since In is a low melting point element, when added to aluminum, this alloy can be used as a casting material. Although it can be used as a wrought material, cracks occur in the material during ingot formation and rolling, making it impossible to use it as a fin material. However, if these problems can be solved with Al-In alloys, this type of aluminum alloy core material does not have the above-mentioned problems with Al-Zn and Al-Sn alloy core materials, so sacrificial anode brazing is possible. It can be suitable for sheet and fin materials. Therefore, the object of the present invention is to provide an improved sacrificial anode that does not have the above manufacturing difficulties and exhibits an excellent sacrificial anode effect after vacuum brazing.
By using brazing sheets and fins made of Al-In alloy as the sacrificial anode fins of the core of a serpentine heat exchanger manufactured by vacuum brazing before brazing, the material has extremely excellent corrosion resistance. An object of the present invention is to provide a method for manufacturing a heat exchanger core. [Means for solving the problems] The core of the serpentine heat exchanger of the present invention is
In order to achieve the above object, an aluminum alloy having one of the compositions listed below is used as the core material, and Al--
Brazing sheets and fins made of Si-based, Al-Si-Mg-based, etc. alloy brazing materials are made of pure Al-based, Al-based
-The core is assembled with a working fluid passage consisting of an extruded flat multi-hole tube made of corrosion-resistant aluminum or corrosion-resistant aluminum alloy such as Cu-based, Al-Mn-based, etc., and brazed in an atmosphere of 10 ^-2 Torr or less. It is composed of The composition of the core alloy is as follows. (1) In: 0.005-1%, Li: 0.0005-0.1%, Mn:
An alloy containing 0.5 to 1.5%, Fe: 0.1 to 0.7%, and Si≦0.4%, with the remainder being substantially Al and inevitable impurities. (2) In addition to the alloy of (1) above, Zn: 0.1 to 0.4%,
An alloy containing one or more of Sn: 0.01 to 0.09% and Mg: 0.1 to 2%. (3) In addition to the alloy of (1) above, Cr: 0.05 to 0.5%,
Zr: 0.05~0.5%, Ti: 0.01~0.5%, V: 0.01~
Alloy containing one or more of 0.5%. (4) In addition to the alloy of (1) above, Zn: 0.1 to 0.4%,
Sn: 0.01~0.09%, Mg: 0.1~2%, and Cr: 0.05~0.5%, Zr: 0.05~
0.5%, Ti: 0.01 to 0.5%, and V: 0.01 to 0.5%. The present invention will be explained below. The core alloy of the brazing sheet/fin used for the sacrificial anode fin before vacuum brazing of the serpentine heat exchanger core of the present invention is made of In-Li metal by adding Li to the Al-In alloy. Intermediate compounds are formed, which prevent this alloy from cracking during casting or rolling as occurs with conventional Al-In alloy materials, and when the brazing sheets and fins of this alloy core are heated under vacuum. During the process, In is liberated by evaporating and scattering Li, which has a low vapor pressure, to form Al-In.
It is possible to exhibit the sacrificial anode effect as an alloy. As is clear from the In-Li binary system phase diagram, the melting point of the In-Li intermetallic compound is approximately 625°C, so
Even if it precipitates in a normal Al alloy, it will not cause cracks in the material due to its low melting point, unlike when In alone is added during normal casting or hot working. Next, the significance of each additive element in the Al--In--Li alloy used as the core material of the brazing sheet/fin used in the fin before vacuum brazing of the heat exchanger core of the present invention will be described. In: Makes the potential of the fin more basic and enhances the sacrificial anode effect. This effect is small at addition amounts lower than 0.005, while at amounts exceeding 1%, the self-corrosion resistance of the fins decreases. Li: Creates an intermetallic compound with In to prevent cracks that occur in ingots and plates during casting and rolling. If the amount added is less than 0.0005% with respect to In, the above effect will not be obtained, while if it is more than 0.1%, the effect will not be further increased and it is meaningless, and oxidation consumption will be severe during addition. Self-corrosion resistance also deteriorates. Mn, Fe, Si: All additions are effective in improving the strength of the fins, and also improve their high-temperature buckling resistance. If the amount added is less than 0.5% for Mn, less than 0.1% for Fe, and a small amount of Si, the above effect will be small.
On the other hand, if the amount exceeds 1.5% for Mn, 0.7% for Fe, and 0.4% for Si, the fin formability and self-corrosion resistance of the fins deteriorate. Zn, Sn, Mg: Any addition makes the potential of the fin less noble and enhances the sacrificial anode effect. In addition, Mg
is effective for improving strength. Addition amount is 0.1% Zn,
If the amount is less than 0.01% for Sn and 0.1% for Mg, the above effect will be small;
If the amount is higher than 0.09% and 2% for Mg,
Both of them reduce the self-corrosion resistance of the fins, and
Mg makes the fin forming process difficult, and Zn reduces the buckling resistance of the fin. Cr, Zr, Ti, V: Any addition improves the high temperature buckling resistance of the fin. If the amount of addition is less than 0.05% for both Cr and Zr, and less than 0.01% for both Ti and V, the above effect will be small, while if the amount of any of the elements is more than 0.5%, fin workability and corrosion resistance will deteriorate. Next, an embodiment of the exchanger core of the present invention will be described. [Example] Table 1 lists the composition of the aluminum alloy used for the core material of the brazing sheet/fin in the examples and comparative examples of the present invention. Further, in both examples, the compositions of four types of alloys used for the working fluid passage material are shown in the second table.

【table】

【table】

[Table] For each alloy listed in Table 1, use this as the core material,
Both surfaces were covered with 4004 alloy by 10% as a skin material to form a brazing sheet, which was then molded to obtain a brazing sheet/fin. On the other hand, each alloy material in Table 2 was extruded into a flat multi-hole extruded tube (outer wall thickness 0.7 mm, width 100 mm, height 5 mm,
26 holes) and used them as working fluid passages. Each of these brazing sheets and fins was arbitrarily combined with a working fluid passage and vacuum brazed (2×10 ⁻⁵ Torr, 600° C.) to fabricate a serpentine heat exchanger core. However, brazing sheets and fins are made by soaking core alloy ingots at 540°C for 8 hours, then hot-pressing them with 4004 alloy skin material at 480°C, cold rolling, and intermediate annealing. Plate thickness 0.16mmt
Finished with a fin board equivalent to H14, and corrugated it to make brazing sheets and fins. When manufacturing the heat exchanger core, assemble the brazing sheet/fins in the working fluid passage so that the surface area of the fins after brazing is six times the outer surface area of the working fluid passage, and the fin pitch is 4 mm. I attached it. Next, the corrosion resistance of the working fluid passages was investigated for all of the manufactured heat exchanger cores. Corrosion resistance was evaluated by conducting the following three types of corrosion tests for one month and measuring the maximum pitting depth that occurred in the working fluid passage. (1) Salt spray test: JIS-Z-2371 (2) Dry-wet alternate immersion test: 3% NaCl aqueous solution, PH=
3 (adjusted with citric acid), 40℃ x 30 minutes immersion at 50℃
x 30 minutes drying, repeated (3) CASS test: JIS-H-8681 The results of each test above were as shown in Table 3.

[Table] As is clear from Table 3, the heat exchanger cores of the present invention have extremely excellent corrosion resistance of the working fluid passages due to the sacrificial anode effect of the fins. On the other hand, in the heat exchanger cores of the comparative examples, the corrosion resistance of the passages is poor. In particular, the No. 17 core has Finn's In, and the No. 18 and No. 22 cores also have Mn,
Since the amount of Zn is too large, self-corrosion of the fins is significant, and therefore corrosion of the working fluid passage is significant. In addition, for each core No. 20 to 23, the fins
Since there is a large amount of any one of Cr, Ti, Zr, and V, the sacrificial anode effect of the fins is insufficient, and the corrosion resistance of the working fluid passage is inferior to any of the cores of the present invention. Furthermore, core Nos. 13 to 16 have no sacrificial anode effect on the fins, or even if they do, it is insufficient.
The corrosion resistance of the working fluid passage is extremely poor. In addition to the above, the brazing sheets and fins made of Al-In-Li alloy core material used for the fins before vacuum brazing of the core of the present invention had no problems in the manufacturing process, but the core of the comparative example During the manufacturing process of brazing sheets and fins,
Some material cracked during ingot formation and rolling. [Effects of the Invention] The core of the serpentine heat exchanger according to the present invention has Al-In on the fins before vacuum brazing, which exhibits an excellent sacrificial anode effect after vacuum heating.
- By using a brazing sheet/fin made of Li-based alloy as the core material, the heat exchanger core manufactured by vacuum brazing has excellent corrosion resistance of the working fluid passage.

Claims (1)

[Claims] 1 In: 0.005-1%, Li: 0.0005-0.1%, Mn:
Contains 0.5-1.5%, Fe: 0.1-0.7%, Si≦0.4%,
The core material is an aluminum alloy in which the remainder consists essentially of Al and unavoidable impurities, and the surface of the core material is
The brazing sheet/fin is made of Al-Si or Al-Si-Mg alloy brazing material, and the brazing sheet/fin is combined with a working fluid passage made of an extruded flat multi-hole tube made of corrosion-resistant aluminum alloy. A method for manufacturing a serpentine aluminum alloy heat exchanger core, which comprises brazing in an atmosphere of 10 ^-2 Torr or less. 2 In: 0.005-1%, Li: 0.0005-0.1%, Mn:
Contains 0.5-1.5%, Fe: 0.1-0.7%, Si≦0.4%,
Furthermore, Zn: 0.1-0.4%, Sn: 0.01-0.09%, Mg:
The core material is an aluminum alloy containing 0.1 to 2% of any one or more of Al--Si with the remainder consisting essentially of Al and unavoidable impurities.
A brazing sheet/fin is made of Al--Si--Mg based alloy solder as a skin material, and the brazing sheet/fin is combined with a working fluid passage made of an extruded flat multi-hole tube made of corrosion-resistant aluminum alloy.
A method for manufacturing a serpentine-type aluminum alloy heat exchanger core, characterized by brazing in an atmosphere of 10 ^-2 Torr or less. 3 In: 0.005-1%, Li: 0.0005-0.1%, Mn:
Contains 0.5-1.5%, Fe: 0.1-0.7%, Si≦0.4%,
Furthermore, Cr: 0.05-0.5%, Zr: 0.05-0.5%, Ti:
The core material is an aluminum alloy containing one or more of the following: 0.01 to 0.5%, V: 0.01 to 0.5%, and the remainder substantially consists of Al and unavoidable impurities, and the surface of the core material contains Al-Si system, Al- A brazing sheet/fin made of Si--Mg based alloy solder is used as a skin material, and the brazing sheet/fin is combined with a working fluid passage made of an extruded flat multi-hole pipe made of corrosion-resistant aluminum alloy to achieve a flow rate of 10 ^-2 Torr or less. A method for manufacturing a serpentine-type aluminum alloy heat exchanger core, characterized by brazing in an atmosphere. 4 In: 0.005-1%, Li: 0.0005-0.1%, Mn:
Contains 0.5-1.5%, Fe: 0.1-0.7%, Si≦0.4%,
Furthermore, Zn: 0.1-0.4%, Sn: 0.01-0.09%, Mg:
Any one or more of 0.1-2% and Cr: 0.05-
0.5%, Zr: 0.05~0.5%, Ti: 0.01~0.5%, V:
The core material is an aluminum alloy containing any one or more of 0.01 to 0.5%, with the remainder consisting essentially of Al and unavoidable impurities, and the surface of the core material is coated with Al-
A brazing sheet/fin is made of Si-based or Al-Si-Mg-based alloy solder as a skin material, and the brazing sheet/fin is combined with a working fluid passage made of an extruded flat multi-hole tube made of corrosion-resistant aluminum alloy.
A method for manufacturing a serpentine-type aluminum alloy heat exchanger core, characterized by brazing in an atmosphere of 10 ^-2 Torr or less.