JPH0224185B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing a core of a laminate heat exchanger, which is obtained by joining fins and working fluid passages by vacuum brazing. [Prior Art] Conventionally, most of the laminated aluminum alloy heat exchangers, in which the core is constructed by joining the fins and the working fluid passages by vacuum brazing, have used a sacrificial anode as the fin material. Instead of using a corrosion-resistant alloy, a non-corrosion-proof alloy was used. [Problems to be Solved by the Invention] As mentioned above, conventional laminated aluminum alloy heat exchangers whose cores are formed by vacuum brazing do not use sacrificial anode fins. The main reason was that no material alloy suitable for sacrificial anode fins had been developed. In aluminum alloy heat exchangers other than the laminate type, the one commonly used as the sacrificial anode fin material is an Al-Zn alloy, but this alloy has low vapor pressure Zn that evaporates and scatters during vacuum brazing. Not only does the sacrificial anode effect of the fin not work effectively, but the evaporated Zn adheres to the furnace walls and other parts of the furnace, increasing the frequency of furnace repairs. As for the Al-Zn-based sacrificial anode fin,
There are relatively many examples of its use in brazing seat fins. This fin uses Al-Zn alloy for the core material,
The skin material is clad with an Al-Si-Mg aluminum alloy solder, and this alloy solder material allows
Since the evaporation of Zn during vacuum heating is somewhat inhibited,
The amount of Zn in the core material is increased to, for example, about 1.5%, and the sacrificial anode effect due to the amount of Zn remaining after evaporation and scattering is utilized. However, in a laminated heat exchanger, since the fins are bare material, the above-mentioned effects cannot be expected as with the glass fins. This is the fin material for conventional laminated heat exchangers.
This is also the reason why Al-Zn alloys are not used. On the other hand, the sacrificial anode effect of In has been known for a long time, but since In is a low melting point element, when added to Al, this alloy can be used as a casting material, but it cannot be used as a wrought material for ingot making or Cracks occurred in the material during rolling, making it impossible to use it as a fin material. However, if these points can be solved, this Al-In-Li alloy is suitable for the sacrificial anode fin material of the laminated heat exchanger core because it does not have the above-mentioned problems of the Al-Zn alloy. It can become something. SUMMARY OF THE INVENTION Therefore, the object of the present invention is to create an improved Aluminum anode that does not have the above manufacturing difficulties and exhibits an excellent sacrificial anode effect after vacuum brazing.
- By applying an In-based alloy to the material of the sacrificial anode fin of a laminated aluminum alloy heat exchanger core manufactured by vacuum brazing, a method for manufacturing a heat exchanger core with extremely excellent corrosion resistance has been developed. It is about providing. [Means for Solving the Problems] In order to achieve the above object, the core of the laminate heat exchanger of the present invention is made of Al-In-Li based alloy fins having any of the compositions described below, and Al −Mn
In combination with a working fluid passage consisting of a brazing sheet whose core material is a corrosion-resistant aluminum alloy such as Al-Mn-Cu type or Al-Mn-Cu type alloy and whose skin material is an Al-Si or Al-Si-Mg type alloy brazing material, The core is constructed by brazing in an atmosphere of ^-2 Torr or higher. The composition of the alloy is as follows. (1) In: 0.005-1%, Li: 0.0005-0.1%, Mn:
An alloy containing 0.5-1.5%, Fe: 0.1-0.7%, Si: ≦0.4%, and the remainder is substantially Al and 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 alloy used for the material of the sacrificial anode fin of the laminated heat exchanger core of the present invention is formed by adding Li to the Al-In alloy to form an In-Li intermetallic compound. As a result, this alloy material prevents cracking during casting or rolling that occurs with conventional Al-In alloy materials, and when the fins of this alloy are heated in vacuum, Li, which has a low vapor pressure, is evaporated and scattered. By doing so, it is possible to liberate In and exhibit the sacrificial anode effect as an Al-In 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 raw 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 fin material 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%, no further increase in effect will be obtained 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 Zn 0.1%,
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 greater than 0.09% and 2% for Mg,
Both 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 added 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 it is more than 0.5% for either element, the fin processability and corrosion resistance will deteriorate. Next, examples of the heat exchanger core of the present invention will be described. [Example] Table 1 lists the composition of the aluminum alloy used as the material for the fins in the examples and comparative examples of the present invention.

【table】

[Table] For each alloy in Table 1, the ingot was heated to 540℃ x 8 hours.
After soaking, it was hot rolled at 480°C, cold rolled, and intermediate annealed to produce a fin original plate equivalent to H14 with a final thickness of 0.16 mmt, which was corrugated to form fins. On the other hand, for each fin obtained in this way,
A brazing sheet with a thickness of 0.5 mm was obtained by using 3004 alloy as a core material and 10% cladding with 4004 alloy on both sides as a skin material. A working fluid passage was fabricated from this brazing sheet. The fins and the working fluid passage were combined and vacuum brazed (2×10 ⁻⁵ Torr, 600° C.) to manufacture a heat exchanger core. At this time, set the fins so that their surface area is six times the outer surface area of the working fluid passage.
Moreover, the fin pitch was set to 4 mm, and it was assembled into the working fluid passage. 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 and wet alternate immersion test: 3% NaCl aqueous solution, PH=
3 (adjusted with citric acid) 40℃ x 30 minutes immersion 50℃ x 30
Repeated drying (3) CASS test: JIS-H-8681 The results of each test above were as shown in Table 2. The core numbers in Table 2 correspond to the numbers of the fin material alloys in Table 1.

[Table] As is clear from Table 2, the heat exchanger core of the present invention has the following effects due to the sacrificial anode effect of the fins:
The working fluid passage has excellent corrosion resistance. 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. 19 cores have the same In.
Since the amounts of Mn and Zn are 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 fins of the core of the present invention
Although no problems were observed in the manufacturing process of the Al-In-Li alloy, some of the cores of comparative examples developed cracks during ingot formation and rolling during the manufacturing process of the fin raw material. [Effect of the invention] The core of the laminate type heat exchanger according to the invention has the following features:
By using an Al-In-Li alloy that exhibits an excellent sacrificial anode effect after vacuum heating as the fin material, the heat exchanger core manufactured by vacuum brazing can be used as the working fluid passage. It has excellent corrosion resistance.

Claims (1)

[Claims] 1 In: 0.005-1%, Li: 0.0005-0.1%, Mn:
A fin material made of an aluminum alloy containing 0.5 to 1.5%, Fe: 0.1 to 0.7%, and Si: ≦0.4%, with the remainder consisting essentially of Al and unavoidable impurities, and a core material of a corrosion-resistant aluminum alloy containing Al-Si. system, Al-Si
-In combination with a working fluid passage consisting of a brazing sheet made of Mg-based alloy brazing material,
A method for manufacturing a laminated 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%, and further Zn: 0.1-0.4%, Sn: 0.01-0.09%,
A fin material made of an aluminum alloy containing one or more of Mg: 0.1 to 2%, with the remainder consisting essentially of Al and unavoidable impurities, and a core material of a corrosion-resistant aluminum alloy, including Al-Si based, Al-Si - A method for manufacturing a laminated heat exchanger core, which comprises combining working fluid passages made of brazing sheets made of Mg-based alloy brazing material and brazing them 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%, further Cr: 0.05-0.5%, Zr: 0.05-0.5%,
Any one of Ti: 0.01~0.5%, V: 0.01~0.5%
Al-
A laminated thermal type that is characterized by combining a working fluid passage made of a brazing sheet made of Si-based or Al-Si-Mg-based alloy brazing material and brazing in an atmosphere of 10 ^-2 Torr or less. Method of manufacturing an exchanger core. 4 In: 0.005-1%, Li: 0.0005-0.1%, Mn:
Contains 0.5-1.5%, Fe: 0.1-0.7%, Si: ≦0.4%, and further Zn: 0.1-0.4%, Sn: 0.01-0.09%,
Mg: 0.1 to 2% of any one or more and Cr:
0.05~0.5%, Zr: 0.05~0.5%, Ti: 0.01~0.5%,
V: Contains one or more of 0.01 to 0.5%,
A fin material made of an aluminum alloy, the remainder of which is essentially Al and unavoidable impurities, and a core material of a corrosion-resistant aluminum alloy containing Al-Si and Al-Si-Mg.
A method for manufacturing a laminated heat exchanger core, which comprises combining a working fluid passage made of a brazing sheet made of a brazing sheet made of a brazing alloy and brazing it in an atmosphere of 10 ^-2 Torr or less.