JPS62127445A - Laminate-type core for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain the titled core excellent in corrosion resistance by vacuum- brazing a fin of Al alloy having a specific composition consisting of In, Li, Mn, Fe, and Si and a working fluid path composed of a core material of corrosion resistant Al alloy and a brazing filler metal of Al-Si alloy. CONSTITUTION:The fin is formed of the Al alloy consisting of 0.005-1% In, 0.0005-0.1% Li, 0.5-1.5% Mn, 0.1-0.7% Fe, <=0.4% Si, and the balance essentially Al, or further additively containing one or more kinds among 0.1-0.4% Zn, 0.01-0.09% Sn, and 0.1-2% Mg and/or one or more kinds among 0.05-0.5% Cr, 0.05-0.5% Zr, 0.01-0.5% Ti, and 0.01-0.5% V, or further containing <=0.5% Cu. On the other hand, the working fluid path is formed of a brazing sheet composed of the core material of corrosion resistant Al alloy such as the one of Al-Mn, Al-Cu, etc., and the cladding material of brazing filler metal of Al-Si or Al-Si-Mg alloy. Above-mentioned fin and working fluid path are combined, which are brazed in an atmosphere under <=10<-2>Torr, so that the titled core can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a core of a laminated heat exchanger obtained by joining fins and working fluid passages by vacuum brazing.

[Prior Art] Conventionally, most laminate-type aluminum alloy heat exchangers, in which the fins and the working fluid passage are joined to form the core by vacuum brazing, have sacrificial anode fins. It is a non-corrosion-proof type that is not used.

[Problems to be Solved by the Invention] J: Uni Conventionally, laminated aluminum alloy heat exchangers whose cores are formed by vacuum brazing do not use sacrificial anode fins. The main reason was that a material alloy for the sacrificial anode fin that was suitable for brazing had not been developed.

In aluminum alloy heat exchangers other than the laminate type, aluminum is generally used as the sacrificial anode fin material.
-7: This is an n-based alloy, but in this alloy, Zn with low vapor pressure evaporates and scatters during vacuum brazing, and not only does the sacrificial anode effect of the fin not work effectively, but also the evaporated Zn
If it is a furnace type, it will adhere to the inside of the furnace and increase the frequency of furnace repairs.

As for the Al-7-n-based sacrificial anode fin mentioned above, there are relatively many examples of its use in brazing sheet fins.

This fin uses an Al-Zn alloy for the core material and is clad with an Al-Si-Mc+ aluminum alloy solder for the skin material, and this alloy solder material slows down the evaporation of Zn during vacuum heating. Since the zn of the heartwood is blocked by
For example, t is increased to about 1.5% to utilize the sacrificial anode effect due to the amount of Zn remaining after evaporation and scattering.

However, in a laminated heat exchanger, since the fins are made of bare material, the above-mentioned effects as with blood fins cannot be expected. This is also the reason why Al-Zn alloys are not used as fin materials in conventional laminated heat exchangers.

On the other hand, although the sacrificial anode effect of In has been known for a long time,
Since in is a low melting point element, when added to Al, this alloy can be used as a casting material, but when used as a wrought material, cracks occur in the material during ingot making and rolling, making it difficult to use as a fin material. It was not available.

However, if these points can be solved, this Al-
Since In-1i alloys do not have the above-mentioned problems of Al-Zn alloys, they can be suitable as sacrificial anode fin materials for laminated heat exchanger cores.・Therefore, the object of the present invention is to vacuum-braze an Al-[based alloy that is improved in such a way that it does not have the above-mentioned manufacturing difficulties and that vacuum brazing later exhibits an excellent sacrificial anode effect. By applying the present invention to the material of the sacrificial anode fin of the laminated aluminum alloy heat exchanger core produced by the above method, the present invention provides a heat exchanger core with extremely excellent corrosion resistance.

[Means for Solving the Problems] In order to quickly achieve the above object, the core of the laminate heat exchanger of the present invention is made of Al-I having any of the compositions described below.
Fins of n-1-i alloy, Al-Mn alloy, Al-C
Corrosion-resistant aluminum alloy such as U type is used as the core material, and Al-S
The core is constructed by combining a working fluid passage made of a brazing sheet made of i-based, Al-5r-Mg based alloy brazing material and brazing in an atmosphere of 1O-2 Torr or higher. It is something.

The composition of the alloy is as follows.

In: 0.005-1%, Li: 0.0
005-0.1%, Mn: 0.5-1.5%, Fe
: 0.1 to 0.7%, including Si: 50.4%,
The remainder is essentially Al, or the composition is further supplemented with Zn.
: 0.1-0.4%, 3n: 0.01-0.09
%, Mg: 0.1 to 2%, or Cr: 0.05 to 0.5%, Zr: 0.05 to 0
．． 5%, Ti: 0.01-0.5, V: 0.01
~0.5% of any one or more, or Zn: 0.1
~0.4%, Sn: 0.01~0.09%, Mg
: Any one or more of 0.1 to 2%, and Cr: 0
．． 05-0.5%, Zr: 0.05-0.5%,
One or more of Ti: 0.01 to 0.5% and V: 0.01 to 0.5% are added, or Cu: 50.5% is further added to each of the above compositions. including.

The present invention will be explained in detail below.

The alloy used as the material for the sacrificial anode fin of the laminated heat exchanger core of the present invention is formed by adding Li to an Al-1n alloy to form a 1n-1i intermetallic compound, which results in the formation of a 1n-1i intermetallic compound. Conventional Al-
In addition to preventing cracks during casting or rolling that occur with 1N alloy materials, when the fins of this alloy are heated under vacuum, by evaporating and scattering l-i, which has a low vapor pressure, Ins: is liberated. Therefore, it is possible to exhibit the sacrificial anode effect as an Al-7n alloy.

As is clear from the In-1-i binary system phase diagram, the melting point of the 1n-1i gold metal compound is 625°C. During hot working, cracking of the raw material due to the low melting point does not occur, unlike when lnn is added at medium temperatures.

Next, Al-
The significance of each additive element in the In-Li alloy will be described.

In: Makes the potential of the fin less noble 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.

1-i: Creates an intermetallic compound with In to prevent cracks that occur in ingots and plate materials 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 the fermentation rate at the time of addition will be reduced. There is a lot of wear and tear,
Self-corrosion resistance also deteriorates.

Mn, Fe, Si: Any addition is effective in improving the strength of the fin, and also improves its high temperature and pressure resistance.

If the amount added is less than 0.5% at 1vln, less than 0.1% for Fe, and a small amount of Si, the above effect will be small;
If the amount exceeds 1.5% for n, 0.7% for Fe, and 0.4% for Si, the fin moldability and self-corrosion resistance of the fin will deteriorate.

Zn, Sn, MCI: Any addition makes the potential of the fin less noble and enhances the sacrificial anode effect. In addition, MCI is effective in improving strength.

The amount added is 0.1% for Zn, 0.01% for Sn, and 0 for Mg.
．． When the amount is less than 1%, the above effect is small, and when the amount is more than 0.4% for Zn, 0.09% for 3N, and 2% for MO, the self-corrosion resistance of the fins is reduced. , Furthermore, Mg makes fin forming processing difficult, and Z
n reduces the buckling resistance of the fin.

Cr, Zr, Ti, V : Either addition improves the high temperature buckling resistance of the fin.

The amount added is less than 0.05% for both Qr and Zr, and T
If both i and V are less than 0.01%, the above effects will be small, while if either element is more than 0.5%, fin workability and corrosion resistance will deteriorate.

Cu: Increases the strength of the fin. If the amount added is small,
This effect is small. On the other hand, if the amount is more than 0.5%, the potential of the fin becomes small and the sacrificial anode effect is impaired.

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 1 Chemical composition of fin material alloy (%)1; Ingot for each alloy of Man'1: 57) O'CX8
1) After r sawing, hot rolling at 480°○,)
", lj4, IXi, intermediate "iQ fftun" (after the harshest winter) anti-790.16 mmt 1-11411 fin 1.
Close and fin-stitch.

Meanwhile, in this way, for each fin with 4
Temporarily, the brazing sheet for a 905℃ sail is made by using 004 alloy as the core material and cladding 10% of 4004 base metal as a membrane material on both sides. A working fluid passage was manufactured from this brazing sea 1~.

The fins and the working fluid passage were combined and vacuum brazed at <2X 10'r, 600°C> to form a heat exchanger core. The fins were attached to the working fluid passage so that the fins were 6 times the size of the ram and the pitch of the fins was 4 mm.

Next, for all the manufactured heat exchanger cores,
The corrosion resistance of the fluid passage was investigated. Corrosion resistance d・)ilt
h was determined by conducting the following three types of brightness tests for one month and measuring the maximum pitting depth that occurred in the working fluid passage.

(1) Waterproof spray chant: J I 5-Z-2371
(2) Wet and dry exchange! '7 Soaking test: 3[! /, ＼aCl aqueous solution, discharge 1-3 (Cut Y 1♂] Adjustment) Immerse at 40°C for 30 minutes and repeat drying at 50°C for 30 minutes 3) CASS test: JIS-)-( -8681
The results of each of the above tests are summarized in Table 2. The number of cores in Table 2 (Yo, ＼0 of the fin material alloy in Table 1. Therefore, it must correspond to the number of cores in Table 2.

Table 2 Vacuum brazing/assembly core corrosion test results As is clear from Table 2, the heat exchanger core of the present invention has extremely low corrosion resistance in the working fluid passage 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, NO,
The In of the fin for the core of 17 is No, 18, No, 20
, N022, each of the periphery <Mn, CLI, and In is too large, so the self-corrosion of the fins is significant, and therefore the working fluid passage is severely corroded. Also N 0.24
~27 cores each have Cr, Ti, and Zrt in their fins.
Since there is a large amount of either V, the sacrificial anode effect of the fins is not sufficient, and the corrosion resistance of the working fluid passage is inferior to any of the cores of the present invention. Further, in No. 28 to 31, the fins have no or insufficient anode effect, so the durability of the working fluid passage is extremely poor.

In addition to the above, Al-1n used for the fin of the core of the present invention
-1-i series alloy has no problems recognized in its manufacturing process, but in comparative example core, the material cracked during ingot formation and rolling during the manufacturing process of fin material. there were.

[Effects of the Invention] A of the laminated heat exchanger according to the present invention is that the fin material is an Al-In-Li alloy that exhibits an excellent sacrificial anode effect in the first stage of air heating.
The heat exchanger core manufactured by vacuum brazing has excellent corrosion resistance of its working fluid passages.

Claims (1)

[Claims] In: 0.005-1%, Li: 0.0005-0.1
%, Mn: 0.5-1.5%, Fe: 0.1-0.7%
, Si: ≦0.4%, the balance being substantially Al, or this composition further contains Zn: 0.1-0.4%, Sn:
0.01 to 0.09%, Mg: 0.1 to 2%, or Cr: 0.05 to 0.5%, Zr:
0.05-0.5%, Ti: 0.01-0.5%, V:
Any one or more of 0.01 to 0.5%, or Zn
:0.1~0.4%, Sn:0.01~0.09%, M
g: any one or more of 0.1 to 2%, and Cr: 0.
05-0.5%, Zr: 0.05-0.5%, Ti: 0
．． 01 to 0.5%, V: 0.05 to 0.5%, or each of the above compositions further contains Cu.
:A fin of aluminum alloy containing ≦0.5% added, a corrosion-resistant aluminum alloy such as Al-Mn type or Al-Cu type as the core material, and an alloy brazing material of Al-Si type or Al-Si-Mg type. 1. A core of a laminated heat exchanger, characterized in that it is constructed by combining working fluid passages made of brazing sheets as skin materials and brazing them in an atmosphere of 10^-^2 Torr or less.