JPS6242987B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a brazed aluminum heat exchanger using brazed sheet fins with improved corrosion resistance. Aluminum alloys have generally been widely known as alloy materials with excellent corrosion resistance, but when used as brazed structures such as heat exchangers, Al-Si brazing filler metals are used as aluminum base metals. On the other hand, it acts as a cathode and electrochemically accelerates corrosion, resulting in insufficient corrosion resistance, so some kind of countermeasure against this problem is desired. The present invention has focused on the above-mentioned actual situation and has been made to improve the situation.The present invention has been made to improve the above-mentioned situation. An alloy that has been given a noble potential is used for the fins, which will not cause fatal damage even if they corrode, and an alloy that is less base than the fluid passage components is used to make the brazed aluminum heat exchanger more lethal. In an aluminum heat exchanger that uses plate material or shape material and a brazing sheet for fins, the plate material or shape material has Cu: 0.2 to 2.0% (meaning of weight %: the same hereinafter), or Furthermore, Mn, Cu, Zr
One or more of the following: Al-Si type or Al containing 0.01 to 0.5% of each, with the balance consisting of Al and unavoidable impurities, as a brazing material for fin brazing sheets, containing 0.25% or less of Fe as impurities. −Si
-Mg-based alloy is used, and the core material is pure Al-based, Al-Mn-based, or Al-Mg-Si-based alloy with impurity Cu of 0.1% or less and Fe of 0.25% or less. Therein lies the gist. In this aluminum heat exchanger, the core material of the fin brazing sheet contains Zn: 0.1 to 1.0% and Sn: 0.01 to 0.1%.
% and In: 0.01 to 0.1%, the performance can be further improved. The specific contents of the present invention will be further explained in detail below. First, the materials used as the fluid passage construction materials are:
It is an alloy that contains 0.2 to 2.0% Cu as an essential component, and if necessary, 0.01 to 0.5% of one or more of Mn, Cr, and Zr, and the balance is Al and impurities. is Al-Si or Al-Si- with less than 0.25% Fe as an impurity.
Brazing filler metal made of Mg-based alloy and Fe as an impurity
Pure aluminum with 0.25% or less and Cu 0.1% or less,
Al-Mn series, Al-Mg-Si series alloys, and if necessary, 0.1 to 1.0% Zn, 0.01 to 0.1% to these alloys.
It is composed of a brazing sheet whose core material is an alloy containing one or more of Sn and In, with the remainder being Al and impurities. In the present invention described above, the blending amount of each component of the fluid passage component and the composition of the fin material constitute important features of the present invention, and the intended results of the present invention cannot be obtained outside of the above conditions. do not have. In other words, Cu in Al alloy improves strength,
It is known as a component that shifts the potential in a noble direction, but since the addition of Cu inhibits corrosion resistance, it is generally not used as a corrosion-resistant aluminum alloy.
The current situation is that we use materials with a Cu content of 0.2% or less. However, when assembling Al alloy materials by brazing, high-temperature heating of 570 to 610°C is applied to melt the Al-Si brazing filler metal, but even when subjected to such high-temperature heating,
It has been found that when a material containing a relatively large amount of Cu is used as described above, the Cu additive component acts effectively as a strength-improving component and a potential-improving component without substantially reducing subsequent corrosion resistance. Cu of alloy for fluid passage component in the present invention
If the amount added is less than 0.2%, the potential of the base metal cannot be made sufficiently noble, and therefore Zn,
Addition of Sn, In, etc. is essential, and each element needs to be added in a higher concentration than in the present invention, resulting in contamination of the brazing furnace and reduction in workability. Further, when Cu increases beyond the upper limit of 2%, the potential becomes noble, but corrosion resistance decreases. Therefore, 0.2 to 2% was selected as an appropriate range for increasing the potential without significantly reducing corrosion resistance. Next, in addition to Cu, Mn is added as necessary.
Cr and Zr are each effective in suppressing recrystallization and improving strength during brazing heating, and each element
If it is less than 0.01%, the effect will not be exhibited effectively, and
If it exceeds 0.5%, corrosion resistance and workability will decrease. Therefore, the amount added is preferably 0.01 to 0.5%, and the total amount of the three elements is preferably less than 1.0%. Further, the reason why the impurity Fe in the brazing sheet brazing material for fins in the present invention is limited to 0.25% or less is to improve general corrosion resistance and to prevent the potential from becoming noble. Fe in Al-Si or Al-Si-Mg brazing filler metal is
and intermetallic compounds such as FeSi or FeSi ₂ , which crystallize during brazing. These FeSi-based compounds have a nobler potential than crystallized Si and have a strong effect as an effective cathode, so when the Fe content in the brazing filler metal increases, the potential shifts to a nobler direction, and the general corrosion resistance also decreases. descend.
This effect is small if the Fe content in the brazing filler metal is 0.25% or less, but if it exceeds 0.3%, the potential increases and corrosion resistance decreases significantly, so the upper limit of impurity Fe in the brazing filler metal is set at 0.25%. did. Next, an upper limit was set on the amount of Fe and Cu impurities in the brazing sheet core material in order to prevent the potential from becoming noble. As alloys for the core material, pure aluminum (JIS1XXX) and Al-Mn are selected due to their potential, corrosion resistance, brazing properties, and strength.
(3XXX) and Al-Mg-Si (6XXX) are preferred.
For example, (JIS6XXX) is like JIS6001.
Refers to alloys in the 6000 series. In addition, for applications that require active cathodic protection by fins, these alloys contain 0.1 to 1.0% Zn and 0.01 to 0.1% Zn.
Favorable results can be obtained by adding one or more of Sn and In. If each element is less than the lower limit, the effect is insufficient, and if the upper limit is exceeded, although the effect can be obtained, it is not preferable because it causes secondary damage such as contamination of the furnace and reduction in workability. Thus, by selecting the compositions of the components of the fluid component and the fin brazing sheet as described above, corrosion resistance can be significantly improved. Next, the present invention will be explained in more detail with reference to Examples. Example First, alloys having respective compositions shown in Tables 1, 2, and 3 were prepared. However, Si and Fe in Table 1 are impurities that are inevitably mixed into the aluminum alloy, and Ti is an element added as necessary to improve physical properties and workability. In other words, when a small amount of Ti is added to an aluminum alloy, it has the effect of refining the crystal grains of the ingot and prevents cracking of the ingot during casting, and also improves hot workability. Ti is added. However, from the viewpoint of improving corrosion resistance, which is the objective of the present invention, Ti should not be specified as an essential component. In addition, No. 37 and No. 42 in Table 3 have Si actively added.
Although it is a JIS6000 series Al-Mg-Si alloy, any Si contained in the core material other than those listed above is an unavoidable impurity, and Si specified for JIS1050 (pure Al) material:
Meets the requirement of 0.25% or less. Table 1 shows members for forming fluid passages, Nos. 1 to 8 are materials of the present invention, and Nos. 9 to 8 are materials of the present invention.
11 is a similar comparative material to the above alloy material. Table 2 shows brazing filler metals for brazing sheets, and No.
Nos. 21, 22, and 24 are materials of the present invention, and Nos. 23 and 25 are conventional materials. Table 3 shows alloys for core materials of brazing sheets for fins, with Nos. 31 to 39 being materials of the present invention and Nos. 40 to 43 being similar comparative materials. Note that the heat exchanger of the present invention is constructed by a combination of the above-mentioned members that meet the requirements of the invention. Using an alloy having the composition shown in Table 1, a multi-hole molded material having the cross-sectional shape shown in FIG. 1 was produced by hot extrusion. In addition, by combining the brazing filler metal shown in Table 2 and the core material alloy shown in Table 3, the cladding rate is 10% and the plate thickness is 0.5 mm.
A brazing sheet was created. The multi-hole material 1 and the brazing sheet 2 were combined into the shape shown in Fig. 2 and heated at 595°C x 3 in vacuum (10 ^-4 to 10 ^-5 Torr).
A sample material was prepared by heating for 1 minute. A CASS test in accordance with JIS H8681 was conducted on this sample material. Table 4 shows the maximum corrosion depth after 500 hours of continuous testing.

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[Table] As is clear from Table 4, all of the combination materials according to the present invention have slight corrosion, but no matter which fins are used for the conventionally used 1050-hole material, there is Clear penetration corrosion also occurred in the combination of hole-shaped material and AA No. 8 brazing sheet. Although the multi-hole heat exchanger has been described above, almost the same results were obtained in the case of a plate-fin heat exchanger consisting of a plate material 3 and brazing fins 4 as shown in FIG. As described above, the present invention constitutes a heat exchanger by combining a fluid passage-forming material made of an alloy with a specific composition and a brazing sheet fin material compatible with the fluid passage-forming material. Provides improved corrosion resistance. As a result, damage accidents caused by corrosion can be prevented, and the performance of the heat exchanger can be significantly improved compared to conventional aluminum heat exchangers.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of the multi-hole material used in the examples, FIG. 2 is a schematic diagram of the assembly of the sample material, and FIG. 3 is a schematic cross-sectional view of the plate-fin type heat exchange element.

Claims (1)

[Scope of Claims] 1. In an aluminum heat exchanger using plate material or shape material and brazing sheet for fins,
An alloy containing Cu: 0.2 to 2.0% (meaning of weight %: the same hereinafter) is used as the plate material or mold material, and the balance is Al and unavoidable impurities.
% or less, and as the core material, the impurity Cu is 0.1% or less.
% or less, pure Al type with Fe content of 0.25% or less,
A brazed aluminum heat exchanger characterized in that it is made of an Al-Mn-based or Al-Mg-Si-based alloy. 2. In aluminum heat exchangers that use plates or shapes and brazing sheets for fins,
As a plate material or shape material, it contains Cu: 0.2 to 2.0% (meaning of weight %: the same below), and one or more of Mn, Cr, and Zr: 0.01 to 0.5% each, and the balance is Al.
and unavoidable impurities as a brazing material for fin brazing sheets.
Al-Si system or Al-Si-Mg with Fe content of 0.25% or less
A type of alloy is used, and the core material is free from impurities.
Pure with Cu less than 0.1% and Fe less than 0.25%
A brazed aluminum heat exchanger characterized in that it is made of an Al-based, Al-Mn-based, or Al-Mg-Si-based alloy.