JPS5824719B2 - Aluminum alloy heat exchanger core with good corrosion resistance and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum alloy heat exchanger core with good corrosion resistance, and its purpose is to:
When used in heat exchangers such as car air conditioner condensers, evaporators, and car radiators, the fin material's sacrificial anode action protects the plates, shapes, or pipes that serve as working fluid passages from corrosion.

The core of an air-cooled heat exchanger made of aluminum alloy, which is generally assembled by brazing, is composed of a passage for working fluid (refrigerant, cooling water, etc.) and cooling fins on the air side.

In this case, a plating sheet (with a core made of aluminum or a corrosion-resistant aluminum alloy, and an At-81-Mg-based alloy Usually, the metals are joined by brazing using a laminated plate with a skin material.

However, when these heat exchangers are used in harsh corrosive environments, such as salty marine atmospheres, roads where anti-freezing agents are used, or high-temperature, high-humidity areas, the materials constituting the working fluid passages may suffer from more severe pitting corrosion than the air side. As a result, the range of use of the heat exchanger has been subject to many restrictions.

In addition, quite modest external corrosion protection (surface treatment) has been applied.

That is, in the conventional heat exchanger, as shown in FIG. 1, when the fins 1 and the working fluid passages 3 are brazed, the potential of the fillet portion 2 is high, and the working fluid passages 3 act as an anode, causing corrosion current. As shown by the arrow, the brazing fluid flows from the working fluid passage 3 to the fillet portion 2, causing pitting corrosion 4 in the working fluid passage 3.

The present invention has been made in consideration of this point, and by specifying the composition and combination of the material constituting the working fluid passage and the material constituting the fins, and by specifying the manufacturing method, it is possible to form the fins on the air side. The purpose is to protect the outer surface of the working fluid passage by making the sacrificial anode effect work most effectively.

That is, as shown in FIG. 2, according to the present invention, the fin 1
becomes an anode, and the working fluid passage 3 becomes a cathode, and the corrosion current flows from the fin 1 to the working fluid passage 3 and the fillet part 2 as shown by the arrow, so that pitting corrosion 5 occurs on the fin 1 and the working fluid passage 3 It is protected against corrosion.

For this purpose, it is necessary to supply the cathode current necessary for corrosion protection to the entire outer surface of the working fluid passage 3, and it is also necessary that the corrosion rate of the fins be low to some extent.

The present invention has been made to solve this problem.

That is, the present invention uses ZnO, 1-5%tMn0.2-2
or further Mg0.1"-1.

CuO, 01-1%, Cr0.01-0.5%pZrO
Placing made of an aluminum alloy containing one or more of 1O1-0.5% and F e O, 05-1% as a core material and an At-8i or At-81-Mg brazing filler metal as a skin material. The sheet constitutes a fin material, containing 1 to 2% MnO, 101 to 1% CuO, or further containing 0.1 to 1% Mg and 0.01 to 0% Ti.
5%, Zr 0.01~0.5%t CrO1O1~0
．． The present invention is an aluminum alloy heat exchanger having good corrosion resistance, characterized in that the working fluid passage is made of a corrosion-resistant aluminum alloy containing one or more of 5% and 0.05% to 2% Si.

The present invention also provides a method for manufacturing an aluminum alloy heat exchanger with good corrosion resistance, characterized in that the fin material having the above composition and the working fluid passage are brazed at an atmospheric pressure of 10-2 Torr or higher.

The plating sheet constituting the fin material in the present invention contains 0.1 to 5% Zn in the aluminum alloy core material.
It is characterized by containing 0.2 to 2% Mn,
Zn lowers the potential of the fins so that when assembled as a heat exchanger, the fins act as an anode.

If the content is less than 0.1%, the above effects will not be obtained, and if it exceeds 5%, self-corrosion of the fins will become severe.

Mn is useful for improving the strength, buckling resistance, and corrugation of the fin; it also improves workability, but if it is less than 0.2 mm, this effect is absent, and if it exceeds 2 mm, a huge intermetallic compound will crystallize during casting. This may cause material defects.

The heartwood is also one of Mg, Cup Cr, and Zrt Fe.
These may contain one or more species, but these serve to improve the strength and buckling resistance of the fin, and if the content is less than the lower limit, there is no such effect, and if the content exceeds the upper limit, brazing becomes difficult. deterioration, corrugate processability, etc.

The core material further contains impurities of less than 1% Si, TiO, 5
It may include less than or equal to many, Bo, less than or equal to 1, and less than or equal to Nil.

Kl-8i (6-15%) and Az-si (6-15%)-Mg (0,2-15%) are used for the skin material of the praising sheet.
3) A brazing filler metal of a system alloy is used.

The material constituting the working fluid passage has an M n of 0.1 to 2.

It is characterized by containing 0.01 to 1% Cu, while Mn increases the potential of the working fluid passage material and increases the potential difference between the fins and the working fluid passage material when assembled as a heat exchanger core. Useful for preventing corrosion of working fluid passage materials.

If the content is less than 0.1%, the above effects will not be obtained, and 2
If this value is exceeded, a huge intermetallic compound is formed during casting, causing defects in the material and significantly reducing extrudability.

Like Mn, Cu is also responsible for the potential of the working driftwood passage material.

If the content is less than 0.01%, this effect will not be achieved, and if the content exceeds 1%, self-corrosion of the working fluid passage material will increase and extrudability will be reduced.

The working fluid passage material is also Mgs Tie Zr+ Cr+
One or more types of Si may be included, but these serve to increase the strength of the working fluid passage material without impairing its corrosion resistance, and if the content is less than the lower limit, there is no such effect, and if the content exceeds the upper limit, it will not be effective. When attached, properties such as extrudability and extrudability decrease.

The working fluid passage material further contains Fe1% or less as impurities, 8
It may contain 0.1% or less, and 1% or less Ni.

The glazing sheet and the working fluid passage material are brazed together, and the present invention is characterized in that the brazing is performed at an atmospheric pressure of 10-2 Torr or higher.

This is because brazing prevents evaporation of Zn, which is the main component, and obtains an effective sacrificial anode effect.

If brazing is performed at an atmospheric pressure of 10-2 Torr, the Zn in the fin material will evaporate, reducing the effective sacrificial anode effect.

In addition, evaporated Zn adheres to the furnace wall, making it necessary to clean the furnace.

According to the present invention, due to the sacrificial anode effect of the fin material,
Corrosion of the working fluid passage material is prevented, and the corrosion resistance of the heat exchanger is improved.

In addition, brazing can prevent the furnace from being contaminated, making it easier to maintain the furnace.

The present invention can be applied not only to heat exchangers for automobiles (car air conditioners, radiators, oil coolers, etc.), but also to heat exchangers for railway vehicles and industry where external corrosion is a problem.

Next, examples and test results of the present invention will be described together with comparative examples.

Table 1 shows the chemical composition of the core material of the plating sheet for fins used.

A8 in the table. A9. AIO is a comparative example.

Note that the main component is, of course, At. A plating sheet with a core material of the above-mentioned Al to AIO alloy and a skin material of At-"0% pSi i, s%, Mg and At-10%5i-0,1% Bi alloy brazing material was prepared with a thickness of 0. The fin material was constructed with a heat refining H of 14 degrees and a clad ratio of 12.

Table 2 shows the chemical composition of the materials that make up the working fluid passages.

B8 in the table. B9. BIO is a comparative example.

Note that the main component is, of course, At. The above-mentioned 81-BIO alloy was extruded into a shape having four holes, which was used as a working fluid passage.

Table 3 summarizes the potential measurement results of the materials in Tables 1 and 2 above.

Table 4 shows the structure of the heat exchanger and the corrosion test results thereof.

AI5-20 are comparative examples.

Heartwood and At-10 ratio 5i-1, 5 ratio Mg or A, /,
A plating sheet was prepared using -1o% Si-o, i%Bi as a skin material, and this was used for the fin.

At-10%Si -1,5%Mg is used as the skin material for brazing at an atmospheric pressure of less than O,1 Torr, and A,/, -10 coefficient 5i-0,1% Bi is used for brazing at an atmospheric pressure of less than O,1 Torr. The material used as the skin material was used for brazing at an atmospheric pressure of 1 Torr (N2) or higher.

This fin and a working fluid passage material (a shape having four holes) were combined and brazed to form a heat exchanger core, and a corrosion test was conducted.

As is clear from Table 4 above, the heat exchanger core according to the present invention has superior corrosion resistance compared to the comparative example (excluding A16).

Next, Table 5 shows the Z in the alloy material during brazing heating.
Changes in the amount of n and brazing indicate the test results for the properties.

Table 5 above shows the fin materials of A1 to AIO from IATM to 1.
600°C95 at an atmospheric pressure of 0 ”l' o r r
This shows the result of heating for a minute, and in the present invention, Z
The amount of evaporation of Zn was small and the brazing properties were good.
There was a large amount of evaporated Zn, and the scattered Zn adhered to the furnace wall. A9 was unusable due to frequent buckling of the fins during brazing.

In addition, the brazing properties of the working fluid passage material (pipe material) are BI
Only O had a lot of erosion phenomenon, but other B
1 to B9 were all good.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the corrosion state of a conventional heat exchanger, and FIG. 2 is an explanatory diagram of the sacrificial anode action of the heat exchanger according to the present invention. 1... Fin, 2... Fin part to be brazed, 3... Working fluid passage, 4, 5...
... Pitting corrosion.

Claims (1)

[Claims] I Zno, 1-5%, Mn 0.2-2%, or further Mg 0.1-1%, CuO, 01-2%.
1%. Cr 0.01~0.5%* Zr 0.01~0
．． 5%t F eO005 to 1% or 2
The core material is an aluminum alloy containing more than 10% of Al-8i.
Alternatively, the fin material is constituted by a plating sheet made of At-81-Mg brazing material as a skin material, and Mn0.
1-2%, Cu O, 01-1%, or further KMg 0.1-1% pT 10.01-0.5
%-Zro, 01-0.5%, CrO, 01
An aluminum alloy heat exchanger with good corrosion resistance, characterized in that the working fluid passage is made of a corrosion-resistant aluminum alloy containing one or more of the following: -0.5%, Sio, and 05-2%. core. 2Zn 0.1-5% e M n 0.2-2 %, or further M g 0.1-1% y Cu 0.0
1-1%. Cr O, 01~0.5% p Z r o, o 1~
o, 5% p FeO0005~1% Al-6 nicum alloy containing one or more of the following is used as the core material, and At-
The fin material is composed of a plating sheet made of 8i or Al-81Mg brazing material as a skin material, and Mn0
．． 1-2%, CuO, 01-1%, or further Mg0.1-1%-TiO, 01-0.5% 5Zr
O, 01-0.5%, Cr O, 01-0.5%5
Aluminum with good corrosion resistance, characterized in that the working fluid passage is made of a corrosion-resistant aluminum alloy containing one or more types of SX0.05 to 2%, and these are brazed at an atmospheric pressure of 10" Torr or more. Method of manufacturing alloy heat exchanger core.