JPH04293747A - Fin material for heat exchanger made of aluminum - Google Patents

Abstract

PURPOSE:To stabilize the surface of a material and to improve the durability of a fin to be manufactured. CONSTITUTION:The compsn. of the fin material is formed into a one contg., by weight, 0.02 to 0.10% Zn, 0.10 to 0.15% Sn, 0.2 to 0.8% Mn, <=0.2% Si, <=0.06% Fe, <=0.05% Cu and the balance Al with inevitable impurities. Or, if required, one or >= two kinds among 0.01 to 0.15% Zr, 0.01 to 0.10% Ti and 0.05 to 0.3% Cr are incorporated therein.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The aluminum heat exchanger fin material according to the present invention is suitable for making fins constituting the core of a heat exchanger used, for example, as a radiator for cooling water heat dissipation in an automobile engine. Make use of it.

0002

2. Description of the Related Art Conventionally, a heat exchanger used as a radiator or the like has a structure as shown in FIG. 1, for example.

[0003] This heat exchanger 1 includes a pair of tanks 2a and 2b arranged at an interval, a plurality of heat exchanger tubes 3, 3 that communicate between the tanks 2a and 2b, and adjacent heat exchanger tubes 3,
3, a fluid inlet 6 provided in one tank 2a, and a fluid inlet 6 provided in the other tank 2a.
and a fluid outlet 7 provided at b. However, in addition to providing a partition wall in the middle of one tank 2a,
There is also a structure in which a fluid inlet and a fluid outlet are provided at both ends of the tank 2a.

[0004] When performing heat dissipation of cooling water, etc., the cooling water etc. sent into one tank 2a through the fluid inlet 6 is sent toward the other tank 2b through a plurality of heat transfer tubes 3, 3. While flowing through each heat exchanger tube 3, 3, the above cooling water etc.
Core part 5 composed of heat exchanger tubes 3, 3 and fins 4, 4
The fluid is cooled by heat exchange with the air passing through the tank 2b, and is sent out again toward the engine etc. from the fluid outlet 7 provided in the other tank 2b.

The fins 4, 4, which together with the heat transfer tubes 3, constitute the core portion 5, are of corrugated type as shown in FIGS. 1 and 2, and also of plate type as shown in FIG.

[0006] In recent years, such a heat exchanger 1 is often made of aluminum or an aluminum alloy (hereinafter referred to as "aluminum etc.").

[0007] When the heat exchanger 1 is made of aluminum or the like, each component is made of different types of aluminum or the like in order to meet the requirements of corrosion resistance and heat transfer performance depending on the part in which it is used. The fins 4 and 4 are
It is required to have sufficient strength at high temperatures and to have a sacrificial corrosion effect. For this reason, it has traditionally been
As disclosed in Publication No. 1-9377, Sn and In
The use of a material that has a sacrificial corrosion effect by adding and lowering the potential is being considered.

The aluminum heat exchanger fin material disclosed in this publication contains 0.03 to 0.3% by weight of Sn.
and 0.03 to 0.8% by weight of Mg, and 0.3 to 1.5% by weight.
% by weight of Mn, 0.1-0.8% by weight of Fe, further 0.01-0.3% by weight of Cr, and 0.01-0.
．． Contains one or more of 3% by weight of Zr, 0.01 to 0.8% by weight of Si, and 0.01 to 0.8% by weight of Cu, with the remainder being Al and inevitable impurities. It is something.

[0009]

[Problems to be Solved by the Invention] However, in the case of the aluminum alloy conventionally used to construct the fins 4, 4, as described above, the surface is extremely active due to the influence of Sn, and if left as it is, it will not heat up. It turned out that it was not suitable for constructing an exchanger.

That is, when the present inventor immersed the aluminum heat exchanger fin material described in the above-mentioned publication in tap water, bubbles were generated and it was confirmed that the surface was very active. This is because in aluminum alloys containing Sn, the Al2O3 film formed on the surface is weak, and the Al2O3 film formed on the surface is weak.
This is thought to be because the surface of -Sn becomes extremely active.

[0011] As described above, if the surface is extremely active due to the influence of Sn, the surface layer will dissolve into the water, and the durability of the fin made of this aluminum alloy will be insufficient (the self-corrosion rate will be too fast). ), and the Sn2+ ions may have an adverse effect on the surface-treated material.

The aluminum heat exchanger fin material of the present invention solves the above-mentioned disadvantages.

[0013]

[Means for Solving the Problems] The fin material for an aluminum heat exchanger of the present invention contains 0.02 to 0.10% by weight of Zn.
and 0.10-0.15% by weight of Sn, and 0.2-0.
8% by weight Mn, 0.2% by weight or less Si, 0.6% by weight
It contains Fe of less than 0.05% by weight and Cu of less than 0.05% by weight, and the remainder is Al and unavoidable impurities.

[0014] Also, if necessary, 0.01 to 0.15% by weight of Zr, 0.01 to 0.10% by weight of Ti, and 0.01 to 0.15% by weight of Zr,
．． 05 to 0.3% by weight of Cr.

[0015]

[Function] By adding Zn to the aluminum heat exchanger fin material of the present invention constructed as described above, a film of Al2O3 is formed on the surface, which makes the surface stable. Therefore, the surface layer will not dissolve into water and the durability of the fin will become insufficient, or Sn2+ ions will not have an adverse effect on the surface treated material.

Furthermore, compared to the aluminum alloy constituting the heat exchanger tube, a sufficiently low (base) potential can be secured, and the sacrificial corrosion effect can sufficiently protect the heat exchanger tube from corrosion.

The reason why the amount of each element added is limited to the above range is as follows.

First, regarding Zn, the amount added is 0.02
If it is less than % by weight, the Al2O3 film will not be formed sufficiently,
If the self-corrosion rate cannot be reduced and, on the other hand, it is added in an amount exceeding 0.10% by weight, it will cause significant contamination of the vacuum brazing furnace during brazing assembly of aluminum heat exchangers. Therefore, as mentioned above, the amount of Zn added was limited to the range of 0.02 to 0.10% by weight.

Regarding Sn, if the amount added is less than 0.10% by weight, the effect of lowering the electric potential (making it less noble) will be insufficient, and the effect of preventing corrosion of the heat exchanger tube will be insufficient; 1
If added in excess of 5% by weight, processability will deteriorate. For this reason, as mentioned above, the amount of Sn added was limited to the range of 0.10 to 0.15% by weight.

[0020] Regarding Mn, if the amount added is less than 0.2% by weight, the high temperature strength will be insufficient; on the other hand, if it is added in excess of 0.8% by weight, the potential will become high (noble). ), it becomes impossible to obtain sufficient sacrificial corrosion effects. For this reason, as mentioned above, the amount of Mn added was limited to the range of 0.2 to 0.8% by weight.

[0021]Also, Si and Cu are added for the purpose of improving sagging resistance and strength, but if the amount of Si added exceeds 0.2% by weight or the amount of Cu added exceeds 0.05% by weight, weight%
If it exceeds C, not only will corrosion resistance be poor, but C
When the amount of u added increases, the potential increases,
A sufficient sacrificial corrosion effect cannot be obtained. Therefore, as described above, the amount of Si added was set to 0.2% by weight or less, and the amount of Cu added was set to 0.05% by weight or less. In order to achieve the purpose of improving sagging resistance and strength, it is preferable that the amounts of Si and Cu added are each 0.01% by weight or more.

[0022]Furthermore, Fe is added for the purpose of improving the sagging resistance and the formability of the fin, but if the amount added exceeds 0.6% by weight, the corrosion resistance will only deteriorate. However, rolling workability and brazing properties become poor. For this reason, as mentioned above, the amount of Fe added was set to 0.6% by weight or less. Incidentally, in order to achieve the purpose of improving droop resistance and molding processability of the fin, it is preferable that the amount of Fe added is 0.1% by weight or more.

Furthermore, Zr, Ti, and Cr are added for the purpose of improving the sagging resistance and the molding processability of the fin, but if the amount added is less than the lower limit of each, they may not be added. On the other hand, if the added amount exceeds the upper limit, not only will the formability of the fin deteriorate, but also the sacrificial corrosion effect will decrease. For this reason, even when added, the amount of each addition was limited to the above range.

[0024]

[Example] Next, experiments conducted to confirm the effects of the present invention will be explained.

The experiment was conducted using 10 types of aluminum alloys as shown in the following table, namely 7 types of aluminum alloys belonging to the present invention and 3 types of aluminum alloys conventionally used for fins. This was done by observing the presence or absence of bubbles after immersion in tap water and measuring the pitting potential.

[Table 1]

[0026] Prior to immersion in tap water, the test piece plate was heated at 600°C for 5 minutes under a pressure of 10-3 to 10-5 torr. After this heat treatment, the plate material was immersed in tap water at room temperature, and visually observed to see if bubbles were generated from the surface.

Regarding the pitting corrosion potential, the potential of the plate material subjected to the heat treatment described above was measured in a 5% NaCl aqueous solution using a saturated calomel electrode as a reference. Then, the JIS 3003 material (Si content of 0.6% by weight or less,
Contains 0.7% by weight or less of Fe, 0.05 to 0.20% by weight of Cu, 1.0 to 1.5% by weight of Mn, and 0.10% by weight of Zn, with the remainder being unavoidable impurities and Al. What I did. ), which is the pitting corrosion potential of -710 mV, 100 mV
Those with a mean rating above were considered good.

The above results are shown in the table above. As is clear from the table, the fin material for aluminum heat exchangers of the present invention is superior to the aluminum alloys conventionally used for making fin materials. In comparison, it is possible to stabilize the surface and suppress the self-corrosion rate while ensuring sufficient sacrificial anodic properties.

[0029]

[Effects of the Invention] Since the fin material for an aluminum heat exchanger of the present invention is constructed and functions as described above, a heat exchanger with excellent durability can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front view of an aluminum heat exchanger using corrugated fins.

FIG. 2 is a perspective view of a corrugated fin.

FIG. 3 is a front view of an aluminum heat exchanger using plate-type fins.

[Explanation of sign]

1 Heat exchanger 2a Tank 2b Tank 3 Heat exchanger tube 4 Fin 5 Core part 6 Fluid inlet 7 Fluid outlet

Claims (2)

[Claims] Claim 1: 0.02 to 0.10% by weight of Zn;
0.10 to 0.15 wt% Sn, 0.2 to 0.8 wt% Mn, 0.2 wt% or less Si, 0.6 wt% or less Fe, 0.05 wt% % or less of Cu,
Fin material for aluminum heat exchangers with the remainder being Al and inevitable impurities. 2. 0.01 to 0.15% by weight of Zr;
0.01-0.10 wt% Ti and 0.05-0.3
The fin material for an aluminum heat exchanger according to claim 1, comprising one or more of the following by weight% of Cr.