JPS62138695A - Fin material for radiator - Google Patents

Abstract

PURPOSE:To obtain a material for radiator fins with excellent corrosion resistance and a balance in heat conductivity by using as a fin material a material in which the surface of copper or copper alloy is covered by a Zn diffusion layer. CONSTITUTION:Only the surface of copper or copper alloy is covered with a Zn diffusion layer to obtain a brass composition on the surface in order to attempt a balance between the corrosion resistance and the heat conductivity. Here, it is preferable that the concentration of Zn on the surface is below 50%, because, if Zn concentration is over 50%, it becomes difficult to make press work or to work fins for corrugate fin type and the heat conductivity drops. The thickness of the diffusion layer is more than 1mum by taking in consideration the corrosion resistance and the heat conductivity although it is possible to change freely the heat conductivity by adjusting the thickness of the diffusion layer, and the thickness on one side is less than 1/3 of the total thickness of the fin. With this constitution it is possible to obtain improved life and lighter weight of a radiator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a fin material made of copper or copper alloy that constitutes a radiator of an automobile.

[Prior art and its problems] The automatic heavy duty radiator has copper alloy fins.

It consists of a tube and a tank and dissipates the heat of the engine's cooling water through fins. However, recently, as fins have become thinner in order to reduce the weight of radiators, deterioration in the heat dissipation performance of radiators due to corrosion of the fins has become a problem in coastal areas and cold regions where antifreeze salt is sprayed.

Cupronickel, which is made by adding nickel to copper, is known as a copper alloy that is resistant to salt corrosion.
In this case, if the composition is made of nickel, which exhibits corrosion resistance, the thermal conductivity will be greatly reduced, making it unsuitable as a fin material.

Therefore, a new material to be developed must be able to sufficiently withstand salt corrosion even if the fins are made thinner, and have a good balance between corrosion resistance and thermal conductivity.

[Object of the Invention 1 An object of the present invention is to provide a radiator fin material with excellent corrosion resistance.

[Summary of the Invention] The gist of the present invention is that the surface of copper or copper alloy is coated with Zn in advance.
The point is that a material covered with a diffusion layer is used for the fin material.

Copper-zinc alloy, so-called brass, is a material that has corrosion resistance in the corrosive environment of a radiator, but its thermal conductivity is significantly lower than that of conventional fin materials, and in this respect it is not suitable as a fin material. Therefore, in the present invention, only the surface of copper or copper alloy is
The composition of the n diffusion layer, that is, the brass composition 1, was balanced with corrosion resistance and thermal conductivity.

Here, the concentration of 70 on the surface is preferably 50% or less. This is because if the Zn1 degree is 50% or more, it becomes difficult to process the fins by rolling or in the case of corrugated fin type, and at the same time, the thermal conductivity is extremely reduced.

Furthermore, by adjusting the thickness of the diffusion W, the thermal conductivity of the fin material can be freely changed, and therefore, the thickness should be appropriate for the heat dissipation performance of the radiator. However, due to the trade-off between corrosion resistance and thermal conductivity, this thickness is 1 μm or more, and the thickness on one side is 1 μm or more of the total thickness of the fin.
It is preferable to set it as /3 or less.

[Embodiments of the invention] Examples of the present invention will be described below.

Both surfaces of a 0.1# thick copper strip made of oxygen-free copper were coated with Zn by a conventional electroplating method. Next, a heating diffusion treatment was performed at 600° C. to 800° C., which also served as annealing of the material, to create samples with various surface ZnW degrees and different diffusion layer thicknesses. Thereafter, the sample was cold rolled to a thickness of 0.05 m and subjected to testing. In the corrosion test, the sample was left in an atmosphere of 650°C and 90% RH or higher for 8 hours, and then exposed to 5% NaC for 30 minutes.
The process was carried out by repeating a cycle of spraying an aqueous solution of No. 1 and drying naturally for 16 hours 60 times. Afterwards, the corrosion products were removed with a dilute sulfuric acid solution, and the city determined the corroded raw materials by measurement.

Table 1 shows the test results. As a comparative example, Cu-〇, 1% 3n, which has traditionally been widely used in radiator fin materials, was used.
The alloy was tested.

Among the materials coated with Zn on the surface, all of the conventional materials C
It can be seen that the corrosion loss is smaller than that of the u-3n alloy, and the corrosion resistance is excellent. However, the surface Zn11 degree is 50
%, cracks would occur on the surface when the sample was rolled to a thickness of 0.1 to 0.05, which was undesirable.

Furthermore, when the thickness of the diffusion layer is extremely thin, corrosion tends to progress through the Znm coating metal member, resulting in a decrease in corrosion resistance.

Therefore, by selecting the surface Zn of 1 degree and the coating thickness, it is possible to form a fin material with good workability and corrosion resistance.

Regarding the method of coating Zn, in the embodiment, a method of heat treatment after electroplating was described, but any other method may be used as long as it is possible to coat Zn.

For example, hot-dip plating, vapor deposition, sputtering, etc.

Further, although an example has been described in which the material is roughly cold rolled after Zn coating treatment, it is of course possible to use the material as it is as a fin material without cold rolling.

[Effects of the Invention] Since the fin material of the present invention has a Zn diffusion layer at a specific temperature on the surface, corrosion resistance is improved, the service life of the radiator can be extended, and the weight of the radiator can be reduced. It has the advantage that it can also be applied to the targeted thinning of fins.

Table 1

Claims (1)

[Claims] (1) A radiator that is a fin material made of copper or copper alloy that constitutes an automobile heat exchanger, whose surface is covered with a Zn diffusion layer, and whose Zn concentration on the surface is 50% or less. fin material.