JPS60165335A - Copper alloy for fin of heat exchanger of automobile - Google Patents

Abstract

PURPOSE:To provide the titled copper alloy enhanced in corrosion resistance without lowering a heat dissipation characteristic and making it possible to prolong the life of a radiator and to reduce the wt. thereof, constituted of a specific composition of Y and Cu. CONSTITUTION:A copper alloy for the fin of the heat exchanger of an automobile consists of 0.07-1.0wt% Y and the remainder Cu and shows excellent corrosion resistance in a corrosive environment in which chlorine and sulfur are present and is good in heat conductivity. The above mentioned alloy is one of which the corrosion resistance is enhanced by suppressing the formation and growth of Cu2O through the addition of Y to Cu. If Y is below 0.7%, effect to corrosion followed by the growth of Cu2O is low and, if exceeds 1.0%, corrosion resistance is good but its cost rises. Furthermore, as Cu, both of the one with reduced O2-content prepared by non-oxidative melting and one prepared by atmospheric melting can be adapted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copper alloy for the fins of automobile radiators and heaters, and in particular improves the corrosion resistance of the fins without deteriorating the heat dissipation characteristics of the radiator.

In general, a radiator for an automobile is a device that prevents the temperature of the engine from rising.By circulating water, which is a cooling medium, between the engine and the radiator, and dissipating the heat of the water that has risen in temperature in the engine, the radiator cools the engine. is being cooled. A radiator consists of a tube through which water passes and fins that dissipate heat from the tube into the atmosphere. A radiator is usually attached to the front of a car and uses forced air to blow air to promote heat dissipation.

Conventionally, the fins of automobile radiators are made of Cu and Sn.
, a copper alloy to which 0.1-1.0 Wt % (hereinafter wt % is simply abbreviated as 俤) of CA or Ag is used.

These alloys have a certain degree of strength and good heat resistance, and when used as a radiator, they are only 5 to 10 inches lower than tough pitch copper, which has the highest heat dissipation property among copper-based materials. The high temperature and soldering during the manufacture of the radiator has the advantage that it does not soften when heated.

However, recently, chlorine, nitrogen oxides, sulfur dioxide gas, etc. have increased in the air, and chlorine compounds have been sprayed on roads as antifreeze agents, which has significantly worsened the driving environment for cars. is continuing to accelerate. In particular, the radiator needs to improve its heat dissipation characteristics.
Since it is installed at the front of the car and polluted air is forcibly blown into the radiator, corrosion of the radiator accelerates under certain humidity and temperature conditions, deteriorating the heat exchange characteristics of the radiator and shortening its lifespan. There were drawbacks.

In view of this, the present invention has made a detailed observation of the corrosion state of the fin, and has found that corrosion is caused by the formation of multiple layers of oxide (A120) on the metal surface of the fin, and the aggregation of chlorine and sulfur at the interface between Cu2O and the metal, resulting in corrosion on the corroded surface. We found that copper alloys are generally dry and contain only a trace amount of moisture, and we conducted research on corrosion-resistant materials under these conditions.As a result, we developed a copper alloy for use in fins for automotive radiators and heaters that has sufficient heat dissipation properties and excellent corrosion resistance. It was developed and contains Yo, 07-10%,
It is characterized in that the remainder is made of Cu, and as the remaining O, both those produced by non-oxidizing melting with a low O2 content and those dissolved in the atmosphere can be used.

That is, the present invention is based on the above knowledge, and as a result of conducting corrosion tests on various copper alloys in an environment where sulfur and chlorine are simultaneously present as corrosive media and with little moisture, CuK
By adding Y, the formation and proliferation of a layered film of Cu2O could be prevented.

However, in the present invention, the alloy composition is limited as described above for the following reasons.

That is, if the Y content is less than 0.074, there is little effect on corrosion accompanied by the proliferation of Cu2O, and if the Y content is less than 1.
This is because if it exceeds 0, the corrosion resistance will be good, but the cost will be high.

Hereinafter, the present invention will be described in detail with reference to examples.

After melting Cu using a graphite crucible and coating the hot water surface with charcoal powder, additional elements were inserted to create an ingot with a thickness of 25 mm, a width of 250 mm, and a length of 250 mm with the composition shown in Table 1. I got it. Next, the ingot was milled by 2.5 mm per side, hot rolled according to a conventional method, and then intermediate annealing and cold rolling were repeated until the ingot had a thickness of 0.5 mm (final processing rate: liO%). ) was finished on the board. This plate was examined for corrosion resistance, thermal conductivity, and rolling workability. The results are shown in Table 1.

Corrosion resistance was measured by cutting a sample 100111111 long and 100 m wide and exposing it to air containing 03% SO2 gas and 0.3% ct2 gas for 118 hours, followed by a temperature of 60°C.
The sample was kept in a constant temperature and humidity chamber at a humidity of 80 degrees for 96 hours, and then Cu2, a corrosion product on the surface of the sample, was removed.
After removing O, the weight was measured, and the corrosion loss per unit area was calculated based on the weight before and after the test. Regarding thermal conductivity, we measured electrical conductivity, which has a strong positive correlation. In order to measure the rolling workability of a thin plate, the above-mentioned 0.5 mm thick plate was rolled and annealed to make a 0.1 mm thick plate, which was then rolled to a thickness of 0020 (rolling).
Rolling workability was measured by the number of times rolling breaks occurred during rolling for 100 m using a flat plate, and the results are also listed in Table 1.

Table 1 As is clear from Table 1, the alloy of the present invention (Nα1 to Nα5
) has sufficient thermal conductivity even when collapsed, compared to conventional alloys (Na9).
It has superior corrosion resistance compared to

On the other hand, the comparative alloy (Na6), which has a lower Y content than the composition range of the present alloy, has sufficient thermal conductivity, but the improvement in corrosion resistance is insufficient. Comparative alloys (N[L'l) containing more than the range of ingredients have good corrosion resistance, but have poor rolling workability, greatly increase manufacturing costs, and have no industrial value.

As described above, the alloy of the present invention exhibits excellent corrosion resistance in a corrosive environment containing chlorine and sulfur, and can be used for fins for radiators and heaters in automobile heat exchangers to extend the life of radiators and reduce their weight. It has a remarkable effect on

Patent applicant: Furukawa Electric Co., Ltd.

Claims (1)

[Claims] Y007~1. A copper alloy for use in fins of automobile heat exchangers, characterized in that the copper alloy contains 50% by weight and the remainder is Cu.