JPH0480101B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a copper alloy for the fins of heat exchangers such as automobile radiators and heaters, and is particularly excellent in corrosion resistance, improving the life of the radiator and making it possible to reduce the weight. An automobile radiator prevents the temperature of the engine from rising.It cools the engine by circulating water, which is a cooling medium, between the engine and the radiator, and radiating heat from the water that has risen in temperature in the engine. It's summery. A radiator usually consists of a tube through which water passes and fins that dissipate heat into the atmosphere through heat transfer, and air is forcedly blown onto the fins to promote heat dissipation. Conventionally, the fins of such radiators were made of Cu.
with a thickness of 0.03 containing 0.1 to 1.0 wt% of Cd or Sn.
~0.2mm copper alloy thin plates were used, but recently the environment in which cars drive has changed, with chlorine, nitrogen oxides, sulfur dioxide, etc. increasing in the air, and chlorine compounds being sprayed on roads as antifreeze agents. has significantly worsened,
Corrosion not only in cars but also in the radiators installed in cars is accelerating. That is, in order to improve heat dissipation, the radiator is usually attached to the front of the car and blows the contaminated air onto it, and anti-freezing agent jumps up from the road and mixes with the contaminated air, which comes into direct contact with the fins of the radiator. It turns out. Therefore, the fins of the radiator are exposed to severe corrosive conditions as they come into contact with the above-mentioned corrosive substances. When the fins corrode, the heat dissipation performance of the radiator deteriorates, and as the corrosion progresses, the fins fall off from the tube and the radiator is no longer used. become unable. In recent years, automobiles have been required to be lighter to save energy and reduce exhaust gas, and radiators and heaters, which are part of automobiles, are no exception.
The fins that are the constituent members of these devices are also required to be thinner and lighter. Therefore, improving the heat dissipation per unit area and maintaining the service life of the fins are important issues. Under these circumstances, the copper alloys that are currently used as fin materials, which are made by adding Cd or Sn to Cu, have almost no resistance to corrosion, and there is a strong desire to improve the corrosion resistance. In view of this, the present invention has carefully observed the corrosion state of the fins and found that corrosion is caused by oxides on the metal surface of the fins.
It was discovered that Cu ₂ O overlaps in multiple layers and chlorine and sulfur aggregate at the interface between Cu ₂ O and the metal, and that corroded surfaces are generally dry with only a trace amount of moisture. As a result of repeated research, we have developed a copper alloy for automotive radiators and heater fins that has excellent thermal conductivity, corrosion resistance, and good workability.
It is characterized by consisting of 0.005 to 1.0 wt% Mg and the balance Cu. That is, the present invention adds a small amount of Y and Mg to Cu, without significantly reducing the thermal conductivity characteristic of Cu, and suppresses the formation of cuprous oxide in air containing chlorine, nitrogen oxides, sulfur dioxide, etc. It suppresses proliferation and improves corrosion resistance. The reason why the alloy composition of the present invention is limited as described above is as follows. The Y content was limited to 0.005-1.0wt% because Y
If the content is less than 0.005wt%, the effect of suppressing the formation and proliferation of cuprous oxide is insufficient, and if it exceeds 1.0wt%, the effect of improving corrosion resistance will be saturated and the thermal conductivity, which is important as a fin, will be reduced. This is because the rolling processability of the thin plate is deteriorated. Next, we limited the Mg content to 0.005 to 1.0 wt% because if the Mg content is less than 0.005 wt%, the effect of suppressing the production and proliferation of cuprous oxide is insufficient, similar to Y. If it exceeds Y0.005, the thermal conductivity will be greatly reduced.In order to greatly improve the corrosion resistance without significantly reducing the thermal conductivity due to the mutual effect of Y and Mg, the above limitation is Y0.005. ~
1.0wt%, Mg preferably in the range of 0.005 to 1.0wt%. The alloy of the present invention will be specifically explained below with reference to Examples. After melting Cu using a graphite crucible and coating the hot water surface with charcoal powder, each additive element was inserted, and this was cast into a mold with a thickness of 25 mm and a width as shown in Table 1.
An ingot with a length of 250 mm and a length of 250 mm was obtained. Next, this ingot was face-milled by 2.5 mm per side, hot-rolled according to a conventional method, and then intermediate annealing and cold rolling were repeated to obtain a thickness of 0.5 mm (final processing rate = 40%). Finished on a board. A corrosion test sample and a thermal conductivity sample were taken from this plate and their corrosion resistance and heat conductivity were measured. The results are shown in Table 1. Corrosion resistance was measured by cutting a sample 100 mm long and 100 mm wide, exposing it to air containing 0.3% SO ₂ gas and 0.3% Cl ₂ gas for 48 hours, and then placing it in a constant temperature and humidity chamber at a temperature of 60°C and humidity of 80%. Holding was repeated for 96 hours, and then Cu ₂ O, which is a corrosion product on the sample surface, was removed, the weight was measured, and the corrosion loss was determined from the weight before and after the test, and the corrosion loss per unit area was calculated. In addition, in order to measure the rolling workability of a thin plate, the 0.5 mm thick plate mentioned above was rolled and annealed to make a 0.1 mm thick plate, which was rolled to a thickness of 0.020 mm, and then rolled to a thickness of 0.1 mm. The rolling workability was measured based on the number of times rolling breaks occurred during rolling of 100 mm of the plate, and the results are also listed in Table 1.

【table】

[Table] As is clear from Table 1, the alloys of the present invention (No. 1 to No.
All 7) have sufficient thermal conductivity and are superior in corrosion resistance compared to the conventional alloy (No. 13). On the other hand, comparative alloys (Nos. 8 and 9) with lower Y or Mg content than the composition range of the present alloy have sufficient thermal conductivity but insufficient improvement in corrosion resistance.
Comparative alloys (Nos. 10 to 12) with a higher Y or Mg content than the component range in the present invention have good corrosion resistance, but have a lower thermal conductivity, which is important as a fin material, and poor rolling workability. As a result, the manufacturing cost becomes extremely high and there is no industrial value. In addition, in the composition range of the present invention alloy,
Similar characteristics are exhibited even when the amount of O ₂ is 50 ppm or less, and the alloy of the present invention exhibits excellent corrosion resistance in a corrosive environment containing chlorine and sulfur, making it suitable for use in radiators and heaters of automobiles and heat exchangers. When used in the fins of radiators, it has the remarkable effect of extending the life of the radiator and making it possible to reduce its weight.

Claims (1)

[Claims] 1 Y0.005~1.0wt%, Mg0.005~1.0wt%, balance
A copper alloy for automotive heat exchanger fins, characterized by being made of Cu.