JPS60165333A - Copper alloy for fin of heat exchanger of automobile - Google Patents

Abstract

PURPOSE:To provide the titled alloy excellent in heat conductivity and corrosion resistance, good in processability and capable of enhancing the lift of radiator and reducing the wt. thereof, obtained by adding a specific amount of Y and Mg to Cu. CONSTITUTION:A copper alloy for the fin of the heat exchanger of an automobile consists of 0.005-1.0wt% Y, 0.005-1.0% Mg and the remainder of Cu and is one of which the corrosion resistance is enhanced by suppressing the formation and growth of Cu2O in air having chlorine, nigrogen oxide and sulfur dioxide gas mixed therein without too lowering the inherent heat conductivity of Cu. In Y and Mg being the above mentioned additive components, if the addition amounts thereof are below lower limits, action for suppressing the formation and growth of Cu2O is insufficient and, if exceed the upper limit, the effect of the enhancement in corrosion resistance is saturated and heat conductivity and rolling processability are lowered.

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, which has particularly excellent corrosion resistance, improves the life of the radiator, and makes it possible to reduce the weight.

The radiator for automobiles 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 dissipating the heat of the water that has risen in temperature in the engine through the radiator. It has become. A radiator usually consists of a tube through which water passes and fins that dissipate heat into the atmosphere by heat transfer from the tube, and air is forcedly blown onto the fins to promote heat dissipation.

Conventionally, the fins of such a radiator are made by adding Cd or Sn to Cu in a range of 01 to 1. Thickness 005 containing Owt
Copper alloy thin sheets with a strength of 0.2 to The driving environment has deteriorated significantly, and corrosion of not only automobiles but also the radiators installed in automobiles is accelerating.

That is, in order to improve heat dissipation, the radiator is usually installed at the front of the car to prevent the contaminated air from being blown out.Furthermore, the anti-freezing agent jumps up from the road and mixes with the contaminated air, which causes the radiator's fins to will be in direct contact with. Therefore, the fins of the radiator are exposed to severe corrosive conditions as they come into contact with the corrosive substances, and when the fins corrode, the heat dissipation performance of the radiator deteriorates, and if the corrosion progresses further, the tubes and fins fall off, making the radiator unusable. It disappears.

In recent years, automobiles have been required to be lighter in order to save energy and reduce exhaust gas, and radiators and heaters, which are parts of automobiles, are no exception, and fins, which are their constituent parts, are also being made thinner and lighter. Therefore, it is important for fins to improve their heat dissipation per unit area and maintain their service life.

In this situation, the current fin material au
The copper alloys to which Kad or Sn are added have almost no resistance to corrosion, and it is strongly desired to improve the corrosion resistance.

In view of this, the present invention has carefully observed the corrosion state of fins. As a result, corrosion occurs due to multi-layered oxide 0u20 on the metal surface of the fin, chlorine and sulfur condensing at the interface between Cu2O and the metal, and the corrosion surface is generally After discovering that there is a trace amount of moisture in the dry state, we conducted repeated research into corrosion-resistant materials under such conditions.As a result, we developed a fin for automotive radiators and heaters that has excellent thermal conductivity and corrosion resistance, and is easy to process. Developed copper alloy with Y 0.005~1.0w
t%, MgO, 005~1. Owt%, remainder O
It is characterized by consisting of u.

That is, the present invention adds a small amount of YXMg to Cu without disturbing or reducing the thermal conductivity of Cu%.
It improves corrosion resistance by suppressing the formation and proliferation of cuprous oxide in air containing chlorine, nitrogen oxides, sulfur dioxide, etc.

The reason why the alloy composition of the present invention is limited as described above is as follows.

The Y content was limited to 0005 to 1.0 wt% because
If the Y content is less than 0.005 wt%, the effect of suppressing the formation and proliferation of cuprous oxide is not sufficient (if it exceeds 1.0 wt%, the effect of improving corrosion resistance is saturated, and the heat resistance, which is important for fins, is insufficient). This is because conductivity is lowered and thin plate rolling workability is deteriorated.

Next, the Mg content is set to 0005 to 1. The reason for limiting the Mg content to Owt% is that if the Mg content is less than 0.005 wt%, the effect of suppressing the production and proliferation of cuprous oxide, like Y, will not be sufficient, and if it exceeds 1.0wt%, the thermal conductivity will decrease. It's because it reduces it drastically #) Y,! : In order to greatly improve corrosion resistance without reducing thermal conductivity to 1] due to the mutual effect of Mg, the above limitations (YO, 005 to 1) should be applied.
．． 0 wt%, MgO, 005-1. A range of Qwt is preferred.

The alloy of the present invention will be specifically explained below with reference to Examples.

Ciu is melted using a graphite crucible, the latter additive element whose hot water surface is coated with charcoal powder is inserted, and this is cast into a mold to a thickness of 25.5 mm with the composition shown in Table 1. ．． 1125011111
An ingot with a length of 1% and 250 cylinders was obtained. Next, this 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 to achieve a thickness of 0.5 mm (final working rate - 100%). 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 determined by cutting out a sample of 100 mm (length: 10' Omm) and exposing it to air containing 0.3% SO2 gas and 0.3% O12 gas for 118 hours, followed by heating at a temperature of 60°C.
The sample was kept in a constant temperature and humidity chamber at 80% humidity for 96 hours, and then Cu, which is a corrosion product on the sample surface, was
After removing 2O, 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.

1. In order to measure the rolling workability of a thin plate, the thickness described above is 0.
A plate with a thickness of 0.1 mm was produced by rolling and annealing a 5-mm plate.
This was rolled to a thickness of 0.020 wm, and then 0.1 m
Rolling workability was measured based on the number of times rolling breakage occurred during rolling of 100 cylinders of a plate with a thickness of m, and the results are also listed in Table 1.

Table 1 As is clear from Table 1, the alloy of the present invention (Nllll~N(L
7) all have sufficient thermal conductivity, and conventional alloys (Nu
13) has superior corrosion resistance. On the other hand, a comparative alloy (Nα8.9) with a lower Yl or Mg content than the composition range of the present alloy has sufficient thermal conductivity, but the improvement in corrosion resistance is insufficient, and the Y-spanning Mg A comparative alloy whose content is higher than the component range in the present invention (NalO~1
Although the corrosion resistance of 2) is good, the thermal conductivity, which is important as fin efficiency, is reduced, the rolling workability is deteriorated, and the manufacturing cost is considerably high, so that it has no industrial value.

In addition, within the range of ingredients in the alloy of the present invention, similar characteristics are obtained even when the amount of 02 is 50 ppm or less, and thus the alloy of the present invention exhibits excellent corrosion resistance in a corrosive environment containing chlorine and sulfur. When used in radiators and heater fins for automobiles and heat exchangers, it has the remarkable effect of extending the life of the radiator and making it possible to reduce its weight.

Claims (1)

[Claims] YO, 005~1. Owt%, Mg 0.00
5-1. A steel alloy for fins of an automobile heat exchanger, characterized by comprising Owt and the remainder O.