JPH03114659A - Heat exchanger - Google Patents

Abstract

PURPOSE:To obtain a heat exchanger having no deformation nor reduction of joining strength by applying the mixture of the Al alloy powder in the limited grain size containing Si and Zn of a limited weight ratio and the balance being composed of Al and impurities and a binder to the heat exchanger core and executing the brazing. CONSTITUTION:Brazing is executed by applying the mixture of the Al alloy powder in 10-200mum grain size containing a 7-12wt.% Si and 0.5-10wt.% Zn and consisting of Al and impurities at the balance and a binder to the heat exchanger core. At this time, no corrosion resistance effect is observed in the case of Zn in <=0.5wt.%, no corrosion resistance effect is obtained in the case of >10wt.% and yet the brazing property is reduced. Also, in the case of the diameter of the Al alloy powder in <=10mum, the brazing property is degraded and in the case of exceeding 200mum vice versa, the uniform coating can not be attained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a heat exchanger manufactured by ^1 used, for example, in automobile radiators, air conditioner condensers, evaporators, and the like.

[Background of the invention]

For example, heat exchangers have many joints, such as extruded tubes and fins, or tubes and headers, and the joints have complicated shapes. The heat exchanger material was made of a plating sheet clad with surplus brazing filler metal, which was then joined by brazing. This method has excellent productivity and is practically useful because the complex core portions can be completely joined by heating at -degrees. However, if a plating sheet is used for a thin material such as a fin, the solder on the surface of the material will penetrate into the base material during heating, significantly reducing the deformation resistance of the material at high temperatures, and the brazing will easily occur due to its own weight. Due to the deformation, the desired shape cannot be maintained, which may deteriorate the bonding strength in some cases. Also, brazing is not desirable from the viewpoint that only the minimum necessary amount of solder is supplied to the part.In other words, brazing is not desirable because there is a non-negligible amount of solder in parts other than the part where no solder is needed. Corrosion resistance of parts is poor. For this reason, attempts have been made to increase the corrosion resistance of the tube by attaching Zn to the surface of the tube, but this increases the cost.

[Disclosure of the invention]

A first object of the present invention is to provide a heat exchanger in which the members of the heat exchanger are not deformed by brazing and the joint strength is not reduced due to this. A second object of the present invention is to provide a heat exchanger in which a large amount of wax is not attached to unnecessary parts and the corrosion resistance is not deteriorated. The object of the present invention is as follows: 7-12% by weight device i and 0.5%
A heat exchanger characterized by applying a mixture of 10 to 200 μm of He1 alloy powder and a binder containing ~10% by weight of Zn, the balance being Al and unavoidable impurities, to the heat exchanger core and brazing it. This is accomplished by an exchanger. That is, the inventor of the present invention has conducted various studies to solve the problems of deformation of the internal members when brazing a heat exchanger using a plating sheet, brazing under a stiff paper, and corrosion resistance, and as a result, the inventor found that a method containing Zn was found. ^1-Si-based brazing filler metal is powdered, and a mixture of this powder and a binder is applied to the joint, for example, 580-6
It was discovered that the above problem could be solved by flux brazing at a temperature of 30°C, and the present invention was completed based on this finding. The heat exchanger of the present invention is obtained by applying a conventional flux brazing method using fluoride, chloride, etc., and the Si content of the solder is 7 to 12% by weight. The brazing temperature was set at 580 to 630°C, which is the melting temperature of the wax. And Zn in the wax electrochemically makes the brazing material base,
This protects the duplex and header from corrosion through the sacrificial anode effect, and if the content is too small (less than 0.5% by weight, 1%), the above effect cannot be fully exhibited, and if the content exceeds 10% by weight, it will cause further corrosion. You can't expect great results,
On the contrary, a large amount of Zn tends to reduce the brazing properties, so it is important to use a Zn content of 0.5 to 10% by weight. If the diameter of the solder powder is too small (less than 10 μm), the surface area of the powder will be large and the amount of oxides will be large, resulting in poor brazing properties and difficult handling due to the fine powder. If it is too large, it will not be possible to coat the material thinly and evenly on the surface of the material.
It is important to set the thickness to 00 μm. 4 The above-mentioned brazing alloy powder has little variation in composition and is fine, so that it can be easily melted at high temperatures for brazing, and excellent brazing properties can be ensured. Also, according to the above method, The same effect can be obtained not only by brazing but also by attaching Zn to the tube surface.

[Examples and comparative examples]

JIS 1050 ^1 extruded multi-hole tube (thickness 0.5+
Assemble the header plate 2 and the header plate 2 as shown in FIG.
I inserted fin 3 made by I into S 3003. Incidentally, the surface of the extruded multi-hole tube 1 in the above assembly is coated with Al-5i-Zn brazing filler metal in advance using a binder made of acrylic resin. Further, the brazing filler metal was applied by spraying between the extruded multi-hole tube 1 and the header plate 2 in the assembly. After spraying fluoride flux on the assembly shown in Figure 1, it was heated to 600°C in a nitrogen gas atmosphere.
, heat treatment was performed for 5 minutes and brazing was performed. For comparison, instead of using the brazing filler metal made of the mixture of Al-5i-Zn alloy powder and binder, J
Using fins made of 0, 10 scale 0 thickness glazing sheets clad with Al-8%Si alloy brazing material on both surfaces of IS 3003, fluoride flux was applied by spray, and then 600°C was applied in a nitrogen gas atmosphere. ℃ for 5 minutes to perform brazing. After brazing the heat exchanger, the deformation of the fins 3 and the joining of the fins 3 and the extruded multi-hole tube 1 were observed. In addition, a 300-hour CASS test was conducted to examine the corrosion resistance of the assembled assembly after the above-mentioned brazing. These results are shown in Table 1. As is clear from Table 1, in the heat exchanger of the present invention, since the fins are not plating sheets, there is almost no deformation of the fins during brazing, and the joint between the extruded multi-hole chamber 1 and the fins 3 is good. , the corrosion resistance is also good due to the effect of Zn in the brazing filler metal, whereas the product using brazing sea 1 of the comparative example has problems in all of the deformation of the fin, the joint condition, and the corrosion resistance. Moreover, if the particle size of the Al-5i-Zn alloy powder is too large, the bonding condition will be poor, and conversely, if the particle size is too small, the corrosion resistance will be poor. Furthermore, if the amount of Zn in the Al-5i-Zn alloy powder becomes too large, deformation of the fins will be observed and the bonding condition will also deteriorate.

[Brief explanation of drawings]

FIG. 1 is an assembly diagram of an extruded multi-hole tube, a header plate, and a fin. 1... Extruded large tube, 2... Header plate, 3...
fin.

Claims (1)

[Claims] 10-200 containing 7-12% by weight of Si and 0.5-10% by weight of Zn, with the remainder consisting of Al and unavoidable impurities.
A heat exchanger characterized in that a mixture of micrometer Al alloy powder and a binder is applied to a heat exchanger core and brazed.