JPS61199572A - Al alloy cladding material for 'alcan nocolok (r)' brazing - Google Patents

Abstract

PURPOSE:To improve a sealing and corrosion resistance by cladding Al-Si group alloy brazing filler metal on one face of the core metal made of corrosion resistance Al alloy and by cladding the shell containing the specified quantity of Mg, Ca on the other side of the core metal. CONSTITUTION:Al-Si group alloy is cladded on one side of the core metal consisting of corrosion resistant Al alloy. The shell containing 0.3-1.0wt% Mg, 0.2-0.4wt% Ca, 0.3-1.0wt% Mg and either one of 0.2-0.4wt% Ca and the balance Al consisting of inevitable impurities is cladded on the other side of the core metal. The surface coarseness of the shell adhering flux after braz ing is reduced and the initial sealing in assembling state of radiator, etc. is improved. Also the core metal is subjected to a cathodic protection by holding the shell at low potential even after brazing, the elusion of the shell is moreover controlled and yet the pitting corrosion resistance of the shell itself can be increased. The clad ratio of the shell varies according to the total plate thick ness as well but it had better to determine so that the thickness of the shell makes 50-120mum. For instance the thickness of the core plate of the radiator for automobiles is generally about 1.4-1.6mm, so the clad ratio of the shell is requlated to about 10%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an Al alloy clad material for Nocolock brazing.

[Conventional technology]

The Nocolok brazing method requires flux brazing using a fluorine-based flux (Km AlF6-KAlF3) that is non-hygroscopic and non-corrosive. It has advantages.

On the other hand, the Afi alloy cladding material for this Nokolock brazing is a corrosion-resistant Alt alloy, such as Al-0°15
wt%Cu -1,1%Mn alloy (A3003) is used as the core material, and A I -0,1wt%Z is applied to both or one side of the core material.
A cladding made of an n-0.5wt% Mg alloy as a skin material is known. When this clasp material is exposed to a corrosive environment, the skin material, which has a potential closer to that of the core material, acts as a sacrificial anode and corrodes preferentially, and the core material has a so-called cathodic protection effect that protects the core material, which has become a cathode, from corroding. This prevents the occurrence of deep pitting corrosion (failure to penetrate).

[Problem that the invention seeks to solve]

However, when one side of the core material is clad with the skin material and Nocolock brazing is performed, the surface of the skin material where the flux has adhered is covered with flux that has minute irregularities, and the surface roughness remains. The maximum degree is about 20μ. Therefore, when using the above-mentioned cladding material in an aluminum radiator with a resin tank, if flux residue adheres to the surface of the cladding material where the tank and core plate are sealed via the O-ring, the initial sealing performance will be affected. This has the problem of not having sufficient durability.

In addition, if a skin material containing Zn is used in the seal part that contacts the O-ring, like the above-mentioned skin material, corrosion will be accelerated only at the part that contacts the O-ring, resulting in so-called crevice corrosion, which will cause damage to the radiator, etc. There have also been reports of problems with water leakage when used as a heat exchanger.

The present invention has been made in view of the above points, and the present invention has been made in view of the above-mentioned points. In Nocolok brazing, the surface roughness after brazing is small, that is, the initial sealing performance is good, and the Nocolok brazing has corrosion resistance and high strength. The purpose of the present invention is to provide an Al alloy cladding material for use in aluminum alloys.

[Means for solving the problem] In view of the above points, the present inventors have conducted various tests and studies, and have found that
It was discovered that the skin material containing a trace amount of Mg + Ca or Ca and Mg is superior in surface roughness of the skin material to which flux is attached after Nocolock brazing. .

Alternatively, various heat exchangers were fabricated by Nokolock brazing using brazing filler metal clad with a skin material made of Al-Mg-Ca alloy, and tests were conducted.
It has been found that a material containing g, Ca has a small surface roughness, that is, a highly practical product having good sealing properties and corrosion resistance can be produced.

In the present invention, Nocoroc brazing has a small surface roughness of the skin material in the part where flux is attached, and the pitting corrosion of the skin material does not become deep even in a severe corrosive environment, and it is almost the same as vacuum brazing. First, we have developed an Al alloy clad material for Nocolock brazing that can withstand long-term use. One side of the core material made of corrosion-resistant A2 alloy is clad with Al-5i alloy brazing material, and the other side of the core material is clad with Al-5i alloy brazing material. to Mg: 0.3~
l, Q wt%, Ca: 0.2-0.4wt%, M
g:0.3-1. Owt% and Ca: 0.2-0.4
It is characterized by being clad with a skin material containing any one of the following wt% and the remainder being Al and unavoidable impurities.

That is, the clad material of the present invention is obtained by cladding one side of a core material made of a corrosion-resistant Al alloy with an Al-Si alloy brazing material for sawlock brazing, and cladding the above-mentioned skin material on the other side of the core material. Brazing the skin with flux reduces the later surface roughness, and installing a radiator etc. improves the initial sealing performance. Brazing also maintains the skin at a low potential and improves the core material. It provides cathodic protection, suppresses elution of the skin material, and improves the pitting corrosion resistance of the skin material itself. The cladding ratio of the skin material varies depending on the total plate thickness, but it is best to set it so that the thickness of the skin material is 50 to 120μ.
For example, since the core plate thickness of an automobile radiator is generally about 1.4 to 1.6 m, the crund ratio of the skin material may be about 10%.

As the core material of the craft material of the present invention, A3003, A3
203, A3XXX series such as A3005, A6951, A6
5 from the liquidus temperature of An-Si alloys clad on one side, such as ASxxx series corrosion-resistant Al alloys such as 063.
A corrosion-resistant Al alloy having a solidus temperature higher than 0° C. is used. In addition, Al-5i alloy brazing filler metals include A4004 and A4004.
An AdXXX alloy brazing filler metal such as 4045 is used.

However, in the clad material of the present invention, the composition of the skin material is limited as described above for the following reasons.

The purpose of adding Mg is to improve the surface roughness of the skin material and lower the potential of the skin material to obtain a cathodic protection effect for the core material, and the content is set to 0.3 to 1. Q w t% is limited to Q
This is because if it is less than 3 wt%, the effect of lowering the electrical potential is small and the effect of cathodic protection of the core material cannot be obtained, and if it exceeds 1.0 wt%, the maximum surface roughness will be about 11μ or more and the initial sealing performance will be poor.

The purpose of adding Ca is to obtain the same effect as the addition of Mg, and the reason why the content is limited to 0.2 to Q, 4 wt% is Q, and if it is less than lwt%, the core material cathode No anticorrosive effect can be obtained, and if Q exceeds 4 wt %, the above-mentioned potential lowering effect will be large, and the amount of the skin material in contact with the O-ring etc. will increase, making so-called crevice corrosion more likely to occur.

Further, even when Mg and Ca are mixed, the same limited range as described above is preferable.

The reason why the thickness of this skin material is preferably in the range of 50 to 120μ is that if it is less than 50μ, the cathodic protection effect of the core material cannot be obtained, and if it exceeds 120μ, it cannot be used as a core plate for radiators etc. This is because the strength is insufficient.

〔Example〕

First, an aluminum radiator with a resin tank to which the cladding material of the present invention is applied will be explained below.

FIG. 1 shows a radiator for an automobile, and Sl is an aluminum alloy tube whose surface is clad with a brazing material. 2 is a fin molded into a corrugated shape. Reference numeral 5 denotes core plates disposed at both ends 1a of the tube 1, which are also made of aluminum alloy. These members (tube 1, fins 2, core plate 5) are integrally brazed together in a nitrogen atmosphere furnace using the Nocolock brazing method to form the radiator core portion A. Reference numeral 3 denotes an upper tank, which is made of a molded product of nylon resin containing glass fiber as a reinforcing agent, and is integrally molded with an artificial vibrator (not shown) for introducing cooling water from the engine.

6 is a lower tank also made of resin, and an outlet vibrator for sending the cooling water heat exchanged in the core part A to the engine and a drain pipe are integrally molded therein. And this upper part,
The lower tanks 3, 6 and the core part A are connected by tightening as shown in FIG. That is, between the end portion 5a of the core plate 5 and the shoulder portion 3a of the tank 3 (6), a sealing member 13 (for example, made of ethylene/propylene rubber) having a rectangular shape as a whole is installed along the bridge portion 5a of the core plate 5. ), and in this interposed state, the core plate end 5a is squeezed onto the shoulder 3a, thereby securing the core plate in a watertight manner.

Examples of the cladding material of the present invention will be described below.

A l -0,45 wt%Cu-0,80%Mn alloy is used as the core material, and A l -10,Ow t% is used on one side of the core material.
An Al alloy cladding material for Nocolock brazing was produced by cladding 100 μm of Si alloy brazing material and 100 μm thick skin material having the composition shown in Table 1 on the other side, and used it as the core plate 5 described above. The core plate 5, the tube 1, and the fin 2 are assembled, and the radiator core part At- is formed by performing the Nokolock brazing method. The conditions in the heating furnace for Nocolok brazing were a temperature of 600 to 620°C, a time of about 10 minutes, and a dew point of -40°C or less. Thereafter, as described above, the resin tanks 3 and 6 are integrally tightened at the end portion 5a of the core plate 5 via the seal member 13 to manufacture a radiator with a resin tank.

Here, Nokolock brazing is performed by adjusting the maximum surface roughness of the skin material 11 to which the flux of the subsequent core plate 5 is attached to JrSB0.
601-701 based on the specified Saletail surface roughness measurement method, and the potential (VSS
CE) was measured. Also, for assembly, the later radiator is JIS
Based on the circulation test method specified in 2234 (however, the corrosive liquid specified in Section 6.34 is used as the circulating fluid),
In addition to measuring the maximum pitting depth after 000 hours, the sealing performance of the intervening portion of the seal member 13 was determined to be 700% based on the CASS test method (specified in Appendix (2) of JIS DO201). After a period of time, the presence or absence of seal leakage was determined. These results are also listed in Table 1. In addition, cases with seal leakage were marked with an X, and cases with no seal leakage were marked with an ○ mark.

As is clear from the margin table 1 below, the crund materials of the present invention-1 to 8
The maximum surface roughness is small, that is, the initial sealing performance is good, and the potential of the skin material is more than 0.50 V lower than the potential of the core material (about 0.72 V), and the maximum pitting depth is 0. .0
It can be seen that the pitting corrosion resistance is excellent as it is stopped by the layer of skin material 7--. It is also seen that the sealing performance of the O-ring seal portion can be maintained in a good state, and that all of the cladding material magnets 1 to 8 of the present invention have a small amount of elution of the skin material and pose no practical problem.

On the other hand, in comparison kraft materials whose skin compositions are outside the range of the present invention, the maximum surface roughness of the skin material to which flux is attached is large. Or it can be seen that the pitting corrosion resistance is poor. That is, the comparative kraft material Na8,10.1 with a high Mg content
2, the maximum surface roughness is large and the initial sealing performance is poor, and the comparative clad material Magnetic 9゜11, which has a low Mg content, does not lower the potential of the skin material sufficiently and has poor pitting corrosion resistance. is inferior. Comparative cladding material with high Ca content
Nos. 10, 13, and 14 all had seal leakage at the O-ring seal part, which caused so-called crevice corrosion, and the comparative kraft material Nal 1°15, which has a low Ca content, did not have a sufficiently low potential of the skin material. Poor corrosion resistance.

In addition, the cladding materials 1 to 3 of the present invention containing only Mg are as follows:
After Nocolok brazing, powdered M g F t was produced which reacted with the flux. Therefore, before assembling the radiator, this product was blown away with compressed air, and the sealing member 13 was interposed between the core plate 5 and the tank 3.6. However, the clad material Na4-7 of the present invention containing Ca,
Brazing has a practical advantage since it does not later produce the products mentioned above (such as MgF).

In the above-mentioned embodiments, an application example was explained for an automobile radiator, but the cladding material of the present invention is not limited to the above-mentioned material, and is applicable to a material that combines liquid and air, such as a heater core used in an automobile heating system. Needless to say, it can be applied to devices that exchange heat between objects, and can also be applied to various general devices such as tanks.

〔Effect of the invention〕

In this way, the clad material of the present invention reduces the surface roughness of the skin material to which flux is applied after Nocolock brazing.

In other words, the initial sealing performance is improved, and brazing does not cause deep pitting corrosion even if it is exposed to a harsh corrosive environment afterward. It can be applied to various types of equipment made up of the above, especially the core plates of heat exchangers, etc., and has remarkable effects such as improving the service life of the devices.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of an aluminum radiator with a resin tank, Figure 2
The figure is a partial sectional view taken along line 1-1 in FIG. 1.

Claims (1)

[Claims] One side of a core material made of a corrosion-resistant Al alloy is clad with an Al-Si alloy brazing material, and the other side of the core material is [1] Mg0.3 to 1.0 wt% [2] Ca0.2 ~0.4wt% [3] Mg0.3~1.0wt% and Ca0.2~0.4
An Al alloy cladding material for Nokolock brazing, characterized in that it is clad with a skin material containing any one of [1] to [3] in wt%, and the remainder being Al and unavoidable impurities.