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Method for improving electrochemical corrosion resistance of Al and Al alloy connector formed through ultrasound-combined brazing adopting Sn-based lead-free brazing filler metal

A lead-free solder, corrosion-resistant technology, used in welding equipment, metal processing equipment, manufacturing tools, etc., can solve the problems of limited improvement in joint corrosion resistance, broken oxide film, and thin anodic oxide film thickness. The effect of improving electrochemical corrosion resistance, improving corrosion resistance and reducing potential difference

Active Publication Date: 2017-01-04
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It was found that the Al / Sn / Al joint with a thickness of 2 mm was completely cracked after soaking in 3.5% (wt.%) NaCl aqueous solution for only 1 day, and the corrosion resistance was very poor
The standard electrode potential of Zn is -0.763V, which is between Sn and Al. Therefore, the addition of Zn in the solder can reduce the electrode potential difference between the base metal and the solder and improve the corrosion resistance of the joint. This method cannot fundamentally solve the electrochemical corrosion of the interface, and the Al / Sn-9Zn / Al joint with a thickness of 2mm is completely cracked after soaking in 3.5% NaCl aqueous solution for 5 days
The electrochemical reaction is hindered by making an anodic oxide film on the interface, but the thickness of the anodic oxide film is relatively thin, and the corrosion resistance of the SnZn solder used at the same time is very poor, and the ultrasonic application on the base material is easy to cause the oxide film to break
Therefore, the effect of improving the corrosion resistance of the joint is very limited

Method used

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  • Method for improving electrochemical corrosion resistance of Al and Al alloy connector formed through ultrasound-combined brazing adopting Sn-based lead-free brazing filler metal
  • Method for improving electrochemical corrosion resistance of Al and Al alloy connector formed through ultrasound-combined brazing adopting Sn-based lead-free brazing filler metal
  • Method for improving electrochemical corrosion resistance of Al and Al alloy connector formed through ultrasound-combined brazing adopting Sn-based lead-free brazing filler metal

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Experimental program
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Effect test

specific Embodiment approach 1

[0053] Embodiment 1: after the Al alloy is anodized, ultrasonic brazing is performed by using SnZnAgAl solder.

[0054] When performing anodic oxidation, use 15g / L oxalic acid aqueous solution as the electrolyte, and the current is 0.25A / dm 2 , the constant current mode is used for oxidation, the oxidation time is about 10 minutes, and the thickness of the thickened oxide film obtained is about 5 μm.

[0055] Table 1 is the chemical composition (weight percent) of low-temperature Sn-based active solder

[0056]

[0057] The welding method in the present embodiment is as follows:

[0058] Step 1, ultrasonically cleaning the oxidized Al alloy and solder in acetone for 10 minutes to remove surface oil stains;

[0059] Step 2, the welding process is carried out in the atmosphere, the solder is placed on the base metal, and the whole is heated to 240°C;

[0060] Step 3. After the solder is melted, use an ultrasonic soldering iron to apply ultrasound in the liquid solder, and ...

specific Embodiment approach 2

[0064] Embodiment 2: after micro-arc oxidation of Al alloy, ultrasonic brazing is performed by using SnBiZnAlTi solder.

[0065] During micro-arc oxidation, the solution is 15g / L sodium silicate aqueous solution, 2g / L potassium hydroxide aqueous solution, the frequency is 500Hz, and the current is 2A / dm 2 , the constant current mode is adopted, the oxidation time is 15min, and the thickness of the oxide film on the Al surface is increased to 40μm.

[0066] Table 2 is the chemical composition (weight percent) of low-temperature Sn-based active solder

[0067]

[0068] The welding method in the present embodiment is as follows:

[0069] Step 1, ultrasonically cleaning the oxidized Al alloy and solder in acetone for 10 minutes to remove surface oil stains;

[0070] Step 2. Assemble the aluminum alloy on the self-made jig in the form of a lap joint, place the brazing material on one side of the brazing seam gap, and the size of the brazing seam is 400 μm;

[0071] Step 3. Th...

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Abstract

The invention discloses a method for improving the electrochemical corrosion resistance of Al and Al alloy connector formed through ultrasound-combined brazing adopting Sn-based lead-free brazing filler metal, and belongs to the technical field of brazing. According to the method, oxidation films are prepared on the surface of the Al and the surface of the Al alloy correspondingly, an electrochemical reaction between the element Sn in brazing filler metal alloy and the element Al in a base material is blocked, and the problem that the electrochemical corrosion resistance of the Al and the Al alloy connector formed through ultrasound-combined brazing adopting the Sn-based lead-free brazing filler metal is poor is solved. An anodic oxidation mode or a micro-arc oxidation mode is firstly utilized, and the oxidation films are prepared on the surface of the Al and the surface of the Al alloy correspondingly; and then the Sn-based lead-free active brazing filler metal is adopted for conducting ultrasound-combined brazing on the Al and the Al alloy. By adoption of the method, the electrochemical corrosion resistance of the Al and the Al alloy connector is remarkably improved.

Description

technical field [0001] The invention relates to a method for improving the corrosion resistance of aluminum alloy joints, in particular to a method for improving the electrochemical corrosion resistance of Sn-based lead-free solder ultrasonic composite brazing aluminum and its alloy joints, and belongs to the field of brazing technology. Background technique [0002] Aluminum alloys have good specific strength, electrical and thermal conductivity, and are widely used in the fields of aerospace, automobiles, and precision instruments. However, most high-strength aluminum alloys are very sensitive to heat, and the welding heat process will cause the decline in the mechanical properties of the base metal. Therefore, it is necessary to Aluminum alloy connections are achieved at lower temperatures. At the same time, aluminum alloys are increasingly used in electrodes of functional devices, radio frequency antennas, electronic packaging and other fields. Therefore, realizing the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K1/06B23K1/19B23K1/20
CPCB23K1/06B23K1/19B23K1/20B23K1/206
Inventor 郭卫兵闫久春
Owner HARBIN INST OF TECH
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