Pretreatment method for hard solder on partial surface of magnesite product

A local, brazing technology, applied in the direction of welding medium, welding equipment, metal material coating process, etc., can solve the problems of segregation, deformation of magnesium alloy, and corrosion of magnesium alloy by flux without consideration

Inactive Publication Date: 2009-05-13

何靖

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AI-Extracted Technical Summary

Problems solved by technology

[0002] The properties of magnesium alloy workpieces are extremely sensitive to heat treatment. The reason is that the thermal expansion coefficient of magnesium alloys is 2 to 3 times higher than that of ordinary metals. If the heating is uneven, problems of deformation and internal stress will be left inside the magnesium alloy; It will also leave the problem of segregation and denaturation

Therefore, the traditional heat welding (welding temperature exceeds the melting point of the material) method is not suitable for magnesium alloy workpieces, and it is particularly difficult to weld thin plates.

In terms of thin plates, the best way is to consider cold welding (welding temperature is lower than the melting point of the material) to avoid the aforementioned shortcomin...

Abstract

The invention relates to a preprocessing method for brazing on the partial surface of magnesium material, wherein, the preprocessing method includes two novel technologies including the magnesium alloy surface upgrading and processing technology without electronickelling and the technology for manufacturing special soldering flux to coordinate with a plurality of leadless tin alloy solders; the welding method adopts the process flow that the medium phosphorus (the content of phosphorus is 3-7 percent ) without electronickelling process is performed on the surface of the magnesium-alloy work piece at first, then the high phosphorus (the content of phosphorus is 7-12 percent) without electronickelling process is performed, and the tin welding process is performed finally.

Application Domain

Liquid/solution decomposition chemical coatingWelding/cutting media/materials +2

Technology Topic

Nickel electroplatingL&D process +6

Image

Examples

Experimental program(1)

Example Embodiment

[0011] Magnesium alloy AZ31 plate test piece, thickness 0.4mm, after hot rolling forming, try to weld 3mm outer diameter copper nut on it. For example, the process shown in Example 1 of Patent Application No. 095117849, proceed to the first electroless nickel plating process (the plate test piece at this stage is referred to as test piece A), directly put into operation conditions as shown in Table 1 without washing The process of chemically immersing nickel is carried out in the high-phosphorus electroless nickel plating bath shown (the plate test piece at this stage is referred to as test piece B).

[0012] Table 1: Operating conditions of high-phosphorus electroless nickel plating

[0013]

[0014] Prepare the commercial flux (Alfa 100T2) as shown in Table 2 and mix it with the corresponding tin alloy particles to form a tin paste of different composition. After reflowing as shown in Table 2, the nut is welded on the magnesium alloy test piece. The tensile test was performed thereafter, and the results shown in Table 2 were obtained.

[0015] Table 2: Test conditions and results of magnesium alloy cold welding

[0016] Solder A Solder B Solder C Solder D Test piece A Test piece B Test piece A Test piece B Test piece A Test piece B Test piece A Test piece B FLUX0 ● ● ● ● ● ● ● ● Tensile strength - -- - -- - -- - --

[0017] degree - - - - FLUX1 ● ○

[0018] Note:

[0019] 1. Solder A: Sn95.5/Ag3.9/Cu0.6 alloy combination.

[0020] 2. Solder B: Sn96.5/Ag3.0/Cu0.5 alloy combination.

[0021] 3. Solder C: Sn96.5/Ag3.8/Cu0.7 alloy combination.

[0022] 4. Solder D: Sn42/Bi58 alloy combination.

[0023] 5. FLUX0: Alfa 100T2, provided by Alfa Metal Co., Ltd.

[0024] 6. FLUX1: Alfa 100T2 as the base, mixed with 5% succinic acid chelating agent.

[0025] 7. FLUX2: Alfa 100T2 as the matrix, mixed with 1% passivating agent ammonium fluoride.

[0026] 8. FLUX3: Alfa 100T2 as the matrix, mixed with 2% volatile agent melamine phosphate.

[0027] 9. FLUX12: Alfa 100T2 as the matrix, mixed with 5% succinic acid chelating agent and 1% passivating agent ammonium fluoride.

[0028] 10. FLUX13: Alfa 100T2 as the base, mixed with 5% succinic acid chelating agent and 2% volatile agent melamine phosphate.

[0029] 11. FLUX23: Alfa 100T2 as the matrix, mixed with 1% passivating agent ammonium fluoride and 2% volatile agent melamine phosphate.

[0030] 12. FLUX123: Alfa 100T2 as the matrix, mixed with 5% of succinic acid chelating agent mixed with 5%, 1% passivating agent ammonium fluoride and 2% volatile agent melamine phosphate.

[0031] 13. Tensile strength unit kg f /cm 2.

[0032] ○: There is wettability and welding is completed.

[0033] ●: No wettability, welding failure.

[0034] △: No corrosion state.

[0035] ▲: Corroded state.

[0036] ◇: No skip welding and empty welding phenomenon.

[0037] ◆: There are skip welding and empty welding.

[0038] □: No gradual corrosion occurred in 60 days.

[0039] ■: Gradual corrosion occurred on the 60th.

PUM

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