CZ9902562A3 - Soldering rings and process for producing thereof - Google Patents

Abstract

Soldering rings, preferably for soldering of aluminium and aluminium alloy parts, are based on an aluminium alloy with a flux content. The soldering rings are compact homogenous rings comprised of aluminium AlSi alloy particles (2) surrounded by flux particles (1). They are prepared by powder metallurgy methods, i.e. by moulding a homogenised compostion of said alloy and flux particles in the air and at the room temperature into the desired shapes of a circular ring and then by heating up the rings loosely deposited in an oven under a protective atmosphere to a temperature within the range from 350 to 600 DEG C.

Description

Technical field

The present invention relates to flux-type compact composite solder rings for brazing aluminum or aluminum alloy parts.

BACKGROUND OF THE INVENTION

In the prior art methods for soldering aluminum and aluminum alloy parts, it is common practice to first apply a flux in the form of a paste or a suspension or powders, and then to add a brazing agent generally in the form of aluminum or aluminum silicon wire. The soldering node thus prepared is heated by flame or in an oven where the parts to be soldered are heated.

In these flux and solder soldering methods, the solder and the flux must be applied to the soldered surfaces separately one after the other. This process is relatively complex, especially with respect to the use of automation of the brazing process. A further disadvantage is that for individual soldering node applications it is necessary to vary the ratio of flux to solder as the lack of flux causes imperfect soldering and the excess will disrupt the appearance, workability of the surface and other problems, e.g. In many cases, flux residues need to be difficult to remove.

Another method is to use a flux-filled Al or Al-Si wire or a wire formed from a mixture of Al and Si or an Al-Si alloy with a flux. In all these cases, it is necessary to create rings - eg by cutting and shaping the wire. Another disadvantage is that accurate geometry is not achieved, which is a defect in the automation of brazing processes.

SUMMARY OF THE INVENTION

These drawbacks are overcome by the use of the compact composite solder rings of the present invention, which are a homogeneous composite system consisting of a base matrix in the form of Al-Si-alloy particles surrounded by selected flux particles and powder metallurgy processes made in compact rings of arbitrarily selectable shapes. Adjustable combination of the amount of flux and Al-Si - alloy as required by the brazed parts.

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-2Each Al-Si alloy powder particle is surrounded by flux particles and is thus protected from oxidation when heated.

In addition, Si-containing AISi alloy powders in the 5-14 wt. %, or more preferably 10-13 wt. % may preferably be alloyed with one or more optional additives such as Fe (iron), Cu (copper), Mn (manganese), Zn (zinc) or Ti (titanium) with a Fe content of up to 0.6 wt. %, Cu up to 0.1 wt. %, Mn to 0.5 wt. %, Zn up to 0.8 wt. % and Ti up to 0.5 wt. %.

Other additives of one or more of Mg (magnesium), In (indium), Bi (bismuth) and Be (beryllium) elements up to 0.5 wt. % are not defective.

Any suitable flux may be used, but preferably a Ki ₃ AlF ₄ fluoride. ₆ (potassium aluminosilicates) or chloride based on ZnCl 2 (zinc chloride). The best is the eutectic mixture of KF-AIF3.

The compact composite solder ring of the present invention can be made by conventional powder metallurgy processes, i.e. the starting powder components of defined grain size are mixed in the desired ratio in a mixer, compressed at 100-600 MPa in air at room temperature to the desired shape. The compact rings shaped in this way are freely stored and heated in a protective atmosphere to a temperature of 350-600 ° C. The rings prepared in this way can be cold pressed, calibrated or machined if necessary.

Overview of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a compact composite solder ring and FIG. 2 shows the internal structure of a solder ring formed by Al-Si alloy particles surrounded by flux particles. / 1 /.

DETAILED DESCRIPTION OF THE INVENTION

A compact composite solder ring in accordance with the present invention comprising:

hm. % AISi 12 powder alloy with additives Fe 0.5 wt. %, Cu 0.05 wt. %, Mn 0.3 wt. %, Ti 0.2 wt. % wt. flux eutectic mixture KF-AIF3 and dimensions D = 16,5 mm d = 11,95 mm h = 2 mm

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The soldering ring is made by powder metallurgy processes, namely:

a) by pressing from homogenized mixture of AISi alloy powders and flux at room temperature by pressure of 500 MPa in air

b) heating the pressed compact rings loose in the furnace in a protective atmosphere of H2 at 450 ° C

c) calibrating the heat treated rings at room temperature to the desired dimension by pressure of 200 MPa in air

By using such prepared rings, excellent solderability of aluminum parts or aluminum alloy parts was achieved. No joint structure defects and undesirable flux residues on the surface were noted. The use of a compact composite ring does not require rinsing of the brazed parts.

The solder ring showed excellent solderability and satisfactory results in terms of appearance and surface quality.

Industrial applicability

The brazing of aluminum and aluminum alloy parts is considerably easier when using compact composite solder rings. From the ecological point of view, it is not necessary to rinse the soldered joints, resp. disposal of rinse water. It enables the use of automation elements for the brazing process, eg in the automotive industry, in the manufacture of refrigeration and air-conditioning equipment, resulting in increased production productivity and reduced costs.

Claims (4)

PATENT CLAIMS 1. Solder rings for soldering aluminum or aluminum alloy parts, characterized in that they are compact, homogeneous rings composed of aluminum alloy AISi particles surrounded by flux particles. Solder rings according to claim 1, characterized in that they are prepared by compressing the homogenized powder mixture in air at room temperature into the necessary annulus shapes and heated in a free-standing furnace to a temperature of 350 - 600 ° C. Solder rings according to claim 1, characterized in that the AISi alloy powder comprises one or more of Mn (manganese), Fe (iron), Zn (zinc), Cu (copper), Ti (titanium). Solder rings according to claim 3, characterized in that the Fe (iron) content is up to 0.6 wt. %, Cu (copper) to 0.1 wt. %, Mn (manganese) to 0.5 wt. %, Zn (zinc) to 0.8 wt. % and Ti (titanium) to 0.5 wt. %.