JPH01253435A - Gold/silver composite material - Google Patents

Abstract

PURPOSE:To improve the value of a decoration by sufficiently utilizing the contrast of gold and silver colors without diffusing a gold layer and a silver layer between layers by interposing a palladium or palladium alloy layer between a gold or gold alloy layer and a silver or silver alloy layer. CONSTITUTION:A palladium tube 2 having high purity is, for example, superposed on the outer periphery of a silver columnar rod 1, a 18K gold alloy tube 3 is superposed on its outer periphery to form a multilayer columnar post. In order to assemble it, the multilayer post is associated in copper dummy blocks 4, 5 having an inner hole to be engaged with the post, a gap 6 between the blocks 4 and 5 is evacuated, and they are circumferentially welded in the gap 6 to manufacture a columnar billet 7. Further, the billet is hot hydrostatically extruded with grease as pressure medium to form a composite rod. This rod is wire drawn, copper of its surface layer is removed, it is further wire drawn to form a 18K alloy clad gold/silver composite wire. Moreover, after a groove 10 is formed along the outer periphery of the composite wire in this manner, it is bent in a ring state, and coupled at its both ends by gold brazing 9, thereby providing a ring 10.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a layer of gold and a gold alloy (hereinafter referred to as gold, meaning gold and/or gold alloy) and a layer of silver and a silver alloy (hereinafter referred to as silver, meaning gold and/or gold alloy). and/or silver alloy) layer, which does not cause diffusion between the layers and maintains a clear contrast between the gold layer and the silver layer even if the composite material is heated and processed. It is something.

[Prior Art] Gold and silver are used in various forms as decorative materials.
Various composite materials made of these precious metals and other metals are also in practical use. For example, composite materials of the above-mentioned precious metals and titanium, or materials in which inexpensive metals such as aluminum and copper are clad with gold, are cheaper than materials made entirely of precious metal materials, and can have the characteristics of precious metal materials. Therefore, it is heavily used as a decorative material.

In addition, gold/silver composite materials, which are silver clad with gold, have a good contrast between gold and silver tones when used as decorative items, and are prized as materials that suit people's tastes.

[Problems to be Solved by the Invention] However, when producing the above-mentioned gold/silver composite material, since gold and silver are elements that are completely dissolved in solid solution, when heated to high temperatures during processing, the gold melts due to the Kirkendall effect. When the metal is diffused into the silver layer or the metal into the gold layer, for example, when high temperatures are applied during brazing or cladding, alloying is promoted between the gold/silver layers, destroying the color contrast. Therefore, its value as a decorative item decreases.

As a method of preventing alloying at the interface between gold and silver, a technique was proposed in Japanese Patent Publication No. 62-51497 in which a copper layer was interposed between the gold layer and the silver layer to prevent silver from diffusing into the gold layer. It is disclosed in the publication No. This relates to electronic parts, but if a decorative item were to be formed from a composite material with this structure, rust would occur in an atmosphere containing salt such as sweat, since copper has poor corrosion resistance. Therefore, such ornaments are not only fragile, but also detract from their aesthetic appeal, making them of low value as ornaments.

In view of the above circumstances, in the present invention, we have investigated a gold/silver composite material that can fully utilize the contrast between gold and silver without causing the gold layer and silver layer to diffuse between the eyebrows, and which is highly valuable as an ornament. .

[Means for Solving the Problems] The present invention that has solved the above problems comprises interposing a palladium or palladium alloy layer between a gold or gold alloy layer and a silver or silver alloy layer. This is a summary.

[Function] As a basic structure for preventing interdiffusion between the gold layer and the silver layer, a layer of another metal is interposed between the two layers, but in this case, the characteristics of the metal forming the metal layer are ■It is a vine metal that maintains a state in which gold and silver do not interdiffuse even if heated to a temperature at which the gold and silver layers interdiffuse and melt, ■Gold or silver The color tone should be similar to that of silver and there should be no discomfort, ■ Good corrosion resistance (being a precious metal), ■ Good bonding with gold and silver, ■ Between the gold layer and the silver layer. It is desired that even if the material is interposed, it can be easily processed into various sizes and shapes such as wires, plates, and rods. As a result of studies conducted by the present inventors, it was found that palladium and palladium alloys can satisfy all of the conditions (1) to (4) above.

Therefore, a thin layer of palladium or palladium alloy was placed between the gold layer and the silver layer, and a gold/silver composite material was prototyped and used for experiments.

The melting point of the opposite is 1063°C, the melting point of silver is 960°C,
The melting point of palladium is 1554°C.

Furthermore, since palladium is a noble metal, it has excellent corrosion resistance and is rich in ductility and malleability, so it has good workability.

Therefore, when palladium or a palladium alloy is interposed between the gold layer and the silver layer, a composite material can be obtained that prevents diffusion between the gold layer and the silver layer and has good workability.

Next, examples of a gold/silver composite wire and a gold/silver composite plate will be described as examples, but these examples are not intended to limit the present invention.

[Example] Example 1 As shown in the cross-sectional view of FIG.
．． 25ml 1nt, inner diameter 72.5mm, purity 99.98%
palladium tubes 2 are stacked on top of each other, and 0.
The gold alloy tube 3 was superimposed on the tube 18 having a diameter of 4 mm and an inner diameter of 73.5 mm to form a multilayer cylinder. In assembling, the multilayer cylinder is assembled into copper dummy blocks 4 and 5 that have inner holes that fit into the multilayer cylinder, and the gap 6 of the dummy blocks 4 and 5 is evacuated and the gap 6 is circumferentially welded. A cylindrical billet 7 having an outer diameter of 79.5 mm and a length of 180+ nm was prepared. Further, the billet was subjected to hot isostatic extrusion using grease as a pressure medium (600°C, 6300 Kg/cm'') to obtain a composite rod with a diameter of 20 mm as shown in the cross-sectional view of Fig. 2(a). This composite rod was passed through a die and wire-drawn to a diameter of 3.4 mm, and after removing the copper on the surface layer, wire-drawing was further performed to obtain the shape shown in Figure 2 (1).
)) An alloy clad gold/silver composite wire with a diameter of 2.3 mm was obtained as shown in the cross-sectional view. In addition, - for boat fishing, a cylindrical billet is prepared as described above, and the billet is
When subjected to hot isostatic extrusion at a temperature of .degree. C., bondability between the various metals becomes good and surface oxidation of the metals can be prevented. Further, since no diffusion occurs between metals, the composite ratio of metals can be made uniform.

Furthermore, as shown in FIG. 3(a), the composite wire obtained as described above is provided with a grooved portion 8 along its outer periphery, and then bent into a ring shape and both ends are joined by residual brazing 9. did. The resulting ring 10 retains gold/
No interdiffusion was observed between the silvers, and the color tone was beautiful with a clear contrast between the silvery white of the grooved portion 8 and the golden color of the surface. That is, although the palladium layer was present between the gold layer and the silver layer, since the palladium layer was silvery white, it appeared to have a two-layer structure of gold/silver.

Example 2 Next, an example of a composite board will be described.

10mmtX100mm' as shown in the cross-sectional view of Figure 4
90 P d − of 0.5 +++ mt between the gold alloy plate 11 and the pure silver plate 12 of the same shape at 18 of X 50 mmW.
A laminate was made by sandwiching 10.4 g of palladium alloy thin plates 13.

For assembly, a jacket block 1 made of a 10% Ni-Cu alloy is used, which has an inner hole into which the laminate can be fitted.
A billet 15 is prepared by incorporating the laminate into Step 4, and the billet is hot-rolled to 5 ml 1 lt using a rolling mill with a roll diameter of 300 mm at a billet heating temperature of 700° C., and then the copper alloy forming the outer jacket is rolled. 2.5 mmt after pickling removal
18, a three-layer plate consisting of gold alloy/palladium alloy/pure silver was obtained. Further, this plate was cold rolled using a rolling mill with a roll diameter of 150 mm to obtain a composite plate of 0.5 mmt. Although a palladium alloy layer was clearly present between the gold alloy layer and the pure silver layer in this composite plate 18, the appearance was the same as in Example 1, showing a two-layer gold/silver layer.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to produce a gold/silver composite material with a clear contrast between the gold layer and the silver layer without causing diffusion between the gold layer and the silver layer even when heat processing is applied. This gold/silver composite material is also useful as a decorative item.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a billet for manufacturing gold/silver composite wire, Figure 2 (a) is a cross-sectional view of the central part of the billet in Figure 1 after hot isostatic processing, and Figure 2 (b) 18 is a cross-sectional view of the gold alloy clad silver composite wire, and FIGS. 3(a) and 3(b) are 1
8 is a diagram showing an example of processing a gold alloy clad silver composite wire, and FIG. 4 is a cross-sectional view of a billet for obtaining a composite plate. 1... Silver cylindrical rod 2... Palladium tube 3...
・Gold alloy tube for 18 4, 5...Dummy block 6...
・Between 31 7, 15... Billet 8...
Groove processing part 9... Gold brazing 10... Ring 11... 18 Gold alloy plate 12... Pure silver plate] 3... Palladium alloy thin plate 14... Outer cover block Fig. 1\ ( a), b7.・

Claims (1)

[Claims] A gold/silver composite material characterized by having a palladium or palladium alloy layer interposed between a gold or gold alloy layer and a silver or silver alloy layer.