JPH11217638A - Silver alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver alloy excellent in sulfidation resistance and having a pinkish color. SOLUTION: This alloy is a silver alloy composed essentially of silver and containing copper and palladium. This silver alloy has a composition satisfying X+Y+Z=100 when X, Y, and Z represent silver, copper, and palladium, respectively, and this composition is within the composition range enclosed with lines connecting respective points of (X=85, Y=12, Z=3), (X=39.5, Y=38.5, Z=22), and (X=48.5, Y=48.5, Z=3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver alloy, and more particularly to a silver alloy that can be suitably used for decorative members and the like.

[0002]

2. Description of the Related Art Silver and silver alloys have been widely used as decorative members since ancient times. A typical copper alloy is silver 92.
5% by weight-copper alloy (sterling silver), and as a decorative material, an alloy of 80% by weight or more of silver is used, and 90% by weight of silver-copper alloy (coin silver) or silver 9
There is also a 5.8% by weight copper alloy (Britania Silver).

[0003] In a normal state, silver does not react with oxygen, but easily reacts with hydrogen sulfide or sulfur dioxide, forming a black film of silver sulfide on the surface thereof, thereby reducing the decorative effect.

[0004] In order to prevent such sulfidation, an organic compound that strongly binds to the surface thereof is applied, gold or rhodium plating is applied, or alloying is performed.

When copper is alloyed with silver, up to about 14% by weight of copper, the mechanical properties can be improved in white and the melting point is lowered, so that the castability is also improved. No, corrosion resistance deteriorates. This is because two phases coexist when the solid solubility limit of copper in silver is exceeded.

[0006] Silver alloys for improving the sulfuration resistance include silver-
Palladium alloys and silver-platinum alloys are known. In this silver-palladium alloy, in order to completely prevent sulfuration of silver, it is necessary to add 40% by weight or more of palladium and 60% by weight or more of platinum. The color is also limited to those of white type.

On the other hand, recently, there are demands for various noble metal materials for decoration in various colors. Gold-based yellow and pink-based ones are accepted in the market, but silver alloys for decoration are also required in various colors.

The present inventor has conducted intensive studies in view of such a situation. As a result, if copper is added to silver, a silver alloy exhibiting a pink color while having a two-phase coexisting composition can be obtained. It has been found that silver alloys with improved sulfuration resistance can be obtained by adding platinum or platinum.

Accordingly, the present invention has been made based on such findings, and an object of the present invention is to provide a silver alloy exhibiting a pink color and having excellent sulfuration resistance.

[0010]

In order to achieve the above object, a silver alloy according to claim 1 is a silver alloy containing silver and copper and palladium, wherein silver is X, copper is Y, and palladium is silver. Is Z (X + Y + Z = 100), the following composition (X = 85, Y = 12, Z = 3), (X = 3
9.5, Y = 38.5, Z = 22), (X = 48.5,
(Y = 48.5, Z = 3) in a composition range surrounded by a line connecting the respective points.

According to a silver alloy according to a second aspect of the present invention, in a silver alloy containing silver as a main component and copper and platinum,
When the silver is X, the copper is Y, and the platinum is Z (X + Y
+ Z = 100), the following composition, (X = 75, Y = 15,
(Z = 10), (X = 45, Y = 35, Z = 20), (X
= 40, Y = 40, Z = 20), (X = 45.5, Y =
45.5, Z = 10) in a composition range surrounded by a line connecting the respective points.

Among the above components, silver is a main component, copper is a component for imparting a pink color, and palladium and platinum are components for improving sulfuration resistance.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention; FIG. 1 is a view showing a range of appropriate addition amounts of silver, copper and palladium in the silver alloy according to the first aspect of the present invention. In the present invention, silver (A
g) -copper (Cu) -palladium (Pd) ternary alloy. When silver is X, copper is Y, and palladium is Z (X + Y + Z = 100), (X = 85, Y = 12, Z
= 3): a, (X = 39.5, Y = 38.5, Z = 2)
2): b, (X = 48.5, Y = 48.5, Z = 3):
The composition range is set so as to be a composition range surrounded by a line connecting the points c. The region below the line a-c in FIG. 1 is a region where the weight of palladium in the alloy is less than 3% by weight,
Poor sulfide resistance. Therefore, in order to improve the sulfuration resistance, the composition is set to be above the bc line. The bc line in FIG. 1 is a line in which the weight ratio of silver: copper in the alloy is 1: 1. The left side of the bc line is a region where copper is the main component. Therefore, since silver is the main component, the composition is set on the right side of the bc line. Further, the color of the alloy is white based on the line ab in FIG. Therefore, in order to make the color of the alloy pink, a
The composition is on the lower right side of the -b line.

In order to maintain the above composition range, copper is 12 to
It is added in the range of 48.5% by weight. When the content of copper is 12% by weight or less, the white color of silver and the white color of palladium become strong, and the pink color is not obtained. On the other hand, if the content is 48.5% by weight or more, the amount of palladium becomes relatively small, and sulfuration resistance cannot be obtained.

Further, palladium is added in a range of 3% by weight to 22% by weight. If the palladium content is less than 3% by weight, the sulfuration resistance cannot be obtained. If the palladium content is more than 22% by weight, the addition amount of copper is relatively reduced to give a pink color. Is not.

The silver alloy according to the present invention is processed into a decorative member such as a ring, a pendant, a necklace, and a pierce through a casting process such as a conventionally known lost wax method.

The color and the corrosion resistance (sulfuration resistance) were examined with various additions of silver, copper and palladium. Table 1 shows the results.
Shown in The color is prepared by mixing the raw materials, melting at a temperature of 1000 ° C., casting to make a metal, buffing the metal, and comparing it with sterling silver to see if there is pink coloration. The O mark was given to those having pink color development compared to sterling silver, and the X mark was given to those having no pink color development. The corrosion resistance (sulfuration resistance) was evaluated by blending the raw materials, melting them at a temperature of 1000 ° C., casting them into a round-shaped ring, buffing the ring, and then putting it on a finger for one month. Those who performed daily life for a period of time and visually evaluated the presence or absence of discoloration.Evaluated with a circle when there was no discoloration or blackening during one month of daily life, and those who had discoloration or blackening Is marked with a cross.

[0018]

[Table 1]

As is apparent from Table 1, palladium is 3
% By weight (Sample Nos. 1, 2, 3, 4,
6, 7, 13) have poor corrosion resistance (sulfuration resistance). Further, in the case of the composition above the line ab in FIG.
7, 8, 16, 20, 21, and 23) do not exhibit a pink color. Further, in the case of the composition range surrounded by the line connecting the points a, b, and c in FIG. 1, the composition exhibits pink color and has good corrosion resistance.

FIG. 2 is a view showing the range of the appropriate addition amounts of silver, copper and platinum in the silver alloy according to the second aspect of the present invention. In the present invention, it is composed of a ternary alloy of silver (Ag) -copper (Cu) -platinum (Pt). X for silver, Y for copper,
When platinum is Z (X + Y + Z = 100), (X
= 75, Y = 15, Z = 10): a, (X = 45, Y =
35, Z = 20): b, (X = 40, Y = 40, Z = 2)
0): c, (X = 45.5, Y = 45.5, Z = 1)
0): Set so as to be a composition range surrounded by a line connecting each point of d. The region below the ad line in FIG. 1 is a region where the weight of platinum added to the alloy is less than 10% by weight, and the sulfuration resistance is poor. Therefore, in order to improve the sulfuration resistance, the composition is set above the ad line. The cd line in FIG. 2 is a line in which the weight ratio of silver: copper in the alloy is 1: 1. The left side of the cd line is a region where copper is the main component. Therefore, since silver is the main component, the composition is on the right side of the cd line. Further, the color of the alloy is white based on the line abc in FIG. Therefore, in order to make the color of the alloy pink, the composition is set lower than the abc line.

In order to make the above composition range, copper is 15 to
It is added in the range of 45% by weight. When this copper is 15% by weight or less, the white color of silver and the white color of platinum become strong, and the pink color is not obtained. On the other hand, when the content is 45% by weight or more, the amount of platinum becomes relatively small, and sulfuration resistance cannot be obtained.

Platinum is added in a range of 10% by weight or more and 20% by weight or less. If the platinum content is less than 10% by weight, sulfur resistance is not obtained. If the content is more than 20% by weight, the amount of copper added is relatively reduced, resulting in a pinkish color. Is not.

This silver alloy is also processed into decorative members such as rings, pendants, necklaces, and earrings through a casting process such as the conventionally known lost wax method.

The color and the corrosion resistance (sulfuration resistance) were examined with various amounts of silver, copper and platinum added. Table 2 shows the results.
Shown in The color is prepared by mixing the raw materials, melting at a temperature of 1000 ° C., then casting to make a metal, buffing the metal, and comparing with sterling silver to see if there is pink coloration. The O mark was given to those having pink color development compared to sterling silver, and the X mark was given to those having no pink color development. The corrosion resistance (sulfuration resistance) was evaluated by blending the raw materials, melting them at a temperature of 1000 ° C., casting them into a round-shaped ring, buffing the ring, and then putting it on a finger for one month. Those who performed daily life for a period of time and visually evaluated the presence or absence of discoloration.Evaluated with a circle when there was no discoloration or blackening during one month of daily life, and those who had discoloration or blackening Is marked with a cross.

[0025]

[Table 2]

As is clear from Table 2, the amount of platinum was 10
When the amount is less than the weight% (sample Nos. 6, 7, 21), the corrosion resistance (sulfuration resistance) is poor. Further, abc in FIG.
In the case of the composition above the line (sample Nos. 2, 12, 1
3, 17, 18, and 20) do not exhibit a pink color.
Further, in the case of the composition range surrounded by the line connecting the points a, b, and c in FIG. 1, the composition exhibits pink color and has good corrosion resistance.

[0027]

As described above, according to the silver alloy according to the first aspect of the present invention, when silver is X, copper is Y, and palladium is Z (X + Y + Z = 100), (X = 85, Y = 12,
Z = 3), (X = 39.5, Y = 38.5, Z = 2
2) Since (X = 48.5, Y = 48.5, Z = 3) were set in the composition range surrounded by the line connecting the points, excellent sulfuration resistance having a pink color was obtained. Silver alloys can be provided.

According to the silver alloy according to the second aspect of the present invention, in a silver alloy containing silver as a main component and copper and platinum, when silver is X, copper is Y, and platinum is Z, (X + Y + Z = 100), the following composition, (X = 75, Y
= 15, Z = 10), (X = 45, Y = 35, Z = 2
0), (X = 40, Y = 40, Z = 20), (X = 4
5.5, Y = 45.5, Z = 10), the composition range surrounded by the line connecting the points provides a silver alloy having a pink color and excellent sulfuration resistance. be able to.

[Brief description of the drawings]

FIG. 1 is a view showing a composition range of a silver alloy according to the first aspect of the present invention.

FIG. 2 is a view showing a composition range of a silver alloy according to the invention of claim 2;

Claims (2)

[Claims] 1. In a silver alloy containing silver as a main component and copper and palladium, when the silver is X, the copper is Y, and the palladium is Z (X + Y + Z = 100), the following composition (X = 85, Y = 12, Z = 3) (X = 39.5, Y = 38.5, Z = 22) (X = 48.5, Y = 48.5, Z = 3) A silver alloy characterized by having a composition in the following range. 2. In a silver alloy containing silver as a main component and copper and platinum, when the silver is X, the copper is Y, and the platinum is Z (X + Y + Z = 100), the following composition (X = 75, Y = 15, Z = 10) (X = 45, Y = 35, Z = 20) (X = 40, Y = 40, Z = 20) (X = 45.5, Y = 45.5, Z = 10) A silver alloy having a composition range surrounded by a line connecting the points.