JP2008214718A - K18 white gold alloy for ornament - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assure the hardness suitable for use as ornament by fining of a crystal by solving the problem of optimization of the hardness due to fining of the crystal of a K18 white gold alloy containing ≥75.0% Au and the smallness in as-cast hardness of Au-Pt-Pd-Ag, and the problem that makes the casting made from the alloy easily flawable. <P>SOLUTION: The K18 white gold alloy for ornament is obtained by incorporating, by weight, 0.5 to 20% Pt, 0.5 to 15% Pd, 0.5 to 10% Ag, and 0.1 to 3.0% Ir into Au which is a principal component. Also, the K18 white gold alloy for ornament is obtained by incorporating, by weight, 0.5 to 20% Pt, 0.5 to 15% Pd, 0.5 to 10% Ag, and 0.1 to 5.0% Rh into the Au which is the principal component. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a K18 gold alloy for decoration, and relates to a white gold alloy excellent in color tone, hardness and workability.

K18 white gold alloy containing 75.0% or more of Au is an alloy developed as a substitute for Pt for decoration. This K18 white gold alloy is roughly classified into Au—Pd and Au—Ni. As for Ni-based, the onset of metal allergy type 4 contact dermatitis has been pointed out.
For Pd, there is a problem with the whitening of the alloy and the dark color tone peculiar to Pd. Most of them are used with Rh plating, but when the plating is peeled off, the original dark color tone of the alloy is exposed. Have aesthetic issues.

Therefore, a quaternary alloy of Au—Pt—Pd—Ag and a quinary alloy of Au—Pt—Pd—Ag—Cu have been developed as glossy white gold alloys (see, for example, Patent Document 1).
JP 2000-80423 A

However, in the above-described conventional technology, there is a problem in the optimization of hardness due to the refinement of crystals, and the hardness after casting of general Au—Pt—Pd—Ag is Hv 72 to 75, which is processed into a decorative product. In such a case, there is a problem that it is easy to scratch.
An object of the present invention is to solve the above-described problems and to secure hardness suitable for decoration by refining crystals.

Therefore, in the present invention, the main component Au contains Pt 0.5 to 20%, Pd 0.5 to 15%, Ag 0.5 to 10%, and Ir 0.1 to 3.0% by weight ratio. A white gold alloy was used.
Also, the main component Au is Pt 0.5-20%, Pd 0.5-15%, Ag 0.5-10%, Cu 0.1-5.0%, Ir 0.1-3.0% by weight ratio. To obtain a K18 white gold alloy.

In addition, the main component Au contains Pt 0.5 to 20%, Pd 0.5 to 15%, Ag 0.5 to 10%, Rh 0.1 to 5.0% by weight ratio, and decorative K18 white gold. It was an alloy.
Moreover, Pt 0.5-20%, Pd 0.5-15%, Ag 0.5-10%, Rh 0.1-3.0%, Ir 0.1-3.0% by weight ratio to the main component Au To give a decorative K18 white gold alloy.

In the above configuration, the purpose of adding Pt in an amount of 0.5 to 20% is that the gold color of Au is decolored, and there is an effect on prevention of oxidation and hardness during casting, and 0.5% This is because the effect of addition cannot be obtained below, and if it exceeds 20%, the effect of whitening by other added metals cannot be expected.
The purpose of adding Pd is because it has the effect of decoloring the gold color of Au rather than Pt. However, when only Pd is added to Au, the value of brightness increases and darkness increases. This is because if 0.5% or less, the effect of addition cannot be obtained, and if it exceeds 15%, it is too dark.

The purpose of adding Ag is to improve castability and to bring out a white color close to Pt. When Ag is added to Au, it becomes a gold-colored gold color, and when the added amount exceeds 10%, whitening of the entire alloy is hindered. Moreover, it is because there is no influence on a color difference with the addition amount of 0.5% or less.
The purpose of adding Cu is to improve castability and to have an effect on hardness. When the added amount exceeds 5.0%, it works in the yellow direction in color difference and saturation, and the alloy is whitened. Will interfere. Moreover, it is because the effect with respect to hardness is not acquired with the addition amount of 0.1% or less.

  The purpose of adding Ir can be expected to have an effect on hardness due to crystal atomization, and it has been found that the effect on hardness is significant when 0.1% or more is added in the gold alloy. The 75Au-10.0Pt-5.0Pd-10.0Ag alloy has a cast-up hardness of Hv73, whereas the hardness at an Ir addition of 0.1% is Hv78, 1.0% The hardness at an addition amount of Hv94 is Hv94, the hardness at an addition amount of 1.5% is Hv112, and the hardness at an addition amount of 3.0% is Hv152. If it exceeds 3.0%, the workability is affected, the melting point becomes high, and it is not suitable for decoration.

  The purpose of adding Rh is to make white gold white. Rh, like the other platinum groups, is silvery white and exhibits particularly high reflectivity. In this gold alloy, the hardness when added at 0.1% or more by weight is Hv75, the hardness when added at 1.0% is Hv77, and Hv83 is added at 3.0%. In the addition of 5.0%, Hv107 was shown.

  Further, the addition of Rh was found to be effective for whitening of this alloy by measurement with a color difference meter. This is considered to be due to the high reflectance of Rh, and whitening is effective at a weight ratio of 3.0%, and addition of 5.0% or more is effective for hardness. However, since the price of Rh is very expensive, the amount of Rh added is limited to 5.0%, and in order to supplement the hardness, Ir should be added, and Rh and Ir should be added. Thus, an alloy satisfying both hardness and whitening was obtained.

  In the present invention as described above, in a K18 white gold alloy containing 75.0% or more of Au, the value of the color difference (ΔE) can be made equal to Pt900 (Pd division), and the hardness It showed remarkable characteristics.

  Examples of the present invention are shown in Table 1 below. A conventional example is shown in Table 2 for comparison.

The color difference (ΔE), lightness (L), and saturation (a * b *) shown in Table 1 are measured based on a standard sample (a sample obtained by plating Rh on Ag925) using a color difference meter. .
The color difference is a color difference from the standard sample, the lightness indicates the degree of brightness, + indicates bright and − indicates dark. The saturation a * value is + for red,-for green, + for b * for yellow, and-for blue. As the amount of Pd and Cu added increases, the darkness increases, Ag, Brightness increases as the amount of Pt added increases.

  The region where the color difference value is visually perceived as white is ΔE8 or less, and each composition shown in Table 1 is a K18 white gold alloy. Furthermore, it is noted that the present invention has an appropriate hardness as a decorative article.

Claims (4)

A decorative K18 white gold alloy having a weight ratio of Pt 0.5 to 20%, Pd 0.5 to 15%, Ag 0.5 to 10%, Ir 0.1 to 3.0%, and the rest Au. In terms of weight ratio, Pt 0.5 to 20%, Pd 0.5 to 15%, Ag 0.5 to 10%, Cu 0.1 to 5.0%, Ir 0.1 to 3.0%, the rest being Au Characteristic decorative K18 white gold alloy. A decorative K18 white gold alloy having a weight ratio of Pt 0.5 to 20%, Pd 0.5 to 15%, Ag 0.5 to 10%, Rh 0.1 to 5.0%, and the rest being Au. In terms of weight ratio, Pt 0.5 to 20%, Pd 0.5 to 15%, Ag 0.5 to 10%, Rh 0.1 to 3.0%, Ir 0.1 to 3.0%, and the rest being Au Characteristic decorative K18 white gold alloy.