JPS6040980B2 - Metal materials for ornaments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal material for decorative articles, and the surface of a Ni-based alloy containing 4 to 20% Cr and at least 6% of one or more elements selected from Te and Pb is covered with a Rh layer. The object of the present invention is to provide a decorative metal material with extremely excellent corrosion resistance.

Some decorative items such as watches, watch bands, and eyeglass frames are made by covering a base metal with a precious metal layer.

This is mainly done to increase the value of the product from a decorative perspective, but technically it is to improve the corrosion resistance and durability of the decorative item. As such a precious metal, AwP
Rh, which is more expensive than Au, Pt, etc., is sometimes used.

Rh is a white metal with good corrosion resistance and is also good for decoration, making it extremely desirable as a noble metal layer covering for decorative items. Conventionally, Rh
When forming a layer, the base metal is a metal with a white appearance, such as stainless steel (for example, SUS3).
04), nickel silver or nickel silver coated with gold cladding is used.

This is considered to be mainly from a decorative point of view when the Rh layer peels off. However, decorative articles provided with such a base metal Rh layer have the disadvantage of causing pitting after long-term use, and are not suitable for practical use. The object of the present invention is to eliminate such drawbacks and to provide a base alloy provided with a Rh layer that does not cause pitting even after long-term use and is therefore sufficiently practical.

That is, the first metal material for ornaments of the present invention contains 4 to 20% chromium Cr and 6% or less of an element selected from tellurium Te and lead Pb, and the remainder is substantially nickel Ni. It is characterized by being covered with layers.

Further, the second metal material for decorative articles of the present invention is the first metal material described above.
The Ni-based alloy in the metal material for decorative articles further contains one or more elements selected from U and iron-Fe in an amount that is 6% or less in total with the Cu and Fe. It is.

Decorations such as watches, watch bands, eyeglass frames, lighters, etc. can be made using the metal material according to the present invention.
When musical instruments, ornaments, necklaces, bracelets, etc. are manufactured, not only are they decorative, but they do not suffer from pitting even after years of use. The present inventor has discovered that Cr4-20% and T
e or Pb or in addition to these Cu or Fe
It has been discovered that when an Nj-based alloy containing at least one type and 6% or less of the following is used as a base metal, the base metal can withstand long-term use because it is covered with a Rh layer.

This invention is based on these discoveries. This is considered to be due to the following reasons.

Corrosion of a metal material formed by providing an Rh layer on a base metal is considered to be mainly controlled by the magnitude of the potential difference of a chemical cell composed of the base metal and the Rh layer.

That is, if such a potential difference is large, corrosion is likely to occur. This means that the Rh layer in decorative materials is 0.1 to several meters.
Because it is thin and therefore porous in nature, when an electrolyte solution such as sweat (which contains a lot of salt) comes into contact with these pores, Rh
This is because a battery is formed between the layer and the base metal, which accelerates corrosion. Therefore, in this invention, Rh and 4 to 20% of Cr, Te and Pb have good corrosion resistance.
This is thought to be because the potential difference between the alloy and the Ni-based alloy containing 6% or less of Cu and Fe is 4. It is expected that the pitting of ornamental materials with a Rh layer on the base metal can be solved by selecting the type of base metal, but the ionization tendency of Rh is unknown (although various literatures suggest that Since the standard electrode potential is also unknown, the selection is difficult, and the Ni alloy of the parentheses' invention is limited to a certain range of Cr and contains Te, Pb, Cu, and Fe up to a certain limit. Since it was not clear that the overall standard electrode potential of the alloy with the oxidized metal could be obtained as close to the potential of Rh, decorative materials were developed in which a Rh layer was provided on a base metal with good corrosion resistance. It is assumed that it did not exist.

This invention will be explained in more detail.

The base metal used in this invention is Cr4-20%
It is a Ni-based alloy containing.

This Motomura alloy may optionally contain one or more deoxidizers such as C, Si, Nn, N, Ti, etc., in a total of up to 4% as typical impurities. The alloy of the present invention further contains up to 6% of Te or Pb or one or more selected from the group consisting of Cu or Fe in addition to Te or Pb. Cr is added to minimize the potential difference with Rh, and unless it is in the range of 4 to 20%, the desired effect of the present invention cannot be achieved.

In addition, Te, Pb, and CuQ Fe are added to improve the machinability (free machinability) of decorative materials. As the potential difference between the

More specifically, Te and Pb improve machinability by not melting into the alloy matrix, but by becoming dispersed particles and causing structural defects in the cutting piece (acting as a chip breaker). , Cu, and Fe have the effect of improving machinability by solidifying into the matrix and reducing its viscosity.The method of providing the Rh layer on this base alloy is basically not limited.

For example, it can be provided by plating or cladding. Rh
The thickness of the layer is 0.1 to several meters as in the conventional case. below,
Examples of this invention will be described. This example is not intended to limit the invention. EXAMPLE The potential difference between a base alloy according to the invention and a conventional base alloy and Rh was measured in the manner shown in the figure.

In the figure, 1' is 3% saline, 2 is Rh, 3 is
indicates the base metal, and 4 indicates the potentiometer.

Such a potentiometer 4 can measure within a range of ±30 mV. In addition, after plating Rh on the above base alloy to a thickness of 2.0 fm (however, in the table below, nickel silver clad with Au and silver not plated), JISZ23
A salt water fog test according to No. 71 was conducted to evaluate corrosion resistance.

Furthermore, machinability tests were conducted on each of the above base alloys.

That is, each sample to be tested for machinability was prepared by melting the specified components in a high-frequency induction furnace to create an ingot.
After heating to 0.0°C, water moths were added, and then 50% processed was used. Cutting performance was 1.5k using a straight drill with a diameter of 2.5 which satisfies the standards of JISB4301.
The depth of the hole is shown when the hole is drilled for 30 seconds with a drilling machine at a rotational speed of 175 pm while applying a load of 9.

The depth of the perforation was measured with a 1'100 mill point micrometer. The evaluation results of the potential difference, corrosion resistance, and machinability described above are summarized in the table below.

Looking at the results in the table above, it can be seen that the base alloy used in this invention is Rh
It can be seen that the potential difference between the two materials is significantly smaller than that of conventional base alloys, and the resulting decorative material has an excellent balance of insect resistance and machinability.

[Brief explanation of drawings]

The figure is a schematic diagram showing a method of measuring potential difference in an example. 1...3% saline solution, 2...Rh (anode),
3...Base alloy material (cathode).

Claims (1)

[Claims] 1 Rh A metal material for decorative items characterized by being covered with layers. 2 Contains 4 to 20% of Cr, one or more elements selected from Te and Pb and 6% or less, and one or more elements selected from Cu and Fe in a total amount of 6% or less with Te and Pb, A metal material for ornaments, characterized in that the surface of a Ni-based alloy, the remainder of which is substantially Ni, is covered with a Rh layer.