KR940010769B1 - Au alloy and making method thereof - Google Patents

Abstract

The Au alloy consists of (in wt.%) 70-99.8 % Au, 0.1-5 % Cr and 0.1-25 % Cu. The article plated with TiN is plated with the above Au alloy by ion-plating method. The Au-plated layer has excellent adhesion property and abrasion resistance, and is useful for decoration. The method can lower production cost.

Description

Gold alloy for ion plating and its manufacturing method

1a, b are cross-sectional views of the gold alloy layer and the base layer obtained by the ion plating method of the present invention for the brass base material and stainless steel base material, respectively.

Figure 2 shows the phase equilibrium of gold and chromium ("Binary Alloy Phase Diagrams" 2nd e .. Ed .: thaddeus B. Massalski, Vol. 1, p.356)

Figure 3 shows the spectroscopic reflection characteristics of gold, copper and chromium (松 永 正 久, etc .: 表面 改 質 技術 〈日刊 工業 新聞 社, 1988〉, p288)

4 is a change in color according to the weight ratio of gold to gold-winter.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gold alloy for ion plating and a method of manufacturing the same, and more particularly, to an ion plating gold alloy excellent in adhesion and abrasion resistance of an ion plating layer to a material to be plated to obtain a gold color, and a method of manufacturing such a gold alloy layer.

Conventionally, in order to obtain a gold-colored surface decoration by plating various kinds of metal ornaments and the like, gold or gold alloy is plated by a wet method or ion-plated TiN by an ion plating method.

Gold plating by the wet method is suitable for the expression of gold color, but there are disadvantages such as excessive gold consumption, inferior plating layer adhesion and abrasion resistance, and environmental pollution. In addition, when TiN is plated by ion plating, the adhesion and abrasion resistance are excellent, but there is a problem that the color expression is inferior and uniform color production is difficult.

The present inventors fabricated a TiN layer on the surface of the material to be plated, and then plated the negative voltage (50 V to 100 V) by evaporating gold or a gold alloy under an Ar gas atmosphere (pressure: 5 × 10 ^-4 Torr to 10 ^-1 Torr). A gold or gold alloy layer was prepared on the TiN layer of material (see FIG. 1).

In order to improve the inferior mechanical properties of the pure gold thin film, a small amount of chromium was added to the pure gold in the present invention. Through the mechanism of solid solution hardening and precipitation hardening (precipitation of α "phase -Au ₄ Cr-, see FIG. 2), the addition of a small amount of chromium significantly improved the inferior mechanical properties of pure gold. However, the weight percentage of chromium As is increased, it starts to deviate from the pure spectral reflection characteristic (see FIG. 3) that selectively reflects light of yellow and red wavelengths in the visible ray region and selectively absorbs light with other wavelengths. To compensate for this, another metal, copper, was added to the alloy, with selective reflection in the visible range.

Since copper selectively reflects only red light with a higher wavelength than gold (see Figure 3), the addition of chromium could effectively compensate for the discoloration of the alloy into a white system. However, it was found that as the content of copper increases, the color of the alloy becomes red, and the color of the alloy becomes red at 25 wt% or more of copper (see FIG. 4).

Based on the above experimental results, the gold alloy composition of the present invention, which is characterized by a composition of 70 to 99.9% by weight of gold, 0.1 to 5% by weight of chromium, and 0.1 to 25% of copper, was determined.

The invention is described in detail with reference to the following examples.

EXAMPLE

A. Plated Material:

Watch case: Brass base material with Ni (6㎛) / Cr (0.5㎛) layer coated by wet plating method

Watch band: Stainless steel (SUS 304)

B. Surface cleaning process of plated material:

(1) Ultrasonic Cleaning in Alkaline Solution Tank

(2) washing in lactic acid solution tank

(3) water washing

(4) moisture removal

(5) Ultrasonic cleaning in a trichloroethylene (TCE) solution bath at 60 to 80 ° C

C. Plating Method:

(1) Production of gold alloy evaporation source:

i) Split the chromium into fines (0.83 mm).

ii) When manufacturing alloy by melting method, put gold, copper and chromium powder in the quartz plate according to the weight ratio in order to minimize the reaction between additive elements and gas atoms in the atmosphere and lower the pressure in the pipe to 10 ^-2 Torr or less. After sealing, seal the quartz plate.

iii) using a high frequency induction furnace at a temperature higher than the liquidus in each of the additive compositions of chromium according to the phase equilibrium shown in FIG. 2 to produce a homogeneous solution of chromium in which the chromium is completely dissolved. Heat the mixture. The time required for complete dissolution of the chromium powder is shortened as the particle size of the powder is fine and as the heating temperature is increased. When 0.83mm chromium powder is used, it takes about 10 minutes to completely dissolve the chromium powder when the specimen is added at 1170 ℃ ~ 1260 ℃, which is 100 ℃ higher than the liquid line when the weight ratio of chromium is 0.1-5%.

iv) After stirring the liquid solution in the quartz tube to mix well, quench it.

(2) Pretreatment of the surface of the material to be plated in the vacuum chamber before plating:

The surface bonding layer for removing residual impurities on the surface through the sputtering effect and improving the adhesion of the plating material by applying a cathode high voltage to the material to be plated under Ar gas atmosphere (10 ^-2 Torr) after mounting in the vacuum chamber of the 4 plated material. Induces the formation of.

(3) Ti nitride layer (TiN) formation:

Ti is evaporated under a nitrogen plasma atmosphere to form a Ti nitride (TiN) layer on the surface of the material to be plated.

(4) Au alloy layer production by ion plating method:

Evaporate gold or gold alloy under Ar plasma atmosphere (pressure: 5 × 10 ^-4 Torr to 10 ^-1 Torr) using electron gun heating, electric resistance heating, hollow cathode heating or high frequency induction melting A gold alloy layer having a thickness of 500 to 10,000 kPa is produced on the TiN layer to which the cathode voltage is applied (50 to 1000). Some of the gold or alloying elements of gold are ionized due to collision with electrons from the evaporation source to the substrate and they collide with the surface of the material to be plated with high energy together with the ions of the Ar element. As a result, a uniform gold alloy layer having a high density and excellent adhesion is formed on the TiN surface.

According to the present invention, the above mentioned composition ratio, 70 to 99.9 wt% of gold, 0.1 to 5 wt% of chromium, and 0.1 to 25 wt% of copper, is applied to the plated material plated with nitride (TiN) as mentioned above. When manufacturing a gold alloy layer having an ion plating method, it is possible to produce a decorative gold plated layer with good gold color and excellent adhesion and wear resistance at a much lower production price than a wet gold plated ornament.

Claims (9)

A gold alloy to be ion-plated on a material to be plated, wherein the gold alloy for ion plating is composed of 70 to 99.8 wt% gold, 0.1 to 5 wt% chromium and 0.1 to 25 wt% copper. A method of plating a gold or gold alloy layer on an object to be plated with nitride (TiN, ZrN, HfN) by ion plating. The method according to claim 2, wherein the evaporation source is heated by an electric resistance heating method, an electron gun heating method, a hollow cathode heating method, a high frequency induction melting method, or the like. The method of claim 2, wherein the voltage applied to the material to be plated is 50V to 1000V. The method of claim 2, wherein the Ar pressure is between 5 × 10 ⁻⁴ Torr and 10 ⁻¹ Torr. The method of claim 2, wherein the temperature of the plated material is from room temperature to 300 ℃. The method of claim 2, wherein the thickness of the thin film layer is 500 kPa to 10,000 kPa. 3. The method of claim 2 wherein the Ar ions impinge on the surface of the material to be plated. 3. The method of claim 2 wherein the ions of the gold or gold alloy element impinge on the surface of the plated material.

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