Process for the production of coloured 18k gold

Abstract

The application discloses a preparation method of colored 18K gold, comprising the following steps: S1, preparing 18K gold; S2, performing plastic processing on the 18K gold prepared in the step S1 at room temperature to obtain a required shape, and no annealing treatment is performed in the plastic processing process; S3, performing annealing on the 18K gold which has completed the plastic processing in the step S2 in an atmospheric atmosphere, the annealing temperature is 220-370 DEG C, the annealing time is 3-60 minutes, the colored 18K gold with corresponding colors is obtained by selecting different annealing temperatures and annealing times, and the colors include light yellow, orange, brick red, brown, purple, blue and blue-black. According to the application, the colored 18K gold can be produced only by using conventional jewelry processing and production equipment, a series of colors different from conventional Au-Ag-Cu series alloys can be realized, the colored 18K gold has good processing performance, can adapt to conventional K gold processing and preparation processes, and has lower cost than the Au-Ag-Cu series alloys.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-ferrous materials, in particular to a preparation method of colored 18K gold. BACKGROUND

[0002] Colored K gold can obtain different colors from pure gold, thereby manufacturing and developing colorful colored K gold jewelry alloy. The existing colored K gold is mainly Au-Ag-Cu alloy, and its color depends on the alloy composition. At present, only a few colors such as rose, white and pink can be realized. Although more colorful colors can also be realized by surface treatment methods such as electroplating, new production equipment and processes need to be added, thereby increasing the production cost, and the electroplating process usually involves toxic substances, sewage treatment, environmental protection and other problems. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application aims to provide a preparation method of colored 18K gold.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] A preparation method of colored 18K gold, comprising the following steps:

[0006] S1, preparing 18K gold: the raw material of the 18K gold contains Au≥75.0% by mass fraction; the total content of Fe and Cr elements is≤24.99%, wherein the content of Fe is 24-24.99%, and the content of Cr is≤0.99%; the total content of impurity elements is≤0.01%; the raw material is melted by using a vacuum atmosphere furnace, and after vacuumizing, Ar gas is back-filled to above one standard atmosphere as a protective gas; after the raw material is fully melted, the liquid metal is poured into a mold to cool and form 18K gold for subsequent processing, and at this time the color of the 18K gold is silver white;

[0007] S2, plastic processing the 18K gold prepared in step S1 at room temperature to obtain a required shape, and no annealing treatment is performed during the plastic processing;

[0008] S3, annealing the 18K gold subjected to plastic processing in step S2 in an atmospheric atmosphere, the annealing temperature is 220-370℃, and the annealing time is 3-60 minutes, and by selecting different annealing temperature and annealing time, colored 18K gold with target color can be obtained, and the color includes light yellow, orange, brick red, brown, purple, blue and blue black.

[0009] Further, in step S2, the plastic processing includes one or more of rolling, stamping, drawing, extruding, cutting and engraving.

[0010] Further, in step S3, the 18K gold after plastic processing is put into the furnace for annealing after the furnace temperature is raised to the required annealing temperature.

[0011] Further, in step S3, the 18K product is rapidly cooled after annealing.

[0012] Further, in step S3, the color sequence of the 18K gold changes to light yellow-orange-brick red-brown with the extension of the annealing time in the temperature range of 220-250℃.

[0013] Further, in step S3, the color sequence of the 18K gold changes to orange-brick red-brown-purple with the extension of the annealing time in the temperature range of 250-300℃.

[0014] Further, in step S3, the color sequence of the 18K gold changes to brick red-brown-purple-blue with the extension of the annealing time in the temperature range of 300-340℃.

[0015] Further, in step S3, the color sequence of the 18K gold changes to purple-blue-blue black with the extension of the annealing time in the temperature range of 340-370℃.

[0016] Further, in step S3, the color produced by the 18K gold is deeper with the increase of the Cr content.

[0017] The present application has the advantages that the colored 18K gold can be produced by using the present application with conventional jewelry processing and production equipment, a series of colors different from the conventional Au-Ag-Cu alloy can be realized, the processing performance is good, the production process can be adapted to the conventional K gold, and the cost is lower than that of the Au-Ag-Cu alloy. DETAILED DESCRIPTION

[0018] The present application will be further described below, and it should be noted that the present embodiment is based on the technical solution, and detailed implementation and specific operation processes are given, but the protection scope of the present application is not limited to the present embodiment.

[0019] Embodiment 1

[0020] The present embodiment provides a preparation method of brown 18K gold, and the specific process is as follows:

[0021] The raw material of 18K gold in this embodiment (wt%) is: Au content 75.08%, Fe element content 24.91%, no Cr element is added, and the rest is other unavoidable impurity elements, and the total content of impurity elements is 0.01%. The raw material is smelted by using a vacuum atmosphere furnace, and after vacuumizing, Ar gas is backfilled to more than one standard atmosphere as a protective gas. After heating to fully melt the raw material, the liquid metal is poured into a mold to cool and form. The obtained casting blank is processed into a coin shape at room temperature by stamping. Then the annealing furnace temperature is raised to 220°C, the material processed into a coin shape is put into the annealing furnace and kept for a certain time, and then taken out and rapidly cooled by forced air cooling with a high-power fan. The annealing time and sample color corresponding relationship is shown in Table 1.

[0022] Table 1 Annealing time and sample color corresponding relationship at 220°C

[0023] Hold time / min 3 8 15 25 Sample color Light yellow Orange Brick red Brown

[0024] By using the above process, the prepared 18K gold has a gold content of 75.08%, which meets the gold standard, and various colors described in Table 1 can be obtained.

[0025] Example 2

[0026] This embodiment provides a method for preparing blue 18K gold, and the specific process is as follows:

[0027] The raw material of 18K gold in this embodiment (wt%) is: Au content 75.09%, Fe element content 24.0%, Cr element content 0.91%, and the rest is other unavoidable impurity elements, and the total content of impurity elements is 0.01%. The raw material is smelted by using a vacuum atmosphere furnace, and after vacuumizing, Ar gas is backfilled to more than one standard atmosphere as a protective gas. After heating to fully melt the raw material, the liquid metal is poured into a mold to cool and form. The obtained casting blank is processed into a coin shape at room temperature by stamping. The furnace temperature of the annealing furnace is raised to 370°C, the material processed into a coin shape is put into the furnace and kept for a certain time, and then taken out and rapidly cooled by forced air cooling with a high-power fan. The annealing time and sample color corresponding relationship is shown in Table 2.

[0028] Table 2 Annealing time and sample color corresponding relationship at 370°C

[0029] Hold time / min 5 10 60 Sample color Purple Blue Blue black

[0030] By using the above process, the prepared 18K gold has a gold content of 75.09%, which meets the 18K gold standard, and various colors described in Table 2 can be obtained.

[0031] For those skilled in the art, various corresponding changes and modifications can be made to the above technical solutions and concepts, and all these changes and modifications should be included in the protection scope of the claims of the present application.

Claims

1. A method for preparing colored 18K gold, characterized in that, Includes the following steps: S1. Preparation of 18K gold: The raw materials for the 18K gold, by mass percentage, have an Au content ≥ 75.0%; the total content of Fe and Cr elements ≤ 24.99%, of which the Fe content is 24-24.99% and the Cr content is ≤ 0.99%; the total content of impurity elements is ≤ 0.01%; the raw materials are melted in a vacuum atmosphere furnace, and after vacuuming, Ar gas is refilled to above one standard atmosphere as a protective gas; after the raw materials are fully melted, the liquid metal is poured into a mold to cool and form 18K gold for subsequent processing, at which time the color of the 18K gold is silver-white; S2. The 18K gold prepared in step S1 is plastically processed at room temperature to obtain the desired shape. No annealing is performed during the plastic processing. S3. Anneal the 18K gold that has undergone plastic processing in step S2 in an atmospheric atmosphere. The annealing temperature is 220-370℃ and the annealing time is 3-60 minutes. By selecting different annealing temperatures and annealing times, colored 18K gold of the target color can be obtained. The colors include light yellow, orange, brick red, brown, purple, blue and blue-black. At temperatures ranging from 220 to 250°C, the color sequence of 18K gold changes from light yellow to orange to brick red to brown as the annealing time increases. At temperatures ranging from 250 to 300°C, the color sequence of 18K gold changes from orange to brick red to brown to purple as the annealing time increases. At temperatures ranging from 300 to 340°C, as annealing time increases, the color sequence of 18K gold changes from brick red to brown to purple to blue. At temperatures ranging from 340 to 370°C, the color sequence of 18K gold changes from purple to blue to blue-black as the annealing time increases. As the Cr content in 18K gold increases, the resulting color becomes darker.

2. The method for preparing colored 18K gold according to claim 1, characterized in that, In step S2, the plastic processing includes one or more of rolling, stamping, drawing, extrusion, cutting, and engraving.

3. The method for preparing colored 18K gold according to claim 1, characterized in that, In step S3, the furnace temperature is first raised to the required annealing temperature before the 18K gold that has completed plastic processing is placed into the furnace for annealing.

4. The method for preparing colored 18K gold according to claim 1, characterized in that, In step S3, after the 18K product has been annealed, it is rapidly cooled.