A method for preparing highly efficient and corrosion-resistant 18K purple gold aluminum alloy

Abstract

The invention discloses a method for preparing an efficient and corrosion-resistant 18K purple gold aluminum alloy. Step 1: prepare the following raw materials by mass ratio: 75-83 parts of gold, 23-24.5 parts of aluminum, 0.5-2 parts of rare earth, and 0.5-2 parts of tantalum or niobium; Step 2: first mix gold and part of aluminum and put them into a vacuum medium frequency induction furnace, prepare the gold aluminum alloy and take it out, then mix the rare earth and the remaining aluminum and put them into a vacuum medium frequency induction furnace, prepare the aluminum-based rare earth alloy and take it out; grind the gold aluminum alloy and the aluminum-based rare earth alloy into powder together; Step 3: stir the alloy powder evenly and compact it into a cake, melt it under argon protection, and grind it for fine polishing; Step 4: ion-implant tantalum or niobium on the surface of AuAl2, and then anneal and diffuse it under argon protection; Step 5: prepare an anodizing electrolyte; Step 6: perform an anodizing treatment. It can not only ensure the color quality of the 18K purple gold aluminum alloy, but also obtain a dense composite oxide film to improve corrosion resistance.

Description

Technical Field

[0001] The invention relates to a method for preparing a gold alloy, which is mainly used as a jewelry material or an electronic material, and specifically relates to a method for preparing a high-efficiency, corrosion-resistant 18K purple gold aluminum alloy. Background Art

[0002] Gold aluminum alloy (chemical formula AuAl2) has a bright purple color and a high gold content of 79%, which meets the requirements of 18K gold and has potential application value in the jewelry industry. In the integrated circuit industry, AuAl2 exists at the bonding interface. After long-term use, the heat generated by the current will cause AuAl2 to be easily oxidized or corroded, affecting the service life of components. In addition, AuAl2 is a filter material that effectively cuts off the ultraviolet and infrared parts of the spectrum, but because its corrosion resistance and oxidation resistance need to be improved, research on improving the corrosion resistance of gold aluminum alloy is of great significance. Anodizing is a surface treatment process widely used for aluminum alloys. The corrosion resistance of the aluminum oxide film on its surface is closely related to process parameters such as electrolyte composition, oxidation voltage, oxidation time, and oxidation temperature. Domestic and foreign scholars have conducted a lot of research on the preparation of anodized films of aluminum alloys and their related properties, but there are few studies on anodizing treatment of gold aluminum alloys. Summary of the invention

[0003] The present invention aims to improve the corrosion resistance of 18K purple gold aluminum alloy by anodizing. By configuring a special electrolyte, the gold aluminum alloy is anodized under different process parameters such as voltage, oxidation time and temperature, which can not only ensure the color quality of the gold aluminum alloy, but also improve the corrosion resistance.

[0004] To this end, the technical solution adopted by the present invention is: a method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy, comprising the following steps:

[0005] Step 1: Raw material preparation;

[0006] Prepare the following raw materials by mass ratio: 75-83 parts of gold, 23-24.5 parts of aluminum, 0.5-2 parts of rare earth, and 0.5-2 parts of other metals such as tantalum or niobium, wherein the gold content of the gold raw material is 99.99%, and the aluminum content of the aluminum raw material is 99.99%;

[0007] Step 2: first, mix the gold raw material and part of the aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the gold-aluminum alloy, then mix the rare earth raw material and the remaining aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the aluminum-based rare earth alloy; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder together, the grinding time is 28 to 32 hours, and grind to a minimum particle size of 0.1 to 0.5 microns;

[0008] Step 3: Before smelting, stir the ground alloy powder evenly and compact it into a cake using a die; use a water-cooled copper crucible in a vacuum arc melting furnace to melt the alloy powder under argon protection, and repeat the melting 3 to 5 times to obtain 18K purple AuAl2; then polish it to a mirror effect, and observe under a 100x microscope without scratches or stains;

[0009] Step 4: ion implantation of tantalum or niobium on the surface of 18K purple AuAl2, with an implantation energy of 60-80 kV and an implantation dose of 0.5×10 17 cm -2 ~8×10 17 cm -2 , then annealing and diffusion are carried out under the protection of 5% hydrogen and 95% argon, the annealing time is 3h~5h, the annealing temperature is 300~500℃, and a tantalum or niobium layer is obtained on the 18K purple AuAl2 surface;

[0010] Step 5, preparing an electrolyte for anodizing;

[0011] Add oxalic acid, boric acid, cubane dicarboxylic acid and an activator into a deionized water solvent, and prepare a mixed solution according to the ratio of 28-32 g oxalic acid: 8-12 g boric acid: 4-6 g cubane dicarboxylic acid: 4-6 g activator: 1 L deionized water, and then use 0.1-0.2 mol / L sodium hydroxide solution to adjust the pH value of the mixed solution to 1-5, so as to prepare an electrolyte for anodization;

[0012] Step six, pour the prepared anodizing electrolyte into the electrolytic cell, place the electrolytic cell in a constant temperature water bath, then fix the AuAl2 alloy as the anode on the acrylic plate and put it into the electrolyte, 45 to 50 mm away from the lead plate as the cathode, and perform anodizing treatment at a voltage of 3 to 10 V, a time of 45 to 300 s, and a temperature of 25 to 40 ° C.

[0013] As a preferred embodiment of this solution, the rare earth is at least one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, yttrium or scandium.

[0014] More preferably, the activator of the electrolyte is a mixture of ammonium dichromate and potassium citrate, and the mass ratio of ammonium dichromate to potassium citrate is 1:1.

[0015] More preferably, the voltage of the anodizing treatment is 5 V, the time is 120 s, and the temperature is 35° C.

[0016] More preferably, the vacuum induction melting temperature is 1000-1500°C.

[0017] More preferably, the vacuum arc melting is performed four times.

[0018] More preferably, when preparing the mixed solution, the ratio is 30 g of oxalic acid: 10 g of boric acid: 5 g of cubanedicarboxylic acid: 5 g of activator: 1 L of deionized water.

[0019] More preferably, the vacuum ball mill is set to have a revolution speed of 300 r / min and a rotation speed of 600 r / min.

[0020] Beneficial effects of the present invention:

[0021] (1) By adding rare earth elements to the gold-aluminum alloy, it can play a role in microalloying, improve the metallographic structure of the alloy, refine the grains, and help improve the corrosion resistance of the alloy; other elements such as tantalum or niobium can also form a dense oxide film on the surface of the alloy, enhancing the corrosion resistance of the gold-aluminum alloy, making the gold-aluminum alloy a new type of material with excellent corrosion resistance.

[0022] (2) The aluminum-based rare earth intermediate alloy is melted by vacuum induction melting technology, which can remove impurity elements and reduce the burn-out of rare earth elements; at the same time, the aluminum raw material is divided into two parts, one part is mixed with the gold raw material and placed in a vacuum medium frequency induction furnace to prepare the gold-aluminum alloy, and the other part is mixed with the rare earth raw material and placed in a vacuum medium frequency induction furnace to prepare the aluminum-based rare earth alloy. This can effectively avoid the burn-out of rare earth due to evaporation when gold, aluminum and rare earth are placed in a vacuum medium frequency induction furnace at the same time to prepare the gold-aluminum alloy, thereby effectively controlling the rare earth content in the alloy, so that the corrosion resistance of the gold-aluminum alloy is improved while maintaining the purple characteristics; vacuum arc melting technology is used to avoid oxidation of the alloy during the melting process.

[0023] (3) The vacuum environment provided by the vacuum ball mill can prevent the alloy from being oxidized during the grinding process; after being ground into powder, the alloy components can be fully mixed. Before smelting, the ground alloy powder is stirred evenly and compacted into a cake using a die to avoid powder splashing during the smelting process; at the same time, a water-cooled copper crucible is used in a vacuum arc melting furnace to melt the alloy powder under argon protection, and the melting is repeated multiple times to ensure that the alloy is fused as evenly as possible.

[0024] (4) Grinding and polishing are performed first, and then ion implantation and anodization are performed. On the one hand, it is more conducive to the subsequent ion implantation and anodization. On the other hand, no grinding and polishing are performed after ion implantation and anodization, which can also avoid damage to the ion implantation layer and the anodized layer during the grinding and polishing process, further improving the corrosion resistance and the appearance quality of the final product.

[0025] (5) Annealing diffusion after ion implantation is more conducive to the uniform distribution of the implanted tantalum ions on the surface of the alloy than conventional diffusion in the atmosphere, thereby avoiding the premature formation of an oxide film; implanting tantalum ions alone, rather than with rare earth, is conducive to obtaining a composite oxide film of aluminum oxide and tantalum oxide / niobium in the subsequent anodization process, further improving the corrosion resistance of the alloy.

[0026] (6) Using a mixed solution of oxalic acid, boric acid, cubanedicarboxylic acid and an activator at a certain concentration as the electrolyte can increase the temperature range and oxidation efficiency of anodizing, improve the hardness and wear resistance of the film layer, and anodize the gold-aluminum alloy at a certain voltage, oxidation time and temperature. The surface aluminum oxide film forms a protection for the gold-aluminum alloy, thereby improving the corrosion resistance of the gold-aluminum alloy.

[0027] In summary, the present invention uses gold and aluminum as the matrix material of the alloy, adds a certain amount of rare earth elements and other elements such as tantalum or niobium, and melts them into gold-aluminum alloy through vacuum induction melting and vacuum arc melting technology, and combines grinding, compaction, polishing, ion implantation, anodizing and other treatment processes to improve the corrosion resistance of 18K purple gold aluminum alloy, which can not only ensure the color quality of 18K purple gold aluminum alloy, but also obtain a composite oxide film with a dense film layer, and obtain a purple 18K gold aluminum alloy material with bright color and improved corrosion resistance. DETAILED DESCRIPTION

[0028] The present invention will be further described below by way of examples:

[0029] Embodiment 1:

[0030] A method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy comprises the following steps:

[0031] Step 1: Raw material preparation;

[0032] Prepare the following raw materials according to the mass ratio: 83 parts of gold, 24.5 parts of aluminum, 2 parts of rare earth lanthanum, and 2 parts of other metal tantalum. The gold content of the gold raw material is 99.99%, and the aluminum content of the aluminum raw material is 99.99%.

[0033] Step 2: First, 83 parts of gold raw material and 10 parts of aluminum raw material are mixed into a vacuum medium frequency induction furnace, and the gold-aluminum alloy is prepared and then taken out. Then, 2 parts of rare earth lanthanum raw material and the remaining 14.5 parts of aluminum raw material are mixed into a vacuum medium frequency induction furnace, and the aluminum-based rare earth alloy is prepared and then taken out; the vacuum induction melting temperature is 1000-1500°C. Use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder together, the grinding time is 32 hours, and the minimum particle size is 0.1 micron. The vacuum ball mill is set to revolve at 300r / min and rotate at 600r / min, but not limited to this.

[0034] Step 3: Stir the ground alloy powder evenly before smelting, and use a die to compact it into a cake to avoid powder splashing during the smelting process. Use a water-cooled copper crucible in a vacuum arc melting furnace to melt the alloy powder under argon protection, and repeat the melting 5 times to ensure that the alloy is fused as evenly as possible to obtain 18K purple AuAl2. Then polish it to a mirror effect, and observe under a 100x microscope to see if there are any scratches or stains.

[0035] Step 4: ion implantation of tantalum on the surface of 18K purple AuAl2 with an implantation energy of 80 kV and an implantation dose of 8×10 17 cm -2 Then, annealing diffusion is performed under the protection of 5% hydrogen and 95% argon, the annealing time is 5h, the annealing temperature is 500°C, tantalum is obtained on the surface of 18K purple AuAl2, and the ion-implanted tantalum forms an oxide film on the surface of 18K purple AuAl2. Step 5: Prepare an electrolyte for anodization.

[0036] Oxalic acid, boric acid, cubane dicarboxylic acid and an activator are added to a deionized water solvent to prepare a mixed solution according to the ratio of 32 g oxalic acid: 12 g boric acid: 6 g cubane dicarboxylic acid: 6 g activator: 1 L deionized water, and then a 0.2 mol / L sodium hydroxide solution is used to adjust the pH value of the mixed solution to 5 to prepare an electrolyte for anodization.

[0037] Step six, pour the prepared anodized electrolyte into the electrolytic cell, place the electrolytic cell in a constant temperature water bath, then fix the AuAl2 alloy as the anode on the acrylic plate and put it into the electrolyte, 50 mm away from the lead plate as the cathode, and perform anodizing treatment at a voltage of 10 V, a time of 300 s, and a temperature of 40°C, thereby forming a composite oxide film of aluminum oxide and tantalum oxide on the surface of the 18K purple AuAl2 alloy.

[0038] Embodiment 2:

[0039] A method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy comprises the following steps:

[0040] Step 1: Raw material preparation;

[0041] Prepare the following raw materials according to the mass ratio: 80 parts of gold, 24 parts of aluminum, 1 part of rare earth neodymium, and 1 part of other metal niobium. The gold content of the gold raw material is 99.99%, and the aluminum content of the aluminum raw material is 99.99%.

[0042] Step 2: first mix 80 parts of gold raw material and 12 parts of aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the gold-aluminum alloy, then mix 1 part of rare earth neodymium raw material and the remaining 12 parts of aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the aluminum-based rare earth alloy; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder together, the grinding time is 30 hours, and grind to a minimum particle size of 0.3 microns.

[0043] Step 3: Before smelting, stir the ground alloy powder evenly and compact it into a cake using a die. Use a water-cooled copper crucible in a vacuum arc melting furnace to melt the alloy powder under argon protection, and repeat the melting 4 times to obtain 18K purple AuAl2. Then polish it to a mirror effect, and observe it under a 100x microscope to see if there are any scratches or stains.

[0044] Step 4: Niobium ion implantation is performed on the surface of 18K purple AuAl2 with an implantation energy of 70 kV and an implantation dose of 4×10 17 cm -2 , and then annealing diffusion is carried out under the protection of 5% hydrogen and 95% argon. The annealing time is 4h and the annealing temperature is 400℃. Niobium is obtained on the surface of 18K purple AuAl2. The ion-implanted niobium forms an oxide film on the surface of 18K purple AuAl2.

[0045] Step 5: Prepare anodizing electrolyte.

[0046] Oxalic acid, boric acid, cubane dicarboxylic acid and an activator are added to a deionized water solvent to prepare a mixed solution according to the ratio of 30 g oxalic acid: 10 g boric acid: 5 g cubane dicarboxylic acid: 5 g activator: 1 L deionized water, and then 0.1 / L sodium hydroxide solution is used to adjust the pH value of the mixed solution to 3 to prepare an electrolyte for anodizing.

[0047] Step six, pour the prepared anodized electrolyte into the electrolytic cell, place the electrolytic cell in a constant temperature water bath, then fix the AuAl2 alloy as the anode on the acrylic plate and put it into the electrolyte, 48mm away from the lead plate as the cathode, and perform anodizing treatment under the conditions of voltage of 5V, time of 120s and temperature of 35°C, so as to form a composite oxide film of aluminum oxide and niobium oxide on the surface of the 18K purple AuAl2 alloy.

[0048] Embodiment 3:

[0049] A method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy comprises the following steps:

[0050] Step 1: Raw material preparation;

[0051] Prepare the following raw materials in proportion by mass: 75 parts of gold, 23 parts of aluminum, 0.5 parts of rare earth yttrium, and 0.5 parts of other metal niobium. The gold content of the gold raw material is 99.99%, and the aluminum content of the aluminum raw material is 99.99%.

[0052] Step 2: first mix 75 parts of gold raw material and 8 parts of aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the gold-aluminum alloy, then mix 0.5 parts of rare earth yttrium raw material and the remaining 15 parts of aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the aluminum-based rare earth alloy; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder together, the grinding time is 28 hours, and grind to a minimum particle size of 0.5 microns.

[0053] Step 3: Before smelting, stir the ground alloy powder evenly and use a die to compact it into a cake. Use a water-cooled copper crucible in a vacuum arc melting furnace to melt the alloy powder under argon protection, and repeat the melting three times to obtain 18K purple AuAl2. Then polish it to a mirror effect, and observe it under a 100x microscope to see if there are any scratches or stains.

[0054] Step 4: Niobium is ion-implanted on the surface of 18K purple AuAl2 with an injection energy of 60 kV and an injection dose of 0.5×10 17 cm -2 , and then annealing diffusion is carried out under the protection of 5% hydrogen and 95% argon. The annealing time is 3h and the annealing temperature is 300℃. Niobium is obtained on the surface of 18K purple AuAl2. The ion-implanted niobium forms an oxide film on the surface of 18K purple AuAl2.

[0055] Step 5: Prepare anodizing electrolyte.

[0056] Oxalic acid, boric acid, cubane dicarboxylic acid and an activator are added to a deionized water solvent to prepare a mixed solution according to the ratio of 28 g oxalic acid: 8 g boric acid: 4 g cubane dicarboxylic acid: 4 g activator: 1 L deionized water, and then a 0.1 / L sodium hydroxide solution is used to adjust the pH value of the mixed solution to 1 to prepare an electrolyte for anodizing.

[0057] Step six, pour the prepared anodized electrolyte into the electrolytic cell, place the electrolytic cell in a constant temperature water bath, then fix the AuAl2 alloy as the anode on the acrylic plate and put it into the electrolyte, 45mm away from the lead plate as the cathode, and perform anodizing treatment under the conditions of voltage of 3V, time of 45s, and temperature of 25°C, so as to form a composite oxide film of aluminum oxide and niobium oxide on the surface of the 18K purple AuAl2 alloy.

[0058] Furthermore, the rare earth may be at least one of cerium, praseodymium, promethium, samarium, europium or scandium in addition to lanthanum, neodymium and yttrium. The active agent for the electrolyte is preferably a mixture of ammonium dichromate and potassium citrate, and the mass ratio of ammonium dichromate to potassium citrate is 1:1.

Claims

1. A method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy, characterized in that: The following steps are involved: Step 1: Raw material preparation; Prepare the following raw materials by mass ratio: 75-83 parts of gold, 23-24.5 parts of aluminum, 0.5-2 parts of rare earth, and 0.5-2 parts of other metals such as tantalum or niobium, wherein the gold content of the gold raw material is 99.99%, and the aluminum content of the aluminum raw material is 99.99%; Step 2: first, mix the gold raw material and part of the aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the gold-aluminum alloy, then mix the rare earth raw material and the remaining aluminum raw material into a vacuum medium frequency induction furnace, take out after preparing the aluminum-based rare earth alloy; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder together, the grinding time is 28 to 32 hours, and grind to a minimum particle size of 0.1 to 0.5 microns; Step 3: Before smelting, the ground alloy powder is stirred evenly and compacted into a cake using a die; a water-cooled copper crucible is used in a vacuum arc melting furnace to melt the alloy powder under argon protection, and the melting is repeated 3 to 5 times to obtain an 18K purple gold aluminum alloy; then the alloy powder is polished to a mirror effect, and no scratches or stains are observed under a 100x microscope; Step 4: ion implantation of tantalum or niobium is performed on the surface of the 18K purple gold aluminum alloy. The implantation energy is 60-80 kV and the implantation dose is 0.5×10 17 cm -2 ~8×10 17 cm -2 , then annealing and diffusion are carried out under the protection of 5% hydrogen and 95% argon, the annealing time is 3h~5h, the annealing temperature is 300~500℃, and a tantalum or niobium layer is obtained on the surface of the 18K purple gold aluminum alloy; Step 5, preparing an electrolyte for anodizing; Add oxalic acid, boric acid, cubane dicarboxylic acid and an activator into a deionized water solvent, and prepare a mixed solution according to the ratio of oxalic acid 28-32g: boric acid 8-12g: cubane dicarboxylic acid 4-6g: activator 4-6g: deionized water 1L, and then use 0.1-0.2 mol / L sodium hydroxide solution to adjust the pH value of the mixed solution to 1-5, and prepare an electrolyte for anodization; Step six, pour the prepared anodizing electrolyte into the electrolytic cell, place the electrolytic cell in a constant temperature water bath, then fix the gold-aluminum alloy as the anode on the acrylic plate and put it into the electrolyte, 45~50mm away from the lead plate as the cathode, and perform anodizing treatment under the conditions of voltage of 3~10V, time of 45~300s, and temperature of 25~40℃.

2. The method for preparing the high-efficiency corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: The rare earth is at least one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, yttrium or scandium.

3. The method for preparing the highly efficient and corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: The active agent of the electrolyte is a mixture of ammonium dichromate and potassium citrate, and the mass ratio of ammonium dichromate to potassium citrate is 1:

1.

4. The method for preparing the highly efficient and corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: The voltage of the anodizing treatment was 5 V, the time was 120 s, and the temperature was 35 °C.

5. The method for preparing the highly efficient and corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: The vacuum induction melting temperature is 1000~1500℃.

6. The method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: The vacuum arc melting times are 4 times.

7. The method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: When preparing the mixed solution, the ratio is 30 g of oxalic acid: 10 g of boric acid: 5 g of cubanedicarboxylic acid: 5 g of activator: 1 L of deionized water.

8. The method for preparing a highly efficient and corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: The vacuum ball mill was set to have a revolution speed of 300 r / min and a rotation speed of 600 r / min.