CN116926357A - A preparation method for highly efficient corrosion-resistant 18K purple gold aluminum alloy - Google Patents

Abstract

The invention discloses a method for preparing an 18K purple gold aluminum alloy with high efficiency and corrosion resistance. The first step is to prepare the following raw materials according to the mass ratio: 75 to 83 parts of gold, 23 to 24.5 parts of aluminum, 0.5 to 2 parts of rare earth, and tantalum. Or 0.5 to 2 parts of niobium; step two, first mix gold and part of the aluminum into a vacuum medium frequency induction furnace to prepare a gold-aluminum alloy and then take it out, then mix the rare earth and the remaining aluminum into a vacuum medium frequency induction furnace to prepare The aluminum-based rare earth alloy is then taken out; the gold-aluminum alloy and the aluminum-based rare earth alloy are ground together into powder; step three, stir the alloy powder evenly and compact it into a cake, smelt under argon protection, and grind and polish; step four, Carry out ion implantation of tantalum or niobium on the surface of AuAl ₂ , and then perform annealing and diffusion under the protection of argon gas; Step 5 is to prepare an electrolyte for anodizing; Step 6 is to perform anodizing treatment. It can not only ensure the color quality of 18K purple gold aluminum alloy, but also obtain a dense composite oxide film to improve corrosion resistance.

Description

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

Technical field

The present invention relates to a preparation method of gold alloy, which is mainly used as jewelry material or electronic material. Specifically, it is a preparation method of highly efficient and corrosion-resistant 18K purple gold aluminum alloy.

Background technique

Gold aluminum alloy (chemical formula AuAl ₂ ) 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, AuAl ₂ exists at the bonding interface. After long-term use, the heat generated by the current will cause AuAl ₂ to be easily oxidized or corroded, affecting the service life of components. In addition, AuAl ₂ 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 alloys is of great significance. Anodizing is a surface treatment process widely used for aluminum alloys. The corrosion resistance of the surface aluminum oxide film is closely related to process parameters such as electrolyte composition, oxidation voltage, oxidation time, and oxidation temperature. Domestic and foreign scholars have conducted a large number of studies on the preparation of anodized films of aluminum alloys and their related properties, but there are few studies on the anodizing treatment of gold-aluminum alloys.

Contents of the invention

This invention aims to improve the corrosion resistance of 18K purple gold-aluminum alloy through anodizing. By configuring a special electrolyte, the gold-aluminum alloy is anodized under different process parameters such as voltage, oxidation time and temperature, and a deposit is required. The color quality of aluminum alloy can also improve the corrosion resistance.

To this end, the technical solution adopted by the present invention is: a preparation method of highly efficient corrosion-resistant 18K purple gold aluminum alloy, which includes the following steps:

Step 1, raw material preparation;

Prepare the following raw materials according to the mass ratio: 75 to 83 parts of gold, 23 to 24.5 parts of aluminum, 0.5 to 2 parts of rare earth, and 0.5 to 2 parts of other metal tantalum or niobium. The gold content of the gold raw material is 99.99%, and the aluminum raw material is 99.99%. Aluminum content is 99.99%;

Step 2: First mix gold raw materials and part of aluminum raw materials into a vacuum medium frequency induction furnace to prepare a gold-aluminum alloy and then take it out. Then mix rare earth raw materials and remaining aluminum raw materials into a vacuum medium frequency induction furnace to prepare aluminum-based rare earth materials. Take out the alloy; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder. The grinding time is 28 to 32 hours, and the minimum particle size is 0.1 to 0.5 microns;

Step 3: Stir the ground alloy powder evenly before smelting, and use a die to compact it into a cake; use a water-cooled copper crucible in a vacuum arc melting furnace to smelt the alloy powder under the protection of argon gas, and repeatedly turn it over. After smelting 3 to 5 times, 18K purple AuAl ₂ is obtained; then it is polished and polished to a mirror-like effect, and there are no scratches or stains when observed under a 100x microscope;

Step 4: Carry out ion implantation of tantalum or niobium on the surface of 18K purple AuAl ₂ , the implantation energy is 60~80kv, the implantation dose is 0.5×10 ¹⁷ cm ^-2 ~ 8×10 ¹⁷ cm ^-2 , and then in 5% hydrogen and 95 Perform annealing and diffusion under the protection of argon gas, the annealing time is 3h~5h, the annealing temperature is 300~500℃, and a tantalum or niobium layer is obtained on the surface of 18K purple _AuAl2 ;

Step 5: Equip with anodized electrolyte;

Add oxalic acid, boric acid, cubanedicarboxylic acid and active agent to the deionized water solvent, as follows: oxalic acid 28~32g: boric acid 8~12g: cubanedicarboxylic acid 4~6g: active agent 4~6g: deionized water Configure a mixed solution with a ratio of 1L, and then use 0.1 to 0.2 mol/L sodium hydroxide solution to adjust the pH value of the mixed solution to 1 to 5 to form an electrolyte for anodization;

Step 6: Pour the prepared anodized electrolyte into the electrolytic tank, place the electrolytic tank in a constant temperature water bath, then fix the AuAl ₂ alloy as the anode on the acrylic plate and put it into the electrolyte, and mix it with the cathode. The lead plates are 45 to 50 mm apart and anodized at a voltage of 3 to 10 V, a time of 45 to 300 seconds, and a temperature of 25 to 40°C.

Preferably, the rare earth is at least one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, yttrium or scandium.

It is further preferred that the active agent provided with the electrolyte is a mixture of ammonium dichromate and potassium citrate, and the mass ratio of ammonium dichromate and potassium citrate is 1:1.

More preferably, the anodizing voltage is 5V, the time is 120s, and the temperature is 35°C.

More preferably, the vacuum induction melting temperature is 1000 to 1500°C.

More preferably, the number of vacuum arc melting times is 4 times.

It is further preferred that when preparing the mixed solution, the ratio is 30g of oxalic acid: 10g of boric acid: 5g of cubanedicarboxylic acid: 5g of active agent: 1L of deionized water.

It is further preferred that the vacuum ball mill is set to have a revolution of 300 r/min and a rotation of 600 r/min.

Beneficial effects of the present invention:

(1) By adding rare earth elements to gold-aluminum alloys, it can play a role in micro-alloying, 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 A dense oxide film is formed on the surface of the alloy to enhance the corrosion resistance of the gold-aluminum alloy, making the gold-aluminum alloy a new material with excellent corrosion resistance.

(2) Vacuum induction melting technology is used to smelt aluminum-based rare earth master alloys. This melting technology can remove impurity elements and reduce the burning loss of rare earth elements; at the same time, the aluminum raw material is divided into two parts, and one part is mixed with the gold raw material and placed in a vacuum medium frequency induction furnace A gold-aluminum alloy is prepared, and the other part is mixed with rare earth raw materials and put into a vacuum medium frequency induction furnace to prepare an aluminum-based rare earth alloy. This can effectively avoid the evaporation of rare earths when gold, aluminum, and rare earth are simultaneously put into a vacuum medium frequency induction furnace to prepare a gold-aluminum alloy. The resulting burning loss can effectively control the rare earth content in the alloy, so that the corrosion resistance of the gold-aluminum alloy can be improved while retaining the purple characteristics; vacuum arc melting technology is used to avoid oxidation of the alloy during the smelting process.

(3) The vacuum environment provided by the vacuum ball mill can avoid the oxidation of the alloy during the grinding process; after grinding into powder, it can ensure that the various alloy components are fully mixed. Before smelting, the ground alloy powder is stirred evenly, and a stamping die is used to Compact into a cake to avoid powder splashing during the smelting process; at the same time, use a water-cooled copper crucible in a vacuum arc melting furnace to smelt the alloy powder under the protection of argon gas, and repeatedly turn it over and smelt multiple times to ensure that the alloy is as high as possible Fusion evenly.

(4) Grinding and polishing are performed first, and then ion implantation and anodizing are performed. On the one hand, it is more convenient for subsequent ion implantation and anodizing. On the other hand, grinding and polishing are no longer performed after ion implantation and anodizing, and grinding and polishing can also be avoided. During the process, the ion implantation layer and the anodized layer are destroyed, further improving the corrosion resistance and improving the appearance quality of the final product.

(5) Annealing diffusion is used after ion implantation. Compared with conventional diffusion in the atmosphere, it can help to uniformly distribute the injected tantalum ions on the surface of the alloy, thereby avoiding the early formation of oxide films; tantalum ions are implanted separately, rather than with rare earths. Injecting them together will help obtain a composite oxide film of aluminum oxide and tantalum oxide/niobium oxide during the subsequent anodization process, further improving the corrosion resistance of the alloy.

(6) Using a mixed solution prepared with a certain concentration of oxalic acid, boric acid, cubanedicarboxylic acid and active agent as the electrolyte can increase the temperature range and oxidation efficiency of anodizing, improve the hardness and wear resistance of the film layer, and within a certain The gold-aluminum alloy is anodized under voltage, oxidation time and temperature. The aluminum oxide film on the surface protects the gold-aluminum alloy and improves the corrosion resistance of the gold-aluminum alloy.

In summary, the present invention uses gold and aluminum as the base material of the alloy, adds a certain amount of rare earth elements and other elements tantalum or niobium, and smelts the gold-aluminum alloy through vacuum induction melting and vacuum arc melting technology, and combines grinding, compaction, and polishing. Polishing, ion implantation, anodizing and other treatment processes 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 dense composite oxide film, achieving bright colors and corrosion resistance. Purple 18K gold aluminum alloy material with improved performance.

Detailed ways

The present invention will be further described below through examples:

Example 1:

A method for preparing highly efficient corrosion-resistant 18K purple gold aluminum alloy, including the following steps:

Step 1, raw material preparation;

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%.

Step 2: First mix 83 parts of gold raw materials and 10 parts of aluminum raw materials into a vacuum medium frequency induction furnace to prepare the gold-aluminum alloy and take it out. Then mix 2 parts of rare earth lanthanum raw materials and the remaining 14.5 parts of aluminum raw materials into a vacuum medium frequency induction furnace. In the furnace, the aluminum-based rare earth alloy is prepared and taken out; the vacuum induction melting temperature is 1000 to 1500°C. Use a vacuum ball mill to grind gold aluminum alloy and 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 rotate at 300r/min and rotate at 600r/min, but it is not limited to this.

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 smelt the alloy powder under the protection of argon gas. Repeat the turning over and smelting 5 times to ensure that the alloy is fused as uniformly as possible to obtain 18K purple AuAl ₂ . Then polish and polish to a mirror-like effect, and observe under a 100x microscope without scratches or stains.

Step 4: Carry out ion implantation of tantalum on the surface of 18K purple AuAl ₂ , the implantation energy is 80kv, the implantation dose is 8×10 ¹⁷ cm ^-2 , and then annealed and diffused 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 AuAl ₂ , and the ion-implanted tantalum forms an oxide film on the surface of 18K purple AuAl ₂ . Step 5: Equip with anodized electrolyte.

Add oxalic acid, boric acid, cubanedicarboxylic acid and active agent to the deionized water solvent, and prepare a mixed solution according to the ratio of 32g of oxalic acid: 12g of boric acid: 6g of cubanedicarboxylic acid: 6g of active agent: 1L of deionized water. , and then use 0.2 mol/L sodium hydroxide solution to adjust the pH value of the mixed solution to 5, and configure it into an electrolyte for anodization.

Step 6: Pour the prepared anodized electrolyte into the electrolytic tank, place the electrolytic tank in a constant temperature water bath, then fix the AuAl ₂ alloy as the anode on the acrylic plate and put it into the electrolyte, and mix it with the cathode. The lead plates are 50mm apart and anodized at a voltage of 10V, a time of 300s, and a temperature of 40°C to form a composite oxide film of aluminum oxide and tantalum oxide on the surface of the 18K purple AuAl ₂ alloy.

Example 2:

A method for preparing highly efficient corrosion-resistant 18K purple gold aluminum alloy, including the following steps:

Step 1, raw material preparation;

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%.

Step 2: First mix 80 parts of gold raw materials and 12 parts of aluminum raw materials into a vacuum medium frequency induction furnace to prepare the gold-aluminum alloy and take it out. Then mix 1 part of rare earth neodymium raw materials and the remaining 12 parts of aluminum raw materials into the vacuum medium frequency induction furnace. In the furnace, prepare the aluminum-based rare earth alloy and take it out; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder. The grinding time is 30 hours and the minimum particle size is 0.3 microns.

Step 3: Stir the ground alloy powder evenly before smelting and compact it into a cake using a die. Use a water-cooled copper crucible in a vacuum arc melting furnace to smelt the alloy powder under the protection of argon gas. Repeat the turning and smelting four times to obtain 18K purple AuAl ₂ . Then polish and polish to a mirror-like effect, and observe under a 100x microscope without scratches or stains.

Step 4: Carry out ion implantation of niobium on the surface of 18K purple AuAl ₂ , the implantation energy is 70kv, the implantation dose is 4×10 ¹⁷ cm ^-2 , and then annealed and diffused under the protection of 5% hydrogen and 95% argon. The annealing time is 4h, the annealing temperature is 400°C, niobium is obtained on the surface of 18K purple AuAl ₂ , and the ion-implanted niobium forms an oxide film on the surface of 18K purple AuAl ₂ .

Step 5: Equip with anodized electrolyte.

Add oxalic acid, boric acid, cubanedicarboxylic acid and active agent to the deionized water solvent, and prepare a mixed solution according to the ratio of 30g of oxalic acid: 10g of boric acid: 5g of cubanedicarboxylic acid: 5g of active agent: 1L of deionized water. , and then use 0.1/L sodium hydroxide solution to adjust the pH value of the mixed solution to 3, and configure it into an electrolyte for anodization.

Step 6: Pour the prepared anodized electrolyte into the electrolytic tank, place the electrolytic tank in a constant temperature water bath, then fix the AuAl ₂ alloy as the anode on the acrylic plate and put it into the electrolyte, and mix it with the cathode. The lead plates are 48mm apart and anodized at a voltage of 5V, a time of 120s, and a temperature of 35°C to form a composite oxide film of aluminum oxide and niobium oxide on the surface of the 18K purple AuAl ₂ alloy.

Example 3:

A method for preparing highly efficient corrosion-resistant 18K purple gold aluminum alloy, including the following steps:

Step 1, raw material preparation;

Prepare the following raw materials according to the mass ratio: 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%.

Step 2: First mix 75 parts of gold raw materials and 8 parts of aluminum raw materials into a vacuum medium frequency induction furnace to prepare the gold-aluminum alloy and take it out. Then mix 0.5 parts of rare earth yttrium raw materials and the remaining 15 parts of aluminum raw materials into the vacuum medium frequency induction furnace. In the furnace, prepare the aluminum-based rare earth alloy and take it out; 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 ground to a minimum particle size of 0.5 microns.

Step 3: Stir the ground alloy powder evenly before smelting and compact it into a cake using a die. Use a water-cooled copper crucible in a vacuum arc melting furnace to smelt the alloy powder under the protection of argon gas. Repeat the turning over and smelting three times to obtain 18K purple AuAl ₂ . Then polish and polish to a mirror-like effect, and observe under a 100x microscope without scratches or stains.

Step 4: Carry out ion implantation of niobium on the surface of 18K purple AuAl ₂ , the implantation energy is 60kv, the implantation dose is 0.5×10 ¹⁷ cm ^-2 , and then annealed and diffused under the protection of 5% hydrogen and 95% argon. The annealing time is 3h, the annealing temperature is 300°C, niobium is obtained on the surface of 18K purple _AuAl2 , and the ion-implanted niobium forms an oxide film on the surface of 18K purple _AuAl2 .

Step 5: Equip with anodized electrolyte.

Add oxalic acid, boric acid, cubanedicarboxylic acid and active agent to the deionized water solvent, and prepare a mixed solution according to the ratio of 28g of oxalic acid: 8g of boric acid: 4g of cubanedicarboxylic acid: 4g of active agent: 1L of deionized water. , and then use 0.1/L sodium hydroxide solution to adjust the pH value of the mixed solution to 1, and configure it into an electrolyte for anodization.

Step 6: Pour the prepared anodized electrolyte into the electrolytic tank, place the electrolytic tank in a constant temperature water bath, then fix the AuAl ₂ alloy as the anode on the acrylic plate and put it into the electrolyte, and mix it with the cathode. The lead plates are 45mm apart and anodized at a voltage of 3V, a time of 45s, and a temperature of 25°C to form a composite oxide film of aluminum oxide and niobium oxide on the surface of the 18K purple AuAl ₂ alloy.

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

Claims (8)

1. A method for preparing a highly corrosion-resistant 18K purple gold aluminum alloy, which is characterized by comprising the following steps: Step 1, raw material preparation; Prepare the following raw materials according to the mass ratio: 75 to 83 parts of gold, 23 to 24.5 parts of aluminum, 0.5 to 2 parts of rare earth, and 0.5 to 2 parts of other metal tantalum or niobium. The gold content of the gold raw material is 99.99%, and the aluminum raw material is 99.99%. Aluminum content is 99.99%; Step 2: First mix gold raw materials and part of aluminum raw materials into a vacuum medium frequency induction furnace to prepare a gold-aluminum alloy and then take it out. Then mix rare earth raw materials and remaining aluminum raw materials into a vacuum medium frequency induction furnace to prepare aluminum-based rare earth materials. Take out the alloy; use a vacuum ball mill to grind the gold-aluminum alloy and the aluminum-based rare earth alloy into powder. The grinding time is 28 to 32 hours, and the minimum particle size is 0.1 to 0.5 microns; Step 3: Stir the ground alloy powder evenly before smelting, and use a die to compact it into a cake; use a water-cooled copper crucible in a vacuum arc melting furnace to smelt the alloy powder under the protection of argon gas, and repeatedly turn it over. Smelting 3 to 5 times to obtain 18K purple AUAL ₂ ; then polished and polished to a mirror effect, no scratches or stains when observed under a 100x microscope; Step 4: Carry out ion implantation of tantalum or niobium on the surface of 18K purple AuAl ₂ , the implantation energy is 60~80kv, the implantation dose is 0.5×10 ¹⁷ cm ^-2 ~ 8×10 ¹⁷ cm ^-2 , and then in 5% hydrogen and 95 Perform annealing and diffusion under the protection of argon gas, the annealing time is 3h~5h, the annealing temperature is 300~500℃, and a tantalum or niobium layer is obtained on the surface of 18K purple _AuAl2 ; Step 5: Equip with anodized electrolyte; Add oxalic acid, boric acid, cubanedicarboxylic acid and active agent to the deionized water solvent, as follows: oxalic acid 28~32g: boric acid 8~12g: cubanedicarboxylic acid 4~6g: active agent 4~6g: deionized water Configure a mixed solution with a ratio of 1L, and then use 0.1 to 0.2 mol/L sodium hydroxide solution to adjust the pH value of the mixed solution to 1 to 5 to form an electrolyte for anodization; Step 6: Pour the prepared anodized electrolyte into the electrolytic tank, place the electrolytic tank in a constant temperature water bath, then fix the AuAl ₂ alloy as the anode on the acrylic plate and put it into the electrolyte, and mix it with the cathode. The lead plates are 45 to 50 mm apart and anodized at a voltage of 3 to 10 V, a time of 45 to 300 seconds, and a temperature of 25 to 40°C. 2. According to the preparation method of highly efficient corrosion-resistant 18K purple gold aluminum alloy according to claim 1, it is characterized in that: the rare earth is at least one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, yttrium or scandium. A sort of. 3. According to the preparation method of high-efficiency corrosion-resistant 18K purple gold aluminum alloy according to claim 1, it is characterized in that: the active agent equipped with the electrolyte is a mixture of ammonium dichromate and potassium citrate, and ammonium dichromate and The mass ratio of potassium citrate is 1:1. 4. The preparation method of the high-efficiency corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: the voltage of the anodizing treatment is 5V, the time is 120s, and the temperature is 35°C. 5. The preparation method of highly efficient corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: the vacuum induction melting temperature is 1000-1500°C. 6. A method for preparing a high-efficiency corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: the number of vacuum arc melting times is 4 times. 7. A method for preparing a high-efficiency corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: when configuring the mixed solution, 30g of oxalic acid: 10g of boric acid: 5g of cubanedicarboxylic acid: 5g of active agent : The ratio of 1L of deionized water. 8. A method for preparing a high-efficiency corrosion-resistant 18K purple gold aluminum alloy according to claim 1, characterized in that: the vacuum ball mill is set to rotate at 300r/min and rotate at 600r/min.