CN110894617A

CN110894617A - 3D platinum electroforming process method

Info

Publication number: CN110894617A
Application number: CN201811068312.0A
Authority: CN
Inventors: 邓达贤
Original assignee: Shenzhen Yongdarui International Technology Co Ltd
Current assignee: Shenzhen Yongdarui International Technology Co Ltd
Priority date: 2018-09-13
Filing date: 2018-09-13
Publication date: 2020-03-20

Abstract

The invention relates to a 3D platinum electroforming process method, which comprises the following steps: coating a conductive silver paste layer on the surface of the wax mould core to change the wax mould core into a conductor; and electrifying and electroforming the wax mold core by adopting a platinum solution in an ultrasonic environment to obtain a corresponding product. The method can remove hydrogen gas attached to the surface of the electroplating layer in the platinum electroforming process, thereby solving the problem of hydrogen embrittlement and realizing the platinum electroforming process.

Description

3D platinum electroforming process method

Technical Field

The invention relates to a platinum electroforming process.

Background

The traditional platinum jewelry processing is produced by adopting a mode of reverse molding, oil pressure or mechanical processing, but some fashionable and exquisite jewelry are difficult to manufacture by adopting the mode. The electroforming process is a common jewelry processing method, the jewelry produced by the process can realize a complex structure and patterns, and compared with a product produced by the traditional process, the 3D jewelry produced by the process can reduce more than half of the weight, has higher hardness which can reach 300-400 HV and purer purity. However, hydrogen is easily attached to the surface of the platinum layer during the electroforming process, and the hydrogen embrittlement cracking phenomenon occurs when the thickness of the platinum layer is more than 10 micrometers.

Disclosure of Invention

One technical problem addressed by one aspect of the present disclosure is to provide an improved electroforming process, which is suitable for electroforming platinum.

The technical scheme adopted by the invention for solving the technical problems is as follows: the 3D platinum electroforming process method comprises the following steps:

coating a conductive silver paste layer on the surface of the wax mould core to change the wax mould core into a conductor;

and electrifying and electroforming the wax mold core by adopting a platinum solution in an ultrasonic environment to obtain a corresponding product.

According to the 3D platinum electroforming process method, dewaxing treatment is carried out on the corresponding product so as to completely dissolve the wax mould core in the dewaxing aqueous solution to obtain a platinum blank; removing the silver paste layer of the platinum blank, and then carrying out annealing treatment to reduce the hardness of the platinum blank; and (4) polishing the annealed platinum blank, and cleaning to obtain a finished product.

The specific way of dewaxing the corresponding product by the 3D platinum electroforming process method is as follows: cooking with 10% wax-removing water solution at 100 deg.C for more than 2 hr.

The 3D platinum electroforming process method has the specific mode of removing the silver paste layer as follows: putting the platinum blank into concentrated nitric acid, continuously replacing the concentrated nitric acid for three times under the boiling condition, and keeping the boiling state of the concentrated nitric acid for one hour each time.

The 3D platinum electroforming process method comprises the following specific steps: annealing at constant temperature of 450 ℃ for 3 hours.

The 3D platinum electroforming process method comprises the following specific steps: connecting the wax mould core coated with the silver paste layer to a negative electrode of a direct current power supply, connecting a positive electrode of the wax mould core to a titanium mesh coated with osmium oxide, putting the wax mould core into a platinum solution at 40-65 ℃, electrifying and electroforming, and weighing the wax mould core according to a certain preset time to obtain the platinum weight of the current electroforming and the time required for completing the whole electroforming.

According to the 3D platinum electroforming process method, the platinum solution is obtained by the following steps: hydrochloric acid is taken to dissolve diammine platinum dinitrate to obtain a solution, sulfuric acid is added to stabilize the pH value of the solution, and an additive nitrous acid is added to reduce the brittleness of the platinum plating layer.

One advantageous effect brought by one aspect of the present disclosure: the problem of hydrogen embrittlement is solved in an ultrasonic environment, and the strong brittleness of the platinum coating is eliminated, so that 3D platinum electroforming is realized.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments.

All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.

The jewelry produced by the 3D platinum electroforming process can realize a complex structure and patterns, and compared with the product produced by the traditional process, the 3D platinum jewelry produced by the process has the advantages that the weight can be reduced by more than half, the hardness is higher and can reach 300-400 HV, the purity is purer, and the Pt content can reach more than 99.9%.

The platinum electroforming process is summarized as follows: 99.99 percent of pure platinum is used as a raw material, dissolved by aqua regia and neutralized by alkali, and then is complexed by nitrite to generate diammineplatinum dinitrate which is used as main salt for producing the 3D electroformed platinum. Dissolving diammineplatinum dinitrate with hydrochloric acid under an acidic condition, depositing metal platinum on the surface of a wax mould (silver paste spraying and conducting should be firstly used on the surface of a wax piece) by using special direct current (generally 220V input and 12V100A output silicon controlled rectifier direct current power supply) at the temperature of 40-65 ℃, performing electrifying deposition for 15-30 hours to form a pure platinum coating with the surface area of the wax mould core reaching 100-200 microns, dissolving the wax mould core at high temperature (such as 150 ℃), and dissolving the internal silver paste coating by using nitric acid to obtain a 3D hard platinum jewelry mould blank. And cleaning the 3D hard platinum jewelry mould blank, and polishing and brightening the surface of the mould blank to obtain a finished product of the 3D hard platinum jewelry.

The platinum electroforming process flow comprises the following steps: wax mold core → coating conductive silver paste → electroforming 3D hard platinum → removing wax mold core → boiling nitric acid to remove silver paste layer → high temperature annealing → surface polishing → finished product.

Wherein:

the wax mold core is made of special 65 ℃ resistant wax for molds by injection molding through a wax injection machine.

And (3) coating conductive silver paste, namely coating a conductive silver paste layer on the surface of the wax mold core by using the nanoscale conductive silver paste so as to change the non-conductive wax mold core into a conductor.

Electroforming 3D hard platinum, wherein the whole process is carried out in an ultrasonic environment (generally, ultrasonic equipment is adopted, and the electroforming process is completed in a groove body), and hydrogen attached to an electroplated layer is removed by utilizing ultrasonic waves. Connecting the wax mould core coated with the silver paste layer to the negative electrode of a direct current power supply, connecting the positive electrode to the upper surface of a titanium mesh coated with osmium oxide, putting the titanium mesh into an electroforming platinum solution for electrifying electroforming, and generally electroforming a platinum layer with the weight of 1 kilogram, wherein the output of the power supply is required to be adjusted to be 15A, and the supplement amount of additive nitrous acid is 1000 milliliters. In the electroforming process, the solution is heated by a titanium material heating pipe with a constant temperature to keep the temperature at 50 ℃, and at the time point of electroforming for 15 hours, the die core piece is taken out and weighed, so that the platinum with the weight which is needed to be electroformed on the surface of the die core piece is observed according to the amount of platinum which is actually electroformed on the surface of the die core piece. And calculating the working time of the subsequent electroforming to the platinum layer with the required weight according to the weight of the platinum and the current of the electroforming in the previous 15 hours. After the electroforming thickness of the platinum layer reaches the required requirement, the surface of an electroformed product needs to be washed clean by pure water, and the washed water is filtered and poured back into the electroforming solution. 2-3 small holes are drilled on the product after electroforming at a hidden position by a 0.8 mm drill bit, and then the product is sent to a dewaxing mould process, so that wax can smoothly flow out when a dewaxing mould core is used for the subsequent process.

And (3) removing the wax mould core, and boiling the wax mould core for more than 2 hours at 100 ℃ by using 10% wax removing aqueous solution so as to completely dissolve the wax mould core in the wax removing aqueous solution.

Boiling nitric acid to remove the silver paste layer: removing the silver paste layer on the inner wall of the 3D hard platinum blank from which the wax mold core is removed by using concentrated nitric acid, continuously replacing the nitric acid for three times under the boiling condition, boiling the nitric acid for one hour each time, and completely removing the silver paste layer on the inner surface of the blank to obtain the 3D hard platinum blank with the purity of more than 99.9 percent.

And (2) high-temperature annealing, wherein the plating layer of the platinum blank treated by the process is hard plated at about 400HV, if the surface is directly polished, the platinum blank is easy to crack, the platinum blank is annealed at the constant temperature of 450 ℃, and after 3 hours of annealing at 450 ℃, the hardness of the plating layer of the platinum blank is reduced to 200HV, and meanwhile, the platinum blank has flexibility and can be subjected to any form of subsequent machining.

And (3) polishing the surface, polishing the annealed platinum blank by using 800 medium size abrasive paper, polishing the rough part of the surface to be smooth, and polishing the platinum blank to a mirror surface effect by using a cloth wheel.

Cleaning and drying to obtain the finished product.

The technological parameters of the electroforming platinum solution are preferably as follows:

hydrochloric acid HCI (10ml/L preferred concentration) is adopted to dissolve diammineplatinum dinitrate so as to prevent the diammineplatinum dinitrate from being hydrolyzed and precipitated, the platinum concentration is 10-20 g/L (preferably 15 g/L), the diammineplatinum dinitrate concentration is 20-35 g/L (preferably 30 g/L), and the additive nitrous acid with the concentration of 3 g/L is used, so that the brittleness of a platinum plating layer can be reduced, and the toughness of the platinum plating layer can be improved; adding 10ml/L sulfuric acid to adjust the pH of the working solution and increase the conductivity, wherein the pH value range of the solution is as follows: 0.1 to 2.0 (optimum condition 1.0), use temperature: 40-65 ℃ (the best using condition is 50 ℃), and the ultrasonic frequency is 60HZ, and the hydrogen attached to the surface of the electroplating layer in the platinum electroforming working process is removed by utilizing ultrasonic waves, so that the problem of hydrogen embrittlement is solved.

A thickness of 1 μm can be electroformed in 5 minutes, generally under conditions of 1A/dm2, and the stirring speed of the solution is preferably 5 m/min. The solution was continuously filtered using a filter of PP material with 1 micron porosity, for more than 6 cycles of filtration, for 1 hour per 1 litre of solution. The platinum electroformed layer preferably has a density of 21.45 g/cm 3, a melting point of 1772 ℃ and a boiling point of 3827 ℃. + -. 100.

The following are specific electroforming examples:

example one

Example two

EXAMPLE III

In combination with the three embodiments, it can be seen that as the electroforming current increases, the electroforming speed and the hardness of the finished product are correspondingly increased.

In conclusion, by matching with ultrasonic equipment, under the acidic condition with extremely high strength, nitrous acid is used as an additive, and the nitrous acid is matched with hydrochloric acid for complexing, so that the problem of hydrogen embrittlement in the platinum electroplating process is solved, the strong brittleness of a platinum coating is eliminated, the coating can reach more than 200 micrometers, and hydrogen embrittlement cracking is avoided, and the 3D platinum electroforming is realized.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the present invention, as it will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

The 3D platinum electroforming process method is characterized by comprising the following steps of:

coating a conductive silver paste layer on the surface of the wax mould core to change the wax mould core into a conductor;

and electrifying and electroforming the wax mold core by adopting a platinum solution in an ultrasonic environment to obtain a corresponding product.
2. The 3D platinum electroforming process of claim 1 wherein:

dewaxing the corresponding product to completely dissolve the wax mold core in a dewaxing aqueous solution to obtain a platinum blank;

removing the silver paste layer of the platinum blank, and then carrying out annealing treatment to reduce the hardness of the platinum blank;

and (4) polishing the annealed platinum blank, and cleaning to obtain a finished product.
3. The 3D platinum electroforming process of claim 2 wherein the specific way to dewax the corresponding article is: cooking with 10% wax-removing water solution at 100 deg.C for more than 2 hr.
4. The 3D platinum electroforming process method according to claim 2 wherein the specific manner of removing the silver paste layer is: putting the platinum blank into concentrated nitric acid, continuously replacing the concentrated nitric acid for three times under the boiling condition, and keeping the boiling state of the concentrated nitric acid for one hour each time.
5. The 3D platinum electroforming process method according to claim 2, wherein the specific manner of the annealing treatment is as follows: annealing at constant temperature of 450 ℃ for 3 hours.
6. The 3D platinum electroforming process method according to claim 1, wherein the specific mode of electroforming is as follows: connecting the wax mould core coated with the silver paste layer to a negative electrode of a direct current power supply, connecting a positive electrode of the wax mould core to a titanium mesh coated with osmium oxide, putting the wax mould core into a platinum solution at 40-65 ℃, electrifying and electroforming, and weighing the wax mould core according to a certain preset time to obtain the platinum weight of the current electroforming and the time required for completing the whole electroforming.
7. The 3D platinum electroforming process method according to claim 1 wherein said platinum solution is obtained by: hydrochloric acid is taken to dissolve diammine platinum dinitrate to obtain a solution, sulfuric acid is added to stabilize the pH value of the solution, and an additive nitrous acid is added to reduce the brittleness of the platinum plating layer.