Process for hardening gold through micro-nano metal powder

Abstract

The invention relates to the technical field of precious metal alloy material manufacturing, in particular to a process for hardening treatment of gold through micro-nano metal powder, which comprises the steps of blank charging, smelting, vacuum ingot casting, surface cleaning, rolling stretching and age hardening, product surface treatment, product welding and the like. The method has the advantages that in the aspect of material selection, the micro-nano metal powder, such as titanium powder and cobalt powder, is diversified and is small in adding amount, various strengthening mechanisms can be provided, and the economical efficiency is guaranteed. The smelting process is accurate, good vacuum and temperature control is achieved, and stirring is uniform after micro-nano metal powder is added. And rapidly solidifying the cast ingot by using a water-cooling copper mold, treating the surface by using aqua regia and the like, and drying. Midway annealing can be executed through rolling and stretching, and the process is flexible. Product manufacturing processes are diversified, and surface treatment includes polishing, electroplating, coloring and the like. Advanced modes such as laser are adopted for welding to avoid hardness reduction. According to the process, the gold hardening treatment effect and quality are improved from multiple aspects, different requirements are met, and wide application prospects are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of precious metal alloy material manufacturing, and in particular to a process for hardening gold using micro-nano metal powder. Background Art

[0002] Traditional gold processing technology has deficiencies in many aspects, which seriously restricts the quality and performance improvement of gold products and is difficult to meet the diversified needs of the market. In gold hardening technology, the alloy addition method faces the problems of single material selection and limited addition ratio. Although commonly used alloying elements can increase hardness, they cannot provide the unique properties of micro-nano metal powders, and each has its own defects, which will also affect the purity, appearance and other properties of gold. The heat treatment method has imprecise temperature control and high energy consumption, resulting in uneven crystal structure, affecting hardness and performance stability, while increasing costs and environmental burdens. The cold working method has uneven hardening and is prone to stress concentration, which affects product quality and performance, reduces fatigue resistance and toughness, and shortens service life. Electroforming technology has complex processes, high costs, and great product limitations. Hard gold products are hollow and differ from traditional pure gold in terms of recycling. Gold smelting and ingot casting technology also has defects. It is difficult to ensure the vacuum degree during the smelting process, which affects the purity and quality of gold and leads to defects such as pores and inclusions. The temperature control during the ingot casting process is unstable, which affects the uniformity of the alloy composition; the slow solidification speed makes the grain size large and the crystal defects numerous, which reduces the strength and hardness; the surface quality is poor, which increases the difficulty and cost of subsequent processing. Gold surface treatment and welding technology also need to be improved. The surface treatment effect is limited and lacks diversity, and it cannot meet the requirements of high gloss and flatness, and the corrosion resistance is poor. The welding quality of welding technology is unstable, and the flame welding temperature and time are difficult to control, which affects the product quality; it has high environmental requirements, produces waste gas and waste slag, and pollutes the environment. These deficiencies have generally restricted the development of gold processing technology and the quality improvement of gold products. There is an urgent need to innovate and improve technology to adapt to market demand and industry development trends.

[0003] The Chinese invention patent application with publication number CN105420650A discloses a hardening process for gold products, which includes placing the gold product workpiece to be processed into a hardness tester to test the hardness, and using a balance to weigh the gold product workpiece to be processed; adjusting the amount of hardening raw materials used according to the hardness and weight data of the gold product workpiece to be processed; placing the hardening raw materials and the gold product workpiece to be processed into a heating crucible, and then placing the crucible into a sealed can, and placing the sealed can into a box-type vacuum resistance furnace for several heating, temperature rise and insulation stages; taking the fired gold product workpiece out of the sealed can, rinsing it with clean water, placing the gold product workpiece into a hardness tester to test the hardness value after treatment, and using a balance to weigh the weight of the gold product workpiece after treatment. It still cannot solve the above-mentioned shortcomings and is difficult to meet the needs of existing processes. Summary of the invention

[0004] The purpose of the present invention is to provide a process for hardening gold with micro-nano metal powder to solve the problems raised in the above background technology. To solve the above technical problems, the technical solution provided by the present invention is: a process for hardening gold with micro-nano metal powder,

[0005] The following steps are involved:

[0006] 1) Billet charging: weighing the gold base material, weighing the micro-nano metal powder according to 0.1-1% mass percentage of the gold base material, putting it into the secondary material boat, and putting the weighed gold base material into the crucible; the micro-nano metal powder is at least one of micro-nano titanium powder, micro-nano cobalt powder, micro-nano beryllium powder, and micro-nano aluminum powder;

[0007] 2) Melting: Turn on the power, evacuate, start the diffusion pump to heat, continue heating to 1400-1700℃, add micro-nano metal powder, wait for the micro-nano metal powder to melt into the gold solution, start the mechanical stirrer to stir it thoroughly, and the melting and batching are completed to obtain 999 gold melt;

[0008] 3) Vacuum ingot casting: 15-18℃ water is passed into the water-cooled copper mold to maintain it, the crucible is poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify into a sub-millimeter smooth and dense body within ten seconds, and the solidification casting is completed to obtain an ingot;

[0009] 4) Surface cleaning: Soak the ingot in a beaker of aqua regia, heat to 80-90℃ for 30-40 minutes, rinse clean, and dry in an oven at 200℃;

[0010] 5) Rolling and stretching, aging hardening: clean the rolls and perform rolling operations;

[0011] 6) Product surface treatment: mechanical grinding and polishing to ensure that it has sufficient strength for gemstone inlay, electroplating and coloring;

[0012] 7) Product welding.

[0013] Preferably, in step 5), the rolling passes and the feed rate are performed according to the designed process, the rolling process causes material hardening, a predetermined intermediate annealing and softening process is performed during the rolling process, and the annealing and softening and aging hardening are performed in a tunnel furnace or a muffle furnace.

[0014] Preferably, in step 8), laser welding, energy storage welding or argon arc welding is used for welding to avoid hardness reduction due to long-term flame heating.

[0015] Preferably, the smelting process in step 2) adopts a vacuum secondary charging smelting furnace, and mechanical stirring is performed in the furnace during the smelting process.

[0016] Preferably, in step 2), the diffusion pump is preheated for 60 minutes; after the vacuum reaches 100 Pa, heating is started, and the temperature is continuously increased at a heating rate of 50-150° C. / min. After the temperature reaches 750-950° C., the diffusion pump is turned on for high vacuum deoxidation, and the vacuum is maintained for 6×10 -2 Pa, fill with argon to maintain 50-100Pa, after the micro-nano metal powder is melted into the gold solution, start the mechanical stirrer to stir it thoroughly for 30 seconds, and the melting and batching is completed.

[0017] Preferably, in the step 2), the micro-nano metal powder is micro-nano cobalt powder which is evacuated and filled with argon at room temperature for protection, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano titanium powder, introduce a mixed gas of oxygen, argon and nitrogen, and heat it at 150°C to keep it warm, and then wait for use after an oxide film is formed on the surface of the powder.

[0018] Preferably, in the step 2), the micro-nano metal powder is made of micro-nano titanium powder, which is evacuated and filled with argon gas for protection at room temperature, and is pre-oxidized before use. The pre-oxidation treatment method is to pre-mix it with micro-nano cobalt powder, introduce oxygen, argon and nitrogen mixed gas, heat it at 150°C and keep it warm, and wait for use after an oxide film is formed on the surface of the powder.

[0019] Preferably, in the step 2), the micro-nano metal powder is made of micro-nano aluminum powder, which is evacuated and filled with argon at room temperature for protection, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano beryllium powder and micro-nano cobalt powder, introduce oxygen, argon and nitrogen mixed gas, heat it at 150°C and keep it warm, and wait for use after an oxide film is formed on the surface of the powder.

[0020] Preferably, in the step 2), the micro-nano metal powder is made of micro-nano beryllium powder, which is evacuated and filled with argon gas for protection at room temperature, and is pre-oxidized before use. The pre-oxidation treatment method is to pre-mix it with micro-nano cobalt powder, micro-nano cobalt powder, and micro-nano titanium powder, and introduce a mixed gas of oxygen, argon, and nitrogen to heat and keep it at 150°C, and then stand by until an oxide film is formed on the surface of the powder.

[0021] The advantages of the present invention are as follows:

[0022] 1) In terms of material selection and proportion, the diversity of micro-nano metal powders: using at least one of micro-nano titanium powder, micro-nano cobalt powder, micro-nano beryllium powder, and micro-nano aluminum powder as an additive material provides a variety of possible strengthening mechanisms for the hardening of gold. Different micro-nano metal powders have their own unique physical and chemical properties. For example, titanium has high strength and good corrosion resistance, and cobalt can improve the magnetism and hardness of the alloy. This diversity can select a suitable combination of micro-nano metal powders according to different needs and application scenarios. Only by weighing the micro-nano metal powder at a mass percentage of 0.1-1% of the gold base material, a significant strengthening effect can be achieved with a small addition amount, which can not only ensure the main properties of gold, but also effectively improve its hardness and other properties, thereby improving the utilization rate and economy of the material.

[0023] 2) In terms of smelting process, vacuum and temperature control are precise: during the smelting process, the mechanical pump is used for pre-vacuuming, and then the Roots pump is started for continuous vacuuming. At the same time, the diffusion pump is started for heating. The preheating time is 60 minutes, which ensures a good vacuum environment in the furnace. After the vacuum reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 50-150℃ / min. This precise temperature control and vacuum condition are conducive to removing impurity gases in the gold raw materials and improving the purity and quality of gold. After the temperature reaches 750-950℃, the diffusion pump is turned on for high vacuum deoxidation, and the vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 50-100Pa, which further optimizes the smelting environment, reduces the occurrence of adverse reactions such as oxidation, and ensures the uniformity and stability of the alloy composition. Optimization of adding and stirring micro-nano metal powder: adding micro-nano metal powder at a high temperature of 1400-1700℃, at which time the gold is in liquid state, is conducive to the uniform melting of micro-nano metal powder. After it is melted in, start the mechanical stirrer to stir it for 30 seconds to evenly distribute the micro-nano metal powder in the gold solution, avoiding component segregation, thus ensuring the uniformity and consistency of the overall performance of the gold alloy. The vacuum secondary feeding melting furnace is used for melting, which provides a stable vacuum and temperature environment for the entire melting process, and facilitates the accurate addition and stirring of micro-nano metal powder, improving the controllability and repeatability of the production process.

[0024] 3) In terms of ingot casting process, the water-cooled copper mold solidifies quickly: it can refine the grains and reduce crystal defects, thereby improving the strength and hardness of the gold alloy. At the same time, the smooth and dense ingot surface is conducive to subsequent processing, reducing surface defects and processing allowances.

[0025] 4) Surface cleaning process: Composite acid cleaning and drying treatment: The ingot is soaked in a beaker of aqua regia, heated to 80-90℃ and maintained for 30 minutes. The composite acid can effectively remove oxides and impurities on the surface of the ingot, making the surface of the ingot cleaner. Then it is moved into a clean water tank for rinsing and dried in an oven at 200℃ to ensure the cleanliness and dryness of the ingot surface, providing good surface conditions for subsequent rolling and stretching processes, which is conducive to improving processing quality and product performance.

[0026] 5) In terms of rolling, stretching and aging hardening processes, process flexibility and material performance optimization: the rolling passes and feed rates are executed according to the designed process, causing material hardening during the rolling process, and the predetermined intermediate annealing process can be performed according to the actual situation. This design not only achieves further hardening of the gold alloy and improves its strength, but also adjusts the hardness and toughness of the material through the annealing process, giving it better processing performance and use performance. Annealing and aging hardening in a tunnel furnace or muffle furnace provides a stable heating environment for the process, ensuring the consistency and reliability of the treatment effect.

[0027] 6) In terms of product manufacturing and surface treatment, diversified processes meet different needs: conventional processes are used for processing sheet and wire materials into jewelry or chains, and casting processes are used for precision casting products. This diversified product manufacturing process can meet the production needs of different types of gold products and expand the application scope of the process. Through mechanical grinding and polishing, it has sufficient strength for inlaying gemstones, which improves the practicality and aesthetics of the product. Electroplating and coloring treatments can not only enhance the corrosion resistance of the product, but also give the product rich colors to meet the market's diverse aesthetic needs for gold jewelry.

[0028] 7) In terms of product welding technology, advanced welding methods ensure product quality: laser welding, energy storage welding or argon arc welding are used to weld products, avoiding the problem of hardness reduction caused by long-term flame heating. These advanced welding technologies can achieve fast and precise welding, ensure the quality and strength of the welded joints, and do not affect the overall performance of the gold alloy, thereby improving the yield and reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the hardening curve of Au-01%Me alloy at different aging temperatures.

[0030] Figure 2 It is a line graph of deformation-hardness change.

[0031] Figure 3 It is a bar graph of micro-nano metal powder addition amount-hardness change. DETAILED DESCRIPTION

[0032] For the purpose of the following detailed description, it should be understood that the present invention may adopt various alternative changes and step sequences, unless expressly specified to the contrary. In addition, except in any operating examples, or otherwise indicated, all numbers representing the amount of ingredients used in the specification and claims should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the attached claims are approximate values ​​that vary according to the desired performance to be obtained by the present invention. At least it is not intended to limit the application of the doctrine of equivalents to the scope of the claims, and each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0033] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0034] In addition, it should be understood that any numerical range described herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the stated minimum value of 1 and the stated maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0035] Embodiment 1

[0036] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0037] Billet charging furnace:

[0038] Weigh the gold base material, weigh the micro-nano titanium powder according to 0.1% mass percentage of the gold base material, put it into the secondary material boat, and put the weighed gold base material into the crucible.

[0039] Smelting:

[0040] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump is pre-vacuumed and then the Roots pump is started to continuously evacuate. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 50℃ / min. After the temperature reaches 750℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 50Pa. Continue to heat to 1400℃, add micro-nano titanium powder, wait for it to melt into the gold solution, start the mechanical stirrer to stir it thoroughly for 30 seconds, and the melting and batching are completed. The micro-nano titanium powder is vacuumed and filled with argon for protection at room temperature, and pre-oxidation treatment is performed before use. The pre-oxidation treatment method is to pre-mix it with micro-nano cobalt powder, pass oxygen, argon and nitrogen mixed gas into it, and heat it at 150℃ for insulation. After the oxide film is formed on the surface of the powder, it is ready for use. It is vacuumed and filled with argon for protection at room temperature. It will spontaneously ignite and directly oxidize when directly exposed to the air.

[0041] Vacuum casting:

[0042] The water-cooled copper mold is maintained by passing 15°C water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0043] Surface cleaning:

[0044] The ingot was soaked in a beaker of aqua regia, heated to 80℃ and maintained for 30 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200℃.

[0045] Rolled and stretched, age hardened:

[0046] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are executed according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is performed during the rolling process. Annealing softening and aging hardening are carried out in a tunnel furnace.

[0047] Product surface treatment:

[0048] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0049] Product welding:

[0050] Use laser welding to avoid long-term flame heating and hardness reduction.

[0051] Embodiment 2

[0052] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0053] Billet charging furnace:

[0054] Weigh the gold base material, weigh the micro-nano cobalt powder according to 0.3% mass percentage of the gold base material, put it into the secondary material boat, and put the weighed gold base material into the crucible.

[0055] Smelting:

[0056] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump is pre-vacuumed and then the Roots pump is started to continuously evacuate. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 80℃ / min. After the temperature reaches 800℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reaction and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 60Pa. Continue to heat to 1500℃, add micro-nano cobalt powder, wait for it to melt into the gold solution, start the mechanical stirrer to stir it thoroughly for 30 seconds, and the melting and batching are completed. The micro-nano cobalt powder is vacuumed and filled with argon for protection at room temperature, and pre-oxidation treatment is performed before use. The pre-oxidation treatment method is to pre-mix it with micro-nano titanium powder, pass oxygen, argon and nitrogen mixed gas into it, and heat it at 150℃ for insulation. After an oxide film is formed on the surface of the powder, it will be used.

[0057] Vacuum casting:

[0058] The water-cooled copper mold is maintained by passing 16°C water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0059] Surface cleaning:

[0060] The ingot was immersed in a beaker of aqua regia, heated to 83°C for 40 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200°C.

[0061] Rolled and stretched, age hardened:

[0062] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are carried out according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is carried out during the rolling process. Annealing softening and aging hardening are carried out in a muffle furnace.

[0063] Product surface treatment:

[0064] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0065] Product welding:

[0066] Use energy storage welding to avoid long-term flame heating and hardness reduction.

[0067] Embodiment 3

[0068] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0069] Billet charging furnace:

[0070] Weigh the gold base material, weigh the micro-nano beryllium powder according to 0.5% mass percentage of the gold base material, put it into the secondary material boat, and put the weighed gold base material into the crucible.

[0071] Smelting:

[0072] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump pre-vacuums and then the Roots pump is started to continuously vacuumize. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 100℃ / min. After the temperature reaches 850℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 75Pa. Continue to heat to 1550℃, add micro-nano beryllium powder, wait for it to melt into the gold solution, start the mechanical stirrer to fully stir for 30 seconds, and the melting and batching are completed. The micro-nano beryllium powder is evacuated and filled with argon for protection at room temperature, and is pre-oxidized before use. The pre-oxidation treatment method is to pre-mix it with micro-nano cobalt powder and micro-nano titanium powder, and introduce a mixed gas of oxygen, argon and nitrogen to heat and keep warm at 150°C. After an oxide film is formed on the surface of the powder, it is ready for use. It is evacuated and filled with argon for protection at room temperature. It will spontaneously combust and directly oxidize if directly exposed to the air.

[0073] Vacuum casting:

[0074] The water-cooled copper mold is maintained by passing 17°C water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0075] Surface cleaning:

[0076] The ingot was soaked in a beaker of aqua regia, heated to 85°C for 30 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200°C.

[0077] Rolled and stretched, age hardened:

[0078] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are executed according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is performed during the rolling process. Annealing softening and aging hardening are carried out in a tunnel furnace.

[0079] Product production:

[0080] Sheet and wire processing accessories or chain making follow conventional processes, and precision casting products follow casting processes.

[0081] Product surface treatment:

[0082] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0083] Product welding:

[0084] Use argon arc welding to avoid long-term flame heating and hardness reduction.

[0085] Embodiment 4

[0086] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0087] Billet charging furnace:

[0088] Weigh the gold base material, weigh the micro-nano aluminum powder according to 0.7% mass percentage of the gold base material, put it into the secondary material boat, and put the weighed gold base material into the crucible.

[0089] Smelting:

[0090] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump pre-vacuums and then the Roots pump is started to continuously vacuumize. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 120℃ / min. After the temperature reaches 900℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 80Pa. Continue to heat to 1600℃, add micro-nano aluminum powder, wait for it to melt into the gold solution, start the mechanical stirrer to fully stir for 30 seconds, and the melting and batching are completed. The micro-nano aluminum powder is evacuated and filled with argon for protection at room temperature, and is pre-oxidized before use. The pre-oxidation treatment method is to pre-mix it with micro-nano beryllium powder and micro-nano cobalt powder, and introduce oxygen, argon and nitrogen mixed gas to heat and keep warm at 150°C. After an oxide film is formed on the surface of the powder, it is ready for use. It is evacuated and filled with argon for protection at room temperature. It will spontaneously combust and directly oxidize if directly exposed to the air.

[0091] Vacuum casting:

[0092] The water-cooled copper mold is maintained by passing 18°C ​​water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0093] Surface cleaning:

[0094] The ingot was soaked in a beaker of aqua regia, heated to 88°C for 30 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200°C.

[0095] Rolled and stretched, age hardened:

[0096] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are carried out according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is carried out during the rolling process. Annealing softening and aging hardening are carried out in a muffle furnace.

[0097] Product production:

[0098] Sheet and wire processing accessories or chain making follow conventional processes, and precision casting products follow casting processes.

[0099] Product surface treatment:

[0100] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0101] Product welding:

[0102] Use laser welding to avoid long-term flame heating and hardness reduction.

[0103] Embodiment 5

[0104] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0105] Billet charging furnace:

[0106] Weigh the gold base material, weigh micro-nano titanium powder and micro-nano beryllium powder (mass ratio 1:1) according to 0.2% mass percentage of the gold base material, put them into the secondary material boat, and put the weighed gold base material into the crucible.

[0107] Smelting:

[0108] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump pre-vacuums and then the Roots pump is started to continuously vacuumize. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 60℃ / min. After the temperature reaches 780℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 55Pa. Continue to heat to 1450℃, add a mixture of micro-nano titanium powder and micro-nano beryllium powder, wait for it to melt into the gold solution, start the mechanical stirrer to fully stir for 30 seconds, and the melting and batching are completed. Micro-nano titanium powder and micro-nano beryllium powder are evacuated and filled with argon for protection at room temperature. Micro-nano titanium powder is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano cobalt powder, pass a mixed gas of oxygen, argon and nitrogen to heat and keep it at 150°C, and wait for an oxide film to be formed on the surface of the powder before use. Micro-nano beryllium powder is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano cobalt powder and micro-nano titanium powder, pass a mixed gas of oxygen, argon and nitrogen to heat and keep it at 150°C, and wait for an oxide film to be formed on the surface of the powder before use. It is evacuated and filled with argon for protection at room temperature. It will spontaneously combust and directly oxidize when directly exposed to the air.

[0109] Vacuum casting:

[0110] The water-cooled copper mold is maintained by passing 15.5℃ water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0111] Surface cleaning:

[0112] The ingot was soaked in a beaker of aqua regia, heated to 82°C for 30 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200°C.

[0113] Rolled and stretched, age hardened:

[0114] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are executed according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is performed during the rolling process. Annealing softening and aging hardening are carried out in a tunnel furnace.

[0115] Product production:

[0116] Sheet and wire processing accessories or chain making follow conventional processes, and precision casting products follow casting processes.

[0117] Product surface treatment:

[0118] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0119] Product welding:

[0120] Use energy storage welding to avoid long-term flame heating and hardness reduction.

[0121] Embodiment 6

[0122] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0123] Billet charging furnace:

[0124] Weigh the gold base material, weigh micro-nano cobalt powder and micro-nano aluminum powder (mass ratio 1:2) according to 0.4% mass percentage of the gold base material, put them into the secondary material boat, and put the weighed gold base material into the crucible.

[0125] Smelting:

[0126] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump pre-vacuums and then the Roots pump is started to continuously vacuumize. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 90℃ / min. After the temperature reaches 830℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 65Pa. Continue to heat to 1520℃, add a mixture of micro-nano cobalt powder and micro-nano aluminum powder, wait for it to melt into the gold solution, start the mechanical stirrer to fully stir for 30 seconds, and the melting and batching are completed. The micro-nano cobalt powder is evacuated and filled with argon for protection at room temperature, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano titanium powder, pass a mixed gas of oxygen, argon and nitrogen, heat it at 150°C and keep it warm, and wait for the formation of an oxide film on the surface of the powder to be used; the micro-nano aluminum powder is evacuated and filled with argon for protection at room temperature, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano beryllium powder and micro-nano cobalt powder, pass a mixed gas of oxygen, argon and nitrogen, heat it at 150°C and keep it warm, and wait for the formation of an oxide film on the surface of the powder to be used. It is evacuated and filled with argon for protection at room temperature. It will spontaneously combust and directly oxidize if directly exposed to the air.

[0127] Vacuum casting:

[0128] The water-cooled copper mold is maintained by passing 16.5℃ water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0129] Surface cleaning:

[0130] The ingot was soaked in a beaker of aqua regia, heated to 84°C for 30 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200°C.

[0131] Rolled and stretched, age hardened:

[0132] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are carried out according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is carried out during the rolling process. Annealing softening and aging hardening are carried out in a muffle furnace.

[0133] Product production:

[0134] Sheet and wire processing accessories or chain making follow conventional processes, and precision casting products follow casting processes.

[0135] Product surface treatment:

[0136] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0137] Product welding:

[0138] Use argon arc welding to avoid long-term flame heating and hardness reduction.

[0139] A process for hardening gold with micro-nano metal powder comprises the following steps:

[0140] Embodiment 7

[0141] Billet charging furnace:

[0142] Weigh the gold base material, weigh micro-nano beryllium powder, micro-nano aluminum powder and micro-nano titanium powder (mass ratio 1:1:2) according to 0.6% mass percentage of the gold base material, put them into the secondary material boat, and put the weighed gold base material into the crucible.

[0143] Smelting:

[0144] A vacuum secondary feeding melting furnace is used. After the power is turned on, the mechanical pump pre-vacuums and then the Roots pump is started to continuously vacuumize. At the same time, the diffusion pump is started for heating. The diffusion pump preheating time is 60 minutes. After the vacuum degree reaches 100Pa, the heating is started, and the temperature is continuously increased at a heating rate of 110℃ / min. After the temperature reaches 870℃, the diffusion pump is turned on for high vacuum deoxidation. The vacuum is maintained at 6×10-2Pa to reduce the occurrence of oxidation reactions and ensure the uniformity and stability of the alloy composition. Argon is filled to maintain 70Pa. Continue to heat to 1570℃, add a mixture of micro-nano beryllium powder, micro-nano aluminum powder and micro-nano titanium powder, wait for it to melt into the gold solution, start the mechanical stirrer to fully stir for 30 seconds, and the melting and batching are completed. Micro-nano beryllium powder is evacuated and filled with argon for protection at room temperature, and pre-oxidation treatment is carried out before use. The pre-oxidation treatment method is to pre-mix it with micro-nano cobalt powder and micro-nano titanium powder, and pass a mixed gas of oxygen, argon and nitrogen to heat and keep it at 150°C, and wait for the oxide film to be formed on the surface of the powder before use; micro-nano aluminum powder is evacuated and filled with argon for protection at room temperature, and pre-oxidation treatment is carried out before use. The pre-oxidation treatment method is to pre-mix it with micro-nano beryllium powder and micro-nano cobalt powder, and pass a mixed gas of oxygen, argon and nitrogen to heat and keep it at 150°C, and wait for the oxide film to be formed on the surface of the powder before use; micro-nano titanium powder is evacuated and filled with argon for protection at room temperature, and pre-oxidation treatment is carried out before use. The pre-oxidation treatment method is to pre-mix it with micro-nano cobalt powder, and pass a mixed gas of oxygen, argon and nitrogen to heat and keep it at 150°C, and wait for the oxide film to be formed on the surface of the powder before use. It is evacuated and filled with argon for protection at room temperature. It will spontaneously ignite and directly oxidize if directly exposed to the air.

[0145] Vacuum casting:

[0146] The water-cooled copper mold is maintained by passing 17.5℃ water, the heating is stopped, the crucible is slowly poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify at a high speed within ten seconds to form a sub-millimeter smooth and dense body, and the casting is completed.

[0147] Surface cleaning:

[0148] The ingot was immersed in a beaker of aqua regia, heated to 86°C for 30 minutes, then moved into a clean water tank for rinsing and dried in an oven at 200°C.

[0149] Rolled and stretched, age hardened:

[0150] The rollers are cleaned and rolling operations are carried out. The rolling passes and feed amount are executed according to the designed process. The rolling process causes material hardening. A predetermined intermediate annealing process is performed during the rolling process. Annealing softening and aging hardening are carried out in a tunnel furnace.

[0151] Product production:

[0152] Sheet and wire processing accessories or chain making follow conventional processes, and precision casting products follow casting processes.

[0153] Product surface treatment:

[0154] It is mechanically ground and polished to give it sufficient strength for setting gemstones, and then electroplated and colored.

[0155] Product welding:

[0156] Use laser welding to avoid long-term flame heating and hardness reduction.

[0157] The basic properties of 999 hard gold are shown in Table 1:

[0158] Table 1

[0159] Relative density (%) Rolled state 99.9 Cast state 99.5 Vickers hardness (HV) 105--190 Yield strength (MPa) 250--500 Gold purity ≥999.0‰ Salt spray test ≥90 hours Remelting Capacity Repeatable casting

[0160] Generally speaking, the thermomechanical treatment process required for common age-hardening alloys to obtain maximum strength is similar to the T8 state of aluminum alloys, that is, solid solution + cold deformation + aging. This is because the defects introduced by cold deformation can promote the non-uniform nucleation of most types of precipitation phases and improve the precipitation strengthening effect. The Au-01%Me alloy was first subjected to 680℃-0.5h solid solution + 80% cold deformation + thermomechanical treatment with different aging parameters, where Me:Ti,Be,Al.Co. The precipitation strengthening law obtained is shown in Figure 1 .

[0161] like Figure 2 and Figure 3 As shown, at 350-400°C, with the increase of aging temperature, the aging peak is advanced, and the 192.6HV peak corresponding to 400°C-0.5h is the maximum hardness value at the above temperature, indicating that the alloy can obtain the required hardness of more than 150HV.

[0162] Since it is difficult to accurately control the amount of deformation during jewelry processing and preparation, and different amounts of deformation will change the precipitation kinetics of the alloy, thereby affecting the aging hardening law. Therefore, from the perspective of process consistency, after obtaining the final desired product shape, a solid solution-aging heat treatment (similar to the T6 state of aluminum alloy) can be performed, so that products with different process paths can obtain similar high hardness. Therefore, this study also studied the hardening law of alloys that are directly aged after solid solution. The hardness peaks corresponding to different process routes are shown in Table 2:

[0163] Table 2 Peak hardness of Au-01%Be / Al alloy according to different process routes

[0164]

[0165] As can be seen from the table, direct aging after solid solution can obtain a hardness equivalent to that after cold rolling, indicating that the nucleation energy of the main strengthening phase Au4Ti of the alloy is low, so it does not require a large number of dislocations to nucleate. From the perspective of process feasibility, the aging time of 2 hours is easier to control, and the production efficiency will not be affected by long-term aging.

[0166] The thermomechanical treatment process of Au-1%Me can be summarized as follows: ingot → cold deformation → softening annealing → repeat the above two steps until the final required specifications are obtained → solution quenching → 350-450° aging. Through the above process, the required shape can be obtained while obtaining a higher hardness. The above-mentioned cold deformation includes rolling, drawing and other means. The specific plastic deformation method selected depends on the final product and the shape of the ingot.

[0167] Different added elements Me and different contents (0.1-1%) will change and adjust the corresponding heat treatment process. Since the process is sensitive, it is not listed here.

[0168] The innovative process of the present invention introduces the concept of micro-nanometers, adopts controllable pre-oxidation film-forming characteristics, exists in the gold body in a hard phase state, and obtains process implementation guarantee thanks to the support of vacuum secondary melting and casting technology. According to demand, the added elements are controllable within the range of 0.1-1% according to design requirements without affecting the design purity of gold.

[0169] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A process for hardening gold with micro-nano metal powder, characterized in that: The following steps are involved: 1) Billet charging: weighing the gold base material, weighing the micro-nano metal powder according to 0.1-1% mass percentage of the gold base material, putting it into the secondary material boat, and putting the weighed gold base material into the crucible; the micro-nano metal powder is at least one of micro-nano titanium powder, micro-nano cobalt powder, micro-nano beryllium powder, and micro-nano aluminum powder; 2) Melting: Turn on the power, evacuate, start the diffusion pump to heat, continue heating to 1400-1700℃, add micro-nano metal powder, wait for the micro-nano metal powder to melt into the gold solution, start the mechanical stirrer to stir it thoroughly, and the melting and batching are completed to obtain 999 gold melt; 3) Vacuum ingot casting: 15-18℃ water is passed into the water-cooled copper mold to maintain it, the crucible is poured, and the 999 gold melt is cast into the copper mold. The water-cooled mold causes the solution to solidify into a sub-millimeter smooth and dense body within ten seconds, and the solidification casting is completed to obtain an ingot; 4) Surface cleaning: Soak the ingot in a beaker of aqua regia, heat to 80-90℃ for 30-40 minutes, rinse clean, and dry in an oven at 200℃ dry; 5) Rolling and stretching, aging hardening: clean the rolls and perform rolling operations; 6) Product surface treatment: mechanical grinding and polishing to ensure that it has sufficient strength for gemstone inlay, electroplating and coloring; 7) Product welding.

2. The process for hardening gold with micro-nano metal powder according to claim 1, characterized in that: In the step 5), the rolling passes and the feed rate are performed according to the designed process. The rolling process causes material hardening. An annealing and softening process is performed during the rolling process. The annealing and softening and aging hardening are performed in a tunnel furnace or a muffle furnace.

3. The process for hardening gold with micro-nano metal powder according to claim 1, characterized in that: In the step 8), laser welding, energy storage welding or argon arc welding is used for welding to avoid the hardness reduction caused by long-term flame heating.

4. The process for hardening gold with micro-nano metal powder according to claim 1, characterized in that: The smelting process in step 2) adopts a vacuum secondary charging smelting furnace, and mechanical stirring is performed in the furnace during the smelting process.

5. The process for hardening gold with micro-nano metal powder according to claim 4, characterized in that: In step 2), the diffusion pump is preheated for 60 minutes; after the vacuum reaches 100 Pa, the heating is started, and the temperature is continuously increased at a heating rate of 50-150°C / min. After the temperature reaches 750-950°C, the diffusion pump is turned on for high vacuum deoxidation, and the vacuum is maintained for 6×10 -2 Pa, fill with argon to maintain 50-100Pa, after the micro-nano metal powder is melted into the gold solution, start the mechanical stirrer to stir it thoroughly for 30 seconds, and the melting and batching is completed.

6. The process for hardening gold with micro-nano metal powder according to claim 4, characterized in that: In the step 2), the micro-nano metal powder is vacuumed and filled with argon at room temperature, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano titanium powder, introduce oxygen, argon and nitrogen mixed gas, heat it at 150° C., and wait for the oxide film to form on the surface of the powder.

7. The process for hardening gold with micro-nano metal powder according to claim 4, characterized in that: In the step 2), the micro-nano metal powder is vacuumed and filled with argon gas for protection at room temperature, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano cobalt powder, introduce oxygen, argon and nitrogen mixed gas, heat it at 150° C., and wait for the oxide film to be formed on the surface of the powder before use.

8. The process for hardening gold with micro-nano metal powder according to claim 4, characterized in that: In the step 2), the micro-nano metal powder is vacuumed and filled with argon at room temperature, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano beryllium powder and micro-nano cobalt powder, introduce oxygen, argon and nitrogen mixed gas, heat it at 150°C, and wait for the oxide film to form on the surface of the powder for use.

9. The process for hardening gold with micro-nano metal powder according to claim 4, characterized in that: In the step 2), the micro-nano metal powder is vacuumed and filled with argon at room temperature, and is pre-oxidized before use. The pre-oxidation method is to pre-mix it with micro-nano cobalt powder, micro-nano cobalt powder, and micro-nano titanium powder, and then introduce oxygen, argon, and nitrogen mixed gas to heat and keep it at 150° C., and then stand by until an oxide film is formed on the surface of the powder.

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