CN111992731A - A method for preparing hard pure gold by powder metallurgy - Google Patents

Abstract

A method for preparing hard pure gold by powder metallurgy disclosed in the invention comprises the following steps: 1) respectively weighing pure metals Au, Y, Ti, Co and Ga to configure alloy raw materials, the total mass is 100%, four alloying elements The total mass percentage of Y, Ti, Co and Ga should not exceed 0.1%; 2) The alloy raw materials are smelted and powdered in gas atomization equipment, and the collected powders are kept at 200 ° C for 2 hours to obtain raw gold powder after stress relief annealing; 3 ) The raw gold powder is placed in a sintering mold, sintered and molded, and after sintering is completed, the sintered sample is obtained by cooling in the furnace; 4) The sintered sample is subjected to solid solution treatment in a heat treatment furnace to obtain a solid solution sample, and water-cooled; 5) The solid solution sample is subjected to aging treatment to obtain a hard pure gold product, which is cooled with the furnace. The method of the invention significantly improves the strength and hardness of the pure gold material.

Description

A method for preparing hard pure gold by powder metallurgy

technical field

The invention belongs to the technical field of precious metal processing, and relates to a method for preparing hard pure gold by powder metallurgy.

technical background

Due to the low hardness of gold, traditional pure gold ornaments or ornaments are easy to be scratched and deformed during use, which is extremely inconvenient to maintain, and the low hardness limits the appearance design of pure gold ornaments, which cannot be inlaid with gemstones and beautifully designed and manufactured. Therefore, traditional pure gold ornaments are mostly rings, bracelets or pendants with simple designs.

At present, hard gold products on the market can be mainly divided into two categories, one is 3D hard gold produced by electroforming process, and the other is hard gold jewelry produced by conventional casting process. 3D hard gold is a 3D hard gold product formed by depositing gold in the plating solution on the surface of the wax mold by electroforming process to form a gold coating of about 0.3mm. However, there are two problems in this process. One is that the electroforming process is complicated, time-consuming, water-consuming, and the electrodes are not environmentally friendly. The second is that 3D hard gold itself is a hard, thin-walled hollow part. Once it collides with a sharp hard object, it is almost impossible to damage it. repair. The hard gold jewelry produced by the conventional casting process is formed by adding microalloying elements to form a solid solution or compound with gold, mainly using the fine grain strengthening effect supplemented by solid solution strengthening, dispersion strengthening and deformation strengthening to improve the hardness of pure gold. However, the problem with this method is that meeting the gold purity requirements limits the content of the added alloying elements, so there is still a lot of room for improvement in the strengthening effect. Complex processes such as thermal processing.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for preparing hard pure gold by powder metallurgy, which solves the problem that it is difficult to form hard pure gold products in the prior art, and the sintering time is too long and the crystal grains grow up.

The technical scheme adopted in the present invention is, a method for preparing hard pure gold by powder metallurgy, which is specifically implemented according to the following steps:

Step 1: Weigh the pure metals Au, Y, Ti, Co, Ga to configure the alloy raw materials, the total mass is 100%, and the total mass percentage of the four alloy elements Y, Ti, Co, Ga does not exceed 0.1%, where Au is 99.99% high purity gold;

Step 2: The alloy raw material prepared in step 1 is smelted and powdered in a gas atomization device, and the collected powder is kept at 200° C. for 2 hours to obtain raw material gold powder after stress relief annealing;

Step 3: The raw gold powder obtained in Step 2 is placed in a sintering mold for sintering and molding, and after the sintering is completed, the sintered sample is obtained by cooling in the furnace;

Step 4: The sintered sample obtained in step 3 is subjected to solid solution treatment in a heat treatment furnace to obtain a solid solution sample, and water-cooled;

Step 5: The solid solution sample obtained in Step 4 is subjected to aging treatment to obtain a hard pure gold product, which is cooled with the furnace.

The beneficial effects of the present invention include the following aspects:

1) The alloying elements Y, Ti and Co added in the present invention can form a solid solution with Au and generate a strengthening precipitation phase to improve the hardness of the gold alloy; the addition of Ga can improve the fluidity of the Au melt, which is beneficial to the gas atomization process to obtain particles. Fine gold powder.

2) The gas atomization method adopted in the present invention combines the two processes of batch smelting and pulverizing, which simplifies the production process and can prepare gold alloy powder simply, conveniently and economically.

3) The characteristics of the spark plasma hot pressing sintering technology adopted in the present invention are that the heating rate is fast, the holding time is short, and the cooling rate is fast, which avoids the grain growth caused by the long-term holding and sintering, and can obtain pure gold with refined grain structure. products, thereby increasing its strength and hardness.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

The powder metallurgy method produces an extremely excellent fine-grain strengthening effect by refining the grain structure of the metal. If appropriate alloying elements are added to produce alloying, the strengthening effect can be greatly improved, and as a near-net-shape processing method, appropriate The advanced powder metallurgy process design can produce metal products that can be applied after simple processing, and there is no powder metallurgy application in the current gold jewelry processing field. Therefore, the present invention utilizes the powder metallurgy production process combined with the gold-based microalloy strengthening mechanism, and proposes a method for preparing hard pure gold by using the powder metallurgy method.

The method for preparing hard pure gold by the powder metallurgy method of the present invention is implemented according to the following steps:

Step 1: Weigh the pure metals Au, Y, Ti, Co, Ga to configure the alloy raw materials, the total mass is 100%, and the total mass percentage of the four alloy elements Y, Ti, Co, Ga does not exceed 0.1%, where Au is 99.99% high purity gold;

Step 2: The alloy raw material configured in step 1 is smelted and powdered in a gas atomization equipment (JVGA-S2 gas atomization equipment produced by Shenyang Jinyan New Material Preparation Technology Co., Ltd.), and the heating temperature is 1150 ℃-1600 ℃ , The atomizing medium is argon gas, and the gas pressure is 0.5MPa-5MPa; the collected powder is kept at 200 ° C for 2 hours to relieve stress and annealed to obtain raw gold powder;

Step 3: The raw gold powder obtained in step 2 is packed in a sintering mold, and sintered in a sintering mold (SPS-20T-10 discharge plasma hot pressing sintering furnace produced by Shanghai Chenhua Electric Furnace Co., Ltd.), and the sintering pressure is 20MPa -70MPa, the sintering temperature is 800℃-1200℃, the heating rate is 80℃/min, and the holding time is 10min-100min. After the sintering is completed, the sintered sample is obtained by cooling with the furnace;

Step 4: Use a heat treatment furnace (VTL-1700 vacuum quenching furnace produced by Nanjing Boyuntong Instrument Technology Co., Ltd.) to perform solution treatment on the sintered sample obtained in step 3 to obtain a solution sample, and the solution temperature is 500 ° C -800℃, holding time 2h, water cooling;

Step 5: The solid solution sample obtained in step 4 is subjected to aging treatment (using the TL1200 vacuum tube furnace produced by Nanjing Boyuntong Instrument Technology Co., Ltd.) to obtain a hard pure gold product, and the aging temperature is 300 ℃-600 ℃, The holding time is 5h-20h, and it is cooled with the furnace.

Example 1

In this embodiment, the mass ratio of the high-purity gold ingot is 99.9%, and the mass percentages of the four alloying elements of Y, Ti, Co, and Ga added are 0.03%, 0.02%, 0.02%, and 0.03%, respectively; The alloy raw materials are smelted and powdered in the gas atomization equipment, and the heating temperature is set to 1150 °C and the gas pressure is 0.5 MPa for gas atomization. The obtained gold powder is kept at 200 °C for 2 hours to relieve stress and anneal, and then sintering can be started.

The gold powder is placed in the sintering mold and sintered in a spark plasma hot pressing sintering furnace. The sintering pressure is set to 20 MPa, the sintering temperature is 800 °C, and the heating rate is 80 °C/min. The sintered sample was heated to 500 °C in a heat treatment furnace for 2 h, then taken out, and then quickly transferred to deionized water and cooled to room temperature to obtain a solid solution sample; Furnace cooling to obtain the required hard gold samples.

Example 2

In this embodiment, the mass ratio of the high-purity gold ingot is 99.9%, and the mass percentages of the four alloying elements Y, Ti, Co, and Ga added are 0.04%, 0.01%, 0.01%, and 0.04%, respectively; The raw materials are smelted and powdered in the gas atomization equipment, and the heating temperature is set to 1250 ° C and the gas pressure is 3 MPa for gas atomization. The obtained gold powder is kept at 200 ° C for 2 hours to relieve stress and anneal, and then sintering can be started.

The gold powder is placed in the sintering mold and sintered in a spark plasma hot pressing sintering furnace. The sintering pressure is set to 40 MPa, the sintering temperature is 1000 °C, and the heating rate is 80 °C/min. The sintered sample was heated to 600 °C in a heat treatment furnace for 2 h, then taken out, and then quickly transferred to deionized water and cooled to room temperature to obtain a solid solution sample; Furnace cooling to obtain the required hard gold samples.

Example 3

In this embodiment, the mass ratio of the high-purity gold ingot is 99.9%, and the mass percentages of the four alloying elements Y, Ti, Co, and Ga added are 0.01%, 0.01%, 0.03%, and 0.05%, respectively; The raw materials are smelted and powdered in the gas atomization equipment, and the heating temperature is set to 1400 ° C and the gas pressure is 5 MPa for gas atomization. The obtained gold powder is kept at 200 ° C for 2 hours to relieve stress and anneal, and then sintering can be started.

The gold powder was placed in the sintering mold and sintered in a spark plasma hot pressing sintering furnace. The sintering pressure was set to 70 MPa, the sintering temperature was 1200 °C, and the heating rate was 80 °C/min. The sintered sample was heated to 800 °C in a heat treatment furnace for 2 h, then taken out, and then quickly transferred to deionized water and cooled to room temperature to obtain a solid solution sample; Furnace cooling to obtain the required hard gold samples.

Example 4

In this embodiment, the mass ratio of the high-purity gold ingot is 99.9%, and the mass percentages of the four alloying elements Y, Ti, Co, and Ga added are 0.02%, 0.02%, 0.02%, and 0.04%, respectively; The raw materials are smelted and powdered in the gas atomization equipment, the heating temperature is set to 1600 ℃, the gas pressure is 4 MPa for gas atomization, and the obtained gold powder is kept at 200 ℃ for 2 hours to relieve stress and anneal, and then sintering can be started.

The gold powder was placed in the sintering mold and sintered in a spark plasma hot pressing sintering furnace. The sintering pressure was set to 60 MPa, the sintering temperature was 1100 °C, and the heating rate was 80 °C/min. The sintered sample was heated to 700 °C in a heat treatment furnace for 2 hours, then taken out, and then quickly transferred to deionized water and cooled to room temperature to obtain a solid solution sample; Furnace cooling to obtain the required hard gold samples.

Example 5

In this embodiment, the mass ratio of the high-purity gold ingot is 99.9%, and the mass percentages of the four alloying elements Y, Ti, Co, and Ga added are 0.025%, 0.025%, 0.025%, and 0.025%, respectively; The raw materials are smelted and powdered in the gas atomization equipment, the heating temperature is set to 1500 ℃, the gas pressure is 3.5 MPa for gas atomization, and the obtained gold powder is kept at 200 ℃ for 2 hours to relieve stress and anneal, and then sintering can be started.

The gold powder was placed in the sintering mold and sintered in a spark plasma hot pressing sintering furnace. The sintering pressure was set to 45 MPa, the sintering temperature was 900 °C, and the heating rate was 80 °C/min. The sintered sample was heated to 650 °C in a heat treatment furnace for 2 h, then taken out, and then quickly transferred to deionized water and cooled to room temperature to obtain a solid solution sample; Furnace cooling to obtain the required hard gold samples.

Claims (5)

1. The method for preparing the hard pure gold by the powder metallurgy method is characterized by comprising the following steps:

step 1: respectively weighing pure metals of Au, Y, Ti, Co and Ga to prepare alloy raw materials, wherein the total mass is 100%, the sum of the mass percentages of the four alloy elements of Y, Ti, Co and Ga is not more than 0.1%, and the Au is 99.99% of high-purity gold;

step 2: smelting the alloy raw material prepared in the step 1 in gas atomization equipment to prepare powder, and carrying out heat preservation on the collected powder at 200 ℃ for 2h to remove stress and anneal to obtain raw material gold powder;

and step 3: the raw material gold powder obtained in the step 2 is filled in a sintering mold, sintering molding is carried out, and a sintered sample is obtained after sintering is completed and is cooled along with a furnace;

and 4, step 4: carrying out solid solution treatment on the sintered sample obtained in the step 3 by using a heat treatment furnace to obtain a solid solution sample, and cooling by water;

and 5: and (4) carrying out aging treatment on the solid solution sample obtained in the step (4) to obtain a hard pure gold product, and cooling along with the furnace.

2. The powder metallurgy method for preparing hard pure gold according to claim 1, characterized in that: in the step 2, the heating temperature is 1150-1600 ℃, the atomizing medium is argon, and the gas pressure is 0.5-5 MPa.

3. The powder metallurgy method for preparing hard pure gold according to claim 1, characterized in that: in the step 3, the sintering pressure is 20MPa to 70MPa, the sintering temperature is 800 ℃ to 1200 ℃, the heating rate is 80 ℃/min, and the heat preservation time is 10min to 100 min.

4. The powder metallurgy method for preparing hard pure gold according to claim 1, characterized in that: in the step 4, the solid solution temperature is 500-800 ℃, and the heat preservation time is 2 h.

5. The powder metallurgy method for preparing hard pure gold according to claim 1, characterized in that: in the step 5, the aging temperature is 300-600 ℃, and the heat preservation time is 5-20 h.