Method for rapidly removing metal cobalt in poly-crystal diamond

Abstract

The present application relates to a kind of poly crystalline diamond decobalt solution, including HF, HNO3, HCl, FeCl3, H2SO4, H2O, and the method for quickly removing metal cobalt in poly crystalline diamond, including S1: according to the proportion in formula, various solutions are mixed in decobalt container, and stirring is fully dissolved;S2: sealed poly crystalline diamond is placed into decobalt container;S3: decobalt container is placed into oven, temperature setting 150 DEG C-220 DEG C decobalt, after 10 days, remove and detect decobalt depth, can quickly remove binder in poly crystalline diamond, can effectively improve decobalt rate, can effectively improve the overall performance of poly crystalline diamond.

Description

Technical Field

[0001] This invention relates to the field of composite superhard materials technology, and in particular to a method for rapidly removing metallic cobalt from polycrystalline diamond. Background Technology

[0002] Polycrystalline diamond (PCD) possesses extremely high wear resistance and hardness, making it widely used in machining, oil, natural gas, and coal mining, and geological exploration. During the synthesis of PCD, the addition of cobalt plays several positive roles, such as grain surface wetting, pressurizing the internal pore space of arch bridges, and dissolving carbon-recrystallization. However, in the application of PCD, cobalt can generate internal stress due to its different coefficient of thermal expansion and accelerate the graphitization of diamond. Therefore, the rapid and effective removal of cobalt from the diamond layer has become a crucial means to enhance the competitiveness of composite sheets.

[0003] Currently, common methods for removing cobalt include chemical leaching and electrolysis. Chemical methods mainly involve aqua regia and Lewis acids; aqua regia has a slow cobalt removal rate, while Lewis acids cannot remove WC. Electrolysis methods include metal salt solutions and alkaline solutions. The performance of products removed by metal salt solutions lacks testing, while alkaline solutions have an excessively slow removal rate. In summary, there is currently a lack of methods for rapidly removing metallic cobalt from polycrystalline diamond. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing methods for removing cobalt from polycrystalline diamond using chemical leaching and electrolysis, and to propose a method for rapidly removing metallic cobalt from polycrystalline diamond. This method can quickly remove the binder from polycrystalline diamond, effectively improve the cobalt removal rate, and effectively improve the overall performance of polycrystalline diamond.

[0005] The objective of this invention is achieved through the following measures:

[0006] A polycrystalline diamond cobalt removal solution comprises 35-40 wt% HF, 65-70 wt% HNO3, 35-40 wt% HCl, FeCl3, and 70-75 wt% H2SO4 and H2O. HNO3 and H2SO4 have strong oxidizing properties and primarily function to remove metallic Co. HCl and HF have strong penetrating power and can react with WC, while FeCl3 is mainly used to open up the cobalt removal pathways. The principle is as follows:

[0007] 2FeCl3+6HCl+3Co=3CoCl2+2FeCl3+3H2

[0008] WC+2HNO3+6HF=WF6+CO2+2NO+2H2O+2H2.

[0009] To further optimize this invention, the following technical solutions may be preferred:

[0010] Preferably, the following are added per 500-1000 ml of H2O by mass: HF: 50-100 ml, HNO3: 50-100 ml, HCl: 200-500 ml, H2SO4: 100-200 ml, FeCl3: 10-100 g.

[0011] Preferably, it also includes an auxiliary component: H2O2 as a catalyst, wherein 50-100 ml of H2O2 is added for every 500-1000 ml of H2O.

[0012] A method for removing cobalt using a cobalt removal solution includes the following steps:

[0013] S1: Mix the various solutions in the cobalt removal container according to the proportions in the formula, and stir to ensure they are fully dissolved;

[0014] S2: Place the sealed polycrystalline diamond into the cobalt removal container;

[0015] S3: Place the cobalt removal container in an oven and set the temperature to 150℃-220℃ for cobalt removal. After 10 days, remove the container and test the cobalt removal depth.

[0016] The beneficial effects of this invention are as follows: HNO3 and H2SO4 have strong oxidizing properties in this process, which mainly play the role of removing metal Co. HCl and HF have strong permeability and can react with WC, while FeCl3 is mainly used to open up the cobalt removal channel. The components cooperate with each other, and this invention can quickly remove the binder in polycrystalline diamond, effectively improve the cobalt removal rate, and effectively improve the overall performance of polycrystalline diamond. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Lewis acids, also known as electrophiles, are substances (including ions, atomic groups, or molecules) that can accept electron pairs. This definition of an acid is based on Gilbert Newton Lewis's electron theory of acids and bases. Because it encompasses a very wide range of substances, it is also called a generalized acid. Lewis acids refer to atoms, molecules, or ions that can act as electron pair acceptors. Common Lewis acids include: 1) Positive ions and metal ions: sodium ions, alkyl cations, nitro cations, etc. 2) Electron acceptor molecules (electron-deficient compounds): boron trifluoride, aluminum trichloride, sulfur trioxide, dichlorocarbene, etc. 3) Polar groups in molecules: carbonyl and cyano groups in magnesium bromide, etc. Magnesium ions are Lewis acids. Lewis bases (1) and anions (2) are classified as neutral molecules with lone pairs, such as NH3, H2O, CO2, CH3OH3. Molecules with carbon-carbon double bonds, such as CH2=CH2. The bromide ion in magnesium bromide is a Lewis base.

[0019] Aqua regia, also known as royal jewel or nitrohydrochloric acid, is a highly corrosive, yellowish liquid. It is a mixture of concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO3) in a volume ratio of 3:1. It is one of the few liquids capable of dissolving gold.

[0020] Example 1:

[0021] HNO3: 50ml, HCl: 200ml, FeCl3: 10g, H2SO4: 100ml, H2O: 500ml, H2O2: 50ml, HF: 50ml, temperature 150℃, cobalt removal for 10 days, cobalt removal depth 800 micrometers.

[0022] Example 2:

[0023] HNO3: 100ml, HCl: 500ml, FeCl3: 100g, H2SO4: 200ml, H2O: 1000ml, H2O2: 100ml, HF: 100ml, temperature 150℃, cobalt removal for 10 days, cobalt removal depth 750 micrometers.

[0024] Example 3:

[0025] HNO3: 50ml, HCl: 200ml, FeCl3: 10g, H2SO4: 100ml, H2O: 500ml, H2O2: 50ml, temperature 120℃, cobalt removal for 10 days, cobalt removal depth 780 micrometers.

[0026] Example 4:

[0027] HNO3: 50ml, HCl: 200ml, FeCl3: 10g, H2SO4: 100ml, H2O: 500ml, HF: 100ml, temperature 200℃, cobalt removal for 8 days, cobalt removal depth 820 micrometers.

[0028] Example 5:

[0029] HNO3: 75ml, HCl: 300ml, FeCl3: 50g, H2SO4: 150ml, H2O: 750ml, HF: 75ml, temperature 120℃, cobalt removal for 10 days, cobalt removal depth 760 micrometers.

[0030] Comparative Example 1: Cobalt removal in aqua regia at 60℃ for 10 days, with HF content of 35-40 wt%, HNO3 content of 65-70 wt%, HCl content of 35-40 wt%, and H2SO4 content of 70-75 wt%. Cobalt removal depth of 400 μm.

[0031] Comparative Example 2: Lewis acid decobalt removal at 60℃ for 10 days, decobalt removal depth 400;

[0032] Comparative Example 3: Cobalt removal by electrolysis at 60℃ for 10 days, cobalt removal depth 180;

[0033] Comparative Example 4: The formula of this invention was used to remove cobalt at 60°C for 10 days, with a cobalt removal depth of 750.

[0034] With the same cobalt removal temperature and cycle, the cobalt removal depth using aqua regia and Lewis acid (chemical leaching) is only about 400 micrometers; using electrolysis, the depth is only about 180 micrometers; using the formula in this invention, the cobalt removal depth can reach over 750 micrometers. Our solution can quickly remove the binder in polycrystalline diamond, effectively improving the cobalt removal rate and the overall performance of polycrystalline diamond, thus significantly enhancing both the cobalt removal rate and depth.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polycrystalline diamond cobalt removal solution, characterized in that: It includes 35-40 wt% HF, 65-70 wt% HNO3, 35-40 wt% HCl, FeCl3, 70-75 wt% H2SO4, and H2O; per 500-1000 ml of H2O, add: HF: 50-100 ml, HNO3: 50-100 ml, HCl: 200-500 ml, H2SO4: 100-200 ml, FeCl3: 10-100 g; also includes auxiliary ingredient: H2O. 2， As a catalyst, 50-100 ml of H2O2 is added for every 500-1000 ml of H2O; HNO3 and H2SO4 have strong oxidizing properties and mainly play a role in removing metal Co, HCl and HF have strong permeability and can react with WC, while FeCl3 is mainly used to open up the cobalt removal channel.

2. A method for removing cobalt using the cobalt removal solution as described in claim 1, characterized in that, Includes the following steps: S1: According to the proportions in the formula, mix the various solutions in a cobalt removal container with good corrosion resistance and stir to ensure they are fully dissolved; S2: Place the sealed polycrystalline diamond into the cobalt removal container; S3: Place the cobalt removal container in an oven and set the temperature to 150℃-220℃ for cobalt removal. After 10 days, remove the container and test the cobalt removal depth.