A method for removing cobalt from the surface of diamond composite sheet

Abstract

The present invention belongs to the field of surface treatment of diamond composite sheets, and specifically relates to a method for removing cobalt from the surface of a diamond composite sheet, comprising the following steps: step 1, setting a protective shell mechanism, injection molding a shell on the outer periphery of the diamond sheet, the shell internally seals the intermediate layer coating of the diamond sheet and the metal substrate, and the shell cooperates with a sealing ring to externally seal the intermediate layer of the diamond sheet and the metal substrate; a plurality of separation rings separate the exposed part of the diamond sheet into cobalt-removed layers that do not interfere with each other, the cobalt-removal depth is controlled by the number of separation rings, and the separation rings are detached to assist the layer-by-layer cobalt-removal of the diamond sheet, effectively improving the cobalt-removal accuracy and directly controlling the cobalt-removal depth, solving the problem of excessive cobalt-removal of the diamond composite sheet, solving the problem of uncontrollable cobalt-removal depth of the traditional protective shell structure, and eliminating the need to prepare a new protective shell injection mold when adjusting the process, thereby reducing production costs.

Description

Technical Field

[0001] The invention relates to the field of surface treatment of diamond composite sheets, and in particular to a method for removing cobalt from the surface of a diamond composite sheet. Background Art

[0002] Diamond composite sheet is made of diamond powder and cemented carbide substrate sintered under ultra-high pressure and high temperature conditions. It has the high hardness, high wear resistance and thermal conductivity of diamond, and the strength and impact toughness of cemented carbide. It is an ideal material for manufacturing cutting tools, drilling bits and other wear-resistant tools.

[0003] The method of removing cobalt from the surface of diamond composite sheets mainly involves chemical treatment to remove the cobalt element in the diamond layer, thereby improving the thermal stability and performance of the composite sheet.

[0004] At present, the commonly used method for removing cobalt is chemical acid etching, which is to mix a certain mass concentration of organic acid (such as tartaric acid, citric acid, etc.), inorganic acid 1 (such as hydrochloric acid, perchloric acid, etc.) and inorganic acid 2 (such as hydrofluoric acid, boric acid, etc.) to obtain a composite acid, and then immerse the diamond composite sheet in the composite acid solution to remove the cobalt phase by immersion.

[0005] The patent with application number CN202210604230.3 discloses a method for decobalting / detungstenizing of polycrystalline diamond composite sheets, and in particular, a method for decobalting / detungstenizing of polycrystalline diamond composite sheets. The method for decobalting / detungstenizing of polycrystalline diamond composite sheets comprises the following steps: Step 1, a sealed shell is provided to form a seal between the sealed shell and the outer peripheral surface of the polycrystalline diamond composite sheet, and a cavity is formed above the part of the polycrystalline diamond layer of the polycrystalline diamond composite sheet to be decobalted / detungstened, so that the part to be decobalted / detungstened is exposed to the cavity; Step 2, a decobalting / detungstenizing liquid is injected into the cavity, so that the part to be decobalted / detungstened of the polycrystalline diamond layer to be decobalted / detungstened is immersed in the decobalting / detungstenizing liquid to achieve decobalting / detungstenizing. The above scheme can solve the problems of the existing decobalting / detungstenizing methods, such as large amount of decobalting / detungstenizing liquid, high cost, and possible environmental pollution.

[0006] The prior art has the following problems:

[0007] 1. When removing cobalt from diamond composite sheets, the depth of the removal is determined by the height of the injection molded casing. When the depth of the removal of cobalt needs to be adjusted, the injection mold needs to be modified, which increases the processing cost;

[0008] 2. Directly using the injection molded shell to assist in decobalting may cause excessive decobalting of the diamond composite sheet due to the unadjustable decobalting depth;

[0009] (1) Reduce structural strength: Cobalt plays a certain bonding role in diamond composite sheets. If the cobalt is removed excessively, the bonding force between diamond particles may be weakened, thereby reducing the overall structural strength of the diamond composite sheet;

[0010] (2) Impact on wear resistance: Although decobalting can improve the wear resistance of diamond composite sheets, excessive decobalting may destroy the integrity of diamond particles, resulting in a decrease in wear resistance;

[0011] (3) Impact on subsequent processing: Diamond composite sheets need to be processed in drilling or cutting applications, such as cutting, grinding, etc. Excessive delamination will affect the processing performance of diamond composite sheets, such as reducing processing accuracy or increasing processing difficulty. Summary of the invention

[0012] 1. Purpose of the invention

[0013] In order to solve the technical problems existing in the background technology, the present invention provides a method for removing cobalt from the surface of a diamond composite sheet, which has the characteristics of adjustable cobalt removal depth and prevention of excessive cobalt removal.

[0014] (II) Technical solution

[0015] In order to solve the above technical problems, the present invention provides a method for removing cobalt from the surface of a diamond composite sheet, comprising the following steps:

[0016] Step 1: Setting a shell protection mechanism, injection molding a shell on the outer periphery of the diamond sheet, the shell internally seals the diamond sheet and the intermediate layer of the metal substrate, and the shell cooperates with a sealing ring to externally seal the intermediate layer of the diamond sheet and the metal substrate;

[0017] Step 2: placing the combination of the protective shell mechanism and the diamond composite sheet into the inner cavity of the cobalt removal tool, wherein the clamping area between the diamond sheet, the sealing ring and the inner wall of the cobalt removal tool is the cobalt removal area;

[0018] Step 3, a plurality of separation rings are arranged in the cobalt removal area, the inner wall of the separation ring is attached to the protruding end of the diamond sheet, and the outer wall of the separation ring is attached to the inner wall of the cobalt removal tooling, and the protruding end of the diamond sheet is sealed and separated layer by layer from bottom to top;

[0019] Step 4: injecting the decobalting liquid from the opening of the decobalting tool, and the exposed part of the diamond sheet is immersed in the decobalting liquid for reaction to carry out surface decobalting. After the decobalting of the exposed part is completed, the sealing separation of the separation ring can be removed layer by layer to control the decobalting depth of the diamond sheet.

[0020] Preferably, the outer spacer sleeve of the metal matrix is ​​provided with a bushing, and when the shell is injection-molded, a bushing groove attached to the bushing is retained in the inner cavity.

[0021] Preferably, the inner cavity of the shell is provided with a positioning groove, the positioning piece in the middle of the sealing ring is embedded in the positioning groove, the convex edge of its outer wall covers the outer circumference of the shell, and the guide piece of its inner wall has the same outward inclined structure as the upper part of the shell.

[0022] Preferably, the end surface of the shell in contact with the diamond sheet and the metal substrate is a first sealing surface, and the end surface of the guide member in contact with the diamond sheet and the shell is a second sealing surface.

[0023] Preferably, the cross-section of the separation ring near the diamond sheet is a straight plate structure with a distal end inclined downward, and the inclined portion of the straight plate structure is formed with a limiting structure that cooperates with the adjacent separation ring and the inner wall of the decobaltizing tooling.

[0024] Preferably, a plurality of the separation rings separate the exposed portion of the diamond sheet into cobalt-removed layers that do not interfere with each other, and the cobalt-removal depth is controlled by the number of the separation rings set.

[0025] Preferably, a raised boss is formed on the bottom of the shell, and a slot matching the raised boss is formed in the inner cavity of the cobalt removal tool, and the boss and the slot are plugged and fixed.

[0026] Preferably, a plurality of raised vertical rods are formed on the sealing ring, and the vertical rods penetrate the stacked separation rings.

[0027] Preferably, the shell is an acid-resistant plastic component, including polytetrafluoroethylene PTFE, polyoxymethylene POM and polycarbonate PC, and the sealing ring and the separating ring are made of acid- and alkali-resistant sealing rubber materials, including butyl rubber, ethylene propylene diene monomer rubber EPDM and fluororubber.

[0028] The above technical scheme of the present invention has the following beneficial technical effects: a plurality of separation rings separate the exposed parts of the diamond sheet into cobalt-removed layers that do not interfere with each other, the cobalt-removal depth is controlled by the number of separation rings, and the separation rings are detached to assist the layer-by-layer cobalt-removal of the diamond sheet, which effectively improves the cobalt-removal accuracy and can directly control the cobalt-removal depth, thereby solving the problem of excessive cobalt-removal of the diamond composite sheet and the problem of uncontrollable cobalt-removal depth of the traditional shell structure. There is no need to prepare a new shell injection mold when adjusting the process, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the separation structure of the present invention;

[0030] Figure 2 It is a cross-sectional structural schematic diagram of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of the shell protection mechanism of the present invention;

[0032] Figure 4 It is a schematic diagram of the structure of the separation mechanism of the present invention;

[0033] Figure 5 It is a schematic diagram of the second implementation structure of the present invention.

[0034] Reference numerals:

[0035] 11. Diamond sheet; 12. Metal substrate; 21. Bushing; 22. Shell; 23. Sealing ring; 231. Positioning piece; 232. Flange; 233. Drainage piece; 3. Cobalt removal tooling; 4. Separation ring; 51. Boss; 52. Slot; 6. Vertical pole. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0037] like Figure 1-4 The present invention provides a method for removing cobalt from the surface of a diamond composite sheet, comprising the following steps:

[0038] Step 1: Setting a shell protection mechanism, injection molding a shell 22 on the outer periphery of the diamond sheet 11, the shell 22 covers the middle layer of the diamond sheet 11 and the metal matrix 12 to perform internal sealing, and the shell 22 cooperates with the sealing ring 23 to perform external sealing on the middle layer of the diamond sheet 11 and the metal matrix 12;

[0039] The inner cavity of the shell 22 is provided with a positioning groove, and the positioning piece 231 in the middle of the sealing ring 23 is embedded in the positioning groove. The positioning piece 231 is a structure that is narrow at the top and wide at the bottom. The protruding part of the lower part is stuck in the positioning groove to prevent loosening. The convex edge 232 of the outer wall is covered on the outer periphery of the shell 22 to prevent the decobalt liquid from penetrating from the outside. The drainage piece 233 of the inner wall is the same outward inclined structure as the upper part of the shell 22. The inclined structure can block the gap in the upper part of the shell 22 on the one hand, and can drain the decobalt liquid to the side on the other hand.

[0040] It can be understood that the end face of the shell 22 in contact with the diamond sheet 11 and the metal matrix 12 is the first sealing surface, and the end face of the guide member 233 in contact with the diamond sheet 11 and the shell 22 is the second sealing surface. Through double sealing, the penetration path of the decobaltizing liquid into the composite intermediate layer of the diamond sheet 11 and the metal matrix 12 is isolated.

[0041] Step 2: Place the combination of the protective shell mechanism and the diamond composite sheet into the inner cavity of the cobalt removal tool 3, and the clamping area between the diamond sheet 11, the sealing ring 23 and the inner wall of the cobalt removal tool 3 is the cobalt removal area;

[0042] Step 3: several separator rings 4 are arranged in the cobalt removal area, the inner wall of the separator ring 4 is attached to the protruding end of the diamond sheet 11, and the outer wall of the separator ring 4 is attached to the inner wall of the cobalt removal tooling 3, and the protruding end of the diamond sheet 11 is sealed and separated layer by layer from bottom to top;

[0043] Step 4: inject the decobalting liquid from the opening of the decobalting tool 3, and the exposed part of the diamond sheet 11 is immersed in the decobalting liquid for surface decobalting. After the decobalting of the exposed part is completed, the sealing separation of the separation ring 4 can be removed layer by layer to control the decobalting depth of the diamond sheet 11.

[0044] It should be noted that the diamond composite sheet is composited by a diamond sheet 11 and a metal matrix 12. The composite middle layer of the two serves as a connecting structure, and the cobalt element plays a connecting role. Cobalt removal will affect the tightness of the connection between the two. Therefore, a shell mechanism is provided to perform double sealing inside and outside of the composite middle layer of the two to ensure that the decobaltizing liquid has no contact with the composite middle layer of the two during the decobalting process.

[0045] In this embodiment, a plurality of separation rings 4 separate the exposed part of the diamond sheet 11 into cobalt-removing layers that do not interfere with each other, and the cobalt-removing depth is controlled by the number of separation rings 4. At this time, the sealing ring 23 serves as a supporting part of the separation ring 4. When the separation ring 4 is installed, the cross-section of the separation ring 4 near the diamond sheet 11 is a straight plate structure with a distal end inclined downward, which is adapted to the guide member 233, and the inclined portion of the straight plate structure is formed with a limiting structure that cooperates with the inner wall of the adjacent separation ring 4 and the cobalt-removing tool 3, so that the separation ring 4 can be stably installed layer by layer from bottom to top, and the exposed part of the diamond sheet 11 is layer by layer. Sealing, when decobalting, first decobaltize the diamond sheet 11 above the topmost separator ring 4, after the surface decobalting of the diamond sheet 11 at the current position is completed, the topmost separator ring 4 can be removed to expose the outer wall of the sealed diamond sheet 11 to the outside for further decobalting. The separation ring 4 is detached to assist the decobalting of the diamond sheet 11 layer by layer, which effectively improves the decobalting accuracy and can directly control the decobalting depth, thereby solving the problem of uncontrollable decobalting depth of the traditional protective shell structure. There is no need to prepare a new protective shell injection mold when adjusting the process, thereby reducing production costs.

[0046] It can be understood that the problem of excessive decobalting of the diamond composite sheet can be solved by performing layer-by-layer decobalting through the separator ring 4 .

[0047] In an optional embodiment, the outer layer of the metal substrate 12 is provided with a bushing 21. When the shell 22 is injection molded, a bushing groove attached to the bushing 21 is retained in the inner cavity. The bushing 21 is spaced and sleeved on the outer periphery of the metal substrate 12. After the cobalt removal is completed, the injection-molded shell 22 is partially directly connected to the metal substrate 12, and partially molded on the outer periphery of the bushing 21 to prevent the shell 22 from being too tightly connected to the metal substrate 12. The shell 22 can be assisted to be removed from the metal substrate 12 by detaching the bushing 21.

[0048] In order to assist the connection between the shell 22 and the cobalt-removing tool 3, further, a protruding boss 51 is formed on the bottom of the shell 22, and a slot 52 matching the protruding boss 51 is formed in the inner cavity of the cobalt-removing tool 3, and the protruding boss 51 and the slot 52 are plugged and fixed.

[0049] like Figure 5 As shown, a plurality of raised vertical rods 6 are formed on the sealing ring 23, and the vertical rods 6 penetrate the stacked separation rings 4.

[0050] In another embodiment, a vertical pole 6 is provided on the sealing ring 23. The vertical pole 6 is vertically provided to guide the installation process of the separator ring 4. At the same time, after the separator ring 4 is installed, it can play a role of a middle limiter to ensure that the separator ring 4 stably seals and protects the diamond sheet 11 coated on the inner wall, and prevents the decobaltizing liquid from penetrating into the side wall of the diamond sheet 11 to cause excessive decobaltization.

[0051] The housing 22 is an acid-resistant plastic component, including polytetrafluoroethylene PTFE, polyoxymethylene POM and polycarbonate PC;

[0052] Polytetrafluoroethylene PTFE: It is resistant to acids, alkalis, and various organic solvents, has an extremely low friction coefficient, and is suitable for high temperature environments;

[0053] Polyoxymethylene POM: It has the characteristics of chemical corrosion resistance, wear resistance and high temperature resistance;

[0054] Polycarbonate PC: resistant to acid and alkali corrosion, impact and aging.

[0055] The sealing ring 23 and the separation ring 4 are made of acid- and alkali-resistant sealing rubber materials, including butyl rubber, EPDM and fluororubber;

[0056] Acid and alkali resistant sealing rubber materials mainly include butyl rubber, EPDM and fluororubber. These materials have excellent corrosion resistance, wear resistance, good elasticity and sealing properties, and are widely used in various environments that require acid and alkali resistance.

[0057] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for removing cobalt from the surface of a diamond composite sheet, characterized in that: The following steps are involved: Step 1: providing a shell protection mechanism, injection molding a shell (22) on the outer periphery of the diamond sheet (11), wherein the shell (22) covers the middle layer of the diamond sheet (11) and the metal matrix (12) to perform internal sealing, and the shell (22) cooperates with a sealing ring (23) to perform external sealing on the middle layer of the diamond sheet (11) and the metal matrix (12); Step 2: placing the combination of the protective shell mechanism and the diamond composite sheet into the inner cavity of the cobalt removal tool (3), wherein the clamping area between the diamond sheet (11), the sealing ring (23) and the inner wall of the cobalt removal tool (3) is the cobalt removal area; Step 3: a plurality of separation rings (4) are arranged in the cobalt removal area, the inner wall of the separation ring (4) is attached to the protruding end of the diamond sheet (11), and the outer wall of the separation ring (4) is attached to the inner wall of the cobalt removal tooling (3), so as to seal and separate the protruding end of the diamond sheet (11) layer by layer from bottom to top; Step 4: injecting a decobaltizing liquid from the opening of the decobaltizing tool (3), and soaking the exposed portion of the diamond sheet (11) in the decobaltizing liquid for reaction to perform surface decobalting. After the decobalting of the exposed portion is completed, the sealing separation of the separation ring (4) can be removed layer by layer to control the decobalting depth of the diamond sheet (11).

2. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: The outer spacer sleeve of the metal base (12) is provided with a bushing (21), and when the shell (22) is injection-molded, a bushing groove attached to the bushing (21) is retained in the inner cavity.

3. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: The inner cavity of the shell (22) is provided with a positioning groove, the positioning piece (231) in the middle of the sealing ring (23) is embedded in the positioning groove, the convex edge (232) of the outer wall thereof covers the outer periphery of the shell (22), and the flow guide piece (233) of the inner wall thereof has the same outwardly inclined structure as the upper part of the shell (22).

4. A method for removing cobalt from the surface of a diamond composite sheet according to claim 3, characterized in that: The end surface of the shell (22) in contact with the diamond sheet (11) and the metal substrate (12) is a first sealing surface, and the end surface of the flow guide member (233) in contact with the diamond sheet (11) and the shell (22) is a second sealing surface.

5. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: The cross section of the separation ring (4) near the diamond sheet (11) is a straight plate structure with the far end tilted downward, and the inclined portion of the straight plate structure is formed with a limiting structure that cooperates with the inner wall of the adjacent separation ring (4) and the decobaltizing tool (3).

6. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: A plurality of the separation rings (4) separate the exposed portion of the diamond sheet (11) into cobalt-removed layers that do not interfere with each other, and the cobalt-removal depth is controlled by the number of separation rings (4) provided.

7. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: A protruding boss (51) is formed on the bottom of the shell (22), and a slot (52) matching the protruding boss (51) is formed in the inner cavity of the cobalt removal tool (3), and the protruding boss (51) and the slot (52) are plugged and fixed.

8. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: A plurality of raised vertical rods (6) are formed on the sealing ring (23), and the vertical rods (6) penetrate the stacked separation rings (4).

9. The method for removing cobalt from the surface of a diamond composite sheet according to claim 1, characterized in that: The housing (22) is an acid-resistant plastic component, including polytetrafluoroethylene (PTFE), polyoxymethylene (POM) and polycarbonate (PC); the sealing ring (23) and the separating ring (4) are made of acid- and alkali-resistant sealing rubber materials, including butyl rubber, ethylene propylene diene monomer (EPDM) and fluororubber.

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