A mirror polishing method for PCD composite sheet

Abstract

The present invention provides a mirror polishing method for a PCD composite sheet, comprising: first subjecting a PCD composite sheet grinding material to a vacuum heating treatment, and then subjecting it to an ultrasonic nano-vibration treatment to obtain a surface nano-crystallized composite sheet, wherein the difference in thickness between the edge and the middle of the PCD composite sheet grinding material is no more than 100 μm; subjecting the surface nano-crystallized composite sheet to a thinning treatment using a laser to obtain a composite sheet of a predetermined thickness; and subjecting the surface of the composite sheet of the predetermined thickness to a chemical mechanical polishing treatment to obtain a PCD mirror composite sheet. In the above-mentioned mirror polishing method, the stress in the composite sheet is released in advance by introducing vacuum heating technology and ultrasonic nano-vibration technology; the generation of stress during the thinning process is reduced by using laser technology, thereby improving the surface flatness and quality of the composite sheet before polishing treatment, and reducing the deformation during the processing process, thereby achieving the purpose of improving the mirror effect and shortening the mirror processing time.

Description

Technical Field

[0001] The present invention relates to the technical field of surface processing of polycrystalline diamond composite sheets, and in particular to a mirror polishing method for PCD composite sheets. Background Art

[0002] The current mainstream surface finishing methods for PCD (polycrystalline diamond) composite sheets in the industry primarily include external cylindrical machining and planar machining. External cylindrical machining methods are relatively fixed, with most companies utilizing centerless grinding. Planar machining, on the other hand, is more critical and determines the quality of the surface finish. Traditional planar machining techniques primarily involve grinding and polishing, which are divided into two basic processes: flattening and polishing. Flattening uses the abrasive force of abrasive particles to smooth the surface of the workpiece to a certain degree of flatness. Polishing, on the other hand, uses the abrasive force of abrasive particles to further refine the workpiece surface to a desired finish. Polycrystalline diamond polishing is not ordinary polishing; it is a metallographic polishing process. To achieve metallographic polishing, the metallographic flattening, or the leveling of the microstructure particles, must first be achieved. Only then, polishing can reveal a clear metallographic structure.

[0003] The main drawbacks of conventional grinding and polishing methods for processing PCD composites are as follows: 1. Low processing efficiency, with processing times typically exceeding 30 hours. 2. The combined effects of stress release within the PCD composite and stress generated during processing can cause deformation and warping of the PCD composite, with the maximum deformation exceeding 15 mm. This makes it difficult to achieve a flat surface after polishing, resulting in inconsistent surface color. 3. Traditional dry polishing takes a long time and generates significant heat, which can easily cause severe scratches on the PCD composite surface. Furthermore, the surface of the polished PCD composite is susceptible to contamination during transportation and transport, which can affect the surface quality of the PCD composite. Summary of the Invention

[0004] In view of this, it is necessary to provide a mirror polishing method for PCD composite sheets in the present invention. Compared with traditional mechanical grinding methods, the mirror polishing method has the advantages of short processing time, small deformation, and good surface quality after polishing.

[0005] Specifically, the technical solution adopted by the present invention is: a method for mirror polishing of a PCD composite sheet, comprising the steps of:

[0006] Pretreatment: first vacuum heating the PCD composite sheet flattening material, and then performing ultrasonic nano-vibration treatment to obtain a surface nano-crystallized composite sheet, wherein the difference between the edge thickness and the middle thickness of the PCD composite sheet flattening material is no more than 100 μm;

[0007] Thinning treatment: using laser to thin the surface nano-structured composite sheet to obtain a composite sheet with a predetermined thickness;

[0008] Polishing treatment: performing chemical mechanical polishing treatment on the surface of the composite sheet of predetermined thickness to polish the surface into a mirror surface to obtain a PCD mirror composite sheet.

[0009] In this article, "PCD composite sheet raw material" refers to the original PCD composite sheet with a cemented carbide matrix obtained by high temperature and high pressure sintering in a synthesis cavity; "hard alloy layer" refers to the hard alloy matrix derived from the synthesized PCD composite sheet raw material; "material layer" refers to the general term for other material layers in the PCD composite sheet raw material except the cemented carbide layer, which includes the PCD layer; "PCD composite sheet ground material" refers to the composite sheet formed after the PCD composite sheet raw material is ground and part of the hard alloy layer is removed.

[0010] Based on the above, the pretreatment step includes: vacuum heat treatment of the PCD composite sheet grinding material for 150 to 300 minutes in an environment with a vacuum degree of -0.03 to -0.085 Pa and a maximum heating temperature of 700 to 1000 ° C to obtain a heat-treated composite sheet; cooling the heat-treated composite sheet to room temperature and subjecting it to ultrasonic nano-vibration treatment at a vibration frequency of 20 to 25 KHZ for 20 to 45 minutes to obtain the surface nano-structured composite sheet. In this pretreatment step, the purpose of the vacuum heat treatment is to remove the internal stress between the cemented carbide layer and the material layer in the PCD composite sheet grinding material.

[0011] Based on the above, the thinning step includes: first ultrasonically cleaning the surface nano-structured composite sheet, and then performing laser processing to reduce the thickness of the surface nano-structured composite sheet by 200-300 μm to obtain the composite sheet of the predetermined thickness.

[0012] Based on the above, the polishing step includes: polishing the composite sheet of predetermined thickness by using a photocatalytic assisted chemical mechanical polishing method under the action of a polishing liquid to obtain the PCD mirror composite sheet.

[0013] Based on the above, in the polishing step, the polishing liquid includes, by mass percentage, diamond powder with a concentration of 50% to 70%, a non-ionic surfactant with a concentration of 1.5% to 3%, and an Au-ZnO composite catalyst with a concentration of 4% to 6%, wherein the particle size of the diamond powder is 4 to 8 μm, and the non-ionic surfactant is fatty acid polyoxyethylene ester or polyoxyethylene alkylamine.

[0014] All “%” in this article refer to mass percentage.

[0015] Based on the above, the Au-ZnO composite catalyst is mainly prepared by using zinc nitrate, chloroauric acid and urea as raw materials and adopting the deflagration method, wherein zinc nitrate accounts for 30% to 40%, urea accounts for 30% to 40%, and chloroauric acid accounts for 20% to 40%.

[0016] The mirror polishing method further includes forming a protective layer by applying a mirror anti-corrosion liquid to the surface of the PCD mirror composite sheet to prevent stains from corroding the mirror surface. The protective layer can be removed by scrubbing with an organic solvent, such as ethanol or acetone, without affecting the mirror surface quality.

[0017] Based on the above, the mirror antiseptic solution includes acetone with a concentration of 0.5% to 1%, sodium benzoate with a concentration of 1% to 2%, and a hydrophobic surfactant with a concentration of 1.5% to 3%.

[0018] Based on the above, the hydrophobic surfactant is a material such as stearic acid or sodium dodecylbenzenesulfonate.

[0019] Based on the above, the PCD composite sheet flat stock is obtained by first removing the carbide layer of the PCD composite sheet rough stock, and then performing an edge grinding process. This step mainly uses existing technologies to first remove 180 to 800 μm of the carbide layer in the PCD composite sheet rough stock, such as wire cutting or flat grinding. At this time, due to the certain amount of deformation of the PCD composite sheet flat stock obtained after wire cutting or flat grinding, the edge is thicker. Then, the edge grinding process is used to ensure that the edge thickness of the PCD composite sheet flat stock is basically consistent with the thickness in the middle.

[0020] In the above-mentioned mirror polishing method provided by the present invention, the pretreatment step treats the PCD composite sheet grinding material by introducing vacuum heating technology and ultrasonic nano-vibration technology, so that the stress therein is released in advance; the thinning step reduces the generation of stress during the processing by adopting laser processing technology, improves the flatness and quality of the composite sheet surface before polishing, and reduces the deformation during the processing, so that the composite sheet is easier to reach the level of metallographic flatness, and thus it is easier to obtain a high-quality surface after polishing, thereby shortening the mirror processing time.

[0021] Furthermore, the addition of a certain amount of nonionic surfactant to the polishing liquid used in the polishing step significantly increases the material removal rate and improves the surface flatness of the composite sheet. The introduction of a composite photocatalyst also enhances its photocatalytic effect. Furthermore, the Au in the photocatalyst exhibits a strong surface ion resonance effect, extending light absorption from ultraviolet light to the visible light range. This photocatalytic effect further improves surface flatness and polishing efficiency, reduces surface scratches, and enhances surface quality.

[0022] Furthermore, the mirror anti-corrosion liquid is a mixture of acetone, sodium benzoate, and a hydrophobic surfactant, which can effectively prevent water and other stains from contaminating and corroding the metallographic structure, and can reduce surface scratches by more than half. The metallographic structure is significantly superior to traditional processes, and it can play a relatively good protective role during transportation and transshipment, thereby allowing the polycrystalline diamond composite sheet to maintain a good cutting edge during subsequent processing and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of the mirror polishing method for a PCD composite sheet provided in Example 1 of the present invention.

[0024] Figure 2 This is a photograph of a PCD mirror composite sheet obtained by the mirror polishing method provided in Example 1 of the present invention.

[0025] Figure 3 This is a Keyence diagram of a PCD mirror composite sheet obtained by the mirror polishing method provided in Example 1 of the present invention.

[0026] Figure 4 This is a photograph of the PCD mirror composite sheet obtained in Comparative Example 1.

[0027] Figure 5 This is a Keyence image of the PCD mirror composite sheet obtained in Comparative Example 1.

[0028] Figure 6 These are comparative photographs of the appearance of PCD mirror composite sheets obtained by the mirror polishing methods provided by Examples 1 and 4 of the present invention after transportation, wherein the left picture in the figure is the appearance photograph provided by Example 4, and the right picture is the appearance photograph provided by Example 1. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0030] Example 1

[0031] See also Figure 1 This embodiment provides a method for mirror polishing of a PCD composite sheet, comprising the following steps:

[0032] The hard alloy layer of the PCD composite sheet rough material is bonded to a steel plate with 502 glue, and the hard alloy layer is flat-ground using laser wire cutting technology to remove about 500 μm of the hard alloy layer, thereby achieving the purpose of the first thinning treatment of the composite sheet and obtaining a PCD composite sheet flat material; wherein the feed amount of the laser wire cutting is 10 μm; in other embodiments, the hard alloy layer can also be removed by flat grinding;

[0033] Edge grinding treatment: The PCD composite sheet is adsorbed on a rotatable circular platform, and the edge of the PCD composite sheet is ground with an oil stone so that the difference between the edge thickness and the middle thickness is controlled within 100 μm to obtain a PCD composite sheet. The main purpose of this step is to obtain a PCD composite sheet with substantially consistent edge thickness and middle thickness.

[0034] Pretreatment: The PCD composite sheet is first placed in a vacuum heat treatment furnace for vacuum heat treatment, with a heat treatment vacuum degree of -0.03 Pa, a maximum temperature of 800°C, and a heat treatment time of 240 min. After the temperature of the vacuum heat-treated PCD composite sheet is reduced to room temperature, it is placed in an ultrasonic metal nano-crystallization device with a vibration frequency of 23 KHZ and a vibration time of 30 min to obtain a surface nano-crystallized composite sheet.

[0035] Thinning treatment: first, the surface nano-crystallized composite sheet is cleaned with ultrasound, and then placed in a laser device for thinning processing, removing 200 to 300 μm of its surface thickness to reach a predetermined thickness, thereby obtaining a composite sheet of predetermined thickness; this step is equivalent to a secondary thinning treatment of the PCD composite sheet raw material. The multiple thinning treatments to reach the predetermined thickness are beneficial to reducing the generation of stress and reducing the deformation during the processing;

[0036] Polishing treatment, putting the composite sheet of predetermined thickness into a polishing machine for polishing and assisting with visible light irradiation, polishing its surface into a mirror surface, and obtaining a composite sheet of predetermined thickness. Figure 2 and Figure 3 The PCD mirror composite sheet shown in the figure; wherein, in the polishing process, the polishing agent used is a polishing liquid prepared by mixing 5 μm diamond powder with water at a concentration of 60%, and 2% fatty acid polyoxyethylene ester and 5% Au-ZnO composite catalyst are added to the polishing liquid, wherein the Au-ZnO composite catalyst is prepared by deflagration method using zinc nitrate, chloroauric acid and urea as raw materials, with zinc nitrate accounting for 35%, urea accounting for 35% and chloroauric acid accounting for 30%.

[0037] Example 2

[0038] This embodiment provides a mirror polishing method for a PCD composite wafer. The mirror polishing method is basically the same as the mirror polishing method provided in Example 1, with the main differences being:

[0039] In the step of wire cutting and polishing, the processing volume of laser wire cutting is about 210 μm;

[0040] In the pretreatment step, the heat treatment vacuum degree is -0.05 Pa, the maximum temperature is 700 ° C, and the heat treatment time is 300 min; the vibration frequency of the ultrasonic metal nano-processing device is 21 KHZ, and the vibration time is 45 min;

[0041] In the polishing step, the polishing liquid includes diamond powder with a concentration of 50%, fatty acid polyoxyethylene ester with a concentration of 1.5%, and Au-ZnO composite catalyst with a concentration of 4%.

[0042] Example 3

[0043] This embodiment provides a mirror polishing method for a PCD composite wafer. The mirror polishing method is basically the same as the mirror polishing method provided in Example 1, with the main differences being:

[0044] In the step of wire cutting and polishing, the processing volume of laser wire cutting is about 350 μm;

[0045] In the pretreatment step, the heat treatment vacuum degree is -0.085 Pa, the maximum temperature is 1000 ° C, and the heat treatment time is 160 min; the vibration frequency of the ultrasonic metal nano-processing device is 25 KHZ, and the vibration time is 20 min;

[0046] In the polishing step, the polishing liquid includes diamond powder with a concentration of 70%, polyoxyethylene alkylamine with a concentration of 3%, and Au-ZnO composite catalyst with a concentration of 5.8%.

[0047] Comparative test

[0048] Under the same conditions, comparative examples 1 to 3 use a traditional mechanical grinding process to perform mirror polishing on the PCD composite sheet rough material. Compared with the methods provided in Examples 1 to 3, the traditional mechanical grinding process used in comparative examples 1 to 3 omits the above-mentioned "pretreatment" and "thinning treatment" steps, and the middle thickness of the PCD composite sheet flattened material obtained by the wire cutting and flattening step of the PCD composite sheet rough material basically reaches the predetermined thickness of the PCD composite sheet flattened material. The PCD mirror composite sheet obtained from comparative example 1 is as follows: Figure 4 and Figure 5 The relevant performance data test results of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

[0049]

[0050] As can be seen from Table 1: Compared with the mirror polishing method provided by the embodiment of the present invention, the comparative example adopts the traditional mechanical grinding process, which has low processing efficiency, the processing time is usually more than 30 hours, the surface flatness and parallelism after processing are poor, the surface gloss after polishing is inconsistent, and the product qualification rate is also relatively low. Figure 2 and Figure 4 、 Figure 3 and Figure 5 Therefore, by using the mirror polishing method provided by the embodiment of the present invention, the processing time can be shortened by more than 30%, the flatness can be increased by more than 60%, and the mirror polishing quality of the PCD composite wafer can be significantly improved, while also increasing the product qualification rate.

[0051] The mirror polishing method provided by the embodiment of the present invention can achieve such an effect mainly because the embodiment introduces the pretreatment technology and ultrasonic nano-vibration technology of the composite sheet to release the stress in advance, and the laser processing technology further performs secondary thinning treatment, thereby reducing the generation of stress during the thickness processing, improving the flatness and quality of the composite sheet surface before polishing, and reducing the deformation during the processing; thus, under the same processing conditions, the flatness of the composite sheet processed by the mirror polishing method provided by the embodiment of the present invention can be controlled within 5 wires, which can be increased by more than 60% compared with the traditional process, and it is easier to reach the level of metallographic flatness, so that it is easier to obtain a high-quality surface after polishing.

[0052] Example 4

[0053] Embodiment 4 of the present invention provides a mirror polishing method for a PCD composite wafer. This mirror polishing method is substantially the same as that of embodiment 1, with the main difference being that this embodiment adds the following steps: forming a protective layer; first, uniformly mixing acetone, sodium benzoate, and a hydrophobic surfactant in a ratio of 1:2:3 to form a mirror preservative; dissolving the mirror preservative in water to form a mirror preservative solution; wherein the acetone concentration in the mirror preservative solution is 0.5% to 1%, the sodium benzoate concentration is 1% to 2%, and the hydrophobic surfactant concentration is 1.5% to 3%. In this embodiment, the mirror preservative solution has an acetone concentration of 0.8%, a sodium benzoate concentration of 1.6%, and a hydrophobic surfactant concentration of 2.4%; and then applying the mirror preservative solution to the surface of the PCD mirror composite wafer to form a protective layer to prevent water and other stains from corroding the metallographic mirror surface. The protective layer can be removed with an organic solvent.

[0054] The appearance of the PCD mirror composite sheets obtained from Example 1 and Example 4 after air transportation under the same conditions is as follows: Figure 6 shown.

[0055] from Figure 6It can be clearly seen that compared with the PCD mirror composite sheet obtained in Example 1, the PCD mirror composite sheet obtained in Example 4 of the present invention is not easily contaminated or scratched by oil during the transfer and transportation process, and the number of surface scratches can be reduced by more than half, which significantly improves the mirror polishing effect, thereby further improving the product rationality rate.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A method for mirror polishing a PCD composite sheet, comprising the steps of: Pretreatment: First, the PCD composite sheet is vacuum heated and then subjected to ultrasonic nano-vibration treatment to obtain a surface nano-crystallized composite sheet, wherein: The difference between the edge thickness and the middle thickness of the PCD composite sheet flattening material is not greater than 100 μm; Thinning treatment; Using laser to perform thinning processing on the surface nano-structured composite sheet to obtain a composite sheet with a predetermined thickness; Polishing treatment: performing chemical mechanical polishing treatment on the surface of the composite sheet of predetermined thickness, polishing the surface into a mirror surface, and obtaining a PCD mirror composite sheet.

2. The mirror polishing method according to claim 1, wherein The pretreatment step includes: performing vacuum heat treatment on the PCD composite sheet grinding material for 150 to 300 minutes in an environment with a vacuum degree of -0.03 to -0.085 Pa and a heating temperature of 700 to 1000°C to obtain a heat-treated composite sheet; cooling the heat-treated composite sheet to room temperature and performing ultrasonic nano-vibration treatment at a vibration frequency of 20 to 25 KHZ for 20 to 45 minutes to obtain the surface nano-sized composite sheet.

3. The mirror polishing method according to claim 1 or 2, wherein The thinning step includes: first ultrasonically cleaning the surface nano-structured composite sheet, and then performing laser processing to reduce the thickness of the surface nano-structured composite sheet by 200 to 300 μm to obtain a composite sheet of the predetermined thickness.

4. The mirror polishing method according to claim 3, wherein The polishing step includes: polishing the composite sheet of predetermined thickness by using a photocatalytic assisted chemical mechanical polishing method under the action of a polishing liquid to obtain the PCD mirror composite sheet.

5. The mirror polishing method according to claim 4, wherein In the polishing step, the polishing liquid includes, by mass percentage, diamond powder with a concentration of 50% to 70%, a non-ionic surfactant with a concentration of 1.5% to 3%, and an Au-ZnO composite catalyst with a concentration of 4% to 6%, wherein the particle size of the diamond powder is 4 to 8 μm, and the non-ionic surfactant is fatty acid polyoxyethylene ester or polyoxyethylene alkylamine.

6. The mirror polishing method according to claim 5, wherein: The Au-ZnO composite catalyst is mainly prepared by using zinc nitrate, chloroauric acid and urea as raw materials and adopting a deflagration method, wherein zinc nitrate accounts for 30-40%, urea accounts for 30-40% and chloroauric acid accounts for 20-40%.

7. The mirror polishing method according to claim 1, 2, 4, 5 or 6, characterized in that: The method further comprises the steps of: forming a protective layer; and coating a mirror surface anti-corrosion liquid on the surface of the PCD mirror surface composite sheet to form a protective layer to prevent stains from corroding the mirror surface.

8. The mirror polishing method according to claim 7, wherein: Calculated by mass percentage, the mirror antiseptic solution includes 0.5% to 1% acetone, 1% to 2% sodium benzoate and 1.5% to 3% hydrophobic surfactant.

9. The mirror polishing method according to claim 8, wherein: The hydrophobic surfactant is stearic acid or sodium dodecylbenzenesulfonate.

10. The mirror polishing method according to claim 1, wherein: The PCD composite sheet flat grinding material is obtained by first removing the hard alloy layer of the PCD composite sheet rough material and then performing an edge grinding process.

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