Diamond grinding fluid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of precise plane grinding and polishing, and discloses diamond grinding liquid as well as a preparation method and application thereof. The diamond grinding fluid comprises the following raw materials in percentage by mass: 0.6-3% of a diamond micro-powder mixture, 1-2% of a dispersing agent, 0.4-1% of a suspending agent, 1-10% of a surfactant, 0.2-2% of a pH regulator and 82-94% of a dispersion medium. The grinding speed with high removal rate is formed by using the sharpness of the polycrystalline diamond powder and the monocrystal diamond powder, and the uneven surface is repaired, scratches are eliminated and the consistency of the surface is ensured by using the self-sharpening of the polycrystalline diamond powder, so that the expectation is achieved; the grinding rate of the sapphire substrate slice reaches 4.0 mu m / min, the grinding efficiency is guaranteed, higher removal rate and toughness are achieved, scratches cannot be formed on the surface of the sapphire substrate slice, and the beneficial effects of being high in grinding rate, good in surface quality and the like are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of precision planar grinding and polishing, and particularly to a diamond grinding fluid, a preparation method thereof, and an application thereof. Background Art

[0002] The diamond micropowder used in diamond grinding fluid is mostly synthetic diamond, which is composed of carbon atoms. The carbon atoms are bonded by covalent bonds, and there are 4 carbon atoms directly and closely connected around each carbon atom, forming a firm crystal. Therefore, the diamond micropowder has a high hardness (the hardness can reach Mohs hardness level 10). The crystal forms of diamond micropowder are rich, and common ones include octahedron, cube, hexagonal octahedron, rhombic dodecahedron, etc. Due to the sharp edges and corners of diamond, it has strong cutting ability, making its grinding efficiency high. The forms of diamond can be divided into single crystal, pseudo-polycrystal, polycrystal, polycrystalline aggregate, etc. Single crystal diamond is a crystal formed by covalent bonds with saturation and directionality. Pseudo-polycrystalline diamond is a material with a honeycomb hole structure formed by surface etching treatment of single crystal diamond as raw material. Polycrystalline diamond is obtained from graphite. Using a unique directional blasting method, the shock wave of directional blasting of high-explosive speed explosive accelerates the flying of metal flyers, and impacts the graphite sheet, resulting in the conversion of graphite into polycrystalline diamond. Polycrystalline diamond is composed of spherical polycrystalline aggregates, and the microcrystal diameter is about 3 - 10 μm. Compared with single crystal diamond, polycrystalline diamond has self-sharpening property, higher removal rate and toughness, and will not form scratches on the surface of sapphire substrate.

[0003] On the premise of ensuring no scratches, diamond grinding fluid products often pursue a higher removal rate. However, the removal rate of existing diamond grinding fluids for sapphire substrates does not exceed 3.5 μm / min. Currently, the research on improving the removal rate mainly focuses on crystal structure, particle size, content, sharpness of crystals, etc., but the improvement effect is not very ideal. For example, in order to increase the removal rate, some grinding fluid products increase the D 50 particle size of single crystal diamond powder by 10 - 30%, and specifically select a sharp crystal structure, and at the same time increase the content of single crystal diamond powder in the formula (generally increase by about 30%). Although the removal rate of the grinding fluid product will increase slightly, it will cause deep scratches on the sapphire substrate. Summary of the Invention

[0004] The purpose of the present invention is to provide a diamond grinding fluid, a preparation method thereof, and an application thereof, to solve the problem that the existing diamond grinding fluid cannot balance the improvement of the removal rate and the grinding effect.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a diamond grinding fluid, comprising raw materials with the following mass fractions:

[0007] 0.6 to 3% of diamond micropowder mixture, 1 to 2% of dispersant, 0.4 to 1% of suspending agent, 1 to 10% of surfactant, 0.2 to 2% of pH regulator, 82 to 94% of dispersion medium;

[0008] Among them, the diamond micropowder mixture includes polycrystalline diamond-like, a mixture of polycrystalline diamond and single crystal diamond;

[0009] The dispersant includes a mixture of alkyl hydroxy ammonium salt and modified styrene maleic anhydride copolymer;

[0010] The suspending agent includes acrylate copolymer.

[0011] Preferably, in the diamond grinding fluid, the mass ratio of the polycrystalline diamond-like, the polycrystalline diamond and the single crystal diamond is 0.2 to 1:0.2 to 1:0.2 to 1.

[0012] Preferably, in the diamond grinding fluid, the particle size conditions of the polycrystalline diamond-like include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm;

[0013] The particle size conditions of the polycrystalline diamond include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm;

[0014] The particle size conditions of the single crystal diamond include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0015] Preferably, in the diamond grinding fluid, the alkyl hydroxy ammonium salt is DISPERBYK-180;

[0016] The modified styrene maleic anhydride copolymer is DISPERBYK-190.

[0017] Preferably, in the diamond grinding fluid, the mass ratio of the alkyl hydroxy ammonium salt and the modified styrene maleic anhydride copolymer is 0.5 to 1:0.5 to 1.

[0018] Preferably, in the diamond grinding fluid, the acrylate copolymer is BYK-154.

[0019] Preferably, in the diamond grinding fluid, the surfactant includes polyethylene glycol 400;

[0020] The dispersion medium includes ethylene glycol.

[0021] Preferably, in the diamond grinding fluid, the pH regulator includes a mixture of monoethanolamine and triethanolamine;

[0022] The mass ratio of the monoethanolamine to the triethanolamine is 0.1 - 1:0.1 - 1.

[0023] The present invention also provides a preparation method of a diamond grinding fluid, comprising the following steps:

[0024] Mix the dispersion medium, pH regulator, surfactant, dispersant, suspending agent, and diamond micropowder mixture according to mass fractions to obtain the diamond grinding fluid.

[0025] The present invention also provides an application of the diamond grinding fluid in the grinding of sapphire substrate wafers.

[0026] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The diamond grinding fluid of the present invention uses diamond micropowders of various crystal forms with multi - gradients as the main raw materials, and is compounded with a dispersant, a suspending agent, a surfactant, a dispersion medium, etc. It makes full use of the sharpness of polycrystalline - like diamond and single - crystal diamond powder to form a high - removal - rate grinding speed, and then uses the self - sharpening property of polycrystalline diamond powder to repair uneven surfaces and eliminate scratches, ensuring surface consistency, thus achieving the expected effect; raw materials such as DISPERBYK - 180, DISPERBYK - 190, BYK - 154, and polyethylene glycol 400 are used to increase the dispersibility, suspension, stability, and anti - redeposition properties of diamond micropowders. Therefore, the present invention is a precision product developed on the basis of strictly selecting various crystal forms and particle sizes, improving particle surface characteristics, and utilizing the principle of chemical - enhanced grinding. This combination has more grinding effects and less rolling effects, so almost no surface deformation layer and Beilby layer will be generated. The grinding rate of the diamond grinding fluid of the present invention for sapphire substrate wafers reaches 4.0 μm / min, ensuring the grinding efficiency of the diamond grinding fluid, having a higher removal rate and toughness, and not forming scratches on the surface of the sapphire substrate wafer, with characteristics such as a high grinding rate and good surface quality.

[0028] (2) The diamond grinding fluid product of the present invention has good dispersion, uniform particle size, stable quality, non - toxic and environmentally friendly. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0030] Figure 1 The surface of the chip after being polished with the diamond polishing liquid of Example 1;

[0031] Figure 2 The surface of the chip after being polished with the diamond polishing liquid of Comparative Example 1. Specific embodiments

[0032] The present invention provides a diamond polishing liquid, comprising raw materials in the following mass fractions:

[0033] Diamond micropowder mixture 0.6 - 3%, dispersant 1 - 2%, suspending agent 0.4 - 1%, surfactant 1 - 10%, pH regulator 0.2 - 2%, dispersion medium 82 - 94%;

[0034] Among them, the diamond micropowder mixture includes a mixture of polycrystalline-like diamond, polycrystalline diamond and single-crystal diamond;

[0035] The dispersant includes a mixture of alkyl hydroxy ammonium salt and modified styrene maleic anhydride copolymer;

[0036] The suspending agent includes acrylate copolymer.

[0037] In the present invention, the mass ratio of the polycrystalline-like diamond, the polycrystalline diamond and the single-crystal diamond is preferably 0.2 - 1:0.2 - 1:0.2 - 1, more preferably 0.6 - 1:0.6 - 1:0.6 - 1, and still more preferably 1:1:1.

[0038] In the present invention, the particle size conditions of the polycrystalline-like diamond preferably include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm.

[0039] In the present invention, the particle size conditions of the polycrystalline diamond preferably include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm.

[0040] In the present invention, the particle size conditions of the single-crystal diamond preferably include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0041] In the present invention, the mass fraction of the diamond micropowder mixture is preferably 0.6 - 2%, more preferably 0.8 - 1.5%, and still more preferably 1%.

[0042] In the present invention, the alkoxyammonium salt is preferably DISPERBYK-180.

[0043] In the present invention, the modified styrene maleic anhydride copolymer is preferably DISPERBYK-190.

[0044] In the present invention, the mass ratio of the alkoxyammonium salt to the modified styrene maleic anhydride copolymer is preferably 0.5 - 1:0.5 - 1, more preferably 0.8 - 1:0.8 - 1, and still more preferably 1:1.

[0045] In the present invention, the mass fraction of the dispersant is preferably 1.2 - 2%, more preferably 1.3 - 1.6%, and still more preferably 1.4%.

[0046] In the present invention, the acrylate copolymer is preferably BYK-154.

[0047] In the present invention, the mass fraction of the suspending agent is preferably 0.4 - 0.8%, more preferably 0.5 - 0.7%, and still more preferably 0.6%.

[0048] In the present invention, the surfactant preferably includes polyethylene glycol 400.

[0049] In the present invention, the mass fraction of the surfactant is preferably 2 - 8%, more preferably 4 - 7%, and still more preferably 5%.

[0050] In the present invention, the pH regulator preferably includes a mixture of monoethanolamine and triethanolamine.

[0051] In the present invention, the mass ratio of monoethanolamine to triethanolamine is preferably 0.1 - 1:0.1 - 1, more preferably 0.5 - 1:0.5 - 1, and still more preferably 1:1.

[0052] In the present invention, the mass fraction of the pH regulator is preferably 0.3 - 1%, more preferably 0.4 - 0.8%, and still more preferably 0.5%.

[0053] In the present invention, the dispersion medium preferably includes ethylene glycol.

[0054] In the present invention, the mass fraction of the dispersion medium is preferably 88 - 94%, more preferably 90 - 92%, and still more preferably 91.7%.

[0055] The present invention also provides a method for preparing a diamond grinding fluid, comprising the following steps:

[0056] Mixing a dispersion medium, a pH regulator, a surfactant, a dispersant, a suspending agent, and a diamond micropowder mixture according to mass fractions to obtain a diamond grinding fluid.

[0057] In the present invention, the method of mixing the dispersion medium, pH regulator, surfactant, dispersant, suspending agent, and diamond micropowder mixture according to mass fraction preferably includes the following steps:

[0058] Add the pH regulator and surfactant to the dispersion medium for the first mixing; add the dispersant and suspending agent to the mixture obtained from the first mixing for the second mixing; add the diamond micropowder mixture to the mixture obtained from the second mixing for the third mixing.

[0059] In the present invention, the rotation speed of the first mixing is preferably 400 - 500 rpm, more preferably 450 - 500 rpm, and most preferably 500 rpm; the time of the first mixing is preferably 12 - 15 min, more preferably 14 - 15 min, and most preferably 15 min.

[0060] In the present invention, the rotation speed of the second mixing is preferably 900 - 1000 rpm, more preferably 950 - 1000 rpm, and most preferably 1000 rpm; the time of the second mixing is preferably 18 - 20 min, more preferably 19 - 20 min, and most preferably 20 min.

[0061] In the present invention, the rotation speed of the third mixing is preferably 900 - 1000 rpm, more preferably 950 - 1000 rpm, and most preferably 1000 rpm; the time of the third mixing is preferably 18 - 20 min, more preferably 19 - 20 min, and most preferably 20 min.

[0062] The present invention also provides an application of a diamond grinding fluid in the grinding of sapphire substrate wafers.

[0063] In the present invention, the method for the application is not limited, and a scheme well-known to those skilled in the art can be adopted.

[0064] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0065] Example 1

[0066] This example provides a diamond grinding fluid, which contains raw materials with the following mass fractions:

[0067] 0.6% polycrystalline diamond-like, 0.2% polycrystalline diamond, 0.2% single-crystal diamond, 0.6% DISPERBYK-180, 0.6% DISPERBYK-190, 0.6% BYK-154, 5% polyethylene glycol 400, 0.2% monoethanolamine, 0.3% triethanolamine, 91.7% ethylene glycol;

[0068] The particle size conditions of polycrystalline diamond-like include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm;

[0069] The particle size conditions of polycrystalline diamond include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm;

[0070] The particle size conditions of single-crystal diamond include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0071] This embodiment also provides a preparation method of the foregoing diamond grinding fluid, including the following steps:

[0072] Put ethylene glycol in a high-speed disperser, adjust the rotation speed to 500 rpm to start stirring, and sequentially add monoethanolamine, triethanolamine, and polyethylene glycol 400, and stir for 15 min; adjust the stirring speed to 1000 rpm, and sequentially add DISPERBYK-180, DISPERBYK-190, and BYK-154 to the foregoing mixture, and stir for 20 min; finally, sequentially add single-crystal diamond, polycrystalline diamond-like, and polycrystalline diamond, and stir at 1000 rpm for 20 min until uniform to obtain the diamond grinding fluid.

[0073] Comparative Example 1

[0074] This comparative example provides a diamond grinding fluid, which is a product of the same type of company, the manufacturer is Beijing Guoruisheng Technology Co., Ltd., and the brand is PC-6-W.

[0075] Conduct grinding tests on the diamond grinding fluids of Example 1 and Comparative Example 1, and the test method is as follows:

[0076] Conduct tests on a single-sided grinding machine, use a copper grinding disc with a diameter of 460 mm, and the diamond grinding fluid is added by pneumatic pressure spraying through a spray pipe; the rotation speed of the grinding disc is 80 rpm, the grinding pressure is 4 psi, the liquid addition speed is 5 mL / min, and the grinding time is 10 min. Observe the grinding effect of the sapphire substrate wafer, and the results are as Figures 1 to 2 shown.

[0077] From Figures 1 to 2 the results, it can be seen that the removal rate of the diamond grinding fluid obtained in Example 1 of the present invention is greater than or equal to 4.0 μm / min, while that of Comparative Example 1 is less than 3.5 μm / min. Under the above test conditions, the chips ground with the product of Example 1 of the present invention have no scratches and meet the requirements of the production line; while the chips ground with the grinding fluid of Comparative Example 1 have scratches.

[0078] Example 2

[0079] This example provides a diamond grinding fluid, comprising raw materials with the following mass fractions:

[0080] Polycrystalline diamond-like 0.5%, polycrystalline diamond 0.3%, single crystal diamond 0.2%, DISPERBYK-180 0.7%, DISPERBYK-190 0.5%, BYK-154 0.6%, polyethylene glycol 400 5%, monoethanolamine 0.2%, triethanolamine 0.3%, ethylene glycol 91.7%;

[0081] The particle size conditions of the polycrystalline diamond-like include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm;

[0082] The particle size conditions of the polycrystalline diamond include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm;

[0083] The particle size conditions of the single crystal diamond include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0084] This example also provides a preparation method of the foregoing diamond grinding fluid, comprising the following steps:

[0085] Put ethylene glycol into a high-speed disperser, adjust the rotation speed to 500 rpm to start stirring, and sequentially add monoethanolamine, triethanolamine, and polyethylene glycol 400, and stir for 15 min; adjust the stirring speed to 1000 rpm, and sequentially add DISPERBYK-180, DISPERBYK-190, and BYK-154 to the foregoing mixture, and stir for 20 min; finally, sequentially add single crystal diamond, polycrystalline diamond-like, and polycrystalline diamond, and stir at 1000 rpm for 20 min until uniform to obtain the diamond grinding fluid.

[0086] Comparative Example 2

[0087] This comparative example provides a diamond grinding fluid, which contains raw materials with the following mass fractions:

[0088] Polycrystalline diamond-like 0.5%, polycrystalline diamond 0.3%, DISPERBYK-180 0.7%, DISPERBYK-190 0.5%, BYK-154 0.6%, polyethylene glycol 400 5%, monoethanolamine 0.2%, triethanolamine 0.3%, ethylene glycol 91.9%;

[0089] The particle size conditions of the polycrystalline diamond-like include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm;

[0090] The particle size conditions of the polycrystalline diamond include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm.

[0091] The preparation method of the diamond grinding fluid of Comparative Example 2 refers to Example 2.

[0092] The diamond grinding fluids of Example 2 and Comparative Example 2 were subjected to a grinding test, and the test method was as follows:

[0093] The test was carried out on a single-sided grinding machine. A copper grinding disc with a diameter of 460 mm was used. The diamond grinding fluid was added by pneumatic pressure spraying through a spray pipe; the rotation speed of the grinding disc was 80 rpm, the grinding pressure was 4 psi, the liquid addition speed was 5 mL / min, the grinding time was 10 min, and the grinding effect of the sapphire substrate was observed.

[0094] The removal rate of the diamond grinding fluid obtained in Example 2 of the present invention was greater than or equal to 4.0 μm / min, while that of Comparative Example 2 was less than 3.6 μm / min.

[0095] Example 3

[0096] This example provides a diamond grinding fluid, which contains raw materials with the following mass fractions:

[0097] Polycrystalline diamond-like 0.55%, polycrystalline diamond 0.25%, single crystal diamond 0.2%, DISPERBYK-180 0.9%, DISPERBYK-190 0.5%, BYK-154 0.4%, polyethylene glycol 400 5%, monoethanolamine 0.2%, triethanolamine 0.3%, ethylene glycol 91.7%;

[0098] The particle size conditions of the polycrystalline diamond-like include: D 10 = 2 μm, D 50 = 4 μm, D 90= 5.8 μm;

[0099] The particle size conditions of polycrystalline diamond include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm;

[0100] The particle size conditions of single crystal diamond include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0101] This embodiment also provides a method for preparing the aforementioned diamond grinding fluid, including the following steps:

[0102] In a high-speed disperser, add ethylene glycol, adjust the rotation speed to 500 rpm and start stirring, and sequentially add monoethanolamine, triethanolamine, and polyethylene glycol 400, and stir for 15 min; adjust the stirring speed to 1000 rpm, and sequentially add DISPERBYK-180, DISPERBYK-190, and BYK-154 to the aforementioned mixture, and stir for 20 min; finally, sequentially add single crystal diamond, polycrystalline-like diamond, and polycrystalline diamond, and stir at 1000 rpm for 20 min until uniform to obtain the diamond grinding fluid.

[0103] Comparative Example 3

[0104] This comparative example provides a diamond grinding fluid containing the following raw materials by mass fraction:

[0105] Polycrystalline-like diamond 0.55%, single crystal diamond 0.2%, DISPERBYK-180 0.9%, DISPERBYK-190 0.5%, BYK-154 0.4%, polyethylene glycol 400 5%, monoethanolamine 0.2%, triethanolamine 0.3%, ethylene glycol 91.95%;

[0106] The particle size conditions of polycrystalline-like diamond include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm;

[0107] The particle size conditions of single crystal diamond include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0108] The preparation method of the diamond grinding fluid of Comparative Example 3 refers to Example 3.

[0109] Conduct a grinding test on the diamond grinding fluids of Example 3 and Comparative Example 3. The test method is as follows:

[0110] The test was carried out on a single-sided grinding machine, using a copper grinding disc with a diameter of 460 mm. The diamond grinding fluid was added by pneumatic pressure spraying through a spray pipe; the rotational speed of the grinding disc was 80 rpm, the grinding pressure was 4 psi, the liquid addition speed was 5 mL / min, the grinding time was 10 min, and the grinding effect of the sapphire substrate wafer was observed.

[0111] The removal rate of the diamond grinding fluid obtained in Example 3 of the present invention is greater than or equal to 4.0 μm / min, while that of Comparative Example 3 is less than 3.2 μm / min.

[0112] Example 4

[0113] This example provides a diamond grinding fluid, which contains raw materials with the following mass fractions:

[0114] Quasi-polycrystalline diamond 0.5%, polycrystalline diamond 0.25%, single-crystal diamond 0.25%, DISPERBYK-180 0.8%, DISPERBYK-190 0.5%, BYK-154 0.5%, polyethylene glycol 400 5%, monoethanolamine 0.2%, triethanolamine 0.3%, ethylene glycol 91.7%;

[0115] The particle size conditions of the quasi-polycrystalline diamond include: D 10 = 2 μm, D 50 = 4 μm, D 90 = 5.8 μm;

[0116] The particle size conditions of the polycrystalline diamond include: D 10 = 0.6 μm, D 50 = 1 μm, D 90 = 1.3 μm;

[0117] The particle size conditions of the single-crystal diamond include: D 10 = 0.4 μm, D 50 = 0.9 μm, D 90 = 1.5 μm.

[0118] This example also provides a preparation method of the foregoing diamond grinding fluid, including the following steps:

[0119] In a high-speed disperser, add ethylene glycol, adjust the rotation speed to 500 rpm to start stirring, and sequentially add monoethanolamine, triethanolamine, and polyethylene glycol 400, and stir for 15 minutes; adjust the stirring speed to 1000 rpm, and sequentially add DISPERBYK-180, DISPERBYK-190, and BYK-154 to the above-mentioned mixture, and stir for 20 minutes; finally, sequentially add single-crystal diamond, polycrystalline diamond-like, and polycrystalline diamond, and stir at 1000 rpm for 20 minutes until uniform to obtain diamond grinding fluid.

[0120] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A diamond polishing liquid, characterized in that: Contains the following raw materials by mass fraction: Diamond powder mixture 0.6-3%, dispersant 1-2%, suspending agent 0.4-1%, surfactant 1-10%, pH regulator 0.2-2%, dispersion medium 82-94%; Wherein, the diamond powder mixture includes a mixture of polycrystalline diamond, polycrystalline diamond and single crystal diamond; The dispersant comprises a mixture of an alkylhydroxyl ammonium salt and a modified styrene maleic acid copolymer; The suspending agent includes an acrylate copolymer.

2. A diamond polishing liquid according to claim 1, characterized in that: The mass ratio of the polycrystalline diamond-like material, the polycrystalline diamond and the single crystal diamond is 0.2-1:0.2-1:0.2-1.

3. A diamond grinding liquid according to claim 1 or 2, characterized in that: The particle size conditions of the polycrystalline diamond include: 10 =2μm, D 50 =4μm, D 90 =5.8μm; The particle size conditions of the polycrystalline diamond include: 10 =0.6μm, D 50 =1μm, D 90 =1.3μm; The particle size conditions of the single crystal diamond include: 10 =0.4μm, D 50 =0.9μm, D 90 =1.5μm.

4. A diamond grinding liquid according to claim 1, characterized in that: The alkylhydroxyl ammonium salt is DISPERBYK-180; The modified styrene maleic acid copolymer is DISPERBYK-190.

5. A diamond polishing liquid according to claim 1 or 4, characterized in that: The mass ratio of the alkylhydroxyl ammonium salt to the modified styrene maleic acid copolymer is 0.5-1:0.5-1.

6. A diamond polishing liquid according to claim 1, characterized in that: The acrylate copolymer is BYK-154.

7. A diamond polishing liquid according to claim 1, characterized in that: The surfactant includes polyethylene glycol 400; The dispersion medium includes ethylene glycol.

8. A diamond polishing liquid according to claim 1, characterized in that: The pH regulator includes a mixture of monoethanolamine and triethanolamine; The mass ratio of the monoethanolamine to the triethanolamine is 0.1-1:0.1-1.

9. The method for preparing a diamond polishing liquid according to any one of claims 1 to 8, characterized in that: The following steps are involved: The dispersion medium, pH regulator, surfactant, dispersant, suspending agent and diamond micro-powder mixture are mixed according to mass fractions to obtain diamond polishing liquid.

10. Use of the diamond polishing liquid according to any one of claims 1 to 8 or the diamond polishing liquid prepared by the preparation method according to claim 9 in polishing a sapphire substrate.

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