Grinding fluid as well as preparation method and application thereof

Abstract

The invention discloses grinding fluid as well as a preparation method and application thereof. The grinding fluid comprises the following components: nano-diamond, high-entropy ceramic powder, a surfactant and water. According to the grinding fluid, water serves as a main body, after the positively charged modified nano-diamond and the negatively charged high-entropy ceramic powder are mixed, on one hand, the charges of the modified nano-diamond and the high-entropy ceramic powder are opposite, mutual adsorption can be generated, a composite grinding material is formed, and on the other hand, the nano-diamond particles and the ceramic particles play a role in deagglomeration, so that the grinding fluid is formed. The agglomeration of the nano-diamond particles can be avoided, and the grinding uniformity is improved. Therefore, the grinding fluid provided by the invention reduces the possibility of agglomeration of the modified nano diamond particles and the ceramic particles to a certain extent, further improves the dispersibility and stability of the grinding fluid, improves the grinding efficiency of the aluminum nitride ceramic substrate, reduces the surface damage, and improves the overall grinding quality and effect.

Description

Technical Field

[0001] This invention belongs to the field of polishing fluid technology, specifically relating to a polishing fluid, its preparation method, and its application. Background Technology

[0002] Aluminum nitride ceramic (AlN) is an ultra-wide bandgap semiconductor material with characteristics such as high hardness, high thermal conductivity, low coefficient of thermal expansion, excellent heat dissipation, excellent corrosion resistance, and low dielectric constant and dielectric loss. It is widely used as a thermally conductive substrate material in high-power devices. In actual production, aluminum nitride ceramic components require surface grinding to effectively achieve the required dimensional accuracy and surface integrity. However, the high hardness and brittleness of aluminum nitride ceramic, as well as the tendency for grains to detach, place high demands on the efficiency and quality of the grinding process.

[0003] Diamond micropowder, due to its extremely high hardness and chemical stability, is often used to prepare grinding slurries for ultra-precision grinding of ceramic materials. However, because of its small particle size, high surface activity, and complex surface functional groups, diamond micropowder is prone to agglomeration during the preparation of grinding slurries. This results in excessively large diamond particles in the slurry, which can easily cause surface damage such as scratches and pits on the workpiece during grinding, hindering further improvement of the workpiece's surface quality. Therefore, there is an urgent need to develop a grinding slurry that can prevent the agglomeration of diamond micropowder. Summary of the Invention

[0004] To overcome the problems existing in the prior art, one objective of the present invention is to provide a polishing slurry. A second objective of the present invention is to provide a method for preparing the aforementioned polishing slurry. A third objective of the present invention is to provide an application of the aforementioned polishing slurry. A fourth objective of the present invention is to provide a method for polishing an aluminum nitride ceramic substrate.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of the present invention provides a polishing fluid comprising the following components: modified nanodiamond, high-entropy ceramic powder, surfactant, and water, wherein the modified nanodiamond has a positive surface charge, and the high-entropy ceramic powder has a negative surface charge.

[0007] Most existing technologies use diamond micron powder as a component of the polishing slurry. This invention further utilizes nanodiamonds with even smaller particle sizes. However, due to their smaller particle size, nanodiamonds are more prone to agglomeration during the polishing slurry preparation process, resulting in excessively large nanodiamond particle sizes in the slurry, leading to low polishing efficiency and difficulty in achieving high surface quality. Therefore, this invention introduces high-entropy ceramic powder into the polishing slurry component. This ceramic powder possesses characteristics such as high melting point, high hardness, high brittleness, good thermal stability, and corrosion resistance. The introduction of ceramic powder can improve the polishing efficiency of aluminum nitride ceramic substrates, enhance polishing quality, and reduce surface damage. The polishing slurry of this invention uses water as the main component. After mixing the positively charged modified nanodiamonds and the negatively charged high-entropy ceramic powder, their opposite charges cause mutual adsorption. On one hand, the larger ceramic particles are coated by the smaller modified nanodiamond particles, forming a composite abrasive. On the other hand, the nanodiamond particles and ceramic particles each play a role in de-agglomeration, preventing agglomeration and improving polishing uniformity. The polishing slurry of the present invention can be applied to polishing aluminum nitride ceramic substrates, and can achieve a low surface roughness with a high material removal rate in ultra-precision polishing.

[0008] Preferably, by mass percentage, it consists of the following components: 0.01%-1% modified nanodiamond, 0.01%-1% high-entropy ceramic powder, 0.005%-0.5% surfactant, and the remainder is water.

[0009] More preferably, by mass percentage, it consists of the following components: 0.1%-0.5% modified nanodiamond, 0.1%-0.5% high-entropy ceramic powder, 0.005%-0.3% surfactant, and the remainder is water.

[0010] Preferably, the modified nanodiamond has a particle size of 1-30 nm.

[0011] More preferably, the modified nanodiamond has a particle size of 1-10 nm.

[0012] Preferably, the modified nanodiamond is a heat-treated nanodiamond.

[0013] More preferably, the preparation method of the modified nanodiamond includes the following steps: the nanodiamond is heat-treated under a protective atmosphere at a temperature of 500-900°C for 1-4 hours.

[0014] More preferably, the protective atmosphere is a nitrogen atmosphere.

[0015] More preferably, the specific heating procedure of the heat treatment includes: heating to 500-900°C at a heating rate of 2-10°C / min, and holding at that temperature for 1-4 hours.

[0016] More preferably, the heat treatment temperature is 600–800°C.

[0017] Preferably, the high-entropy ceramic powder includes high-entropy boride ceramic powder.

[0018] More preferably, the high-entropy boride ceramic powder includes element B, and also includes at least four of the following metallic elements: Ti, Zr, Hf, V, Nb, Ta, Mo, and W.

[0019] More preferably, the particle size of the high-entropy ceramic powder is 100-2000 nm.

[0020] More preferably, the high-entropy ceramic powder comprises (Hf) a Mo b Ta c Nb d Ti e B2 is a high-entropy ceramic powder, wherein 0.1≤a≤1, 0.1≤b≤1, 0.1≤c≤1, 0.1≤d≤1, 0.1≤e≤1, and satisfies a+b+c+d+e=1.

[0021] More preferably, a, b, c, d and e are all 0.2.

[0022] More preferably, the (Hf) a Mo b Ta c Nb d Ti e The preparation method of B2 high-entropy ceramic powder includes the following steps:

[0023] The raw materials are HfO2, MoO3, Ta2O5, Nb2O5, TiO2 oxide powder, B4C, and graphite mixed in a certain proportion. The mixture is ball-milled, crushed, and compacted, and then sintered under vacuum conditions at a temperature of 1400-2000℃ for 0.5-2h.

[0024] More preferably, the process includes the following steps: the mixture is ball-milled for 20-28 hours, dried, ground, sieved, and compacted, and then sintered in a pressureless sintering furnace under vacuum conditions.

[0025] More preferably, the molar ratio of Hf, Mo, Ta, Nb, and Ti in the raw materials is 1:1:1:1:1.

[0026] More preferably, the sintering is carried out in a vacuum environment.

[0027] Preferably, the surfactant is a cationic surfactant.

[0028] More preferably, the cationic surfactant is a quaternary ammonium salt type cationic surfactant.

[0029] More preferably, the quaternary ammonium salt type cationic surfactant includes at least one of dodecyltrimethylammonium chloride (DTAC), hexadecyltrimethylammonium bromide (CTAB), dioctadecyldimethylammonium chloride (DODMAC), distearate dimethylammonium chloride, benzyltrimethylammonium chloride (BTAC), and hexadecylpyridine chloride (CPC).

[0030] Preferably, the particle size of the grinding slurry is 80-1600 nm.

[0031] The second aspect of the present invention provides a method for preparing the polishing slurry described in the first aspect, comprising the following steps: dispersing nanodiamond, high-entropy ceramic powder, and surfactant uniformly in water to obtain the polishing slurry.

[0032] Preferably, the process includes the following steps: first, the modified nanodiamond, high-entropy ceramic powder, and surfactant are mixed evenly to form a dispersed phase, then water is added to make a mixture, and the grinding slurry is obtained after ultrasonic dispersion.

[0033] More preferably, the ultrasonic processor for ultrasonic dispersion has a power of 200-400W.

[0034] The third aspect of the present invention provides the application of the polishing slurry described in the first aspect in the precision polishing of ceramic substrate materials.

[0035] Preferably, the ceramic substrate material includes one of alumina ceramic, beryllium oxide ceramic, aluminum nitride ceramic, or silicon nitride ceramic.

[0036] The fourth aspect of the present invention provides a method for polishing an aluminum nitride ceramic substrate, comprising the following steps: placing the aluminum nitride ceramic substrate in a polishing disc and adding the polishing slurry described in the first aspect for polishing.

[0037] Preferably, the grinding speed is 30-60 r / min.

[0038] Preferably, the grinding time is 0.5-2 hours.

[0039] Preferably, the flow rate of the grinding fluid is 1-5 mL / min.

[0040] The beneficial effects of this invention are:

[0041] This invention provides a polishing slurry, its preparation method, and its application. The invention introduces high-entropy ceramic powder into the polishing slurry components. High-entropy ceramic powder possesses characteristics such as high melting point, high hardness, high brittleness, good thermal stability, and corrosion resistance. The introduction of high-entropy ceramic powder can improve the polishing efficiency of aluminum nitride ceramic substrates, enhance polishing quality, and reduce surface damage. The polishing slurry of this invention uses water as the main component. After mixing positively charged modified nanodiamonds and negatively charged high-entropy ceramic powder, the opposite charges cause mutual adsorption. On one hand, the larger high-entropy ceramic particles are coated by the smaller modified nanodiamond particles, forming a composite abrasive. On the other hand, the nanodiamond particles and ceramic particles each play a de-agglomeration role, preventing nanodiamond particle agglomeration and improving polishing uniformity. Therefore, the polishing slurry of this invention reduces the possibility of agglomeration of modified nanodiamond particles and ceramic particles to a certain extent, further improving the dispersibility and stability of the polishing slurry, fully utilizing its performance, and improving the overall polishing quality and effect.

[0042] The polishing fluid of the present invention can be applied to polishing ceramic substrates. Specifically, in the ultra-precision polishing of aluminum nitride ceramic substrates, it can simultaneously achieve excellent results of high material removal rate and low surface roughness, and is less likely to scratch the workpiece polishing surface, thereby achieving high-efficiency and high-quality polishing of aluminum nitride ceramics. Attached Figure Description

[0043] Figure 1 This is a particle size distribution diagram of the high-entropy ceramic powder prepared in Example 1;

[0044] Figure 2 This is a particle size distribution diagram of the polishing slurry for the aluminum nitride ceramic substrate prepared in Example 1. Detailed Implementation

[0045] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from conventional commercial channels or prepared and isolated through simple synthesis; unless otherwise specified, the processes employed are conventional processes in the art.

[0046] The purpose of this invention is to provide a polishing slurry for aluminum nitride ceramic substrates and its preparation method. The polishing slurry is composed of modified nanodiamond and a ceramic powder. It can achieve a low surface roughness with a high material removal rate and is not easy to scratch the workpiece polishing surface, thus realizing high-efficiency and high-quality polishing of aluminum nitride ceramics.

[0047] The technical solution provided by this invention is as follows:

[0048] A polishing slurry for aluminum nitride ceramic substrates, by mass percentage, comprises the following components: 0.01%-1% nanodiamond, 0.01%-1% high-entropy ceramic powder, 0.005%-0.5% surfactant, with the remainder being deionized water; the nanodiamond has a positive surface charge, and the high-entropy ceramic powder has a negative surface charge.

[0049] The nanodiamond powder is prepared by detonation method, and the median particle size is 5 nm. The modified nanodiamond is nanodiamond that has undergone conventional heat treatment. The conventional heat treatment method is as follows: the nanodiamond is heated to 500-700℃ under nitrogen or other inert gas at a heating rate of 2-10℃ / min, held at the temperature for 1-2 hours, and then cooled in the furnace.

[0050] The chemical composition of the ceramic powder is as follows: (Hf a Mo b Ta c Nb d Ti e B2, wherein 0.1≤a≤1, 0.1≤b≤1, 0.1≤c≤1, 0.1≤d≤1, 0.1≤e≤1, and satisfying a+b+c+d+e=1; the ceramic powder is made by mixing HfO2, MoO3, Ta2O5, Nb2O5, TiO2 oxide powder raw materials with B4C and graphite in a certain proportion, ball milling for 24-96 hours, drying, grinding and sieving, and compacting, and then heating to 1600-2000℃ in a pressureless sintering furnace under vacuum conditions for 0.5-2 hours, cooling and taking it out, and finally refining it by high-energy ball milling for 24-96 hours, so that the particle size of the ceramic powder is 100-2000nm.

[0051] The surfactant mentioned above includes one or more of polyethylene glycol, OP-40 emulsifier, N,N-dimethylformamide, hexadecyltrimethylammonium bromide, sodium laurylate, and sodium hexametaphosphate.

[0052] The method for preparing an polishing slurry for an aluminum nitride ceramic substrate includes the following steps:

[0053] S1: Select appropriate amounts of modified nanodiamond powder, a ceramic powder, and a surfactant according to the weight ratio, and mix them to form a dispersed phase;

[0054] S2: Add deionized water to the dispersed phase to prepare a mixture;

[0055] S3: The mixture obtained in S2 is ultrasonically dispersed. The ultrasonic processor power is 240W, and the mixture is ultrasonically dispersed in a water bath for 20 minutes to obtain a polishing slurry for aluminum nitride ceramic substrates with uniform dispersion and good stability.

[0056] Example 1

[0057] This embodiment provides a polishing slurry for aluminum nitride ceramic substrates, and its preparation method is as follows:

[0058] S1: Modified nanodiamond, (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2 ceramic powder and hexadecyltrimethylammonium bromide were mixed evenly at a mass ratio of 25:25:5 to form a dispersed phase;

[0059] S2: A certain amount of deionized water is added to the dispersed phase to prepare a mixture; the mass percentage of modified nanodiamonds in the mixture is 0.25%, (Hf 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 The mass percentage of B2 ceramic powder is 0.25%, and the mass percentage of hexadecyltrimethylammonium bromide is 0.05%.

[0060] S3: The mixture obtained in S2 is ultrasonically dispersed. The ultrasonic processor power is 240W, and the mixture is ultrasonically dispersed in a water bath for 20 minutes to obtain a polishing slurry for aluminum nitride ceramic substrates with uniform dispersion and good stability.

[0061] The modified nanodiamond is prepared by heating the nanodiamond to 700℃ in a nitrogen atmosphere at a heating rate of 5℃ / min, holding it at that temperature for 2 hours, and then cooling it in the furnace. The raw material nanodiamond powder is prepared by detonation method, and the median particle size is 5nm.

[0062] The chemical formula of the high-entropy ceramic powder is (Hf 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2; The high-entropy ceramic powder is made by mixing HfO2, MoO3, Ta2O5, Nb2O5, TiO2 oxide powder raw materials with B4C and graphite in a certain proportion, ball milling for 24 hours, drying, grinding and sieving, and compacting, and then heating to 1600℃ in a pressureless sintering furnace under vacuum conditions for 1 hour, cooling and taking it out, and finally refining it by high-energy ball milling for 24 hours.

[0063] Example 2

[0064] This embodiment provides a polishing slurry for aluminum nitride ceramic substrates, and its preparation method is as follows:

[0065] S1: Modified nanodiamond, (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2 ceramic powder and hexadecyltrimethylammonium bromide were mixed evenly at a mass ratio of 15:35:5 to form a dispersed phase;

[0066] S2: A certain amount of deionized water is added to the dispersed phase to prepare a mixture; the mass percentage of modified nanodiamonds in the mixture is 0.15%, (Hf 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 The mass percentage of B2 ceramic powder is 0.35%, and the mass percentage of hexadecyltrimethylammonium bromide is 0.05%.

[0067] S3: The mixture obtained in S2 is ultrasonically dispersed. The ultrasonic processor power is 240W, and the mixture is ultrasonically dispersed in a water bath for 20 minutes to obtain a polishing slurry for aluminum nitride ceramic substrates with uniform dispersion and good stability.

[0068] The modified nanodiamond and (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2 ceramic powder is the same as in Example 1.

[0069] Example 3

[0070] This embodiment provides a polishing slurry for aluminum nitride ceramic substrates, and its preparation method is as follows:

[0071] S1: Modified nanodiamond, (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2 ceramic powder and hexadecyltrimethylammonium bromide were mixed evenly at a mass ratio of 35:15:5 to form a dispersed phase;

[0072] S2: A certain amount of deionized water is added to the dispersed phase to prepare a mixture; the mass percentage of modified nanodiamonds in the mixture is 0.35%, (Hf 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 The mass percentage of B2 ceramic powder is 0.15%, and the mass percentage of hexadecyltrimethylammonium bromide is 0.05%.

[0073] S3: The mixture obtained in S2 is ultrasonically dispersed. The ultrasonic processor power is 240W, and the mixture is ultrasonically dispersed in a water bath for 20 minutes to obtain a polishing slurry for aluminum nitride ceramic substrates with uniform dispersion and good stability.

[0074] The modified nanodiamond and (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2 ceramic powder is the same as in Example 1.

[0075] Comparative Example 1

[0076] This comparative example provides a modified nanodiamond polishing slurry, which, by mass percentage, comprises the following components: 0.5 wt% modified nanodiamond, 0.02 wt% nonionic surfactant, 0.01 wt% cationic surfactant, and the balance being deionized water. The nonionic surfactant is OP-40 emulsifier, and the cationic surfactant is N,N-dimethylformamide. In the modified nanodiamond polishing slurry formulation, the above two surfactants exhibit the best dispersion effect compared to a series of added surfactants (including hexadecyltrimethylammonium bromide from Example 1). The specific preparation method is as follows:

[0077] S1: Modified nanodiamonds, nonionic surfactants, and cationic surfactants are mixed evenly in a mass ratio of 50:2:1 to form a dispersed phase;

[0078] S2: Add a certain amount of deionized water to the dispersed phase to prepare a mixture; the mass percentage of modified nanodiamond in the mixture is 0.5%, the mass percentage of nonionic surfactant OP-40 emulsifier is 0.02%, and the mass percentage of cationic surfactant N,N-dimethylformamide is 0.01%.

[0079] S3: The mixture obtained in S2 is ultrasonically dispersed. The ultrasonic processor has a power of 240W. The mixture is ultrasonically dispersed in a water bath for 20 minutes to obtain the modified nanodiamond grinding slurry.

[0080] The modified nanodiamond is the same as in Example 1.

[0081] Comparative Example 2

[0082] This comparative example provides a ceramic powder grinding slurry, which, by mass percentage, consists of the following components: (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2The mixture contains 0.5 wt% B2 ceramic powder, 0.05 wt% anionic surfactant, and the balance is deionized water. The anionic surfactant is sodium laurylate. In the ceramic powder grinding slurry formulation, the above surfactant exhibits the best dispersing effect compared to a series of added surfactants (including hexadecyltrimethylammonium bromide from Example 1). The specific preparation method is as follows:

[0083] S1: (Hf) 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 B2 ceramic powder and anionic surfactant are mixed evenly at a mass ratio of 50:5 to form a dispersed phase;

[0084] S2: Add a certain amount of deionized water to the dispersed phase to prepare a mixture; in the mixture (Hf 0.2 Mo 0.2 Ta 0.2 Nb 0.2 Ti 0.2 The mass percentage of B2 ceramic powder is 0.5%, and the mass percentage of anionic surfactant is 0.05%.

[0085] S3: The mixture obtained in S2 is ultrasonically dispersed. The ultrasonic processor has a power of 240W. The mixture is ultrasonically dispersed in a water bath for 20 minutes to obtain ceramic powder grinding slurry.

[0086] Material characterization

[0087] The polishing slurry for the ceramic powder and aluminum nitride ceramic substrate prepared in Example 1, as well as the modified nanodiamond polishing slurry and ceramic powder polishing slurry of Comparative Examples 1-2, were analyzed using a Zetasizer NANO ZS nanoparticle size and Zeta potential analyzer. The particle size distribution diagrams of the ceramic powder and aluminum nitride ceramic substrate polishing slurry prepared in Example 1 are shown below. Figure 1 and Figure 2The average particle size of the ceramic powder used in Example 1 was 273 nm. The average particle size of the polishing slurry for the aluminum nitride ceramic substrate prepared in Example 1 was 129 nm. Further testing revealed that the average particle size of the modified nanodiamond polishing slurry in Comparative Example 1 was 189.36 nm, and the average particle size of the ceramic powder polishing slurry in Comparative Example 2 was 139 nm. Additionally, the Zeta potential of the modified nanodiamond polishing slurry in Comparative Example 1 was 29.1 mV; the Zeta potential of the ceramic powder polishing slurry in Comparative Example 2 was -42.8 mV; and the Zeta potential of the modified nanodiamond and ceramic powder in Example 1, both at 0.25%, was 31.1 mV. Generally, when the absolute value of the Zeta potential exceeds 30 mV, the solution is considered to have high stability, indicating that the polishing slurry for the aluminum nitride ceramic substrate prepared in Example 1 has high stability.

[0088] Comparative analysis shows that the agglomeration of the aluminum nitride ceramic substrate polishing slurry in Example 1 is reduced, and the average particle size is further reduced. This indicates that when positively charged modified nanodiamonds and negatively charged high-entropy ceramic powders are mixed, their opposite charges will cause mutual adsorption. On the one hand, the larger high-entropy ceramic particles are coated by the smaller modified nanodiamond particles to form a composite abrasive. On the other hand, the nanodiamond particles and ceramic particles each play a role in de-agglomeration, which can prevent the nanodiamond particles and ceramic particles from agglomerating and improve the polishing uniformity.

[0089] Grinding experiment characterization

[0090] Grinding experiments were conducted using the aluminum nitride ceramic substrate grinding slurry prepared in Example 1, as well as the modified nanodiamond grinding slurry and ceramic powder grinding slurry of Comparative Examples 1-2. The ceramic substrate material used was aluminum nitride ceramic, manufactured by Shenzhen Haide Precision Ceramics Co., Ltd. The original sample dimensions were 10mm × 10mm × 6mm. The grinding instrument was an FD-3803X single-sided grinding and polishing machine, with a grinding pressure of 0.2MPa, a grinding disc rotation speed of 45r / min, a grinding slurry flow rate of 2mL / min, and a grinding time of 1h. The grinding results were characterized by surface roughness (Sa) and material removal rate (MRR), where Sa is defined as the arithmetic mean of the absolute values ​​of the height differences of all measurement points relative to the reference plane. The surface roughness of the workpiece was measured using a ContourGT-X white light interferometer manufactured by Bruker GmbH, Germany. Referring to GB / T 29505-2013, "Method for Measuring Surface Roughness of Flat Surfaces of Silicon Wafers," measurements were taken at five points for each sample: the center point and four points around the center point at 2 / 3 of the distance from the center, and the average value was calculated. Material removal rate reflects the ease and efficiency of material processing. Before and after grinding, the workpieces were ultrasonically cleaned with anhydrous ethanol for 5 minutes to remove surface impurities, and then dried in a DHG-9642A electric thermostatic drying oven for 30 minutes. The average value was taken from five weighings using a precision electronic balance (accuracy 0.0001g). The formula for calculating the material removal rate per unit time is:

[0091]

[0092] Where: Δm is the mass difference before and after processing, in g;

[0093] ρ is the density of the material being processed, in g / cm³. 3 ;

[0094] s represents the contact area, in mm. 2 ;

[0095] t represents the processing time, in minutes.

[0096] The results of the grinding experiment are shown in Table 1.

[0097] Table 1. Grinding Experiment Results

[0098]

[0099] Table 1 shows that the polishing slurry of Example 1, compared with that of the comparative example, can achieve uniform and efficient polishing of aluminum nitride ceramic substrates, significantly reduce the surface roughness of the polished aluminum nitride ceramic substrates, and obtain a higher material removal rate, thus improving the application prospects of aluminum nitride ceramic substrates.

[0100] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A polishing liquid characterized by comprising: The modified nanodiamond has a positive surface charge; the high-entropy ceramic powder has a negative surface charge.

2. The polishing liquid according to claim 1, wherein The modified nanodiamond has a positive surface charge; the high-entropy ceramic powder has a negative surface charge.

3. The polishing liquid according to claim 1, wherein The modified nanodiamond has a particle size of 1-30 nm.

4. The polishing liquid according to claim 1, wherein The modified nanodiamond is a heat-treated nanodiamond. Preferably, the preparation method of the modified nanodiamond comprises the following steps: heat treatment of the nanodiamond under a protective atmosphere, heat treatment temperature of 500-900℃, heat treatment time of 1-4h.

5. The polishing liquid according to claim 1, wherein The high-entropy ceramic powder comprises a high-entropy boride ceramic powder. Preferably, the high-entropy boride ceramic powder comprises B element and at least four of Ti, Zr, Hf, V, Nb, Ta, Mo, W metal elements.

6. The polishing liquid according to claim 5, wherein The high-entropy ceramic powder includes (Hf a Mo b Ta c Nb d Ti e )B2 high-entropy ceramic powder, wherein 0.1≤a≤1, 0.1≤b≤1, 0.1≤c≤1, 0.1≤d≤1, 0.1≤e≤1, and a+b+c+d+e=1 is satisfied.

7. The polishing liquid according to claim 1, wherein The surface active agent is a cationic surface active agent.

8. A method of producing the polishing liquid according to any one of claims 1 to 7, characterized by, The modified nanodiamond has a positive surface charge; the high-entropy ceramic powder has a negative surface charge.

9. Use of the polishing liquid of any one of claims 1-7 in precision polishing of ceramic substrate materials.

10. A method of polishing an aluminum nitride ceramic substrate, characterized by, The modified nanodiamond has a positive surface charge; the high-entropy ceramic powder has a negative surface charge.

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