Modified diamond micro powder, its preparation method and application

Abstract

The present application relates to a modified diamond micro-powder and a preparation method and application thereof. The preparation method of the modified diamond micro-powder comprises the following steps: performing hydroxylation treatment on diamond micro-powder to obtain surface hydroxylated diamond micro-powder; performing pretreatment on the surface hydroxylated diamond micro-powder in a mixed solution of a silane coupling agent and an organic solvent under ultrasonic conditions with a frequency of 25KHz-40KHz and an intensity of 1W / cm 2 -3W / cm 2 to obtain pretreated diamond micro-powder; and performing vacuum heat treatment on the pretreated diamond micro-powder to obtain modified diamond micro-powder. The preparation method greatly improves the bonding force between the modified layer and the diamond and improves the micro-powder agglomeration, so that the pretreatment link before chemical plating has the feasibility of batch processing, which not only doubles the production efficiency, but also reduces the production cost to one third of the traditional method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of abrasive tools, in particular to a modified diamond micro-powder and a preparation method and application thereof. BACKGROUND

[0002] Diamond is an important abrasive in abrasive tools, and the surface of diamond usually needs to be modified to enhance the bonding force between diamond and plating layer. The traditional surface modification technology of diamond includes a two-step method of sensitization-activation and a colloidal palladium activation method. Both of the two methods use stannous chloride as a connecting agent for palladium ions and diamond, so that metallic palladium is adsorbed to the surface of diamond as a catalyst for plating layer to enhance the bonding force between diamond and plating layer. However, since the connecting agent is connected by hydrogen bond adsorption, the adsorption force is poor, and especially after high temperature treatment, the hydrogen bond adsorption force is easy to fail, so that there is only mechanical embedding action between diamond and plating layer. Once the plating layer is damaged, the diamond is easy to fall off from the plating layer. SUMMARY

[0003] Therefore, it is necessary to provide a modified diamond micro-powder and a preparation method and application thereof aiming at the above problems. The preparation method greatly improves the bonding force between the modified layer and diamond, and improves the agglomeration of micro-powder, so that the pre-treatment link before chemical plating has the feasibility of batch processing, which not only doubles the production efficiency, but also reduces the production cost to one third of the traditional method.

[0004] A preparation method of a modified diamond micro-powder, comprising the following steps:

[0005] Hydroxylating diamond micro-powder to obtain surface hydroxylated diamond micro-powder;

[0006] Pre-treating the surface hydroxylated diamond micro-powder in a mixed solution of silane coupling agent and organic solvent under ultrasonic conditions with a frequency of 25KHz-40KHz and an intensity of 1W / cm2-3W / cm2 to obtain pre-treated diamond micro-powder;

[0007] Vacuum heat-treating the pre-treated diamond micro-powder to obtain modified diamond micro-powder.

[0008] In one of the embodiments, the mixed solution satisfies at least one of the following conditions:

[0009] (1) the pH of the mixed solution is 3-5;

[0010] (2) the water content of the mixed solution is less than 0.5%;

[0011] (3) the mass ratio of the surface hydroxylated diamond micro-powder to the mixed solution is 0.2:1-1:1;

[0012] (4) the mass fraction of the silane coupling agent in the mixed solution is 2%-10%;

[0013] (5) the silane coupling agent is selected from at least one of γ-aminopropyl triethoxysilane, 5,6-epoxyhexyl triethoxysilane, and trimethyl [3- (trimethoxysilyl) propyl] ammonium chloride;

[0014] (6) the organic solvent is selected from an alcohol organic solvent.

[0015] In one embodiment, the alcohol organic solvent is selected from at least one of butanol, propanol, and ethanol.

[0016] In one embodiment, the vacuum heat treatment includes a first heat treatment and a second heat treatment, and the temperature of the second heat treatment is greater than that of the first heat treatment.

[0017] In one embodiment, the temperature of the first heat treatment is 80°C-120°C, and the time is 6h-12h.

[0018] In one embodiment, the temperature of the second heat treatment is 100°C-150°C, and the time is 12h-24h.

[0019] In one embodiment, the method for preparing the surface-hydroxylated diamond powder includes:

[0020] placing the diamond powder in a 2wt%-5wt% sodium hydroxide solution for 1h-4h;

[0021] or, calcining the diamond powder at 400°C-500°C for 2h-4h under the condition of air being introduced;

[0022] or, using borane-tetrahydrofuran adduct to hydroxylate the diamond powder.

[0023] In one embodiment, after the pre-treated diamond powder is subjected to vacuum heat treatment, it is further subjected to oxidation treatment.

[0024] In one embodiment, when the silane coupling agent is selected from an epoxy-group-containing silane coupling agent, the pre-modified diamond powder obtained after the vacuum heat treatment is placed in an epoxy-group-containing quaternary ammonium salt solution to react, thereby obtaining a modified diamond powder.

[0025] A modified diamond powder prepared by the method for preparing a modified diamond powder as described above, compared with the diamond powder before modification, the particle size D 90 of the modified diamond powder changes by less than 2%.

[0026] An abrasive tool, wherein the abrasive in the abrasive tool comprises modified diamond micron powder as described above.

[0027] The method for preparing modified diamond micropowder according to this invention utilizes ultrasonic waves of a specific intensity in an organic solvent system to stably adsorb all three alkoxy chains of the silane coupling agent onto the diamond surface, thereby achieving directional adsorption of the silane coupling agent on the diamond surface. On one hand, during vacuum heat treatment, the self-assembled silane coupling agent adsorbed on the diamond surface undergoes a siloxane condensation reaction with the hydroxyl groups on the diamond surface, bonding the silane coupling agent to the diamond surface and forming CO-Si bonds. This significantly improves the bonding force between the modified layer and the diamond, and reduces micropowder agglomeration. On the other hand, the directionally adsorbed silane coupling agent results in highly ordered functional groups attached to the diamond surface, which not only increases the number of attached functional groups but also significantly enhances the proportion of reactive functional groups. Furthermore, the mixed solution used in the pretreatment is water-free, which not only avoids the time-limited issues caused by hydrolysis, cross-linking, and self-polymerization of the silane coupling agent but also allows for recycling up to approximately eight times, offering advantages such as high efficiency, environmental friendliness, and low cost.

[0028] Therefore, the preparation method provided by the present invention makes the pretreatment stage of chemical plating feasible for batch processing, which not only doubles the production efficiency, but also reduces the production cost to one-third of the traditional method. Detailed Implementation

[0029] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0031] Traditional methods use water as a modification accelerator and utilize the silanol groups after hydrolysis of silane coupling agents (siloxane polymerization) to form a polymeric molecular network that coats the diamond, thus completing the surface modification. However, the modified layer and the diamond substrate are only wrapped by the polymeric molecular network or connected by a very small number of CO-Si bonds, resulting in poor modification stability. Furthermore, due to the strong self-polymerization tendency of silanol groups, the treated diamond micropowder will agglomerate to varying degrees depending on the particle size. In particular, when treating diamond abrasive with a diameter of less than 10 μm, obvious agglomeration will occur, making it unsuitable for applications requiring high dispersion of diamond micropowder.

[0032] Based on this, the present invention provides a method for preparing modified diamond micro powder, comprising the following steps:

[0033] S1, hydroxylate diamond powder to obtain surface-hydroxylated diamond powder;

[0034] S2, the surface hydroxylated diamond micro powder is pretreated in a mixed solution of silane coupling agent and organic solvent under ultrasonic conditions with a frequency of 25KHz-40KHz and an intensity of 1W / cm2-3W / cm2 to obtain pretreated diamond micro powder.

[0035] S3, the pretreated diamond micro powder is subjected to vacuum heat treatment to obtain modified diamond micro powder.

[0036] It should be noted that the present invention does not limit the preparation method of surface hydroxylated diamond micro powder in step S1. Any existing preparation method is acceptable, such as: treating diamond micro powder in a 2wt%-5wt% sodium hydroxide solution for 1h-4h; or calcining diamond micro powder at 400℃-500℃ for 2h-4h under air-purifying conditions; or hydroxylating diamond micro powder using a borane-tetrahydrofuran adduct.

[0037] In step S2, in an organic solvent system, ultrasound of a specific intensity is used to ensure that all three alkoxy chains of the silane coupling agent are stably adsorbed onto the diamond surface, thereby achieving directional adsorption of the silane coupling agent on the diamond surface. The directional adsorption of the silane coupling agent makes the functional groups attached to the diamond surface highly ordered, which not only helps to increase the number of attached functional groups, but also significantly increases the proportion of reactive functional groups.

[0038] In addition, the mixed solution used in the pretreatment does not contain water, which not only avoids the time-limited problem caused by the hydrolysis, cross-linking and self-polymerization of silane coupling agents, but also allows for recycling up to about 8 times, with advantages such as high efficiency, environmental protection and low cost.

[0039] Specifically, the pretreatment reaction mechanism is as follows: In this context, X-Si-(OR)3 represents a silane coupling agent, and ND-OH represents surface-hydroxylated diamond micropowder.

[0040] In one embodiment, the mixed solution satisfies at least one of the following conditions:

[0041] (1) The pH of the mixed solution is 3-5;

[0042] (2) The water content of the mixed solution is less than 0.5%;

[0043] (3) The mass ratio of the surface hydroxylated diamond micropowder to the mixed solution is 0.2:1-1:1;

[0044] (4) The mass fraction of the silane coupling agent in the mixed solution is 2%-10%;

[0045] (5) The silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane, 5,6-epoxyhexyltriethoxysilane, and trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride;

[0046] (6) The organic solvent is selected from alcohol-based organic solvents.

[0047] Compared with the traditional method that uses water as a modification accelerator, the present invention achieves the effect of completely preventing powder agglomeration under ultra-high processing concentration conditions, and significantly improves the stability of surface modification.

[0048] In one embodiment, the alcoholic organic solvent is selected from at least one of butanol, propanol, and ethanol.

[0049] In step S2, during the vacuum heat treatment process, the silane coupling agent that self-assembles and adsorbs on the diamond surface undergoes a siloxane condensation reaction with the hydroxyl groups on the diamond surface, causing the silane coupling agent to bond with the diamond surface and form CO-Si bonds, thereby significantly improving the bonding force between the modified layer and the diamond and improving the micro powder agglomeration.

[0050] In one embodiment, the vacuum heat treatment process includes a primary heat treatment and a secondary heat treatment, wherein the temperature of the secondary heat treatment is higher than the temperature of the primary heat treatment.

[0051] It should be noted that, unlike traditional silane coupling agents that are directly polymerized and modified after hydrolysis, the silane coupling agent that self-assembles and adsorbs onto the diamond surface in this invention undergoes a siloxane condensation reaction with the hydroxyl groups on the diamond surface, which mainly occurs during the secondary heat treatment process.

[0052] In one embodiment, the temperature of the primary heat treatment is preferably 80℃-120℃, and the time is preferably 6h-12h; and / or, the temperature of the secondary heat treatment is preferably 100℃-150℃, and the time is preferably 12h-24h.

[0053] More preferably, the temperature of the first heat treatment is 80℃-120℃ and the time is 6h-12h, and the temperature of the second heat treatment is 100℃-150℃ and the time is 12h-24h.

[0054] By controlling the temperature and time of segmented heat treatment, it is not only beneficial to improve the stability of surface modification, but also to increase the number of attached functional groups and the proportion of reactive functional groups.

[0055] In one embodiment, after the pretreated diamond micro powder is subjected to vacuum heat treatment, it also includes oxidation treatment, which not only overcomes the difficulty of achieving specific functional group modification in a single modification treatment, but also helps to further reduce costs.

[0056] Specifically, after the pretreated diamond micro powder is subjected to vacuum heat treatment, diamond with amino functional groups on the surface can be obtained. Through further oxidation treatment, the amino groups are oxidized to form nitro groups, thereby obtaining diamond with nitro functional groups on the surface.

[0057] In another embodiment, when the silane coupling agent is selected from silane coupling agents containing epoxy groups, the pre-modified diamond micropowder obtained after vacuum heat treatment is placed in a quaternary ammonium salt solution containing epoxy groups, so that the epoxy functional groups in the pre-modified diamond micropowder undergo an addition reaction with the epoxy functional groups in the quaternary ammonium salt, thereby forming a quaternization modification on the surface of the diamond micropowder. The segmented modification realizes chain extension and re-modification, breaking the limitation of the type of silane coupling agent.

[0058] Preferably, the quaternary ammonium salt containing epoxy groups is 2,3-epoxypropyltrimethylammonium chloride.

[0059] In one embodiment, the pre-modified diamond micropowder is placed in a quaternary ammonium salt solution containing epoxy groups for reaction. After the reaction is completed, the pre-modified diamond micropowder is obtained by drying.

[0060] In one embodiment, the reaction conditions of the pre-modified diamond micropowder in the quaternary ammonium salt solution containing epoxy groups can be ultrasonic conditions. These ultrasonic conditions can be the same as or different from the pretreatment conditions, and the present invention does not limit this.

[0061] It should be noted that when the silane coupling agent is selected from other specific groups, chain extension and re-modification can be carried out using a treatment liquid containing the same specific groups, thereby achieving diversified modification of diamond micro powder. This invention does not limit this.

[0062] Therefore, the preparation method provided by the present invention makes the pretreatment stage of chemical plating feasible for batch processing, which not only doubles the production efficiency, but also reduces the production cost to one-third of the traditional method.

[0063] The present invention provides a modified diamond micro powder prepared by the method described above. It is understood that the modified diamond micro powder includes diamond micro powder and a modified layer distributed on the surface of the diamond.

[0064] Compared with the original diamond micro powder, the particle size D of the modified diamond micro powder is... 90 With a change rate of less than 2%, it is clear that the modified diamond micro powder prepared by the method described in this invention is not prone to agglomeration and can be applied to fields where the dispersibility of diamond micro powder is required to be high.

[0065] It should be noted that D 90 The rate of change is ΔD 90 / D 50 The ratio of , where ΔD 90 D of diamond micron powder before modification 90 With the modified diamond micro powder D 90 The absolute value of the difference, D 50 D of diamond micron powder before modification 50 The present invention also provides an abrasive tool in which the abrasive comprises the modified diamond micro powder as described above.

[0066] When the modified diamond micro powder described in this invention is used as an abrasive in the grinding wheel, it is not easily detached during the grinding process, effectively exerting its grinding performance and giving the grinding wheel better grinding performance and a longer service life.

[0067] It is understood that the abrasive may also include a binder, etc., but the present invention does not limit this.

[0068] The modified diamond micropowder, its preparation method, and its applications will be further illustrated below through specific embodiments. However, those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0069] Example 1

[0070] Take 15000g of diamond micropowder with a particle size of 6μm and place it in 20L of clean water. Add 500g of NaOH, stir, and ultrasonically heat to 90℃ for 4h. After washing and drying, the surface hydroxylated diamond micropowder is obtained.

[0071] Butanol and γ-aminopropyltriethoxysilane were mixed in a mass ratio of 19:1 to form a solution. The pH was adjusted to 3 using aminosulfonic acid. 15,000 g of surface-hydroxylated diamond micropowder was dispersed in 20 L of the mixed solution and subjected to an intensity of 1.6 W / cm at a frequency of 28 kHz. 2 The diamond powder was stirred and sonicated under ultrasonic conditions, and the solvent was removed by filtration to obtain pretreated diamond micro powder.

[0072] 15,000 g of pretreated diamond micro powder was placed in a vacuum oven and heat-treated at 100°C for 8 hours, followed by vacuum heat treatment at 150°C for 12 hours to obtain amination-modified diamond micro powder.

[0073] Example 2

[0074] Take 15000g of diamond micropowder with a particle size of 6μm and place it in 20L of clean water. Add 500g of NaOH, stir, and ultrasonically heat to 90℃ for 4h. After washing and drying, the surface hydroxylated diamond micropowder is obtained.

[0075] Propanol and γ-aminopropyltriethoxysilane were mixed in a mass ratio of 24:1 to form a solution. The pH was adjusted to 4 using aminosulfonic acid. 15,000 g of surface-hydroxylated diamond powder was dispersed in 20 L of the mixed solution and stirred and sonicated under ultrasonic conditions of 30 kHz and 2 W / cm2. The solvent was then removed by filtration to obtain pretreated diamond powder.

[0076] 15,000 g of pretreated diamond micro powder was placed in a vacuum oven and heat-treated at 100°C for 8 hours, followed by vacuum heat treatment at 150°C for 12 hours to obtain amination-modified diamond micro powder.

[0077] 15,000 g of amination-modified diamond micropowder was dispersed in 20 L of 0.5% potassium permanganate solution, stirred and sonicated, washed and dried to obtain nitration-modified diamond micropowder.

[0078] Example 3

[0079] Take 15000g of diamond micro powder with a particle size of 6μm, calcine it at 500℃ for 4h under air circulation, and then clean and dry it to obtain surface hydroxylated diamond micro powder.

[0080] Ethanol and trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride were mixed in a mass ratio of 33:1. The pH was adjusted to 5 using aminosulfonic acid. 15,000 g of surface-hydroxylated diamond powder was dispersed in 20 L of the mixed solution and stirred and sonicated under ultrasonic conditions of 40 kHz and 3 W / cm2. The solvent was then removed by filtration to obtain pretreated diamond powder.

[0081] 15,000 g of pretreated diamond micro powder was placed in a vacuum oven and subjected to vacuum heat treatment at 80°C for 8 hours, followed by vacuum heat treatment at 120°C for 12 hours to obtain quaternized modified diamond micro powder.

[0082] Example 4

[0083] Take 15000g of diamond micro powder with a particle size of 6μm, calcine it at 500℃ for 4h under air circulation, and then clean and dry it to obtain surface hydroxylated diamond micro powder.

[0084] Propanol and 5,6-epoxyhexyltriethoxysilane were mixed in a mass ratio of 24:1 to form a solution. The pH was adjusted to 4 using aminosulfonic acid. 15,000 g of surface-hydroxylated diamond powder was dispersed in 20 L of the mixed solution and stirred and sonicated under ultrasonic conditions of 25 kHz and 1 W / cm2. The solvent was then removed by filtration to obtain pretreated diamond powder.

[0085] 15,000 g of pretreated diamond micro powder was placed in a vacuum oven and heat-treated at 100°C for 8 hours, followed by vacuum heat treatment at 140°C for 12 hours to obtain epoxy-modified diamond micro powder.

[0086] Example 5

[0087] Take 15000g of diamond micro powder with a particle size of 6μm, calcine it at 500℃ for 4h under air circulation, and then clean and dry it to obtain surface hydroxylated diamond micro powder.

[0088] Butanol and 5,6-epoxyhexyltriethoxysilane were mixed in a mass ratio of 19:1 to form a solution. The pH was adjusted to 3 using aminosulfonic acid. 15,000 g of surface-hydroxylated diamond powder was dispersed in 20 L of the mixed solution and stirred and sonicated under ultrasonic conditions of 28 kHz and 1.6 W / cm2. The solvent was then removed by filtration to obtain pretreated diamond powder.

[0089] 15,000 g of pretreated diamond micro powder was placed in a vacuum oven and heat-treated at 100°C for 8 hours, followed by vacuum heat treatment at 140°C for 12 hours to obtain epoxy-modified diamond micro powder.

[0090] Butanol, water, and 2,3-epoxypropyltrimethylammonium chloride were mixed in a mass ratio of 18:1:1 to form a solution. The pH was adjusted to 3 using aminosulfonic acid. 15,000 g of epoxy-modified diamond micropowder was dispersed in 20 L of the mixed solution and stirred and sonicated under ultrasonic conditions of 28 kHz and 1.6 W / cm². After washing and drying at 65 °C, quaternized modified diamond micropowder was obtained.

[0091] Comparative Example 1

[0092] Take 15000g of diamond micropowder with a particle size of 6μm and place it in 20L of clean water. Add 500g of NaOH, stir, and ultrasonically heat to 90℃ for 4h. After washing and drying, the surface hydroxylated diamond micropowder is obtained.

[0093] Butanol, water, and γ-aminopropyltriethoxysilane were mixed in a mass ratio of 17:2:1 to form a solution. 15,000 g of surface-hydroxylated diamond powder was dispersed in 20 L of the solution and stirred and sonicated under ultrasonic conditions of 28 kHz and 1.6 W / cm2. The solvent was then removed by filtration to obtain pretreated diamond powder.

[0094] 15,000 g of pretreated diamond micro powder was placed in a vacuum oven and dried under vacuum at 100 °C to obtain amino-modified diamond micro powder.

[0095] Comparative Example 2

[0096] The difference between Comparative Example 2 and Example 1 is that no ultrasonic conditions were applied.

[0097] Comparative Example 3

[0098] The difference between Comparative Example 3 and Example 1 is that the ultrasonic intensity is 0.5 W / cm2.

[0099] The modified diamond micropowders prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1.

[0100] Table 1

[0101]

[0102] According to Table 1, the D values ​​before and after modification in Example 1 are... 90 The change rate was only 0%. After modification, nitrogen was detected on the XPS surface. The zeta potential changed from -70 to -40, indicating that the functional groups on the diamond surface changed from hydroxyl to amino, and the modification was successful. No significant agglomeration occurred before and after the modification.

[0103] Example 2: Before and after modification D 90 The change rate was only 0.5%. After modification, nitrogen was detected on the XPS surface, and the zeta potential changed from -70 to -50. Combined with Example 1, it can be seen that the functional groups on the diamond surface first changed from hydroxyl to amino, and then from amino to nitro. The modification was successful, and no significant agglomeration occurred before and after the modification.

[0104] Example 3: Before and after modification D 90The change rate was only 1.9%. After modification, nitrogen was detected on the XPS surface, and the zeta potential changed from -70 to +55, indicating that the functional groups on the diamond surface changed from hydroxyl to quaternary ammonium, indicating successful modification. Furthermore, no significant agglomeration occurred before and after modification.

[0105] Example 4: D before and after modification 90 The change rate was only 0.6%. No nitrogen element was detected on the surface of XPS after modification. The zeta potential changed from -70 to +20, indicating that the functional groups on the diamond surface changed from hydroxyl to epoxy groups, and the modification was successful. No significant agglomeration occurred before and after the modification.

[0106] Example 5: Before and after modification D 90 The change rate was only 0.4%. After modification, nitrogen was detected on the XPS surface, and the zeta potential changed from -70 to +50. Combined with Example 4, it can be seen that the functional groups on the diamond surface changed from hydroxyl to quaternary ammonium, indicating successful modification. Moreover, no significant agglomeration occurred before and after modification.

[0107] In Comparative Example 1, water was used as a bonding promoter. Due to the hydrolysis reaction between the silane coupling agent and water, silanol groups were generated. During the heat treatment process, the hydroxyl groups on the diamond surface condensed with the silanol groups to generate ND-O-Si, completing the bonding modification. Condensation also occurred between silanol groups to generate Si-O-Si, resulting in a cross-linking side reaction of the silane coupling agent, causing the particles to be ND-O-(Si-O). n -Si-ND aggregate together, resulting in D before and after modification 90 The rate of change was as high as 17.5%, indicating significant aggregation.

[0108] In Comparative Example 2, due to the absence of ultrasonic treatment, the silane coupling agent could not be directionally adsorbed onto the diamond surface, resulting in a large number of exposed Si-OR alkoxy functional groups. Consequently, the wettability of the micropowder decreased, and the Zeta potential test result changed from -40 to -30 compared to Example 1, indicating a difference in modification effect. Furthermore, the large number of exposed Si-OR alkoxy functional groups caused agglomeration of diamond particles due to the Si-OR crosslinking reaction, leading to a difference in D before and after modification. 90 The rate of change was as high as 8.2%, indicating significant aggregation.

[0109] In Comparative Example 3, when ultrasonic intensity was applied at 0.5 mW / cm², the silane coupling agent could only be partially and directionally adsorbed onto the diamond surface. Therefore, some Si-OR alkoxy functional groups remained exposed. Although this had little effect on the wettability of the micropowder and did not significantly affect the Zeta potential test results compared to Example 1, the exposed Si-OR alkoxy functional groups caused agglomeration of diamond particles due to the Si-OR crosslinking reaction, leading to changes in the D-value before and after modification. 90 The rate of change was as high as 4.9%, indicating significant aggregation.

[0110] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for producing modified diamond micropowder as an abrasive, characterized by, The method comprises the following steps: The diamond powder is subjected to hydroxyl group treatment to obtain surface hydroxyl group diamond powder; The surface-hydroxylated diamond micropowder is pretreated in a mixed solution of silane coupling agent and organic solvent under ultrasonic conditions with a frequency of 25 kHz-40 kHz and an intensity of 1 W / cm 2 -3 W / cm 2 to obtain pretreated diamond micropowder. The pretreated diamond powder is subjected to vacuum heat treatment to obtain modified diamond powder.

2. The method of producing modified diamond micropowder according to claim 1, characterized by, The mixed solution satisfies at least one of the following conditions: (1) the pH of the mixed solution is 3-5; (2) the water content of the mixed solution is less than 0.5%; (3) the mass ratio of the surface hydroxyl group diamond powder to the mixed solution is 0.2:1-1:1; (4) the mass fraction of the silane coupling agent in the mixed solution is 2%-10%; (5) the silane coupling agent is at least one selected from γ-aminopropyl triethoxysilane, 5,6-epoxyhexyl triethoxysilane and trimethyl [3-(trimethoxysilyl) propyl] ammonium chloride; (6) the organic solvent is at least one selected from alcohol organic solvents.

3. The method of producing modified diamond micropowder according to claim 2, characterized by, The alcohol organic solvent is at least one selected from butanol, propanol and ethanol.

4. The method of producing modified diamond micropowder according to claim 1, characterized by, The vacuum heat treatment comprises primary heat treatment and secondary heat treatment, and the temperature of the secondary heat treatment is higher than that of the primary heat treatment.

5. The method of producing modified diamond micropowder according to claim 4, characterized by, The temperature of the primary heat treatment is 80-120℃, and the time is 6-12h; and / or, the temperature of the secondary heat treatment is 100-150℃, and the time is 12-24h.

6. The method of producing modified diamond micropowder according to claim 1, characterized by, The preparation method of the surface hydroxyl group diamond powder comprises: The diamond powder is placed in a 2wt%-5wt% sodium hydroxide solution for 1-4h; or, the diamond powder is calcined at 400-500℃ for 2-4h under the condition of air being introduced; or, the diamond powder is subjected to hydroxyl group treatment by using borane-tetrahydrofuran adduct.

7. The method of producing modified diamond micropowder according to claim 1, characterized by, After the pretreated diamond powder is subjected to vacuum heat treatment, oxidation treatment is further included.

8. The method of producing modified diamond micropowder according to claim 1, characterized by, When the silane coupling agent is selected from an epoxy group-containing silane coupling agent, the pretreated diamond powder is placed in an epoxy group-containing quaternary ammonium salt solution to react, to obtain modified diamond powder.

9. A modified diamond micropowder produced by the method of producing a modified diamond micropowder according to any one of claims 1 to 8, characterized by, The particle size D 90 The change rate is less than 2%.

10. An abrasive tool, characterized by The abrasive in the abrasive tool comprises the modified diamond powder according to claim 9. The abrasive in the abrasive tool comprises the modified diamond powder according to claim 9.

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