阅读说明：本技术 一种超分散纳米金刚石悬浮液的制备方法 (Preparation method of ultra-dispersed nano-diamond suspension ) 是由 王偲偲 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种超分散纳米金刚石悬浮液的制备方法,制备方法包括以下步骤：(1)金刚石预处理：将金刚石加入碱溶液中,控制温度在20～95℃,保温,洗涤,干燥,煅烧；(2)制备金刚石预处理液：将煅烧的金刚石在去离子水中超声分散,加入芳香胺类化合物和亚硝酸酯类化合物,得到金刚石悬浊液,冷却,得到金刚石预处理液；(3)湿法细磨：将金刚石预处理液加入带有筛网的珠磨机,珠磨得到金刚石悬浮液；(4)离心分散：将金刚石悬浮液超声分散,离心收集上层清液,得到超分散纳米金刚石悬浮液。本发明超分散纳米金刚石悬浮液的制备方法,制备的纳米金刚石悬浮液的金刚石粒径分布集中,大小均匀,不团聚。(The invention discloses a preparation method of a super-dispersed nano-diamond suspension, which comprises the following steps: (1) diamond pretreatment: adding diamond into an alkali solution, controlling the temperature to be 20-95 ℃, preserving the heat, washing, drying and calcining; (2) preparing a diamond pretreatment solution: ultrasonically dispersing the calcined diamond in deionized water, adding an aromatic amine compound and a nitrite compound to obtain a diamond suspension, and cooling to obtain a diamond pretreatment solution; (3) and (3) wet fine grinding: adding the diamond pretreatment solution into a bead mill with a screen, and performing bead milling to obtain a diamond suspension; (4) centrifugal dispersion: and ultrasonically dispersing the diamond suspension, centrifuging and collecting supernatant to obtain the ultra-dispersed nano diamond suspension. According to the preparation method of the ultra-dispersed nano-diamond suspension, the prepared nano-diamond suspension has the advantages of concentrated diamond particle size distribution, uniform size and no agglomeration.)

1. A preparation method of a super-dispersed nano-diamond suspension is characterized by comprising the following steps:

(1) diamond pretreatment: adding diamond into an alkali solution, controlling the temperature at 20-95 ℃, preserving heat for 1-38 h, washing until the pH value is neutral, drying and calcining;

(2) preparing a diamond pretreatment solution: ultrasonically dispersing the calcined diamond in deionized water, adding aniline compounds and nitrite compounds to obtain a diamond suspension, heating the diamond suspension, preserving heat for a certain time, and cooling to obtain a diamond pretreatment solution;

(3) and (3) wet fine grinding: adding the diamond pretreatment solution into a bead mill with a screen, and collecting diamond suspension flowing out of the screen after the bead mill is used for a certain time;

(4) centrifugal dispersion: and ultrasonically dispersing the diamond suspension, centrifuging and collecting supernatant to obtain the ultra-dispersed nano diamond suspension.

2. The method for preparing a ultra-dispersed nano-diamond suspension according to claim 1, wherein the diamond in the step 1) is prepared by a CVD method; the CVD method is one of a plasma CVD method, a microwave plasma CVD method and a hot wire CVD method.

3. The method for producing a ultra-dispersed nanodiamond suspension according to claim 2, wherein the diamond includes a substrate and a diamond film provided on the substrate; the diamond film comprises at least one layer of nano-diamond particles; the particle size range of the nano diamond particles is 2-500 nm.

4. The method for preparing the ultra-dispersed nano-diamond suspension according to claim 1, wherein the alkali solution in the step (1) is one or two of a potassium hydroxide solution and a sodium hydroxide solution, and the mass fraction of the alkali solution is 30-40 wt%.

5. The method for preparing a ultra-dispersed nanodiamond suspension according to claim 1, wherein vacuum degree of calcination in step (1) is < 10^-2mbar, the calcining temperature is 900-1200 ℃, and the calcining time is 0.5-2 h.

6. The method for preparing a ultra-dispersed nanodiamond suspension according to claim 1, wherein the mass concentration of the diamond suspension in the step (2) is 0.001-10 wt%.

7. The method for preparing a ultra-dispersed nanodiamond suspension according to claim 1, wherein the aniline compound of step (2) is one or more selected from p-aminobenzoic acid and aminobenzenesulfonic acid; the nitrite ester compound is isoamyl nitrite; the molar concentrations of the aniline compound and the nitrite compound in the pretreatment liquid are both 10^-4～10^-2mol/L。

8. The preparation method of the ultra-dispersed nano-diamond suspension liquid according to claim 1, wherein the heating temperature of the diamond suspension liquid in the step (2) is 40-90 ℃, and the heat preservation time is 1-38 hours.

9. The method for preparing a ultra-dispersed nano-diamond suspension according to claim 1, wherein the mesh size of the screen in the step (3) is 0.50-500 μm, and the rotation speed of the bead mill is 3000-6000 min^-1And the bead milling time is 1-8 h.

10. The method for preparing the ultra-dispersed nano-diamond suspension according to claim 1, wherein the mass fraction of the diamond suspension in the step (4) is 0.005-3 wt%; the ultrasonic dispersion time is 0.5-1 h, and the power is 200-800W; the rotation speed of the centrifugation is 1000-4000 rpm/min, and the centrifugation time is 0.5-8 h.

Technical Field

The invention relates to the field of diamond, in particular to a preparation method of a super-dispersed nano-diamond suspension.

Background

Diamond is an excellent 21 st century material. Because the diamond has the characteristics of excellent thermal conductivity, high hardness, low friction, good optical property, biocompatibility coefficient and the like, the nano-diamond not only inherits the advantages of large-scale diamond particles, but also has the characteristics of nano-materials. Therefore, the nano-diamond has been widely used in various fields such as abrasives, cutting tools, biosensors, electrochemical electrodes, and the like.

The detonation method is the main method for producing nano-diamond at present, and converts graphite in a closed state into diamond through instantaneous high-temperature high-pressure low-oxygen conditions generated by explosion of explosives (such as TNT-RDX mixed explosives). The detonation method has low cost and high speed, but the obtained diamond raw powder has high impurity content (the content can reach 80%). This is due to the non-uniform temperature produced by the detonation process, and the resulting detonation-process diamond has low crystallinity. Besides, the obtained diamond contains a large amount of unconverted graphite and other amorphous carbon, in order to remove impurities in the detonation method diamond, in the prior art (for example, CN 107074555A, a suspension of nano diamond aggregate and nano diamond single-digit nano dispersion liquid) the diamond raw material is put into strong acid, and the oxidation of the strong acid is utilized to remove graphite under the condition of heating. In actual operation, because the content of graphite in diamond raw materials of different batches has large difference, the method has many uncontrollable factors on the technology, large selection span of oxidation time, high requirement on personnel experience and can generate a large amount of strong acid waste liquid, thereby being not beneficial to wide application. In addition, although the particle size diameter of the prepared detonation method diamond particles can reach 3-6 nm, in practice, the obtained nano diamond particles have high specific surface area and serious agglomeration, so the particle size distribution is wide and ranges from nano to millimeter.

Disclosure of Invention

Aiming at the defects, the invention aims to provide a preparation method of the ultra-dispersed nano-diamond suspension, and the prepared nano-diamond suspension has the advantages of concentrated diamond particle size distribution, uniform size and no agglomeration.

The technical scheme of the invention is summarized as follows:

a method for preparing a super-dispersed nano-diamond suspension, wherein the preparation method comprises the following steps:

(1) diamond pretreatment: adding diamond into an alkali solution, controlling the temperature at 20-95 ℃, preserving heat for 1-38 h, washing until the pH value is neutral, drying and calcining;

(2) preparing a diamond pretreatment solution: ultrasonically dispersing the calcined diamond in deionized water, adding an aromatic amine compound and a nitrite compound to obtain a diamond suspension, heating the diamond suspension, preserving heat for a certain time, and cooling to obtain a diamond pretreatment solution;

(3) and (3) wet fine grinding: adding the diamond pretreatment solution into a bead mill with a screen, and collecting diamond suspension flowing out of the screen after the bead mill is used for a certain time;

(4) centrifugal dispersion: and ultrasonically dispersing the diamond suspension, centrifuging and collecting supernatant to obtain the ultra-dispersed nano diamond suspension.

Preferably, the preparation method of the ultra-dispersed nano-diamond suspension comprises the following steps of 1), preparing diamond by a CVD method; the CVD method is one of a plasma CVD method, a microwave plasma CVD method and a hot wire CVD method. Chemical deposition technology (CVD) is a surface technology that has been commercialized to enable rapid production of nanodiamonds. Since the cost of self-grown diamond is very high, a suitable substrate is generally selected for diamond growth using CVD techniques, and the nanodiamonds are deposited as films on the substrate under high temperature and high pressure conditions, and the process gas for producing the nanodiamonds is mostly a mixed gas containing hydrogen and a carbon-containing gas (e.g., methane) for providing a carbon source during the diamond deposition process. The hydrogen gas may etch non-diamond phases (e.g., graphite, amorphous carbon) formed during the deposition of the nanodiamonds. Therefore, the nano-diamond produced by the CVD technology has high crystallinity and low impurity and defect content, and is an ideal raw material for preparing the nano-diamond solution.

Preferably, the preparation method of the ultra-dispersed nano diamond suspension comprises the following steps of (1) preparing a diamond suspension, wherein the diamond comprises a substrate and a diamond film arranged on the substrate; the diamond film comprises at least one layer of nano-diamond particles; the particle size range of the nano diamond particles is 2-500 nm.

Preferably, the preparation method of the ultra-dispersed nano-diamond suspension comprises the step (1) of preparing one or two of potassium hydroxide solution and sodium hydroxide solution by mass percentage of 30-40 wt%. The alkali solution may remove the nanodiamond base substrate.

Preferably, the method for preparing the ultra-dispersed nano-diamond suspension comprises the step (1) of calcining under the vacuum degree of less than 10^-2mbar, the calcining temperature is 900-1200 ℃, and the calcining time is 0.5-2 h.

Preferably, in the preparation method of the ultra-dispersed nano-diamond suspension, the mass concentration of the diamond suspension in the step (2) is 0.001 to 10 wt%.

Preferably, the method for preparing the ultra-dispersed nano-diamond suspension comprises the following steps of (1) preparing an aniline compound in the step (2), wherein the aniline compound is selected from one or more of p-aminobenzoic acid and aminobenzenesulfonic acid; the nitrite ester compound is isoamyl nitrite; the molar concentrations of the aniline compound and the nitrite compound in the pretreatment liquid are both 10^-4～10^{- 2}mol/L. When the aromatic amine compound and the nitrite compound are added into the water in which the diamond particles are dispersed, the diamond particles can be protected, different aromatic functional groups are bridged on the surface of the diamond, and the nano-diamond can be prevented from being agglomerated in the subsequent process.

Preferably, the preparation method of the ultra-dispersed nano-diamond suspension comprises the step (2) heating the diamond suspension at 40-90 ℃ for 1-38 hours.

Preferably, the preparation method of the ultra-dispersed nano diamond suspension comprises the step (3) of sieving the nano diamond suspension with the aperture of 0.50-500 μm and the rotation speed of a bead mill of 3000-6000 min^-1And the bead milling time is 1-8 h. The liquid medium used in the vibrating bead mill is deionized water or an aqueous solution containing aromatic amine compounds and nitrite compounds.

Preferably, the preparation method of the ultra-dispersed nano-diamond suspension comprises the following steps of (1) preparing the diamond suspension in the step (4), wherein the mass fraction of the diamond suspension in the step (4) is 0.005-3 wt%; the ultrasonic dispersion time is 0.5-1 h, and the power is 200-800W; the rotation speed of the centrifugation is 1000-4000 rpm/min, and the centrifugation time is 0.5-8 h. The purpose of the centrifugation is to remove the crushed ceramic abrasive mixed into the diamond suspension during the vibrating bead milling.

The invention has the beneficial effects that:

(1) the invention relates to a preparation method of a super-dispersed nano-diamond suspension, which selects high-quality nano-diamond film raw materials produced by a CVD technology to prepare a uniform super-dispersed nano-diamond suspension, wherein the diamond particle size distribution of the prepared nano-diamond suspension is centralized, the size is uniform, and the nano-diamond suspension is not agglomerated; in the preparation process of the diamond suspension, no reagent polluting the environment and human body is used, and the prepared nano-diamond suspension can be used as an abrasive, a heat dissipation additive and a diamond electrode liquid crystal and can also be used in the field of biological medicines.

(2) The preparation method of the ultra-dispersed nano-diamond suspension liquid takes the high-quality nano-diamond film produced by the CVD technology as a raw material, and the pollutants such as graphite, carbon, metal and the like contained in the nano-diamond film can be almost ignored. Therefore, the prepared nano-diamond solution has high quality. The base plate at the bottom of the nano-diamond is removed by the alkaline solution, and the aromatic amine compound and the nitrite compound are added into the aqueous solution in which the diamond particles are dispersed, so that the diamond particles can be protected, different aromatic functional groups are bridged on the surface of the diamond, and the re-agglomeration of the nano-diamond in the subsequent process can be prevented.

Drawings

FIG. 1 is a Zeta potential profile of a super dispersed nano-diamond suspension prepared according to example 1 of the present invention;

fig. 2 is a graph showing a particle size distribution of a super-dispersed nanodiamond suspension according to example 1 of the present invention.

Detailed Description

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.