JP2006225208A - Highly dispersible single crystal diamond fine powder and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diamond fine powder which has excellent polishing performance and hardly forms rigid agglomerates and which has a D50 value of <50 nm. <P>SOLUTION: 1. The diamond fine powder is an assembly of single crystal diamond particles in which the D50 value is <50 nm. A portion of the surface of each particle is converted into carbon having a non-diamond structure, and the carbon having the non-diamond structure, which is formed in heating operation, is disposed between the particles. 2. A method for producing the diamond fine particles comprises pulverizing a single crystal raw material diamond with a mechanical impact-crushing means, then obtaining the diamond fine powder having a D50 value of <50 nm in a precise classification process, sticking a carbon generating agent on the particle surface by dipping the particles into a solution or a dispersion of the carbon generating agent, and heating the particles at 800-1,400°C in an inert atmosphere. At this time, the carbon having the non-diamond structure, previously formed or formed from the carbon generating agent in situ, is used as a separation agent between the diamond particles, and thereby, the agglomeration of the particles is effectively avoided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fine polishing process as a slurry-like abrasive, and a submicron-grade diamond fine powder suitable for use as a solid lubricant, particularly a diamond fine powder of less than 50 nm with improved dispersibility in a dispersion, and its It relates to a manufacturing method.

  With the recent rapid increase in recording density in hard disks, the processing accuracy required for hard disk bodies and magnetic heads has become higher. As a result, the particle size of diamond powder used as an abrasive is gradually shifting to a finer one, and there is also a demand for abrasive grains capable of achieving high accuracy such as a finished surface roughness of 1 mm. For such fine processing, a slurry in which submicron-sized diamond is suspended in an aqueous or oil-based dispersion medium is widely used.

  The finest diamond obtained so far as an abrasive is an agglomerated particle composed of primary particles of 5 to 10 nm called detonation diamond. This type of diamond is synthesized by incomplete combustion of explosives, but since the synthesis time is on the order of microseconds, the resulting crystals contain a large amount of defects and the outer shape is generally spherical. It is known by TEM observation.

  The primary particles of detonated diamond are fine as described above, so the surface is very active and strongly agglomerates through non-diamond carbonaceous materials and substances contained in the atmosphere during production. It apparently behaves as a secondary particle of 100 nm or more. It is also known that the secondary particles can be crushed into primary particles by performing a strong oxidation treatment.

  A so-called DuPont-type polycrystalline diamond using graphite as a raw material is also widely known as a diamond using ultrahigh pressure due to explosion / detonation energy. This type of diamond generally has a primary particle size of about 20 to 30 nm, but the particles are partially fused with the unreacted graphite taken in by the ultrahigh pressure during the synthesis reaction exceeding 30 GPa. The top is secondary particles of 100 nm or more, and it is difficult to disintegrate into primary particles even if a strong oxidation treatment is applied. In addition, it is recognized by TEM observation that the primary particles exhibit an outer shape close to a sphere having no self-shaped surface, reflecting a short synthesis reaction time.

  In the synthesis of the above two types of diamond, the generation of ultra-high pressure necessary to convert low-pressure or non-diamond structural carbon into high-pressure diamond is due to detonation, and the duration is as short as microseconds. Therefore, it is not sufficient to form a self-shaped crystal, and it is difficult to obtain a sharp cutting edge desired as an abrasive grain. Accordingly, although polishing marks corresponding to the particle size can be obtained in the polishing operation, the polishing rate cannot be increased because the polishing is performed with abrasive grains having no edge. Accordingly, there has been a demand for diamond fine powder having a shape suitable for ultrafine polishing that simultaneously satisfies the requirements of forming finer polishing marks and ensuring a higher polishing rate.

The present inventors use fine powder of single crystalline diamond synthesized under static ultra-high pressure as a raw material, and by adding each step of pulverization, chemical treatment, and heat treatment, Fine powder that satisfies the three requirements at the same time required for the application: a large amount of processing per unit time, that does not cause deep scratches on the polished surface, and does not leave particles encroached on the polished surface for soft workpieces A micron) abrasive was completed and a patent application was filed earlier. Such unique performance is considered to be derived from the non-diamond structure carbon material layer formed on the surface of the diamond powder.
JP 2000-136376 A

  Diamond synthesized using a static ultra-high pressure can be controlled in terms of crystal shape, hardness, brittleness, etc. by selecting a combination of applied pressure / temperature and holding time. The obtained diamond can be easily pulverized by impact crushing using a steel ball. Since pulverization is mainly due to cracking of the cracks, even if the crushed powder is on the order of 10 nm, it is confirmed by TEM observation that most of the crushed powder is a self-shaped crystal piece having a sharp edge. The presence of triangular plate crystal pieces has also been observed.

The present inventors have also found that by combining a fine pulverization technique and a precision classification technique, it is possible to produce single crystalline diamond fine powder in the range of 100 nm to 50 nm in the D50 value particle size display (the same applies hereinafter). And filed a patent earlier.
JP 2002-035636 JP

  However, heat-treated submicron-grade diamond fine powders with an average particle size (D50 value) of 150 nm or less settle immediately when poured into water in the same surface state and are difficult to slurry. However, it can be said that it is impossible for those below 50 nm. The reason for this is that the hydrophilicity of the powder surface is lost by heating, and that a strong bond is formed between the powder particles during heating, resulting in aggregated particles. As a result, as a pretreatment for forming a slurry, there is a drawback that a step of pulverizing the aggregated particles and applying a strong force to mechanically pulverize the aggregated particles is required, which requires a lot of man-hours and time.

  Furthermore, the powder is supplied to the user without being sufficiently crushed due to the strong cohesive force between the particles, and it can be seen that the powder behaves as coarse particles during processing, and troubles that cause scratches can be avoided. There wasn't.

  Moreover, as a result of the non-diamond structure carbon layer on the surface of the diamond powder being destroyed by this long crushing operation, a decrease in performance inherent to the heat-treated particles is also observed.

  According to the knowledge of the present inventors, the cause of the above trouble is estimated as follows. That is, in general, even with chemically stable diamond, the surface reactivity cannot be ignored with submicron fine powder. Various atoms and functional groups such as hydrogen, oxygen, carboxyl group, carbonyl group, and hydroxyl group are attached to or adsorbed on the surface of diamond. In the case of the monocrystalline diamond fine powder, as a result of passing through the steps of pulverization and acid washing, the surface often has a hydrophilic functional group.

When diamond fine powder having a hydrophilic functional group on the surface is heated, the elimination of CO ₂ and CO accompanying the decomposition of the functional group is observed. Since it is considered that the point where the carbon atom is removed becomes an active point, it is presumed that in the conventional diamond fine powder, such an active point is the starting point and a bond is formed between adjacent particles.

  Therefore, one of the main objects of the present invention is to solve the problem of strong agglomeration, which was unavoidable in the heat-treated single crystalline submicron diamond fine powder, and the dispersibility and dispersibility in the dispersion liquid. Is to provide good diamond fine powder.

  Another object of the present invention is to provide a finely divided diamond fine powder having a particle size of less than 50 nm which is a single crystal (automorphous crystal) having a sharp shape based on cleavage and a narrow particle size range.

  It is a further object of the present invention to provide a method for producing such diamond fine powder with high efficiency.

  The above-mentioned drawbacks of the conventional fine powders are that the non-diamond structure carbon material produced in advance from diamond fine powder finely pulverized to contain particles of less than 50 nm and finely classified within a predetermined particle size range. In-situ (under heating to 800 ° C or higher and 1400 ° C or lower) through a separating agent (spacer) made of a substance that can produce a non-diamond structured carbon material. I found out that That is, by depositing the separating agent material on the opposing surfaces of substantially all adjacent particles and separating each particle individually, the constituent particles are kept in an isolated state during heating and the bonding between the particles is prevented. The

  Accordingly, the gist of the present invention is as follows. (1) It is synthesized by conversion from non-diamond structure carbon under static ultra-high pressure, and is ultra-finely divided and precision-classified, and has sharp edges, or even cusps. (2) an aggregate of diamond particles having a D50 value of less than 50 nm as measured by a particle size distribution measuring device Microtrack UPA; and (3) substantially all of the diamond particles in the aggregate have a heat-affected structure. The heat-treated diamond fine powder is characterized in that it is separated from each other through the non-diamond structural carbon material.

The diamond fine powder is effectively produced by a method including the following steps:
(1) D50 value is less than 50nm by pulverizing single-crystal raw material diamond into coarse-grained diamond by mechanical impact crushing means, and further subjecting to precision classification process based on water tank or centrifugal separation or a combination of both A step of making a diamond fine powder composed of an aggregate of diamond particles.
(2) The diamond fine powder is immersed in a solution or dispersion of non-diamond structure carbon or a substance that generates non-diamond structure carbon in situ (hereinafter referred to as “carbon generator”), and at least a part of the particle surface has the carbon. The stage to attach the generating agent.
(3) The diamond fine powder is heated at a treatment temperature of 800 ° C. or higher and 1400 ° C. or lower in an inert atmosphere, so that the surface layer of the diamond particles is converted into non-diamond structured carbon, and at the same time, the carbon generator is decomposed to be non-decomposed. Producing diamond-structured carbon, thereby separating adjacent diamond particles from each other via a non-diamond-structured carbon-carbon material.

  In the method of the present invention, prior to the heat treatment of fine diamond powder finely pulverized and finely classified to less than 50 nm, a carbon generating agent that produces non-diamond structured carbon or a non-diamond structured carbon material under the processing conditions between the diamond particles, Arranged as a separator or spacer. By this method, the agglomeration phenomenon generated between the diamond particles during the heat treatment is effectively avoided, and it becomes possible to obtain a slurry substantially composed of primary particles. As a result, submicron diamond subjected to heat treatment can be put to practical use as an abrasive for obtaining a fine finished surface on the order of angstroms.

  In the method for producing diamond fine powder according to the present invention, the non-diamond carbonaceous material or the carbon generator is dissolved or dispersed using a monocrystalline, fine-grained diamond powder having a hydrophilic group on the surface as a raw material diamond powder. Immerse in water treatment solution to disperse particles. At this time, a solute or dispersoid is attached or deposited on the surface of the diamond particles to coat each particle, and after substantially changing all the particles into discrete particles, heat treatment is performed.

  Such diamond fine powder typically uses a press to finely pulverize diamond synthesized and isolated by conversion from non-diamond carbon such as graphite and amorphous carbon under static ultrahigh pressure and high temperature conditions. It can be obtained by hydrophilic treatment and classification. The diamond fine powder of the present invention comprises a fragment of single crystalline (automorphous) diamond.

  That is, first, single crystal diamond as a raw material synthesized under static ultra-high pressure is subjected to impact crushing to make coarse diamond. As is well known, diamond is cleaved along the 111 plane when subjected to an impact load, and the broken crystal pieces generally have sharp corners, edges, and cusps, and equilateral triangular plate crystals are often found. .

  Ball crushing using steel balls is simple for impact crushing, but vibration mills and planetary mills with larger impact loads can also be used. Although a steel ball having a high density is preferable as the grinding media, coarse particles of synthetic diamond can be used for the purpose of avoiding contamination caused by the media.

  The pulverized diamond fine powder is then subjected to chemical treatment to dissolve and remove crushed media fragments mixed during the pulverization. Further, in the subsequent classification operation, both the elutriation and the centrifugal separation are processed in water. Therefore, it is required that the surface of the fine powder be in a state of being familiar with water and kept suspended in water.

  For this purpose, as an effective treatment method in the present invention, the surface of diamond fine powder is oxidized, and oxygen or a functional group containing oxygen such as a hydroxyl group, a carbonyl group, or a carboxyl group is attached to the surface. For surface oxidation, heating to 300 ° C or higher in air has a certain effect, but sulfuric acid, nitric acid, perchloric acid, hydrogen peroxide, and any of these, potassium permanganate, potassium nitrate Or a wet processing method using a bath composed of a combination with chromium oxide is more reliable.

  In order to keep the suspended state of diamond well in water, various ions coexisting in water are reduced as much as possible, and the surface potential of fine powder is kept in a preferable range for dispersion. It is known that diamond fine powder is weakly alkaline and the surface charge repels and remains suspended. In this respect, the preferred hydrogen ion concentration is pH 7.0 to 10.0, and the zeta (ζ) potential is −40 to − The range is 60 mV.

  As described above, by optimizing the surface condition of the diamond particles, the hydrogen ion concentration of the slurry, and the zeta potential, and effectively performing a precise classification process using a centrifuge, the ratio of the D10 value and the D90 value to the D50 value is achieved. Can be obtained as fine diamond particles having a narrow particle size range of 50% or more and 200% or less, respectively, and a D50 value of less than 50 nm.

  In addition, the water tank that has been widely used for classification of fine diamond particles conventionally requires a long time for separation and has low productivity for diamond fine powder of 100 nm or less because of its low sedimentation rate. The use of a centrifuge is an effective solution.

  The finely sized diamond fine powder is subjected to heat treatment at a temperature in the range of 800 to 1400 ° C. in close contact with a carbon generator, that is, a substance that generates the non-diamond structure carbon material by thermal decomposition. In this way, the adjacent diamond particles constituting the fine powder are separated from each other by the non-diamond structure carbon layer, and heat treatment is performed while ensuring a separated / isolated state, so that the diamond does not cause strong aggregation between the particles. At least a portion of the fine powder surface layer can be converted to non-diamond structured carbon.

  The heat treatment is performed in an inert atmosphere to avoid oxidation of the diamond. Under these conditions, the coating material on the particle surface is converted to non-diamond carbon, but the function as a spacer between adjacent particles is ensured, so that formation of a strong bond close to a chemical bond is prevented between the diamond surfaces. It is thought that. As a result, the diamond powder recovered from the heat treatment can be easily pulverized in a mortar and is easily slurried.

  As the coating layer material functioning as a spacer, various substances can be used that wet the diamond surface and decompose by heating, leaving substantially only carbon. For example, nonionic surfactants such as polycarboxylic acid can be used as a material for forming a strong enveloping film.

  When the surface of the diamond is hydrophilic, a material in which the diamond particles are surrounded by water and decomposed or carbonized by heating in an inert atmosphere, and the heating residue becomes a carbonaceous material can be used. Examples thereof include water retention agents (PVA, polyacrylate, etc.), gelatin, agar, starch and the like.

  It has been confirmed by surface analysis that the hydrophilic groups present on the diamond surface are substantially decomposed when heated to 800 ° C., and the surface activity is considered to decrease at a temperature higher than this. Therefore, the coating layer component may be any component that maintains the spacer function until reaching 800 ° C.

  According to TEM observation, an amorphous layer of one to several atomic layers is observed on the surface of a normal submicron diamond. On the other hand, in the diamond subjected to the heat treatment, the presence of non-diamond structural carbon is recognized by a lattice image similar to graphite in several layers following the lattice image of diamond. The unique performance of heat-treated diamond, that is, the reduced roughness of the workpiece polished surface can be attributed to the presence of this non-diamond structural carbon. In the present invention, “non-diamond structured carbon (material)” is a general term for graphite, amorphous carbon, and a substance in which these are mixed or have an intermediate structure.

  In the present invention, the conversion from diamond to non-diamond structured carbon depends on the treatment temperature and time, so the conversion rate is adjusted by this combination. Since the formation of the non-diamond structure carbon layer becomes remarkable at a temperature of 800 ° C. or higher, the processing temperature in the present invention is suitably 800 ° C. or higher. On the other hand, if an excessively high heating temperature is used, the amount of conversion from diamond to non-diamond structure carbon becomes too large and the action as an abrasive is reduced, so the upper limit of the heating temperature is 1400 ° C.

  On the other hand, in order to ensure the separation between the diamond particles, an appropriate amount of the non-diamond structured carbon generated from the carbon generator added to the diamond is interposed on the surface of each diamond particle as fine particles or a coating. Such a non-diamond carbonaceous material is deposited on at least a part of the opposing surface of adjacent diamond particles, more preferably over the entire surface, so that adjacent particles do not contact each other during the heat treatment.

  The amount of non-diamond carbonaceous material present in the diamond fine powder of the present invention can be determined by wet or dry oxidant treatment. That is, the non-diamond carbonaceous material is easily decomposed by wet treatment using nitric acid or perchloric acid at 200 ° C. or higher, or by dry treatment with oxygen gas at 350 ° C. or higher, while diamond is not substantially oxidized. Therefore, the sample is oxidized as described above and evaluated by the mass change before and after the treatment.

  In the present invention, the non-diamond structural carbon derived from the carbon generator can be isolated by TEM observation, and can provide an isolated, amorphous carbon or graphite-like image having no continuity with the diamond lattice. This material behaves substantially the same as a graphite or non-diamond structured carbon layer converted from diamond to an oxidizer, making it difficult to distinguish between the two, and if necessary, a blank test Quantify.

  The total amount of the non-diamond structural carbon material derived from the carbon generator is preferably 0.2% or more and 2.0% or less (particularly 0.4% or more and 1.0% or less) in terms of the mass ratio with respect to the entire diamond powder. Cannot be separated. On the other hand, the non-diamond structure carbon converted from diamond needs to be 0.5 mass% or more based on the diamond powder, but if it exceeds 25%, the work efficiency of the work will be greatly reduced, so the total amount will not exceed this value It is desirable (both in terms of carbon C).

  The diamond particles used as a raw material in the method of the present invention are subjected to a preliminary heat treatment prior to the heat treatment in order to improve the crushability at the time of processing, or during this heat treatment, Cracks can be generated.

  The effect of using the method of the present invention is that particle size distribution measurement is performed qualitatively from a suspended state for a slurry having a concentration of about 2% prepared by pouring heat-treated diamond powder into water and dispersing by applying ultrasonic waves. It can be evaluated quantitatively from the results.

  That is, in the case of a powder that does not have a strong bond between particles, the entire amount of the charged powder is suspended, and no precipitate is observed at the bottom of the container. On the other hand, when the particle size distribution of the heat-treated powder in the slurry is measured, a result almost equal to the distribution before the heat treatment is obtained. This indicates that it contributes to the polishing operation substantially as primary particles, and in addition to avoiding the occurrence of deep polishing scratches caused by aggregated particles, it corresponds to the combination of polishing surface roughness and polishing speed. Therefore, it is easy to select particles having an optimum particle size range.

  In the diamond powder according to the present invention, the first merit of being easy to slurry as compared with the conventional equivalent heat-treated product is to improve the workability at the time of slurry preparation, as obvious. However, since the mechanical load required to break up the agglomerated particles, which was required in the conventional product, is no longer required, the destruction of the non-diamond structural carbon material layer on the diamond surface is avoided. It is also possible to ensure the improvement in quality as polishing abrasive grains, which is characterized by the fact that the roughness of the polished surface of the workpiece is kept small.

  Next, the present invention will be described by way of examples.

  Surface hydrophilic submicron diamond powder MD40 made by Tomei Dia with an average particle size (D50 value) of 38 nm was used as a starting material. A 300 cc beaker was charged with 10 g of diamond powder and 100 cc of deionized water, and the diamond was suspended in water using ultrasonic waves.

  Next, 0.5 g of gelatin powder as a separating agent was sprinkled little by little and stirred sufficiently to obtain a suspension. The suspension was heated and maintained at 85 ° C. for 2 minutes with continued stirring. Next, the mixture was cooled with water and further dried under reduced pressure to recover a sponge-like substance in which diamond powder was entangled with gelatin fibers.

  This sponge-like substance was placed in an alumina crucible and subjected to a heat treatment at 1100 ° C. for 2 hours in a nitrogen atmosphere to graphitize the diamond surface and decompose gelatin. For comparison, a dry powder of MD40 as a starting material was also heated at the same time.

  The diamond recovered from the heat treatment was black. The non-diamond carbonaceous material adhering to the diamond particle surface was 5.5% as determined by a wet process using an oxidizing agent. The amount of pyrolysis residue at 1100 ° C of the gelatin used was 25%, so the carbon converted from diamond by heat treatment was estimated at 4.3%.

  1 g of the heat-treated diamond obtained according to the present invention was dispersed in 100 cc of deionized water to prepare a slurry. When this particle size distribution was measured, the D50 value was 40 nm, and it was confirmed that the heat-treated diamond was a slurry in which primary particles were dispersed substantially.

  For comparison, MD40 diamond powder was heat-treated in the supplied state, and the resulting diamond was dispersed to prepare a slurry. The D50 value of this slurry was 120 nm, indicating that aggregated particles were formed during the heat treatment.

  Both of these slurries were used for texturing of an aluminum hard disk, and the roughness of the processed surface was evaluated by AFM. As a result, the finished surface using the slurry according to the present invention was 2.3 mm. It was 4.8cm.

  Surface hydrophilic submicron diamond powder made by Tomei Diamond with an average particle diameter (D50 value) of 31 nm, MD30, was used as a starting material. In a 200 cc beaker, 20 g of diamond powder and 20 g of a surfactant polycarboxylic acid solution diluted 10-fold with deionized water were mixed thoroughly. After drying at 60 ° C., it was transferred to an alumina crucible and heated to 300 ° C. to partially carbonize the polycarboxylic acid.

  The crucible contents were heat-treated at 1000 ° C. for 2 hours in a nitrogen atmosphere to graphitize the diamond surface and decompose the surfactant. The surface non-diamond structure carbon material in the diamond powder after the heat treatment was 8.6% as a result of the wet treatment using the oxidizing agent. From this, 0.14 g was subtracted as the carbon content of non-diamond derived from polycarboxylic acid, and the amount of non-diamond converted from diamond was estimated to be 7.9%.

  The obtained heat-treated diamond was subjected to particle size distribution measurement by the same method as in Example 1. A D50 value of 35 nm was obtained, and it was confirmed that this diamond powder was substantially dispersed in a primary particle state.

Claims (13)

(1) Synthesized by conversion from non-diamond carbon under static ultra high pressure, ultra finely divided and precision classified, with sharp edges, or even cusps,
(2) An aggregate of diamond particles having a D50 value of less than 50 nm as measured by a particle size distribution analyzer Microtrack UPA;
(3) It is characterized in that substantially all diamond particles of the aggregate are separated from each other via non-diamond structural carbon having a heat-affected structure and arranged on or between the diamond particles. Heat-treated diamond fine powder.   The diamond fine powder according to claim 1, wherein in the diamond aggregate, the ratio of the D10 value and the D90 value to the D50 value is 50% or more and 200% or less, respectively.   The diamond fine powder according to claim 1, wherein the non-diamond structural carbon is deposited on at least a part of an opposing surface of an adjacent diamond particle.   The diamond fine powder according to claim 1, wherein the surface layer of the diamond particles is at least partially converted to non-diamond structured carbon.   The diamond fine powder according to claim 4, wherein the total amount of non-diamond structured carbon due to conversion of the diamond particles is 0.5% or more in terms of mass ratio to the whole diamond powder.   The diamond fine powder according to claim 1, wherein the total amount of the non-diamond structural carbon existing between the diamond particle surface and between the particles is 0.2% or more in a mass ratio with respect to the whole diamond powder.   Non-diamond-structured carbon particles not derived from diamond exist between at least a part of adjacent diamond particle aggregates, and non-diamond-structured carbon caused by conversion from diamond, and non-diamond-structured non-diamond structure The diamond fine powder according to claim 1, wherein the total amount of carbon is 1.0% or more in a mass ratio with respect to the whole diamond powder.   The diamond fine powder according to claim 1, wherein the heat-affected structure is a crack generated on the surface or inside of the diamond particle and / or a deposit of a non-diamond carbon structural material generated by conversion from the particle. The manufacturing method of the diamond fine powder of Claim 1 including each following step.
(1) Single-crystal raw material diamond is crushed into coarse-grained diamond by mechanical impact crushing means,
(2) Oxidizing the surface of the coarse-grained diamond to bond hydrophilic atoms or functional groups to the surface of the diamond, and then subjecting it to a precision classification process based on elutriation or centrifugation or a combination of both. To obtain a diamond fine powder comprising an aggregate of diamond particles having a D50 value of less than 50 nm.
(3) The diamond fine powder is immersed in a solution or dispersion of non-diamond structured carbon or a substance that generates non-diamond structured carbon in situ (hereinafter referred to as “carbon generator”), and the carbon is deposited on at least a part of the particle surface. The stage to attach the generating agent.
(4) The diamond fine powder is heated at a treatment temperature of 800 ° C. or higher and 1400 ° C. or lower in an inert atmosphere, so that the surface layer of the diamond particles is converted into non-diamond structured carbon, and at the same time, the carbon generator is decomposed and non-decomposed. Producing diamond-structured carbon, thereby separating adjacent diamond particles from each other via a non-diamond carbonaceous material.   The method for producing diamond fine powder according to claim 9, wherein the hydrophilic functional group is selected from a hydroxyl group, a carbonyl group, and a carboxyl group.   The method for producing diamond fine powder according to claim 9, wherein the carbon generator is a nonionic surfactant.   The method for producing diamond fine powder according to claim 9, wherein the carbon generator includes at least one selected from an organic water retention agent, gelatin, agar, and starch.   The manufacturing method of the diamond fine powder of Claim 12 in which the said organic water retention agent contains PVA or polyacrylate.