CN110629192A - Method and equipment for preparing artificial CVD diamond for jewelry - Google Patents
Method and equipment for preparing artificial CVD diamond for jewelry Download PDFInfo
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- CN110629192A CN110629192A CN201810659051.3A CN201810659051A CN110629192A CN 110629192 A CN110629192 A CN 110629192A CN 201810659051 A CN201810659051 A CN 201810659051A CN 110629192 A CN110629192 A CN 110629192A
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- 239000010432 diamond Substances 0.000 title claims abstract description 110
- 229910003460 diamond Inorganic materials 0.000 title claims abstract description 103
- 238000000034 method Methods 0.000 title claims abstract description 34
- 230000008021 deposition Effects 0.000 claims abstract description 140
- 239000000758 substrate Substances 0.000 claims abstract description 83
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 239000007789 gas Substances 0.000 claims description 63
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 34
- 239000013078 crystal Substances 0.000 claims description 25
- 230000006911 nucleation Effects 0.000 claims description 24
- 238000010899 nucleation Methods 0.000 claims description 24
- 239000011159 matrix material Substances 0.000 claims description 21
- 230000005540 biological transmission Effects 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 17
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 14
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 238000004321 preservation Methods 0.000 claims description 9
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 239000001257 hydrogen Substances 0.000 claims description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 239000010453 quartz Substances 0.000 claims description 4
- 230000009467 reduction Effects 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
- 238000009423 ventilation Methods 0.000 claims description 3
- 150000002431 hydrogen Chemical class 0.000 claims description 2
- 238000000151 deposition Methods 0.000 abstract description 116
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 15
- 230000008569 process Effects 0.000 abstract description 13
- 229910002804 graphite Inorganic materials 0.000 abstract description 11
- 239000010439 graphite Substances 0.000 abstract description 11
- 238000002360 preparation method Methods 0.000 abstract description 9
- 239000012535 impurity Substances 0.000 abstract description 3
- 238000000429 assembly Methods 0.000 abstract description 2
- 230000000712 assembly Effects 0.000 abstract description 2
- 239000012495 reaction gas Substances 0.000 description 9
- 238000003825 pressing Methods 0.000 description 8
- 238000001816 cooling Methods 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000004050 hot filament vapor deposition Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 229910003481 amorphous carbon Inorganic materials 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 239000011733 molybdenum Substances 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 239000010437 gem Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000009210 therapy by ultrasound Methods 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010189 synthetic method Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000005491 wire drawing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
- C23C16/27—Diamond only
- C23C16/271—Diamond only using hot filaments
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/4411—Cooling of the reaction chamber walls
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/52—Controlling or regulating the coating process
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Chemical Vapour Deposition (AREA)
Abstract
The application discloses equipment and a method for preparing artificial CVD diamond for jewelry, wherein the equipment comprises the following steps: the device comprises a closed deposition chamber, wherein a hot wire assembly is vertically arranged in the deposition chamber, two sides of the hot wire assembly are respectively provided with a base body assembly, and the base body assemblies can reciprocate along the direction vertical to the surface of a hot wire screen. The substrate table can be continuously and slowly moved in the preparation process by using the equipment provided by the application, so that impurities such as graphite generated in the CVD process are prevented from falling into the interior of the artificial CVD diamond, the quality of the artificial CVD diamond is further improved, in addition, the substrate table is simultaneously arranged on two sides of the hot wire assembly, the manufacturing efficiency is further improved by 1 time, in addition, the temperature of the front end face of the artificial CVD diamond can be kept constant in the preparation process by using the equipment provided by the application, the thickness of the artificial CVD diamond is increased, and the large-size artificial CVD diamond is further obtained.
Description
Technical Field
The application belongs to the field of manufacturing equipment, and particularly relates to a method and equipment for preparing an artificial CVD diamond for jewelry.
Background
Diamond consists of SP3 hybridized carbon atoms, has a cubic crystal structure, and is the hardest of the known materials. In the jewelry field, gem grade large diamond is called diamond after cutting process. The diamond is known as 'the king of precious stones' as a love letter, and is deeply loved by consumers due to the visual effect of the diamond, such as hardness, rarity and bright dazzling, but the natural diamond is rare and expensive, and the appearance of the artificial diamond makes up for the defect. Synthetic diamonds offer significant advantages over natural diamonds in price. Synthetic diamonds are most common as synthetic CVD diamonds. The artificial CVD diamond is polycrystalline diamond synthesized by a CVD method, is a pure diamond component, does not contain any metal binder, has slightly lower hardness than the natural diamond, but is enough to be used as jewelry.
The hot wire CVD method is the most widely used method in the synthetic method of the artificial CVD diamond. Traditional hot filament CVD synthesis equipment is shown in figure 1, and comprises a deposition chamber 001, a hot filament 002 horizontally arranged in the deposition chamber 001, a growth substrate 003 arranged below the hot filament, an air inlet pipe 004 arranged on the top wall of the deposition chamber, and an air outlet pipe 005 arranged on the bottom wall of the deposition chamber, wherein an air inlet of the air inlet pipe 004 and an air outlet of the air outlet pipe 005 are both vertical to the hot filament 002. And after introducing reaction gas into the hot wire CVD synthesis equipment, the reaction gas is heated and decomposed near the hot wire, and then the diamond material is deposited on the growth substrate. Artificial CVD diamonds produced using conventional hot wire CVD synthesis equipment are typically less than 1.5mm thick, making it difficult to obtain artificial CVD diamonds with a thickness greater than 3mm, which are often used as low value small-size diamond dressers due to their small thickness. Further, since the artificial CVD diamond is grown in a columnar growth mode, in the production of the artificial CVD diamond using a conventional CVD apparatus, pores between grains of the artificial CVD diamond gradually increase as the grains of the artificial CVD diamond gradually increase from the nucleation surface to the growth surface, which is more significant for the artificial CVD diamond having a thickness of more than 1.5mm, resulting in a decrease in the wear resistance and polishing effect of the artificial CVD diamond, and the application of the artificial CVD diamond as jewelry or in other fields is limited.
In addition, since amorphous carbon components such as graphite generated on the surface of the hot wire during the growth process are liable to fall on the surface of the diamond under growth, defects are generated in the interior of the diamond finished product, and the quality of the artificial CVD diamond is lowered. Meanwhile, the growth substrate is arranged below the hot wire, so that the traditional hot wire CVD synthesis equipment can only grow the CVD diamond on a single surface, and the utilization rate of heat energy is low.
Disclosure of Invention
The invention aims to provide equipment and a method for preparing artificial CVD diamond for jewelry, which aim to solve the problems that the artificial CVD diamond has small size and cannot achieve the expected decorative effect, the artificial CVD diamond has poor compactness and serious internal defects and the like.
The present invention provides the following aspects:
in a first aspect, the present invention provides an apparatus for producing artificial CVD diamond for jewelry, the apparatus comprising: the device comprises a closed deposition chamber 1, wherein a hot wire assembly 2 is vertically arranged in the deposition chamber 1, two sides of the hot wire assembly 2 are respectively provided with a base assembly 3, the hot wire assembly 2 comprises a fixed electrode plate 21, a sliding electrode plate 22, a hot wire 23 wound between the fixed electrode plate 21 and the sliding electrode plate 22 and two electrode assemblies, each electrode assembly comprises a positive electrode assembly and a negative electrode assembly, the positive electrode assembly is communicated with the fixed electrode plate 21/the sliding electrode plate 22, the negative electrode assembly is communicated with the sliding electrode plate 22/the fixed electrode plate 21, the hot wire 23 is wound into a hot wire mesh surface, and the hot wire mesh surface can do micro reciprocating motion along the hot wire stretching direction; the substrate assembly 3 comprises a transmission rod 31, one end of the transmission rod 31 is provided with a substrate table 32, the other end of the transmission rod 31 is provided with a connecting table 33, the substrate table 32 is arranged inside the deposition chamber 1, the connecting table is arranged outside the deposition chamber 1, and a deposition substrate 34 is arranged on the front end face of the substrate table 32; the deposition substrate 34 is disposed opposite the hot wire 23; the base member 3 is reciprocally movable in a direction perpendicular to the web surface of the hot wire 23.
The hot wire in the equipment for preparing artificial CVD diamond for jewelry provided by the application adopts a vertical mode to be arranged, and the hot wire is coiled between the fixed electrode plate 21 and the sliding electrode plate 22 to form an even hot wire mesh surface, the two sides of the hot wire mesh surface are provided with the substrate tables 32, and the substrate tables are continuously and slowly moved in the preparation process, so that impurities such as graphite generated in the CVD process are prevented from falling into the artificial CVD diamond, the quality of the artificial CVD diamond is improved, in addition, the equipment provided by the application can be used for simultaneously arranging the substrate tables 32 on the two sides of the hot wire mesh, the manufacturing efficiency is improved by 1 time, in addition, the equipment provided by the application can keep the temperature of the front end face of the artificial CVD diamond in the preparation process to be constant, the thickness of the artificial CVD diamond is increased, and then the large-size artificial CVD diamond is obtained.
In an achievable mode, the deposition chamber 1 comprises a double-layer metal liquid cooling sleeve, the temperature of the inner wall of the deposition chamber can be reduced, and the tightness of the deposition chamber is guaranteed.
In an implementation manner, the length of the hot wire mesh surface is 1-1.2 times of the length of the substrate stage 32, the width of the hot wire mesh surface is 1-1.2 times of the width of the substrate stage 32, and the substrate stage 32 is disposed opposite to the center of the hot wire web page. The applicant has found that under the above conditions, the hot wire mesh surface can provide sufficient and uniform heat to the substrate table 32, and the temperature on the substrate table 32 is uniform, so that the resulting artificial CVD diamond has uniform and dense crystal grains and excellent quality.
Further, the hot wire is a metal wire capable of forming carbide with carbon, such as tungsten wire, tantalum wire, rhenium wire, etc., and the diameter of the hot wire is less than 1.0 mm.
In the embodiment of the application, the diameter of the hot wire is 0.2-0.8 mm. The inventor finds that when the temperature of the hot wire mesh surface reaches more than 2600 ℃, the artificial diamond can be normally deposited and grown on the deposition base station, and the sections of the hot wires wound between the sliding electrode hook and the fixed electrode hook are in parallel connection. If the output of the heater screen is constant, the thicker the heater (i.e., the larger the diameter), the greater the output of the single segment heater, and thus, the greater the spacing between the heater and the heater, and thus, the looser the heater screen, and the greater the spacing between the heater screen and the deposition substrate, which may result in a decrease in the diamond growth rate. If the hot wire is too thin (i.e., too small in diameter), the hot wire is particularly likely to be pulled apart and not necessarily maintained until diamond growth is completed, resulting in failure to obtain a diamond of the desired gauge.
In an realizable manner, the sliding electrode plate 22 comprises a first cross bar 221, a sliding hook plate 222 and an elastic support plate 223 are mounted on the first cross bar 221, the sliding hook plate 222 is a linear plate, and the elastic support plate 223 is a broken line plate protruding to the side far away from the hot wire; a sliding electrode hook 224 is provided on a side of the sliding hook plate 222 adjacent to the fixed electrode plate 21, and a plurality of elastic members 24 are provided between the sliding hook plate 222 and the elastic support plate 223, and the sliding hook plate 222 is reciprocatable in a drawing direction of the hot wire.
In the CVD process, the temperature of the hot wire can reach more than 800 ℃, and the hot wire expands at the temperature, so that the elastic piece 24 is arranged on the sliding electrode plate, the hot wire is always kept in a tensioning state after expansion, and the substrate table 32 is uniformly heated. When CVD is finished, the hot wire contracts, the elastic piece rebounds, and the hot wire still keeps a tensioning state.
This application uses a plurality of elastic components 24 for coil all heater between sliding electrode board and fixed electrode board can atress simultaneously, evenly reciprocating motion between two electrode boards, thereby guarantee that the substrate platform is heated evenly, and then make the artificial CVD diamond of making good quality.
In an implementable manner, the fixed electrode plate 21 includes a second cross bar 211, a fixed hook plate 212 is fixedly mounted on the second cross bar 211, the fixed hook plate 212 is a linear type plate, a plurality of fixed electrode hooks 213 are disposed at one side of the fixed hook plate 212, and the hot wire 23 is wound between the fixed electrode hooks 213 and the sliding electrode hooks 224.
Further, the distance between adjacent fixed electrode hooks is 5-20 mm, and the distance between adjacent sliding electrode hooks is 5-20 mm. The selection of the electrode hook spacing is related to the thickness of the hot wire, if the diameter of the hot wire is smaller, the electrode hook spacing is smaller, so that the hot wire mesh surface is compact, if the diameter of the hot wire is larger, the electrode hook spacing is larger, and the hot wire mesh surface is loose, so that the temperature of the hot wire mesh surface reaches more than 2600 ℃.
In an implementation manner, a sliding pressing block 225 is mounted on the sliding electrode plate 22, the sliding pressing block 225 is fixedly mounted on the first cross bar, and the sliding hook plate 222 can reciprocate between the sliding pressing block 225 and the first cross bar. So that the hot wire is in tension.
Optionally, a gasket 226 is disposed between the sliding hook plate 222 and the sliding press block 225, and the gasket 226 may be graphite paper.
In an implementation manner, an air inlet pipe 4 is arranged at the upper end of the deposition chamber 1, an air outlet pipe 5 is arranged at the lower end of the deposition chamber 1, a pipe orifice of the air inlet pipe 4 is arranged between the upper ends of the upper electrode plates, and a pipe orifice of the air outlet pipe 5 is arranged between the lower ends of the lower electrode plates. So that the gases used for the CVD reaction are able to form a gas flow over the hot filament surface, rather than a static reaction gas, so that diamond grains generated from the reaction gas are deposited on the substrate table.
Optionally, there are a plurality of gas inlet pipes 4, and the plurality of gas inlet pipes 4 are uniformly distributed between the two deposition substrates 34; the gas outlet pipes 5 are provided with a plurality of gas outlet pipes 5, and the gas outlet pipes 5 are uniformly distributed between the two deposition substrates 34.
In an achievable mode, the air inlet pipe is a quartz air inlet pipe, and the inner diameter of the air inlet pipe is 5-20 mm.
In an implementation mode, the air outlet pipe is a quartz air outlet pipe, the inner diameter of the air outlet pipe is larger than that of the air inlet pipe, and the inner diameter of the air outlet pipe is 5-30 mm. The inner diameter of the air outlet pipe is larger than that of the air inlet pipe, so that the air flow on the surface of the hot wire is more stable and smooth.
In a second aspect, the present invention also provides a method of producing a synthetic diamond for jewelry using the aforementioned apparatus, the method comprising:
step 1, fixing a deposition matrix at the front end of a substrate table 32, and closing a deposition chamber;
step 2, vacuumizing the background of the deposition chamber to be below 5Pa, introducing nucleation gas into the deposition chamber, electrifying the positive electrode and the negative electrode when the air pressure in the deposition chamber reaches more than 4000Pa, raising the temperature of the hot wire to be more than 2600 ℃, and keeping the air pressure in the deposition chamber at 4000-5000 Pa;
step 3, preserving heat for nucleation reaction, wherein the distance between a hot wire and a matrix is 10-20 mm, and the temperature of the matrix is kept at 650-800 ℃;
step 4, after nucleation is finished, introducing crystal generation gas into the deposition chamber, keeping the air pressure in the deposition chamber at 2500-3000 Pa, keeping the temperature for crystal generation reaction, keeping the distance between the hot wire and the matrix at 5-15 mm, keeping the temperature of the matrix at 700-950 ℃, enabling the transmission rod to move towards the outside of the deposition chamber, and reducing the air pressure in the deposition chamber;
step 5, when the air pressure in the deposition chamber is reduced to 450 pa-550 pa, keeping the air pressure stable, and continuing the heat preservation reaction;
and 6, when the heat preservation crystal growth reaction meets the requirement, stopping electrifying the positive electrode and the negative electrode, stopping ventilation, vacuumizing the background of the deposition chamber to be below 5Pa, and opening the deposition chamber. After the reaction is finished, a large amount of inflammable and explosive gases such as methane, hydrogen and the like exist in the deposition chamber, so that residual gases in the deposition chamber are removed firstly, and then the deposition chamber is opened.
In an achievable manner, in step 2,
the nucleation gas comprises:
methane 1 part by volume
20-55 parts by volume of hydrogen gas,
1 part by volume based on 1L; and/or
The total flow rate of the nucleation gas is 400-600 sccm.
In one realisable approach, in step 4,
the crystal generation gas comprises:
methane 1 part by volume
20-30 parts by volume of hydrogen
20-30 parts by volume of argon gas,
1 part by volume based on 1L; and/or
The total flow of the crystal generation gas is 400-600 sccm; and/or
The moving speed of the transmission rod to the outside of the deposition chamber is 0.1-0.3 mm/24 h.
In one realisable approach, in step 5,
the air pressure reduction speed is 450-550 pa/24 h; and/or
The heat preservation reaction time is 280-320 h.
In a third aspect, the invention also provides a diamond prepared according to the method described above, the diamond having a thickness of greater than 2.8mm, a wear ratio of greater than 50 ten thousand, a fracture strength of greater than 500MPa and a grain size of less than 10 microns.
Compared with the prior art, the equipment for preparing the artificial CVD diamond for the jewelry comprises a deposition chamber, a gas inlet and outlet system, an electrode, a hot wire mesh surface and a substrate table. Wherein, the hot wire net surface sets up perpendicularly, and adopts the perpendicular mode of arranging of hot wire, and the growth substrate is located the hot wire both sides, can get up the energy total utilization of hot wire, greatly reduces artificial CVD diamond growth cost to can avoid amorphous carbon composition such as graphite to drop on the substrate surface, reduce CVD diamond inside and produce the defect. The upper end of the hot wire mesh surface is communicated with an electrode positioned above the deposition chamber, and the lower end of the hot wire mesh surface is communicated with an electrode positioned below the deposition chamber; the gas inlet pipe is communicated with a gas source through the top wall of the deposition chamber, and the gas outlet pipe is communicated with the ball valve through the bottom wall of the deposition chamber; the two substrate tables are connected with the action mechanism through the left wall and the right wall of the deposition chamber respectively. The air inlet pipe in the air inlet and outlet system is positioned right above the hot wire mesh surface, the air outlet pipe is positioned right below the hot wire mesh surface and is made of quartz glass, and therefore amorphous carbon components such as graphite are prevented from being generated. Furthermore, the deposition chamber is made of a double-layer stainless steel water cooling jacket, so that the temperature of the inner wall of the deposition chamber can be reduced, and the sealing performance of the deposition chamber is ensured. The method for preparing the artificial CVD diamond has high thermal efficiency and high utilization rate, and the coarseness and the holes of the crystal grains on the surface of the CVD diamond are inhibited by adding inert gas and continuously adjusting the air pressure of a deposition chamber and the distance between a hot wire and a substrate in the growth process, so that the obtained artificial CVD diamond has extremely high compactness, is suitable for preparing an artificial CVD diamond thick film, can grow jewelry-grade crystals and has the thickness of more than 3 mm.
Drawings
FIG. 1 is a schematic view showing the structure of a conventional CVD apparatus;
FIG. 2 is a schematic diagram showing a cross-sectional side view of an apparatus for producing synthetic CVD diamond for jewelry according to a preferred embodiment;
fig. 3 shows a front sectional view of the apparatus shown in fig. 2.
Description of the reference numerals
1-deposition chamber, 2-hot wire component, 21-fixed electrode plate, 211-second cross bar, 212-fixed hook plate, 213-fixed electrode hook, 22-sliding electrode plate, 221-first cross bar, 222-sliding hook plate, 223-elastic support plate, 2231-elastic piece installation section, 224-sliding electrode hook, 225-sliding press block, 226-gasket, 23-hot wire, 24-elastic piece, 3-substrate component, 31-transmission rod, 32-substrate table, 33-connection table, 34-deposition substrate, 4-air inlet pipe and 5-air outlet pipe.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 2 is a schematic structural view showing an apparatus for manufacturing artificial CVD diamond for jewelry according to a preferred embodiment. As shown in fig. 2, the apparatus includes: the device comprises a closed deposition chamber 1, wherein a hot wire component 2 is vertically arranged in the deposition chamber 1, base body components 3 are respectively arranged on two sides of the hot wire component 2, the top wall of the deposition chamber 1 is communicated with an air inlet pipe 4, and the bottom wall of the deposition chamber is communicated with an air outlet pipe 5.
In this embodiment, the chamber wall of the deposition chamber 1 includes a double-layer metal liquid cooling jacket, wherein the double-layer liquid cooling jacket is communicated with an external refrigeration device, and the cooling liquid may be water or other medium for liquid cooling. The applicant finds that the double-layer metal liquid cooling sleeve arranged on the wall of the deposition chamber 1 can reduce the temperature of the inner wall of the deposition chamber, on one hand, the sealing performance of the deposition chamber can be ensured, on the other hand, the temperature from a hot wire to the wall of the deposition chamber in the deposition chamber is gradually reduced to form a temperature difference, and therefore the quality of the artificial CVD diamond is favorably improved.
In the present embodiment, the hot wire assembly 2 includes a fixed electrode plate 21, a sliding electrode plate 22, a hot wire 23 wound between the fixed electrode plate 21 and the sliding electrode plate 22, and two electrode sets.
Alternatively, the hot wire is a metal wire capable of forming carbide with carbon, such as tungsten wire, tantalum wire, rhenium wire, etc., so that during CVD, the nucleation gas and the crystal growth gas can react with the surface of the hot wire to form diamond grains, which are deposited to form the synthetic CVD diamond.
Further, the diameter of the hot wire is less than 1.0 mm.
In the embodiment of the application, the diameter of the hot wire is 0.2-0.8 mm. The inventor finds that when the temperature of the hot wire mesh surface reaches more than 2600 ℃, the artificial diamond can be normally deposited and grown on the deposition base station, and the sections of the hot wires wound between the sliding electrode hook and the fixed electrode hook are in parallel connection. If the output of the heater screen is constant, the thicker the heater (i.e., the larger the diameter), the greater the output of the single segment heater, and thus, the greater the spacing between the heater and the heater, and thus, the looser the heater screen, and the greater the spacing between the heater screen and the deposition substrate, which may result in a decrease in the diamond growth rate. If the hot wire is too thin (i.e., too small in diameter), the hot wire is particularly likely to be pulled apart and not necessarily maintained until diamond growth is completed, resulting in failure to obtain a diamond of the desired gauge.
Further, the hot wire 23 is wound into a hot wire net surface, and the hot wire net surface can make a slight reciprocating motion along the hot wire drawing direction. The heat produced by a single hot wire is limited, and the hot wire is coiled into a hot wire net between the fixed electrode plate and the sliding electrode plate to form a larger heat radiation surface, and the temperature of the heat radiation surface is uniform and stable, thereby being beneficial to the full decomposition of reaction gas.
In the present embodiment, the electrode groups include a positive electrode group and a negative electrode group, and the two electrode groups are respectively communicated with one electrode plate, specifically, if the positive electrode group is communicated with the fixed electrode plate 21, the negative electrode group is communicated with the sliding electrode plate 22, and if the positive electrode group is communicated with the sliding electrode plate 22, the negative electrode group is communicated with the fixed electrode plate 21, so that the hot wires are simultaneously communicated with the positive and negative electrodes, and current is simultaneously formed in the plurality of hot wires, thereby generating enough heat on the hot wire mesh surface to decompose the reaction gas.
Because the temperature of the hot wire in the CVD process can reach more than 2600 ℃, the high-temperature hot wire has slight expansion, and the hot wire can slightly retract after cooling, so that the sliding electrode plate and the fixed electrode plate are matched with each other in the application, a hot wire mesh surface can be kept in a tensioning state no matter in an expansion state or a retraction state, and a stable and uniform temperature environment is supplied for reaction gas.
In this embodiment, the fixed electrode plate 21 includes a second cross bar 211, a fixed hook plate 212 is fixedly mounted on the second cross bar 211, the fixed hook plate 212 is a linear plate, a plurality of fixed electrode hooks 213 are disposed on one side of the fixed hook plate 212, and the hot wire 23 is wound between the fixed electrode hooks 213 and the sliding electrode hooks 224.
Further, the distance between adjacent fixed electrode hooks is 5-20 mm, and the distance between adjacent sliding electrode hooks is 5-20 mm. The selection of the electrode hook spacing is related to the thickness of the hot wire, if the diameter of the hot wire is smaller, the electrode hook spacing is smaller, so that the hot wire mesh surface is dense, and if the diameter of the hot wire is larger, the electrode hook spacing is larger, and the hot wire mesh surface is loose, so that the temperature of the hot wire mesh surface reaches more than 2600 ℃.
In this embodiment, the sliding electrode plate 22 includes a first cross bar 221, a sliding hook plate 222 and an elastic support plate 223 are mounted on the first cross bar 221, the sliding hook plate 222 is a linear plate, the elastic support plate 223 is a polygonal line plate protruding to a side away from the hot wire, and the elastic support plate 223 includes an elastic member mounting section 2231 parallel to the sliding hook plate 222.
A sliding electrode hook 224 is provided on the side of the sliding hook plate 222 adjacent to the fixed electrode plate 21, and the sliding electrode hook 224 is used to mount the heater wire and the electrode group.
A plurality of elastic members 24 are disposed between the sliding hook plate 222 and the elastic member mounting section 2231 of the elastic support plate 223, and under the stretching action of the elastic members 24, the sliding hook plate 222 can reciprocate along the stretching direction of the hot wire, so as to drive the hot wire to slightly reciprocate along the stretching direction in the process of expansion or retraction.
In one realizable manner, the spring 24 is a tension spring. Optionally, the plurality of tension springs have the same initial length and the same elastic coefficient so as to provide uniform tension to the heat wire mesh surface.
Optionally, the sliding hook plate 222 is a molybdenum plate, a plurality of sliding grooves are formed in the sliding hook plate 222, a plurality of limiting members are correspondingly disposed on the first cross bar, and the sliding grooves are sleeved outside the limiting members and can slide back and forth along the limiting members under the stretching action of the elastic member to keep the hot wire mesh surface tensioned.
In the CVD process, the temperature of the hot wire can reach more than 800 ℃, and the hot wire can expand at the temperature, so that the elastic part 24 is arranged on the sliding electrode plate, the hot wire is always kept in a tensioning state under the stretching action of the elastic part 24 after expansion, and the substrate table 32 is heated uniformly. When CVD is finished, the hot wire contracts, the elastic piece rebounds, and the hot wire still keeps a tensioning state.
In this embodiment, the elastic members 24 are plural, so that all the hot wires wound between the sliding electrode plate and the fixed electrode plate can be simultaneously stressed and can uniformly reciprocate between the two electrode plates, thereby ensuring that the substrate table 32 is uniformly heated, and further ensuring that the manufactured artificial CVD diamond has excellent quality.
In this embodiment, a sliding pressing block 225 is mounted on the sliding electrode plate 22, the sliding pressing block 225 is fixedly mounted on the first cross bar, specifically, the sliding pressing block 225 is mounted above the sliding hook plate 222, and the sliding hook plate 222 can reciprocate between the sliding pressing block 225 and the first cross bar 221 along the direction of the hot wire, so that the hot wire is kept in a tensioned state.
Optionally, a gasket 226 is disposed between the sliding hook plate 222 and the sliding pressing block 225, so that the sliding hook plate 222 is smoother and smoother during the reciprocating motion, and optionally, the gasket 226 may be graphite paper.
In this embodiment, the fixed electrode plate 21 includes a second cross bar 211, a fixed hook plate 212 is fixedly mounted on the second cross bar 211, the fixed hook plate 212 is a linear type plate, one side of the fixed hook plate 212 is provided with a plurality of fixed electrode hooks 213, the fixed electrode hooks 213 are used for fixing a hot wire and electrifying the hot wire, and the hot wire 23 is coiled between the fixed electrode hooks 213 and the sliding electrode hooks 224.
Further, the distance between adjacent fixed electrode hooks is 5-20 mm, the distance between adjacent sliding electrode hooks is 5-20 mm, and further, the distance between adjacent fixed electrode hooks is equal to the distance between adjacent sliding electrode hooks. Therefore, the hot wires in the hot wire mesh surface are uniformly distributed, and the heat provided by the hot wire mesh surface is uniform and stable.
The hot wire in the equipment for preparing artificial CVD diamond for jewelry provided by the application adopts a vertical mode to be arranged, and the hot wire is coiled between the fixed electrode plate 21 and the sliding electrode plate 22 to form an even hot wire mesh surface, the two sides of the hot wire mesh surface are provided with the substrate tables 32, and the substrate tables are continuously and slowly moved in the preparation process, so that impurities such as graphite generated in the CVD process are prevented from falling into the artificial CVD diamond, the quality of the artificial CVD diamond is improved, in addition, the equipment provided by the application can be used for simultaneously arranging the substrate tables 32 on the two sides of the hot wire mesh, the manufacturing efficiency is improved by 1 time, in addition, the equipment provided by the application can keep the temperature of the front end face of the artificial CVD diamond in the preparation process to be constant, the thickness of the artificial CVD diamond is increased, and then the large-size artificial CVD diamond is obtained.
In this embodiment, the substrate assembly 3 comprises a transmission rod 31, a substrate stage 32 is disposed at one end of the transmission rod 31, a connection stage 33 is disposed at the other end of the transmission rod 31, the substrate stage 32 is disposed inside the deposition chamber 1, the connection stage 33 is disposed outside the deposition chamber 1, the transmission rod 31 penetrates into the deposition chamber through a hole formed on a sidewall of the deposition chamber, and a deposition substrate 34 is disposed on a front end surface of the substrate stage 32; the deposition substrate 34 is disposed opposite the hot wire 23; the transmission rod 31 can reciprocate in the direction perpendicular to the hot wire mesh surface, so as to drive the base body assembly 3 to reciprocate in the direction perpendicular to the hot wire mesh surface.
In the present embodiment, the deposition substrate 34 is fixed to the substrate stage 32 by the fixing flange, so that the deposition substrate 34 is prevented from moving when the substrate stage 32 is operated, and the deposition substrate 34 and the substrate stage 32 are ensured to be in good contact with each other, so that the temperature of the deposition substrate 34 can be controlled well. Optionally, a spacer 226 is further disposed between deposition substrate 34 and substrate table 32 to prevent deposition substrate 34 from directly contacting substrate table 32, thereby reducing wear on deposition substrate 34 and substrate table 32.
In this embodiment, the length of the hot wire mesh surface is 1 to 1.2 times of the length of the substrate stage 32, the width of the hot wire mesh surface is 1 to 1.2 times of the width of the substrate stage 32, and the substrate stage 32 is arranged opposite to the center of the hot wire web page. The applicant has found that under the above conditions, the hot wire mesh surface can provide sufficient and uniform heat to the substrate table 32, and the temperature on the substrate table 32 is uniform, so that the resulting artificial CVD diamond has uniform and dense crystal grains and excellent quality.
In this embodiment, the top wall of the deposition chamber 1 is provided with an air inlet pipe 4, the bottom wall of the deposition chamber 1 is provided with an air outlet pipe 5, the pipe orifice of the air inlet pipe 4 is arranged between the upper ends of the upper electrode plates, and the pipe orifice of the air outlet pipe 5 is arranged between the lower ends of the lower electrode plates. Optionally, a pipe orifice of the air inlet pipe is flush with an upper end of an upper electrode plate, and a pipe orifice of the air outlet pipe is flush with a lower end of a lower electrode plate, where the upper electrode plate is a higher-positioned electrode plate in the deposition chamber, and the lower electrode plate is a lower-positioned electrode plate in the deposition chamber, for example, as shown in fig. 2, in the deposition chamber, the heater assembly is a fixed electrode plate, a heater mesh surface, and a sliding electrode plate in sequence from top to bottom, and then the upper electrode plate is the fixed electrode plate, and the lower electrode plate is the sliding electrode plate.
The applicants have found that the above arrangement enables the gases used for the CVD reaction to form a gas stream over the hot filament surface rather than a static reaction gas, thereby causing diamond grains generated from the reaction gas to be deposited on the deposition substrate 34.
Optionally, there are a plurality of gas inlet pipes 4, and the plurality of gas inlet pipes 4 are uniformly distributed between the two deposition substrates 34; the air outlet pipes 5 are provided with a plurality of air outlet pipes 5, the air outlet pipes 5 are uniformly distributed between the two deposition substrates 34, and the air inlet pipes correspond to pipe openings of the air outlet pipes, so that air flow with proper flow speed is formed on the surface of the hot wire mesh.
Further, as shown in fig. 3, the air inlet pipe 4 and the air outlet pipe 5 are all arranged along the extension direction of the hot wire mesh surface, and the distance between the pipe orifice of the air inlet pipe 4 and the hot wire mesh surface is equal, and the distance between the pipe orifices of the air outlet pipes 5 and the hot wire mesh surface is equal, so that the air flow on the surface of the hot wire mesh surface is uniform and stable.
Further, the gas inlet pipe 4 is located right above the hot wire mesh surface, and the gas outlet pipe 5 is located right below the hot wire mesh surface, and a quartz glass gas inlet pipe and a quartz glass gas outlet pipe are preferably used, so that amorphous carbon components such as graphite are prevented from being generated.
In this embodiment, the intake pipe is the quartzy intake pipe, the internal diameter of intake pipe is 5 ~ 20 mm.
Further, the outlet duct is the quartzy outlet duct, the internal diameter of outlet duct is greater than the internal diameter of intake pipe, the internal diameter of outlet duct is 5 ~ 30 mm. The applicant finds that the inner diameter of the air outlet pipe is larger than that of the air inlet pipe, so that the air flow on the surface of the hot wire is more stable and smooth.
Once the hot wire is broken in the CVD process, the temperature in the deposition chamber is violently changed, and the diamond is not continuously generated, or even if the diamond is continuously generated, the prepared diamond shows obvious nonuniformity due to the violent change of the preparation temperature, so that once the hot wire is broken, the CVD process is forced to be terminated, the hot wire in the device provided by the application is uniformly distributed and is not easy to break, and the device provided by the application can ensure the integrity of the preparation process, thereby preparing the artificial CVD diamond with ideal size and excellent quality.
In addition, the device provided by the application is adopted to keep the hot wire stable and motionless in the CVD process and move the deposition matrix, so that the hot wire is further prevented from being broken in the CVD process, and further guarantee is provided for obtaining ideal artificial CVD diamond.
The application also provides a method for preparing the artificial CVD diamond for the jewelry by using the device, specifically, the deposition substrate 34 is a molybdenum deposition substrate, the hot wire is a tantalum wire with the diameter of 0.4mm, the distance between the adjacent sliding electrode hooks is 14mm, and the distance between the fixed electrode hooks is 14 mm. The area of the hot wire mesh surface is 200 multiplied by 200mm2The diameter of the deposition substrate is phi 200mm, the pipe orifice of the air inlet pipe is flush with the upper end of the fixed electrode plate, the pipe orifice of the air outlet pipe is flush with the lower end of the sliding electrode plate, the number of the air inlet pipes is 6, the distance between every two adjacent air inlet pipes is 40mm, the number of the air outlet pipes is 7, and the distance between every two adjacent air outlet pipes is 40 mm. And a graphite gasket is arranged between the deposition substrate and the substrate table.
The method comprises the following steps:
step 1, fixing the deposition matrix 34 at the front end of the substrate table 32, and closing the deposition chamber 1 to form a closed space in the deposition chamber 1.
Step 2, vacuumizing the background of the deposition chamber to be below 5Pa, introducing nucleation gas into the deposition chamber, electrifying the positive electrode and the negative electrode when the air pressure in the deposition chamber reaches more than 4000Pa, raising the temperature of the hot wire to be more than 2600 ℃, and keeping the air pressure in the deposition chamber at 4000-5000 Pa;
since the high temperature hot wire is broken due to the presence of a large amount of oxygen, the residual air in the deposition chamber 1 is removed before the nucleation gas is introduced into the deposition chamber to ensure long-term use of the hot wire.
When the air pressure in the deposition chamber reaches more than 4000Pa, the concentration and the pressure of the nucleation gas in the deposition chamber are both suitable for CVD reaction, at the moment, the positive and negative electrode plates are switched on, the hot wire is electrified to generate heat, the heating speed of the hot wire can be moderate, the nucleation gas is decomposed on the surface of the hot wire, and diamond grains are generated on the surface of the substrate.
Optionally, the nucleation gas comprises:
methane 1 part by volume
20-55 parts by volume of hydrogen gas,
preferably, the first and second liquid crystal materials are,
methane 1 part by volume
24-49 parts by volume of hydrogen gas,
more preferably, the first and second liquid crystal materials are,
methane 1 part by volume
49 parts by volume of hydrogen gas was added,
1 part by volume based on 1L.
The applicant has found that with the device provided by the present application, if the carbon source gas concentration is in the above volume ratio, that is, the methane concentration is between 2% and 4%, especially the low methane concentration (2%), it is beneficial to nucleate fine grains and fill the whole deposition matrix, and the grains are prevented from being concentrated at a certain point and growing rapidly, so that the artificial diamond with larger volume and thicker thickness is formed. If the methane concentration is too high, for example, more than 4%, carbon is formed at both ends of the hot wire, and the efficiency of the hot wire is lowered. Furthermore, the total flow rate of the nucleation gas is 400-600 sccm. For example, the total flow rate of the nucleation gas is 500sccm, and the total flow rate of the nucleation gas is selected to be 400-600 sccm in this embodiment, which can ensure the gas amount required for nucleation and not waste the nucleation gas.
And 3, preserving heat for nucleation reaction, wherein the distance between the hot wire and the matrix is 10-20 mm, and the temperature of the matrix is kept at 650-800 ℃.
And 4, introducing crystal generation gas into the deposition chamber after nucleation is finished, keeping the air pressure in the deposition chamber at 2500-3000 Pa, keeping the temperature for crystal generation reaction, keeping the distance between the hot wire and the matrix at 5-15 mm, keeping the temperature of the matrix at 700-950 ℃, and moving the transmission rod to the outside of the deposition chamber to reduce the air pressure in the deposition chamber.
The crystal generation gas comprises:
methane 1 part by volume
20-30 parts by volume of hydrogen
20-30 parts by volume of argon gas,
preferably, the first and second electrodes are formed of a metal,
methane 1 part by volume
24 parts by volume of hydrogen
25 parts by volume of argon gas is introduced,
1 part by volume based on 1L.
In this embodiment, the above gas volume ratio is selected, and 1 volume part of methane, 24 volume parts of hydrogen, and 25 volume parts of argon are taken as examples, wherein the concentration of methane is 1/(1+24+25) ═ 2%, and the concentration of argon is 25/(1+24+25) ═ 50%. It has been found that low methane concentrations (e.g. 2%) are beneficial in improving the quality of the grown synthetic diamond. According to experimental data, under the device and conditions, the grain refining effect of the argon (such as 50%) in the volume ratio is most remarkable. Optionally, the total flow rate of the crystal growth gas is 400-600 sccm. For example, 500sccm is selected to ensure the gas amount required by the crystal growth without wasting the crystal growth gas.
Furthermore, the moving speed of the transmission rod to the outside of the deposition chamber is 0.1-0.3 mm/24 h.
The applicant has found that by continuously adjusting the gas pressure in the deposition chamber and the distance between the hot wire and the substrate to the above conditions during the growth of diamond crystals, coarsening of crystal grains on the surface of the CVD diamond can be suppressed and formation of pores on the surface of the CVD diamond can be prevented.
And 5, when the air pressure in the deposition chamber is reduced to 450 Pa-550 Pa, keeping the air pressure stable, and continuing the heat preservation reaction.
In one implementation, the rate of reduction of the gas pressure is 450 to 550pa/24 h. The diamond growth mode is a columnar growth mode, the longer the growth time is, the larger the grains are, according to the experience of a large number of growth tests, in the first 100 hours, the surface grains generally do not exceed 10 micrometers, and the low air pressure is also favorable for refining the surface grains of the diamond. Therefore, the present embodiment selects the above-described speed of the air pressure reduction.
Optionally, the heat preservation reaction time is 280-320 h. The applicant has found that the longer the incubation time, the thicker the diamond obtained, and the specific time period can be determined according to the desired diamond thickness.
And 6, when the heat preservation crystal growth reaction meets the requirement, stopping electrifying the positive electrode and the negative electrode, stopping ventilation, vacuumizing the background of the deposition chamber to be below 5Pa, and opening the deposition chamber. After the reaction is finished, a large amount of inflammable and explosive gases such as methane, hydrogen and the like exist in the deposition chamber, so that residual gases in the deposition chamber are removed firstly, and then the deposition chamber is opened.
In this embodiment, before the CVD operation, the method further comprises the following steps:
polishing the molybdenum-made deposition matrix on a grinding machine, wherein the grinding material is W20 diamond micro powder, and after polishing, dipping the surface of the molybdenum matrix for 2min by using dilute hydrochloric acid with the concentration of 5%;
putting the treated molybdenum-made deposition matrix into a W5 diamond micro powder acetone solution for ultrasonic treatment, wherein the concentration of the micro powder is 1g/500mml, and the ultrasonic treatment time is 5 minutes;
and fixing the treated molybdenum deposition matrix and the graphite gasket on the substrate table together by using a fixing flange.
The method for preparing the artificial CVD diamond has the advantages of high preparation efficiency, high heat energy utilization rate, large thickness and high purity of the prepared artificial CVD diamond.
The diamond prepared according to the method has the thickness of more than 2.8mm, the abrasion ratio of more than 50 ten thousand, the breaking strength of more than 500MPa, the grain size of a growth surface of less than 10 microns and the density of 3.50g/cm3。
The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.
Claims (10)
1. An apparatus for preparing an artificial diamond for jewelry, characterized by comprising: a closed deposition chamber (1), a hot wire component (2) is vertically arranged in the deposition chamber (1), two sides of the hot wire component (2) are respectively provided with a base body component (3),
the hot wire assembly (2) comprises a fixed electrode plate (21), a sliding electrode plate (22), a hot wire (23) wound between the fixed electrode plate (21) and the sliding electrode plate (22) and two electrode groups, wherein each electrode group comprises a positive electrode group and a negative electrode group, the positive electrode group is communicated with the fixed electrode plate (21)/the sliding electrode plate (22), the negative electrode group is communicated with the sliding electrode plate (22)/the fixed electrode plate (21), the hot wire (23) is wound into a hot wire screen surface, and the hot wire screen surface can do micro reciprocating motion along the hot wire stretching direction;
the substrate assembly (3) comprises a transmission rod (31), one end of the transmission rod (31) is provided with a substrate table (32), the other end of the transmission rod is provided with a connecting table (33), the substrate table (32) is arranged in the deposition chamber (1), the connecting table is arranged outside the deposition chamber (1), and a deposition substrate (34) is arranged on the front end face of the substrate table (32);
the deposition substrate (34) is disposed opposite the hot wire screen face;
the base body component (3) can reciprocate along the direction vertical to the hot wire mesh surface.
2. The apparatus of claim 1, wherein the sliding electrode plate (22) comprises a first cross bar (221), a sliding hook plate (222) and an elastic support plate (223) are mounted on the first cross bar (221), the sliding hook plate (222) is a linear plate, and the elastic support plate (223) is a polygonal plate protruding to a side away from the hot wire;
a sliding electrode hook (224) is arranged on one side of the sliding hook plate (222) close to the fixed electrode plate (21), a plurality of elastic pieces (24) are arranged between the sliding hook plate (222) and the elastic support plate (223), and the sliding hook plate (222) can reciprocate along the stretching direction of the hot wire.
3. The apparatus according to claim 1 or 2, wherein the fixed electrode plate (21) comprises a second cross bar (211), a fixed hook plate (212) is fixedly mounted on the second cross bar (211), the fixed hook plate (212) is a linear plate, a plurality of fixed electrode hooks (213) are provided at one side of the fixed hook plate (212), and the hot wire (23) is wound between the fixed electrode hooks (213) and the sliding electrode hooks (224).
4. The apparatus according to any one of claims 1 to 3, wherein an air inlet pipe (4) is arranged on the top wall of the deposition chamber (1), an air outlet pipe (5) is arranged on the bottom wall of the deposition chamber (1), the orifice of the air inlet pipe (4) is arranged between the upper end of the upper electrode plate and the deposition chamber, the orifice of the air outlet pipe (5) is arranged between the lower end of the lower electrode plate and the bottom plate of the deposition chamber, the upper electrode plate is the electrode plate close to the top wall of the deposition chamber, and the lower electrode plate is the electrode plate close to the bottom wall of the deposition chamber.
5. The apparatus of claim 4,
the gas inlet pipe is a quartz gas outlet pipe, and the inner diameter of the gas inlet pipe is 5-20 mm; and/or
The air outlet pipe is a quartz air outlet pipe, the inner diameter of the air outlet pipe is larger than that of the air inlet pipe, and the inner diameter of the air outlet pipe is 5-30 mm.
6. A method of making synthetic diamonds for jewelry using the device of any one of claims 1 to 5, said method comprising:
step 1, fixing a deposition matrix at the front end of a substrate table (32), and closing a deposition chamber;
step 2, vacuumizing the background of the deposition chamber to be below 5Pa, introducing nucleation gas into the deposition chamber, electrifying the positive electrode and the negative electrode when the air pressure in the deposition chamber reaches more than 4000Pa, raising the temperature of the hot wire to be more than 2600 ℃, and keeping the air pressure in the deposition chamber at 4000-5000 Pa;
step 3, preserving heat for nucleation reaction, wherein the distance between a hot wire and a matrix is 10-20 mm, and the temperature of the matrix is kept at 650-800 ℃;
step 4, after nucleation is finished, introducing crystal generation gas into the deposition chamber, keeping the air pressure in the deposition chamber at 2500-3000 Pa, keeping the temperature for crystal generation reaction, keeping the distance between the hot wire and the matrix at 5-15 mm, keeping the temperature of the matrix at 700-950 ℃, enabling the transmission rod to move towards the outside of the deposition chamber, and reducing the air pressure in the deposition chamber;
step 5, when the air pressure in the deposition chamber is reduced to 450 pa-550 pa, keeping the air pressure stable, and continuing the heat preservation reaction;
and 6, when the heat preservation crystal growth reaction meets the requirement, stopping electrifying the positive electrode and the negative electrode, stopping ventilation, vacuumizing the background of the deposition chamber to be below 5Pa, and opening the deposition chamber.
7. The method according to claim 6, wherein, in step 2,
the nucleation gas comprises:
methane 1 part by volume
20-55 parts by volume of hydrogen gas,
1 part by volume based on 1L; and/or
The total flow rate of the nucleation gas is 400-600 sccm.
8. The method according to claim 6, wherein, in step 4,
the crystal generation gas comprises:
methane 1 part by volume
20-30 parts by volume of hydrogen
20-30 parts by volume of argon gas,
1 part by volume based on 1L; and/or
The total flow of the crystal generation gas is 400-600 sccm; and/or
The moving speed of the transmission rod to the outside of the deposition chamber is 0.1-0.3 mm/24 h.
9. The method according to claim 6, wherein, in step 5,
the air pressure reduction speed is 450-550 pa/24 h; and/or
The heat preservation reaction time is 280-320 h.
10. A diamond produced according to the method of any one of claims 6 to 9 wherein the diamond has a thickness greater than 2.8mm, a wear ratio greater than 50 ten thousand, a fracture strength greater than 500MPa and a grain size less than 10 microns.
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| CN112323046B (en) * | 2020-08-31 | 2023-02-21 | 广东鼎泰机器人科技有限公司 | Vacuum heating device of coating machine |
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