680results about "Ultra-high pressure processes" patented technology

The invention provides an extremely-hard high-toughness nano polycrystalline diamond composite material and a preparation method thereof. Belongs to the field of preparation of high-toughness extremely-hard materials, and is characterized in that the extremely-hard and high-toughness nano polycrystalline diamond composite material is composed of 70-90% by mole of cubic phase diamond and 10-30% by mole of cubic carbon. The preparation method of the extremely-hard high-toughness nano polycrystalline diamond composite material specifically comprises the following steps: by taking graphene as a raw material, pre-pressing the graphene into a cylinder in a mold, and carrying out high-temperature and high-pressure synthesis reaction on a pre-pressed sample, so as to obtain the extremely-hard high-toughness nano polycrystalline diamond composite material. And after the high-temperature and high-pressure synthesis reaction, cooling and pressure relief are performed to obtain the extremely-hard and high-toughness nano polycrystalline diamond composite material. Compared with the prior art, the extremely-hard high-toughness nano polycrystalline diamond composite material has two phases of cubic diamond and cubic carbon, and compared with single crystal diamond, the toughness is improved by 1-2 times under the condition that the hardness is kept.

Luminescent diamond is made by subjecting a volume of diamond grains to high-pressure / high-temperature conditions with or without a catalyst to cause the grains to undergo plastic deformation to produce nitrogen vacancy defects in the diamond grains, increasing the luminescent activity / intensity of the resulting diamond material. The consolidated diamond material may be further treated to further increase luminescent activity / intensity, which treatment may comprise reducing the consolidated diamond material to diamond particles, heat treatment in vacuum, and air heat treatment, which reducing process further increases luminescent activity / intensity. The resulting luminescent diamond particles display a level of luminescence intensity greater than that of conventional luminescent nanodiamond, and may be functionalized for use in biological applications.

Luminescent diamond is made subjecting a volume of diamond grains and catalyst material to high-pressure / high-temperature (HPHT) conditions. A pressure apparatus and / or a pressure cell is specially configured to impose a differential or asymmetric pressure onto the diamond volume during the HPHT conditions. This subjects the diamond grains to differential strain that increases the degree of plastic deformation of the diamond grains to increase the formation of nitrogen vacancy centers. Diamond pellets formed by such process and subjected to differential pressure can have an aspect ratio, or an aspect ratio change, of greater than one. The temperature of the HPHT process is 1.800° C. or less to facilitate desired nitrogen migration to preferentially promote formation of NV centers over NVN and N3 centers in the diamond pellets to provide a degree of luminescence in a red wavelength spectrum greater than diamond pellets formed by some other HPHT processes.

The utility model relates to the technical field of artificial diamond superhard materials, and discloses a synthetic block device filled with high-density materials in multiple directions, which comprises two outer frames formed by pyrophyllite, a filling groove is arranged on the plane of each outer frame, a filling layer is filled in each filling groove, and the outer frames are filled with high-density materials. Wherein the filling layers in at least one group of symmetrical filling grooves are conductive; a dolomite lining is arranged in the outer frame; according to the utility model, under the precondition of meeting stable growth of crystals, the pressure can be reduced by 8-15 Mpa on the basis of the original pressure, the service life of the cubic press can be directly prolonged, the frequency of beam disassembly and maintenance is reduced, the cost of manpower and material resources is saved, and favorable conditions are provided for enterprises to realize cost reduction and efficiency improvement.

The invention relates to the technical field of superhard material synthesis equipment, and discloses a frame type cubic press which comprises a base, a fixed support is fixedly connected to the middle of the inner wall of the base, a hydraulic pump is fixedly connected to the top of the inner wall of the fixed support, and a supporting block is fixedly connected to the output end of the hydraulic pump; second adjusting rods are rotatably connected to the peripheries of the outer walls of the supporting blocks, a rotating shaft is fixedly connected to one end of the outer wall of each second adjusting rod, a first adjusting rod is rotatably connected to the middle of the inner wall of each rotating shaft, a folding ring is rotatably connected to the bottom of the outer wall of each first adjusting rod, and a movable column is fixedly connected to the adjacent sides of the outer walls of the multiple supporting blocks. And one end of the outer wall of the moving column is fixedly connected with a holding-up hammer. The cubic press is based on the base, the hydraulic pump ensures that the sample is uniformly pressed, the sliding connection of the frame ensures that the holding-up hammer is accurately guided, the hydraulic pump synchronously contracts the holding-up hammer, the pressure on the six surfaces of the sample is uniform, and the experiment accuracy is improved.

Luminescent diamond is made by subjecting a volume of diamond grains to high-pressure / high-temperature conditions with or without a catalyst or pressure transfer media to cause the grains to undergo plastic deformation to produce internal vacancy defects, increasing the luminescent activity / intensity of the resulting diamond material. The luminescent material is then subjected to further treatment to create quantum dots on the surface of the diamond particles. Quantum dot formation can include placing the diamond particles in liquid and subjecting the particles to laser pulses. The consolidated diamond material may be treated to further increase luminescent activity / intensity including reducing the consolidated diamond material to diamond particles, heat treatment in vacuum, and / or air heat treatment. The resulting luminescent diamond particles display a level of luminescence intensity greater than that of conventional luminescent nanodiamond, and may be functionalized for use in biological applications.

A directed energy firefighting device is disclosed to extinguish fires with light, comprising a structured light generator and a directed energy controller for detecting and extinguishing fires remotely and at the speed of light. The device employs structured directed light energy capable of inducing atmospheric avalanche breakdown, generating at least one of sound waves and shockwaves, and dynamically forming space-time acoustic arrays for precise fire suppression. The system may integrate one or more energy sources, including gyrotrons, traveling wave tubes, klystrons, free electron lasers, and others, to produce diffraction-resistant and dynamically structured beams that penetrate through the atmospheric and non-metalic solid physical obstructions. Key features also may include safety mechanisms and artificial intelligence for real-time optimization. Other applications include power beaming, environmental monitoring, medicine, disaster response, and orbital debris clearing are also discussed. A key feature is the ability for arbitrary manipulation of light over large areas.

The invention relates to the technical field of synthesis equipment of superhard materials, in particular to energy-saving type diamond production equipment and a production technology.The energy-saving type diamond production equipment comprises a machine body, a holding-up hammer, a transmission rod, a clamping piece and an adjusting assembly, the machine body is fixedly arranged, a cavity is formed in the machine body, pyrophyllite is located in the center of the cavity, and the holding-up hammer is arranged in the cavity; the holding-up hammers are arranged on the machine body, the extension lines of the transmission rods penetrate through the center and one vertex angle of the pyrophyllite, and the transmission rods slide and can intersect at the center position of the pyrophyllite; the clamping piece is arranged on the transmission rod and used for clamping the vertex angle, corresponding to the transmission rod, of the pyrophyllite. The adjusting assembly is used for guiding each holding-up hammer to slide towards the center position of the cavity. The pyrophyllite can be fixed at the central position in the cavity through the cooperative arrangement of the transmission rod and the clamping piece, so that the phenomenon of pyrophyllite position deviation caused by asynchronous contact between the six holding-up hammers and the pyrophyllite is improved, and the degree of uneven stress of a carbon source is relieved.

The utility model discloses a single-shaft pressurizing device. The single-shaft pressurizing device comprises a pressurizing cavity and a pressure generating assembly, the pressurizing cavity is provided with a channel capable of accommodating the pressure generating assembly, and a placement table for placing a to-be-pressurized sample is arranged at the bottom of the channel; the pressure generating assembly comprises a lower pressing column, an elastic piece, a pressure maintaining sleeve and an upper pressing column which are sequentially arranged in the pressurizing cavity. The top of the pressurizing cavity is fixed to the pressure maintaining sleeve through internal threads, and the upper pressing column can penetrate through the pressure maintaining sleeve to make contact with the elastic piece. The size of the bottom channel of the pressurizing cavity is matched with that of the pressing column, and the pressing column can be exactly contained. In this way, the sample placed on the object placing table is always vertically downward under the force of the downward pressing column, and the out-of-plane direction pressurization regulation and control of the sample are achieved.

The invention relates to the technical field of superhard material machining, in particular to a cubic press and a cubic boron nitride cutter machining method thereof.The cubic press comprises a cubic press body, and a centering mechanism and a bottom cleaning mechanism are arranged at the hydraulic end of a lower pressing mechanism; a discharging mechanism is arranged on the upper surface of the fixed support located on the lower jacking mechanism and arranged on one side of the bottom cleaning mechanism. The method for machining the cubic boron nitride cutter comprises the following steps of raw material mixing, die filling, feeding, high-temperature and high-pressure sintering, discharging, material cutting, cutter welding and the like. A pyrophyllite mold can be located in the center of the hydraulic end through the centering mechanism, the qualified rate of products is increased, pyrophyllite chippings are prevented from adhering to the end face of the hydraulic end and the surface of an abutting sealing top plate through a bottom sweeping mechanism and sweeping brushes on the discharging mechanism, automatic discharging is adopted by the discharging mechanism, pedal installation and manual operation are not needed, and the production efficiency is improved. And the use safety of the cubic press is greatly improved.

The present invention relates to a process for preparing diamond particles, comprising subjecting a nanodiamond precursor material to a pressure of at least 8 GPa and a temperature of at least 900°C, wherein the diamond precursor material comprises a polycyclic aromatic compound which contains from 10 to 200 fused six-membered aromatic rings.

The application relates to the technical field of superhard materials, and discloses a non-magnetic polycrystalline diamond compact as well as a preparation method and application thereof. The non-magnetic polycrystalline diamond compact comprises a nickel-based hard alloy base and a polycrystalline diamond layer combined on the nickel-based hard alloy base; wherein the nickel-based hard alloy base comprises nickel and tungsten carbide, and the polycrystalline diamond layer comprises nickel and diamond micro powder. The non-magnetic polycrystalline diamond compact of the application uses a nickel-based hard alloy base, and the polycrystalline diamond layer uses nickel as a bonding phase, so that the magnetism of the polycrystalline diamond compact is effectively reduced, and the application requirement of a non-magnetic bearing material can be met.

The utility model discloses a hot pressing sintering device for synthesizing diamond, which comprises a working table and a cabinet fixedly arranged on the back of the working table, a rack is fixedly arranged at the top end of the working table, a closed hot pressing sintering mechanism for synthesizing diamond is fixedly arranged in the middle of the rack, and an electric control hydraulic cylinder is fixedly mounted at the top end of the rack. A partition frame is fixedly arranged in the middle of the machine cabinet, a suction mechanism is fixedly installed on the partition frame, and a processing mechanism used for cooling and tail gas purification after diamond hot pressing sintering is fixedly installed at the bottom of the inner wall of the machine cabinet. The treatment mechanism and the suction mechanism which are used for cooling and tail gas purification after diamond hot-pressing sintering are additionally arranged in the machine cabinet, after sintering, ventilation cooling is conducted on the interior of the hot-pressing sintering box, residual harmful substances in the hot-pressing sintering box are purified and absorbed, the cooling efficiency of the hot-pressing sintering box can be remarkably improved, and the service life of the hot-pressing sintering box is prolonged. And the material taking and placing safety of workers is improved.

The present disclosure discloses a high-temperature and high-pressure preparation method for hexagonal diamond, which belongs to the field of superhard material synthesis technology. The method comprises making high-purity graphite into a precursor, assembling the synthesis block, and then subjecting it to heating, pressurizing, temperature holding, and pressure holding processes to obtain hexagonal diamond. The preparation method for hexagonal diamond according to the present disclosure allows high-purity graphite to achieve higher pressure along the c-axis direction, further promoting the phase transition of graphite. In addition, the temperature field where the precursor is located has a certain temperature gradient, which facilitates the transformation of high-purity graphite into hexagonal diamond and achieves a better conversion rate of hexagonal diamond.

The invention provides a high-temperature and high-pressure sintering device for producing polycrystalline cubic boron nitride, relates to the field of cubic boron nitride production equipment, and aims to solve the problems that when a cubic press is used, the pressures of six hammers are inconsistent and the like. Comprising a cubic press main body, the cubic press main body comprises six groups of hinge beams which are distributed up, down, front, back, left and right, oil cylinder parts are coaxially fixed on the inner sides of the hinge beams, a nail hammer part is coaxially fixed on a piston rod of each oil cylinder part through a heat insulation seat, the oil cylinder parts are externally connected with a hydraulic unit, and the cubic press further comprises a compensation mechanism and a pressurization sealing mechanism; through the arrangement of a compensation plate, an annular compensation groove, an annular groove, an oil storage cylinder and the like, six compensation mechanisms which are communicated with one another are arranged in six oil cylinder pieces according to the communicating vessel principle, the cylinder body pressure of the six nail hammers is compensated in real time, the pressure consistency of the six nail hammers is achieved, and meanwhile accumulative errors can be avoided through the mode.

The invention discloses a holding-up hammer pressing and subpackaging device of diamond synthesis equipment, and relates to the technical field of diamond synthesis equipment, the holding-up hammer pressing and subpackaging device comprises a fixed seat, a pressing mechanism and a cleaning mechanism, the pressing mechanism is arranged on the fixed seat, and the cleaning mechanism is arranged on a connecting disc of the pressing mechanism. A piston cylinder of the pressing mechanism drives the holding-up hammer to move and touch the rack, the holding-up hammer is pressed into the protective sleeve, after pressing of the holding-up hammer is completed, impurities on the holding-up hammer and the protective sleeve are cleaned through a cleaning brush of the cleaning mechanism, it is avoided that normal work of the holding-up hammer and the protective sleeve is affected by the impurities, a rotating rod of the cleaning brush can freely move, and the cleaning effect is good. And the cleaning brush is pressed on the holding-up hammer and the protective sleeve under the action of the spring, the cleaning effect of the cleaning brush is improved, after the cleaning brush completes cleaning, the cleaning brush moves on the first arc-shaped rod to collide with the second arc-shaped rod under the action of the elastic force of the spring, impurities remaining on the cleaning brush can be shaken off, and therefore the next cleaning effect of the cleaning brush is improved.

The invention discloses catalyst powder capable of improving toughness of artificial diamond and a preparation method of the catalyst powder, and relates to the technical field of synthesis of artificial diamonds.The catalyst powder is composed of metal nickel, metal iron and nano-zinc oxide which is in an extending and protruding spherical shape in the microscopic state and forms powdery mixed metal powder, and the nano-zinc oxide is stacked in an inserted mode. The metal nickel and the metal iron are filled in an inserting and stacking gap; according to the catalyst powder, the quality of the diamond is improved in two different modes, the impact toughness and the heat impact toughness of the diamond are improved, the preparation method is simple in structure, no redundant component is added, doping of useless impurities is reduced, recycling is convenient, and the resource utilization rate is high.

The invention belongs to the technical field of substrate surface treatment, and particularly relates to a diamond substrate surface treatment device and method. The fixing frame is fixedly connected to the top of the workbench; the mounting seat is arranged below the fixing frame; a second motor is started, an output shaft of the second motor drives a rotating frame to rotate, the rotating frame drives a first grinding wheel and a second grinding wheel to rotate, and when the first grinding wheel rotates to the lowest position, rough grinding is conducted; when the second grinding wheel rotates to the bottommost part, fine grinding is carried out; the effect of converting rough grinding and fine grinding is achieved; when the drying box rotates to the bottommost part, the drying box is used for drying the polished diamond sheets; during grinding, a third motor needs to be started, a second gear is driven to rotate through an output shaft of the third motor, a first gear is driven to rotate through the second gear, a rotating rod is driven to rotate through the first gear, and a first grinding wheel and a second grinding wheel are driven to rotate through the rotating rod, so that the grinding effect is achieved.

The embodiment of the invention discloses a preparation method of a high-purity large-size hexagonal diamond, which comprises the following steps: S1, cutting along the c axis of highly oriented pyrolytic graphite to obtain cylindrical highly oriented pyrolytic graphite as a raw material precursor; s2, assembling the raw material precursor in a high-pressure heating synthesis assembly; s3, the high-pressure heating synthesis assembly is heated and pressurized to set pressure and set temperature, heat preservation is conducted for set time, and the high-purity hexagonal diamond is obtained; wherein the set temperature ranges from 1300 DEG C to 1900 DEG C, the set pressure ranges from 20 GPa to 25 GPa, and the set time ranges from 10 min to 20 min. According to the preparation method of the high-purity large-size hexagonal diamond disclosed by the embodiment of the invention, cylindrical high-orientation pyrolytic graphite cut along a c axis is used as a raw material precursor, the high-orientation pyrolytic graphite is completely converted into the high-purity large-size hexagonal diamond under set conditions, and the size is 1-2 mm; the method has important application prospects in the fields of superhard materials, semiconductor devices and the like.

The invention relates to the technical field of superhard materials, and discloses a non-magnetic polycrystalline diamond compact as well as a preparation method and application thereof. The non-magnetic polycrystalline diamond compact comprises a nickel-based hard alloy matrix and a polycrystalline diamond layer compounded on the nickel-based hard alloy matrix, wherein the nickel-based hard alloy matrix comprises nickel and tungsten carbide, and the polycrystalline diamond layer comprises nickel and diamond micro powder. According to the non-magnetic polycrystalline diamond compact, the nickel-based hard alloy matrix is used, and the polycrystalline diamond layer takes nickel as a binding phase, so that the magnetism of the polycrystalline diamond compact is effectively reduced, and the application requirement of a non-magnetic bearing material can be met.

The invention relates to a preparation method of Ti-plated polycrystalline diamond, which comprises the following steps: step 1, purifying the surface of diamond by using an acid solution, and then drying after treatment; 2, uniformly mixing the treated diamond with Ti powder, Cu powder and a catalyst in a container; step 3, loading the mixture into a sintering boat, and putting the sintering boat into a quartz tube; 4, heating the heat treatment furnace to a certain temperature, pushing the quartz tube into the furnace, and keeping the temperature; 5, cooling to 500 DEG C along with the furnace, pulling out the quartz tube, and air-cooling to room temperature; and 6, taking out the sintering boat from the quartz tube, and screening to obtain the titanium-plated diamond. 7, titanium-plated diamond micro-powder is adopted as a raw material, the purified titanium-plated diamond micro-powder and a sintering aid are packaged in a molybdenum sleeve to be sintered, and after the surface and the cross section of a sintered sample are purified, the sample is analyzed; the adhesive has the advantages that the adhesive strength is improved, high-temperature damage is reduced, the bending strength is good, and the service life is prolonged.

The utility model relates to the technical field of cubic presses, in particular to a deslagging device of a cubic press. Comprising a jacking machine assembly, a collecting assembly, a vehicle body assembly and a slag removal assembly, the jacking machine assembly comprises a base, the collecting assembly comprises a collecting box, the vehicle body assembly comprises a slag removal vehicle, a jacking machine body is arranged at the top of the base, and a sleeve is connected to the end, away from the slag removal vehicle, of a mounting frame; the bottom of the threaded rod is connected with a positioning cover, and the end, away from the first motor, of the rotating shaft is connected with a linkage block. After the use height of the linkage block is adjusted, operation of two first motors is started, then the two first motors rotate relatively, rotation of the linkage block is achieved through relative rotation of the two first motors, and adjustment of the use angle of the cleaning brush is achieved through adjustment of the use angle of the linkage block; and then cleaning and deslagging of the end faces of all the hydraulic push rods of the jacking machine body are achieved.

The invention discloses a polycrystalline diamond synthesis cavity internal temperature indication structure which is located at any position in a synthesis cavity and comprises double-layer carbon paper sheets arranged up and down, a metal layer located in the middle of the double-layer carbon paper sheets and an insulation penetration body arranged on the periphery of the double-layer carbon paper sheets. And a heating body is arranged on the outer side of the insulating permeation body and is a constituent part of the synthesis cavity. When the temperature in the cavity reaches the melting point of the metal ring, the metal ring melts, penetrates through the insulating penetrating body and is in contact with and attached to the inner wall of the heating body to form a new conductive structure, so that the resistance in the cavity is sharply reduced, and the current is intuitively increased to a certain degree within a certain period of time; therefore, it can be determined that the temperature in the cavity reaches or is slightly higher than the melting point of the metal ring, thereby reflecting the temperature reference in the cavity. The heating process can be correspondingly adjusted according to the heating time required for reaching the temperature reference.

The invention relates to the technical field of artificial diamonds, in particular to an artificial diamond single crystal generation process which comprises the following specific steps: A, mixing and granulating graphite, mother powder and a metal catalyst, and then transferring into a pressing workshop to be pressed into a graphite column; b, pyrophyllite powder and boron nitride powder are mixed and then made into a cylindrical blank, and a cylindrical cavity is machined in the center of the pyrophyllite blank; c, assembling the graphite column, the pyrophyllite cylinder, the plug assembly, the heating assembly and the insulating assembly into a synthetic block; and D, a mechanical arm carries the clamping mechanism to position the synthetic block to the center of a cavity of the cubic press, the surface of the anvil in the equipment is blown and swept, dust particles are removed, then the clamping mechanism is taken back, and the cubic press is started for temperature rising and pressure rising. And more time and energy are consumed.

The present invention discloses a top hammer device for a six-sided top press and a method for processing diamonds with high thermal conductivity, and relates to the field of artificial diamond preparation equipment. The present invention includes multiple groups of hammer heads and hydraulic telescopic mechanisms. The hydraulic telescopic mechanisms are fixedly installed inside the six-sided top press. A hammer head is fixedly installed at the telescopic end of each hydraulic telescopic mechanism. The interior of the hydraulic telescopic mechanism is provided with an extension drive chamber that can drive the hydraulic telescopic mechanism to extend and a contraction drive chamber that drives the hydraulic telescopic mechanism to contract. Both the extension drive chamber and the contraction drive chamber are connected to a hydraulic pumping mechanism. A pressure detection mechanism that can detect the surface pressure of the hammer head is installed on the hammer head. The present invention can directly and accurately detect the surface pressure of the hammer head when the top hammer device is working, thereby improving the accuracy of the hammer head pressure detection. When the hammer head pressure overload is detected, the control system drives the hydraulic pumping mechanism to suck and release the pressure in the extension drive chamber to prevent the hammer head from breaking and being damaged due to pressure overload.

The invention relates to the technical field of diamond synthesis, in particular to a colorless diamond and a preparation method thereof. The preparation method comprises the following steps: 1) distributing seed crystals on a catalyst sheet; (2) alternately assembling a plurality of graphite sheets, nitrogen removal sheets and the catalyst sheets after seed distribution, so that the nitrogen removal sheets are contained between any graphite sheet and any catalyst sheet to obtain a core column; 3) coating the core column to obtain a synthetic block; and 4) pressurizing and heating the synthetic block to obtain the colorless diamond. The colorless diamond synthesized through the preparation method is high in purity and can reach the D grade and the E grade, meanwhile, compared with a temperature difference method, the synthesis time is shortened, and the single yield is increased.

The invention relates to the technical field of diamond synthesis raw material modification, and discloses a diamond synthesis raw material modification treatment device and method.The diamond synthesis raw material modification treatment device comprises a barrel body and further comprises a barrel cover, the automatic heating and pressurizing assembly is arranged in the barrel cover, and the automatic heating and pressurizing assembly is used for heating and pressurizing after the pressure in the barrel body is detected; and the detection pressure relief assembly is arranged in the barrel body and the barrel cover, and the detection pressure relief assembly is used for detecting the modification result of the diamond raw material and conducting pressure relief. The diamond raw material modification process can be automatically monitored, after diamond raw material modification is finished and diamonds are formed, pressure relief is automatically conducted on the barrel body, an alarm is automatically given after pressure relief to remind workers, the situation that the modification state of the diamond raw materials is not clear is avoided, and then the using effect of the equipment is improved.

The present invention relates to diamond abrasive grains and a manufacturing method thereof, and provides tetradecahedral diamond abrasive grains with uniform size and shape. The manufacturing method of diamond abrasive grains according to the present invention allows for shape control and minimizes impurities and crystal defects, thereby manufacturing diamond abrasive grains for ultra-precision grinding in chemical mechanical planarization (CMP) processes.

The invention belongs to the technical field of diamond cultivation. The method particularly comprises the following steps: step 1, extracting biological carbon powder from a carbon-containing biological sample; 2, preparing the biological carbon powder into a biological carbon source; 3, pressurizing and heating the biological carbon source by using a cubic press, putting the biological carbon source into a diamond culture bin of the cubic press, forming an artificial high-temperature and high-pressure environment through a synthesis device, and performing phase transformation on graphite to generate diamonds; the carbon-containing biological sample can be fingernails, hair or teeth, a favorable environment can be provided for cultivation and growth of the biological diamonds, the success rate of synthesis of the biological diamonds is greatly increased, and the problems of supply of a biological carbon source and too high purchase cost are solved; and the biological diamond can be grown at a high success rate in the synthesis process of the biological carbon source.

Luminescent diamond is made by creating vacancies in diamond grains and heat treating the diamond grains by controlling a thickness of the diamond grains on a substrate. The heat treatment may occur in a temperature range that does not burn the diamond grains, and the controlled thickness produces an even color change and / or promotes oxygen terminations on the diamond particle surfaces.