679 results about "Polycrystalline diamond" patented technology

The invention provides a method for manufacturing a super-flat polycrystalline diamond film on a large scale. The method comprises the following steps: (1) growing a layer of polycrystalline diamond film on a growth substrate with a diamond seed crystal on the surface by adopting a chemical vapor deposition method; (2) cutting off at least one part of the substrate after growth to form a boundary for jointing the polycrystalline diamond film and the growth substrate; (3) sticking a stripping adhesive tape; and (4) the stripping adhesive tape is pulled to strip the polycrystalline diamond film from the surface of the growth substrate, so that the nucleation surface of the polycrystalline diamond film is exposed, and the roughness of the exposed nucleation surface is smaller than that of the growth surface. According to the method, the nucleation surface of the grown polycrystalline diamond film is turned over, the novel and simple method is developed to manufacture the polycrystalline diamond film which is reasonable in price, capable of growing on a large scale, super-flat and transferable, and the method has huge potential in practical application.

The invention provides a nano polycrystalline diamond and a preparation method thereof, and relates to the technical field of superhard materials. According to the preparation method of the nano polycrystalline diamond, firstly, high-purity low-impurity CVD polycrystalline diamond obtained through growth by using a chemical vapor deposition method is used as an initial sample, the CVD polycrystalline diamond is synthesized through reaction in a vacuum environment, and internal impurities cannot be introduced; the CVD polycrystalline diamond is further converted into a nano polycrystalline graphite block through high-temperature and medium-pressure first treatment, then the pressure and the temperature are increased in situ to a high-temperature and high-pressure environment required by conversion of graphite into diamond, and second treatment is carried out, so that the high-purity colorless and transparent nano polycrystalline diamond can be obtained. The nano polycrystalline diamond disclosed by the invention is uniform in structure and high in purity, and has excellent optical properties and mechanical properties; the method can be widely applied to optical window detection under extreme conditions.

A float collar for use in a wellbore includes: a float valve; a tubular housing having a coupling formed at a longitudinal end thereof for assembly as part of a downhole tubular; a sheath bonding the float valve to an inner surface of the housing within a flow bore thereof, the sheath having a bore formed therein; and a ball deflector seated against a top of the sheath and having: an upper grate and a lower anchor engaged with an inner surface of the sheath adjacent the bore. The float valve, the sheath, and the ball deflector are made from materials drillable by a polycrystalline diamond compact (PDC) drill bit.

The invention provides a polycrystalline diamond material with a double-peak structure and a preparation method of the polycrystalline diamond material, and relates to the technical field of superhard materials. The polycrystalline diamond material comprises the following raw materials: nano onion carbon and micron graphite, and the preparation method comprises the following steps: weighing the nano onion carbon and the micron graphite, carrying out mechanical grinding treatment, fully mixing to obtain mixed powder, pressing the mixed powder with a mold, and wrapping with boron nitride to obtain a green body; and the blank is loaded into a high-temperature and high-pressure synthesis cavity for high-temperature and high-pressure synthesis treatment, then heat preservation and pressure maintaining treatment is carried out, cooling and pressure relief treatment are carried out, and the polycrystalline diamond material with the double-peak structure is obtained. According to the method disclosed by the invention, the grain size with a'double-peak structure 'is constructed in the polycrystalline diamond, so that the fracture toughness of the polycrystalline diamond is improved by more than two times while high hardness is maintained, the extremely-hard and high-toughness polycrystalline diamond is successfully synthesized, and a reference is provided for toughening of other ceramic materials.

The invention discloses a diamond stripping method and system based on MPCVD equipment and a terminal.The method comprises the steps that a target substrate material is placed on a target molybdenum sheet, nucleation generation treatment is conducted on the target substrate material according to target spin-coating liquid, and a target nucleation transition layer is obtained; determining a preset process gas, and performing diamond growth treatment on the target nucleation transition layer to obtain a polycrystalline diamond film; setting a first cooling environment, and performing initial stripping treatment on the polycrystalline diamond film to obtain an initial stripped polycrystalline diamond film; and setting a second cooling environment, and carrying out re-stripping treatment on the initially stripped polycrystalline diamond film to obtain a target polycrystalline diamond film and a target substrate after the polycrystalline diamond film is stripped. The proper binding force between the nucleating layer and the substrate is guaranteed through the nucleating transition layer technology, the temperature difference change between the diamond and the substrate is achieved by setting the cooling environment process, and then effective separation between the diamond and the substrate is achieved.

The invention relates to the technical field of diamond growth, and provides a preparation method of a polycrystalline diamond wafer and the polycrystalline diamond wafer, the method comprises the following steps: providing a sample with a first surface and a second surface opposite to each other, and pre-growing a first polycrystalline diamond layer on the first surface of the sample; the sample is placed on a molybdenum sheet table in chemical vapor deposition equipment, the first polycrystalline diamond layer faces the molybdenum sheet table, a second polycrystalline diamond layer grows on the second face of the sample, the sample is formed, and the thickness of the second polycrystalline diamond layer is larger than that of the first polycrystalline diamond layer; and separating the second polycrystalline diamond layer from the sample to obtain the polycrystalline diamond sheet. According to the polycrystalline diamond wafer prepared by the method, the warping control and the thickness uniformity are remarkably improved, the yield of finished products is high, the processing efficiency is high, and the production cost is low.

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.

The invention discloses a brazing method for improving the welding strength of a polycrystalline diamond cutter and a hard alloy. The brazing method comprises the following steps that S1, brazing filler metal alloying is conducted; and S2, the PCD tool bit and the hard alloy matrix are subjected to vacuum brazing. According to the brazing filler metal, an Ag-Cu-Co system is adopted, Ag mainly plays a role of a solder matrix and provides plasticity and thermal conductivity, Cu mainly plays a role of forming an eutectic structure with Ag and reducing the melting point, and Co mainly plays a role of wetting the surfaces of PCD and hard alloy. Co infiltration is adopted in the preparation process of the PCD tool bit used in the method, so that a certain amount of Co exists on the PCD surface, and the hard alloy tool body also contains Co, and therefore, a small amount of Co in the brazing filler metal can better wet the welding surface according to the similar intermiscible principle. In the vacuum brazing process, additional pressure does not need to be applied, when the brazing filler metal is molten, the brazing filler metal is evenly laid on the welding face under the action of the pressure of the PCD tool bit on the upper portion and the capillary effect, the redundant brazing filler metal can flow out of the two sides of the mold, and the flatness of the welding surface can be effectively guaranteed.

The invention relates to a polycrystalline diamond compact and a preparation method thereof, and belongs to the field of preparation of polycrystalline diamond compacts. The polycrystalline diamond compact is composed of a hard alloy matrix layer and a polycrystalline diamond layer, the hard alloy matrix layer is made of tungsten carbide and Co and Ni adhesives, and the usage amount of Co and the usage amount of Ni account for 8.5%-10% and 1.5%-3% of the mass of the hard alloy matrix layer respectively; tungsten carbide raw materials for preparing the hard alloy matrix layer are composed of, by volume fraction, 10%-15% of coarse particle size tungsten carbide, 75%-80% of medium particle size tungsten carbide and 5%-10% of fine particle size tungsten carbide, the coarse particle size ranges from 10 micrometers to 15 micrometers, the medium particle size ranges from 2 micrometers to 8 micrometers, and the fine particle size is smaller than 1 micrometer. Co and Ni are used as adhesives of the hard alloy matrix layer, the use amount of Co and Ni is controlled, and distribution of the particle size of tungsten carbide is combined, so that the polycrystalline diamond compact has chemical corrosion resistance and wear resistance at the same time.

The invention discloses a semiconductor laser processing method and device, and the method comprises the steps: S1, carrying out the pretreatment of the surface of a diamond blank, coating a layer of optical reinforcing material, and obtaining the morphology data of the surface; s2, identifying a surface fluctuation area according to the morphology data; s3, performing surface regulation and control treatment on the surface fluctuation area by adopting preset laser parameters; s4, performing cutting processing by using a laser beam to form a diamond substrate; s5, after cutting is completed, appearance detection is carried out, and classification is carried out according to a detection result; the surface of a diamond blank is coated with an optical absorption enhancing material, the laser absorption efficiency of the material is remarkably improved, three-dimensional laser scanning and surface regulation and control treatment are utilized, micro fluctuation of the surface of the diamond blank is fully considered, the laser machining uniformity is improved, and the cutting precision and the surface quality in the machining process are improved; and high-quality laser processing of the polycrystalline diamond substrate is realized.

The invention discloses a method for preparing a silicon carbide-diamond composite substrate, and belongs to the field of semiconductor materials. The method for preparing the silicon carbide-diamond composite substrate comprises the following steps: preparation before growth; growing an interface layer; and growing a polycrystalline diamond layer to obtain the silicon carbide-diamond composite substrate. By limiting the preparation process and parameters, in the process of preparing the silicon carbide-diamond composite substrate, an interface layer with small and uniform crystal grains is firstly grown and formed, and the interface layer is better in growth adaptability with a carbon surface of the silicon carbide substrate, so that uniform transition between the silicon carbide substrate and a polycrystalline diamond layer is favorably realized; and the high-quality silicon carbide-diamond composite substrate is obtained.

The invention discloses a silicon carbide-diamond composite substrate and application, and belongs to the field of semiconductor materials. The silicon carbide-diamond composite substrate is characterized by sequentially comprising a silicon carbide substrate layer, an interface layer and a polycrystalline diamond layer from bottom to top, the thermal conductivity of the silicon carbide-diamond composite substrate is greater than or equal to 650 (W / (m.K)); the light transmittance is greater than or equal to 26%; the diameter is not less than 1 inch. According to the silicon carbide-diamond composite substrate, the interface layers are arranged in the silicon carbide substrate layer and the polycrystalline diamond layer, on one hand, the interface thermal resistance between the layers can be reduced, and the overall thermal conductivity of the composite substrate can be improved; on the other hand, the difference between the silicon carbide substrate layer and the polycrystalline diamond layer is reduced, delamination of the silicon carbide substrate layer and the polycrystalline diamond layer is avoided, and the composite substrate with complete crystal morphology is obtained.

The invention relates to the technical field of drilling engineering, and discloses an impact-assisted rock breaking inwards-concave PDC drill bit which comprises a drill bit body and an impact structure, and the drill bit body is provided with an inner cavity and a first transmission protrusion arranged at the head of the drill bit body; the impact structure comprises a turbine, a transmission shaft and an impact blade, the turbine is arranged in the inner cavity of the drill bit body, the impact blade is arranged outside the drill bit body, the transmission shaft is connected between the impact blade and the turbine and provided with a second transmission protrusion, and the turbine is used for driving the transmission shaft to rotate; the second transmission protrusion and the first transmission protrusion abut against each other or are staggered in the rotating process. The impact cutter wings are used for stretching out relative to the drill bit body when the second transmission protrusions abut against the first transmission protrusions; a reset spring is further arranged between the transmission shaft and the drill bit body and used for driving the impact blades to reset when the second transmission protrusions and the first transmission protrusions are staggered. The high-frequency axial reciprocating motion of the impact blades directly crushes the center area of the drill bit, and the rock breaking efficiency of the center area of the drill bit is improved.

A cutting element for an earth-boring tool includes a substrate and a volume of polycrystalline diamond on the substrate. The volume of polycrystalline diamond has exterior surfaces defining a front cutting surface, a peripheral edge, and at least a pair of angled tip surfaces defining at least one cutting tip between the pair of angled tip surfaces. The front cutting surface includes a first planar region and a second planar region, one or both of which may include a cutting tip. The front cutting surface may be characterized as generally concave. Earth-boring tools include a tool body and one or more such cutting elements secured to the tool body.

The utility model discloses a deposition table for preparing a polycrystalline diamond film, and belongs to the technical field of chemical vapor deposition. A positioning groove for placing a substrate is formed in the top of the deposition table body; an annular isolation groove is formed in the edge of the bottom of the groove; and the annular isolation groove is used for isolating the edge of the substrate placed in the positioning groove from the deposition table body. A positioning groove for placing a substrate is formed in the top of a deposition table body, so that the substrate is positioned and mounted, and the edge of the placed substrate is separated from the deposition table body through an annular isolation groove in the edge of the bottom of the positioning groove, so that the edge of the substrate is prevented from being in contact with the deposition table body. Therefore, the influence of the edge effect of microwave discharge on the temperature of the substrate is effectively avoided, it is guaranteed that the difference between the edge temperature and the center temperature of the deposition table and the substrate is small, and the temperature requirement for preparing diamond films of the same grade is met.

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 invention belongs to the technical field of microelectronic devices, and particularly relates to a high-performance surface acoustic wave device and a preparation process thereof. Comprising the following steps: preparing a polycrystalline diamond film layer on a low-resistance silicon substrate; preparing a temperature compensation layer on the polycrystalline diamond film layer; helium ions are injected into the bulk piezoelectric precursor to form a piezoelectric film layer to be transferred; the bulk piezoelectric precursor is bonded to the temperature compensation layer through a bonding technology, the piezoelectric film layer is reserved in a heat treatment mode, and a piezoelectric layer is obtained; preparing an interdigital electrode on the surface of the piezoelectric layer; and preparing a protection layer on the surface of the interdigital electrode and the non-designated area of the low-resistance silicon substrate, and etching the low-resistance silicon substrate on the designated area. According to the method, the polycrystalline diamond film layer is prepared on the low-resistance silicon substrate, the polycrystalline diamond film layer has high sound velocity and can restrain energy from leaking to the substrate, and the low-resistance silicon in the designated area is etched to reduce the radio frequency loss of the device, improve the quality factor of the surface acoustic wave device and improve the performance of the surface acoustic wave device.

An ultra-high thermal-conductivity diamond is provided. The ultra-high thermal-conductivity diamond is polycrystalline diamond with a highly oriented crystals along <110> or <100> direction. It has a diameter of ≥100 mm in linear dimension and a thickness of ≥300 m, a thermal conductivity of ≥1800 W / (m·K) at 298K, and at least one surface with Ra≤10 nm, and further includes one or more of the following features: a content of nitrogen impurity ≤100 ppb, a dielectric constant ≥5.4 a dielectric loss tangent tanδ≤6×10−5, a volume resistivity ≥1×1011 Ωm, and a breakdown voltage ≥1000 V. The method for synthesizing the ultra-high thermal-conductivity diamond includes: providing a substrate for the diamond growth and a microwave plasma reactor, and performing the epitaxial growth of the ultra-high thermal-conductivity diamond on the substrate surface by using the reactor.

The invention discloses an ultrathin PCD / PCBN (Polycrystalline Diamond / Polycrystalline Boron Nitride) composite sheet and an alternate lamination preparation process thereof, and the process comprises the following steps: preparing a PCD prefabricated body layer and a PCBN prefabricated body layer, and depositing gradient transition layers on the surfaces of the two prefabricated body layers respectively; processing a microstructure with a preset pattern on the surface of the gradient transition layer by adopting a laser etching technology, and filling the etched microstructure with a conductive material with high thermal conductivity; the PCD prefabricated body layers and the PCBN prefabricated body layers are alternately stacked and assembled, and interlayer bonding is completed through ultrahigh-pressure staged sintering; injecting a reinforcing phase into the microstructure of the interface of the sintered composite sheet through ultrasonic-assisted permeation so as to carry out interface reinforcing treatment; through the gradient transition layer and the laser etching microstructure, thermal expansion adjustment between multiple layers of composite sheets is achieved, the problems of thermal stress concentration and interlayer stripping are effectively relieved, meanwhile, through the high-thermal-conductivity filling material and reinforced phase permeation, the interface thermal conductivity and shear strength are improved, and the structural stability of the interface between the ultrathin composite sheets is achieved.

The invention provides a laser device and method for removing residual polycrystalline diamond on the surface of a molybdenum support, the device comprises a shell, a laser and an X-ray diffraction processing device, a scanning head of the laser is arranged at the top of an inner cavity of the shell and is used for emitting laser beams to focus and irradiate the surface of the molybdenum support; the X-ray diffraction processing device is composed of an X-ray emitter and a detector which are arranged on the side of the inner cavity and used for conducting in-situ component analysis on the surface of the molybdenum support in the cleaning process, accurately judging the residual state and the residual area of the polycrystalline diamond and conducting secondary scanning on the residual area to ensure that cleaning is thorough and reaches the standard. The method is efficient and rapid, the surface of the molybdenum support can be effectively protected against damage, the uniformity of the heat conduction performance of the molybdenum support is guaranteed, and the service life is remarkably prolonged.

The invention discloses a preparation method of a high-quality self-supporting polycrystalline diamond substrate. The preparation method comprises the following steps: obtaining a larger first substrate and a smaller second substrate; the molybdenum substrate is a polished molybdenum metal substrate; sowing diamond seed crystals on the first substrate by using an ultrasonic sowing method, and growing a nanocrystalline diamond epitaxial layer by using a CVD (Chemical Vapor Deposition) process; cutting the first substrate by using precise laser to obtain an annular polycrystalline diamond solid seed crystal of which the inner diameter is greater than that of the second substrate; placing a second substrate in the inner diameter of the second substrate, guiding generated tiny diamond grains to the second substrate through a boundary induction mechanism and applying direct current bias voltage, and uniformly wrapping the tiny diamond grains to form a self-supporting polycrystalline diamond substrate; according to the preparation method of the self-supporting polycrystalline diamond substrate, the orientation consistency and the crystallization quality of a diamond film are remarkably improved, and the prepared self-supporting polycrystalline diamond substrate has the advantages of being low in surface roughness, compact in structure, simplified in follow-up process and the like.

The invention belongs to the technical field of PDC drill bits, and particularly relates to a rotatable blade PDC drill bit which comprises a drill bit body. A plurality of supports are fixedly connected to the drill bit body, three inserting grooves are formed in each support, and the three inserting grooves are one long inserting groove and two short inserting grooves. A blade wing is arranged on the support; three fasteners of the same type penetrate through one first inserting block and two second inserting blocks respectively to be connected to the support in a threaded mode, so that the blades are assembled, large torque and impact force can be borne in the drilling process, the blades are not prone to loosening, the multiple blades are installed on the drill bit body in the drilling process, and the drilling efficiency is improved. The multiple blades rotate along with the output end of the drilling machine to drill into a soil rock layer, and rotation of the PDC drill bit blades is achieved. When a certain blade is abraded and damaged, the blade can be conveniently taken down from the support to be replaced only by disassembling the corresponding fastener, the whole drill bit does not need to be disassembled on a large scale, the maintenance cost is greatly reduced, and the maintenance time is greatly shortened.

The invention discloses a PDC drill bit with damping teeth. The drill bit comprises a drill bit body, a plurality of blades extending to the drill bit body and water holes formed in the drill bit body, and damping PDC modules are arranged on the blades; the damping PDC module is composed of damping PDC teeth, bushings, elastic elements and limiters, each damping PDC tooth comprises a polycrystalline diamond layer, a first supporting base body and a second supporting base body, and the axis of the first supporting base body and the axis of the second supporting base body are in an L shape; when the damping PDC teeth bear an overlarge axial load, the elastic element is compressed, and the scraping depth of the PDC teeth is reduced, and when the axial load is reduced, the elastic element is extended, and the scraping depth of the PDC teeth is increased. According to the drill bit, the scraping depth of the PDC teeth can be controlled, the characteristic that the PDC teeth are high in rock breaking efficiency in soft stratums is reserved, the phenomenon that the PDC teeth are clamped and slipped due to the fact that the PDC teeth drill too deep in stratums difficult to drill can be prevented, the rock breaking efficiency of the drill bit is improved, and the service life of the drill bit is prolonged.

A method of processing a superabrasive element includes providing a superabrasive element including a polycrystalline diamond table that includes a metallic material disposed in interstitial spaces defined within the polycrystalline diamond table. The method also includes leaching the metallic material from at least a volume of the polycrystalline diamond table to produce a leached volume in the polycrystalline diamond table.

The invention provides a method for improving the thickness uniformity of polycrystalline diamond, and belongs to the technical field of semiconductors, and the method comprises the following steps: carrying out chamfering grinding on an edge intersection angle area of a silicon substrate; covering polycrystalline diamond seed crystals on the surface of the silicon substrate subjected to chamfering treatment; growing polycrystalline diamond on the polycrystalline diamond seed crystal; polishing to enable the thickness deviation between the edge intersection angle area and the central area of the polycrystalline diamond to be 1t; 10 m. By means of the method, the thickness deviation of the edge intersection angle area and the center area of the polycrystalline diamond can be reduced, the thickness uniformity of the polycrystalline diamond is improved, the cracking problem caused by the temperature deviation of the edge intersection angle area and the center area is prevented, the finished product quality is improved, and the rejection rate and the production cost are reduced.

The invention provides a large-area polycrystalline diamond GaN heterostructure with a slowly-changing Sc component transition layer and a preparation method of the large-area polycrystalline diamond GaN heterostructure. The preparation method comprises the steps that polycrystalline diamond is pretreated, and a polycrystalline diamond substrate is obtained; performing etching mask deposition and patterning on the polycrystalline diamond substrate, and forming a plurality of nano columnar structures in the upper region of the polycrystalline diamond substrate; carrying out magnetron sputtering on a first ScAlN transition layer with 35% of Sc component at the nano columnar structure; epitaxially growing a second ScAlN transition layer with 30% of Sc component on the first transition layer; epitaxially growing a third ScAlN transition layer with 20% of Sc component on the second transition layer; epitaxially growing a fourth ScAlN transition layer with 10% of Sc component on the third transition layer; and epitaxially growing a GaN epitaxial layer on the fourth transition layer. According to the method, the magnetron sputtering technology and the epitaxial ScAlN technology are combined, the respective advantages are exerted, the large-area and high-quality diamond-based GaN silbby batch is prepared, and good conductivity, high thermal stability and high reliability are achieved.

The invention discloses a plasma rotation type large-area polycrystalline MPCVD diamond growth method, and relates to the technical field of microwave plasma chemical vapor deposition, and the method comprises the following steps: S1, setting environmental parameters of diamond growth in a reactor through a microwave feeder, sampling plasma state data in the reactor, and calculating the plasma state data; if the plasma is stably started, executing S2; and S2, the plasma state in the reactor is adjusted through the plasma regulator according to the plasma state data in the reactor, the coverage area of plasma discharge is increased, and then the growth area of the polycrystalline diamond is increased.

The invention discloses a superhard cutter surface micro-nano structure preparation method based on ultrafast laser and a cutter. The method comprises the steps that a polycrystalline diamond cutter is fixed to a three-axis precision motion platform and precisely positioned and calibrated; after cleaning and online detection, parameters of the ultrafast laser are configured based on a result, and machining is executed; and evaluating the structure characterization of the generated laser-induced periodic surface. According to the method, thermal damage is avoided by means of the ultrafast laser near-cold machining characteristic, parameters are precisely regulated and controlled, a high-precision structure is efficiently prepared, the process is flexible and controllable, the limitation of a traditional technology is broken through, the tool performance is improved, a scheme is provided for cutting of aerospace materials difficult to machine, and non-damage microtexture preparation on the surface of the superhard tool is achieved.

The invention relates to sintering composite materials based on polycrystalline diamond from a homogeneous, specially prepared mixture of diamond powders with a binder material. The technical problem is to create a possibility to produce a large-sized blank that has homogeneous composition throughout its entire volume, without any free metal catalyst within its structure. A method for producing a large-sized blank made of a polycrystalline composite with a diamond matrix (PCDM) comprises: mixing previously activated with a low-temperature plasma diamond powders in the liquid inert medium, with the addition of aluminum and cobalt powders; evaporating the liquid, forming the green blank and sintering that by the HPHT method up to formation of the large-sized blank made of PCDM which has a homogeneous composition throughout its entire volume.

The invention provides a multi-blade type self-adaptive PDC drill bit and belongs to the technical field of PDC drill bits, the multi-blade type self-adaptive PDC drill bit comprises a drill bit body, blade parts and adjusting nozzles, one end of the drill bit body is a threaded end used for being connected with a drill rod, the other end of the drill bit body is a rock breaking end, the multiple blade parts are arranged at intervals in the circumferential direction of the rock breaking end, and at least one adjusting nozzle is embedded in a branch flow channel. The adjusting nozzle comprises a valve assembly, a sliding block and an elastic component. The valve assembly is arranged at the end, close to the drill bit body, of the branch flow channel and used for controlling on-off and opening of the drilling fluid flow. The sliding block is arranged in the branch flow channel in a sliding mode, and an acceleration flow channel communicating with the branch flow channel is further arranged in the sliding block. One end of the elastic component is connected with the sliding block, the other end of the elastic component is connected with the valve assembly, and the elastic component is used for providing elastic force to drive the valve assembly to telescopically slide to adaptively adjust drilling fluid flow; the pressure needed by sliding of the sliding block is larger than that needed by sliding of the valve assembly. The problem that in the prior art, the rock cleaning and cooling effects of a PDC drill bit are not stable can be effectively solved.