363 results about "Polycrystalline diamond" patented technology

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 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.

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 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 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 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 the technical field of cutting pick machining, in particular to a high-temperature-impact-resistant PDC cutting pick preparation technology, it is guaranteed that the purity and the granularity meet the requirements through selection of raw materials, for example, silicon carbide whiskers and multi-walled carbon nanotubes have high high-temperature resistance, the high-temperature thermal stability of polycrystalline diamond compacts is greatly enhanced through addition of the silicon carbide whiskers and the multi-walled carbon nanotubes, and the high-temperature impact resistance of the polycrystalline diamond compacts is improved through addition of the silicon carbide whiskers and the multi-walled carbon nanotubes; the preparation method comprises the following steps: preparing raw materials, removing impurities on the raw materials through pretreatment to ensure the surface activity so as to facilitate subsequent combination, then removing the surface adsorption phenomenon of the raw materials and avoiding possible oxidation reaction through wet ball milling, sieving and reduction, and then carrying out preliminary forming through low-pressure pre-pressing to discharge air in the raw material powder and improve the pressing density; according to the high-temperature and ultrahigh-pressure sintering process for the polycrystalline diamond compact with the SiCw / CNTs added, the density and the shape of a green body are ensured, and then the finished PDC cutting pick meeting the requirement is obtained through high-temperature and high-pressure sintering, step-by-step pressure relief and finish machining.

The present invention relates to a method for preparing a polycrystalline diamond composite sheet. The method comprises the following steps: soaking diamond particles of primary and secondary sizes in strong acid and alkali, and repeatedly washing with pure water; sandblasting a cemented carbide substrate; mixing the primary and secondary diamond particles in a mixer; placing the mixed diamond particles and cemented carbide substrate in a high-temperature resistant metal cup; placing a composite block in the metal cup, and placing the metal cup in a six-sided top press; and performing three-stage high-pressure and two-stage high-temperature sintering. The first stage is high-pressure, cold pressurization to 6.5-8.2 GPa, maintained for 30-60 seconds; the second stage is high-pressure and simultaneous heating, sintering at a pressure of 6-8 GPa, a temperature of 1490-1580°C, maintained for 300-600 seconds; and the third stage is high-pressure and simultaneous heating, pressure of 5.0-6.0 GPa, a temperature of 1150-1250°C, maintained for 150-200 seconds. The pressure and temperature are then reduced to normal pressure and room temperature to obtain a polycrystalline diamond composite sheet blank. After sintering, fine particles are evenly distributed around coarse particles.

The invention relates to the technical field of superhard materials, and particularly discloses a polycrystalline diamond compact and a preparation method and application thereof.The preparation method of the polycrystalline diamond compact comprises the following steps that WC-Co alloy powder is sintered to obtain a hard alloy matrix; uniformly mixing nano diamond powder, micron diamond powder and cubic boron nitride, adding a reinforcing agent and a binding agent, and uniformly mixing to obtain a polycrystalline diamond layer mixture; the reinforcing agent is a nitrogen-boron doped graphene bonded amino carbon nanotube; a gradient transition layer raw material and a polycrystalline diamond mixture are uniformly spread on the surface of the hard alloy matrix in sequence, and then a composite blank is obtained through mold pressing; and sintering the composite blank to obtain the polycrystalline diamond compact. Graphene and carbon nanotubes are compounded to form a reinforcing agent with a three-dimensional network structure, so that the strength and wear resistance of the material are improved, and the service life of the material under harsh working conditions is prolonged.

The invention provides a large-size CVD (chemical vapor deposition) polycrystalline diamond film surface grinding method, belongs to the technical field of diamond material processing, and aims to solve the technical problems of low CVD polycrystalline diamond chemical mechanical grinding and polishing efficiency and high consumption. The preparation method comprises the following steps: firstly, carrying out graphical processing on the surface of a CVD polycrystalline diamond film by adopting a laser processing method, then plating diamond micro-powder with a nano-thickness catalyst layer, then mixing the diamond micro-powder with the catalyst layer and an oxidizing agent to obtain a grinding liquid, then grinding the polycrystalline diamond film, and finally carrying out annealing treatment to obtain the polycrystalline diamond film with the nano-thickness catalyst layer. And further obtaining the polycrystalline diamond film with low internal stress and nanoscale roughness on the surface. According to the method, the processing efficiency of the polycrystalline diamond film can be improved to a great extent and the surface roughness can be reduced through the surface patterning of the CVD polycrystalline diamond film, the plating of the diamond micro-powder catalyst layer and the grinding fluid preparation coupled grinding processing effect.

A polycrystalline diamond inner and outer surface processing method belongs to the technical field of optical element manufacturing, and comprises the following steps: processing a silicon-based substrate with the outer surface having a predetermined spherical curvature, the outer surface precision and surface roughness meeting the requirements of the inner surface of the processed polycrystalline diamond; growing a polycrystalline diamond layer on the outer surface of the silicon-based substrate to form a composite structure body, and enabling the inner surface of the polycrystalline diamond layer to directly copy the spherical morphology of the outer surface of the silicon-based substrate; multi-stage step-by-step machining is conducted, rough grinding, laser and accurate grinding combined machining or laser and accurate grinding combined machining is conducted on the outer surface of the polycrystalline diamond layer, and therefore the quality of the outer surface is improved; removing the silicon-based substrate to obtain a complete polycrystalline diamond; and cleaning the inner and outer surfaces of the polycrystalline diamond, and detecting the roughness, surface shape precision and wall thickness uniformity of the inner and outer surfaces to meet the process requirements, thereby finishing the machining of the inner and outer surfaces of the polycrystalline diamond. According to the device, efficient removal, low damage and high-precision inner and outer surface forming are achieved.

This disclosure includes a sucker rod string, a tubing protector, and a tool joint with a polycrystalline diamond element positioned thereon for mating with other surfaces in downhole applications. The polycrystalline diamond element can be positioned on the sucker rod guide, sucker rod connector, tubing protector, and tool joint.

The invention provides a diffusion welding method of a CoZrTaB target material, which comprises the following steps: (1) carrying out finish machining on a CoZrTaB target blank to a welding size, and processing a thread on a welding surface of the CoZrTaB target blank by adopting a polycrystalline diamond screwer; (2) first cleaning and PVD titanium film plating are sequentially carried out on the welding face with the machined threads, and a to-be-welded CoZrTaB target blank is obtained; the back plate is subjected to finish machining to the welding size, and a to-be-welded back plate is obtained; and (3) the to-be-welded CoZrTaB target blank and the to-be-welded back plate are sequentially subjected to second cleaning, assembling, sheath welding, high-temperature degassing and diffusion welding, and the diffusion-welded CoZrTaB target material is obtained. According to the diffusion welding method, the polycrystalline diamond screwer is adopted to machine the threads on the welding face of the CoZrTaB target blank, then the titanium film is plated, and the CoZrTaB target material which is high in welding strength and meets the high-temperature sputtering use requirement is obtained.

This application relates to a polycrystalline diamond composite substrate, belonging to the technical field of superhard material composites. It includes a cylinder with one end serving as a bonding surface; a frustum located at one end of the bonding surface, comprising a truncated cone coaxially transitioning onto the cylinder and a frustum coaxially connected to the truncated cone; and a raised structure disposed on the frustum, comprising multiple sets of coaxially arranged raised units, each set of raised units being evenly distributed in a ring around the center of the bonding surface, with grooves formed between adjacent raised units, the grooves being concentric with the bonding surface. This application allows external forces applied to the composite to be more evenly distributed across different parts of the substrate, avoiding localized stress concentration. The raised structure increases the contact area between the substrate and the diamond layer, significantly enhancing the adhesion between them. During drilling, the diamond layer adheres more firmly to the substrate, reducing the risk of premature detachment of the diamond layer due to external forces.

The utility model discloses a polycrystalline diamond radial centralizing sliding bearing which comprises a static ring, a movable ring arranged on the inner side of the static ring, a wear-resistant pad and a first polycrystalline diamond layer arranged on the inner side of the movable ring, a second polycrystalline diamond layer arranged on the outer side of the static ring, and a rolling ball arranged on the static ring. A first lubricating groove and a second lubricating groove are formed in the static ring, a first filter screen is fixedly connected to the top of the first lubricating groove, a first retention groove is fixedly connected to the bottom end of the first lubricating groove, a first lubricating channel and a first calandria are communicated to the first retention groove, and a second filter screen is fixedly connected to the top of the second lubricating groove. The bottom end of the second lubricating groove is fixedly connected with a second detention groove, and the second detention groove communicates with a second calandria and a second lubricating channel. By means of the device, the first lubricating groove, the second lubricating groove, the calandria and the lubricating channel are conveyed to the rolling balls, so that the lubricating efficiency is improved, and frictional wear is reduced.

The present application relates to the preparation method of thick polycrystalline diamond compact for oil and gas drilling, which comprises the following steps: mixing two or more kinds of diamond powder with impurities removed; sand blasting the cemented carbide substrate; sequentially loading the impurity storage layer, the diamond powder mixture layer, the low-melting-point metal sheet, the cobalt sheet and the cemented carbide substrate into a high-temperature-resistant metal cup; placing the high-temperature-resistant metal cup into a synthetic block and then into a six-surface press; performing two-stage high-temperature and high-pressure sintering, wherein the first stage is sintering at a pressure of 5.5-5.8 GPa and a temperature of 800-1300 DEG C for 60-150 seconds, and the second stage is sintering at a pressure of 6-8 GPa and a temperature of 1490-1580 DEG C for 450-700 seconds; and taking out at room temperature and normal pressure. The impurity storage layer, the low-melting-point metal sheet and the cobalt sheet are arranged, and the high-temperature and high-pressure scanning sintering method is adopted, so that the thickness of the diamond layer reaches 3-4 mm after sintering, and the service life is greatly prolonged.

The embodiment of the invention provides a polycrystalline diamond compact and a preparation method thereof and a cutting tool, the polycrystalline diamond compact comprises a three-dimensional skeleton and polycrystalline diamond filled in the three-dimensional skeleton, the three-dimensional skeleton comprises two-dimensional network layers arranged at intervals and first metal wires supporting the two-dimensional network layers, and the two-dimensional network layer comprises metal wires with a grid structure and carbon fibers woven on the metal wires. A tough three-dimensional network composed of metal wires and carbon fibers is arranged in polycrystalline diamond, the polycrystalline diamond is divided into a plurality of small units, when one small unit is cracked, the tough network stretches across cracks, rapid expansion of the cracks is prevented through tension transmission, yield of the tough network needs to consume a large amount of energy, damage to the whole structure is delayed, and the service life of the polycrystalline diamond is prolonged. The compressive strength and ductility of the polycrystalline diamond compact can be improved by the circumferential constraint of the toughness network on the surrounding polycrystalline diamond, the shear failure is inhibited, and the fracture toughness of the polycrystalline diamond compact is improved.

The present invention relates to highly pure high performance polycrystalline diamond monolith, a method for manufacturing a single-crystal diamond, and uses thereof.

The invention belongs to the field of preparation of wide bandgap semiconductor materials, and particularly discloses a preparation method of a low-stress large-size polycrystalline diamond wafer, which comprises the following steps: by taking a substrate as a growth foundation of diamond, sequentially carrying out diamond inoculation treatment and MPCVD process treatment on the substrate so as to grow and form an initial growth layer on the substrate; the primary growth layer serves as a growth foundation of diamond, diamond inoculation treatment and MPCVD process treatment are sequentially conducted on the primary growth layer, a secondary growth layer is formed on the primary growth layer in a growing mode, and an elastic buffer interface is formed between the primary growth layer and the secondary growth layer. By means of the method, the problems of wafer warping, film layer microcracks and film layer stripping caused by the residual stress of the large-size wafer can be solved, active reconstruction and release of the residual stress are facilitated through the successive multiple inoculation and growth processes, and then preparation of the polycrystalline diamond wafer with low stress, large size and high crystallization quality is achieved.

The invention belongs to the technical field of polycrystalline diamond growth, and particularly relates to a growth method of a high-quality self-supporting diamond thick film. Compared with the prior art, the polycrystalline diamond film is obtained on the substrate through multiple times of growth and annealing treatment, accumulation of stress accumulated in the polycrystalline film can be reduced, and the quality self-supporting diamond thick film is obtained.

The invention discloses polycrystalline diamond defect detection and repair equipment and an intelligent repair method. The method comprises the following steps: preprocessing a to-be-processed area of a to-be-detected product, performing excitation scanning, obtaining distribution data of an internal fluorescence signal, and generating a fluorescence signal distribution diagram; carrying out image analysis on the fluorescence signal distribution diagram, identifying and positioning an abnormal fluorescence signal region in the fluorescence signal distribution diagram, constructing a three-dimensional coordinate model according to the abnormal fluorescence signal region, and processing by adopting ultra-short pulse laser processing equipment to form a repair channel; providing a repair alloy, and filling the repair alloy into the repair channel through a directional infiltration technology to realize metallurgical bonding repair of the internal defect area; an optical traceable signal detection mechanism is introduced into a polycrystalline diamond material, and an ultrashort pulse laser micro-channel processing and directional infiltration repairing process is combined, so that positioning and in-situ repairing of internal defects are realized, and the overall mechanical property of the material is effectively recovered; therefore, the service life of the product is obviously prolonged, and the machining reliability is improved.

This invention belongs to the field of superhard material synthesis technology, specifically disclosing a high-temperature, high-pressure preparation method for nano-polycrystalline diamond with synergistic mechanical and thermal properties. The method includes the following steps: precursor preparation: pre-pressing the precursor in a cemented carbide mold; octahedral assembly; wrapping the pre-pressed sample with platinum foil and placing it at the center of the octahedron; high-temperature, high-pressure sintering; stopping heating after heat preservation, allowing it to cool naturally to 23-25°C, then depressurizing, removing the octahedral assembly and the platinum foil wrapping, thus obtaining the synergistically enhanced nano-polycrystalline diamond. This invention employs the above-mentioned high-temperature, high-pressure preparation method for nano-polycrystalline diamond with synergistic mechanical and thermal properties. By combining nanodiamond powder with graphene, the sample assembly is optimized, and nano-polycrystalline diamond samples with excellent mechanical properties and significantly improved thermal conductivity are synthesized under relatively mild temperature and pressure conditions.

The present application provides a kind of micro-nano heterogeneous polycrystalline diamond compact and its preparation method, drill bit.The micro-nano heterogeneous polycrystalline diamond compact includes hard alloy substrate and micro-nano heterogeneous polycrystalline diamond layer arranged on the hard alloy substrate;Wherein, micro-nano heterogeneous polycrystalline diamond layer includes micron diamond microcrystal and nanometer polycrystalline diamond microcrystal.The micro-nano heterogeneous polycrystalline diamond compact introduces the internal structure for nanometer polycrystalline diamond into the traditional polycrystalline diamond layer to replace the original part of micron diamond, can reduce the cobalt content in polycrystalline layer, improve the heat resistance of compact, in addition, since the nanometer polycrystalline diamond with higher hardness, toughness than traditional micron diamond is added, the hardness, wear resistance and impact resistance of polycrystalline diamond compact are improved.

This application relates to the field of superhard materials technology, specifically disclosing a method for preparing polycrystalline diamond composite sheets and their application in drill bits. The method for preparing the polycrystalline diamond composite sheet includes the following steps: S1, molding and sintering WC powder and Co to obtain a cemented carbide substrate; S2, grafting multi-walled carbon nanotubes with free radicals to obtain modified multi-walled carbon nanotubes; S3, surface-treating diamond micropowder to obtain modified diamond micropowder; S4, processing the modified diamond micropowder, modified multi-walled carbon nanotubes, N-rGO, Ti powder, etc., to obtain a powder, which is then combined with the cemented carbide substrate to obtain the polycrystalline diamond composite sheet. This application uses modified diamond and composite reinforcing phases to solve the problems of weak interfaces and thermal stress concentration within the polycrystalline diamond composite sheet, while simultaneously improving structural integrity and impact resistance at high temperatures.

The invention discloses a method for eliminating internal stress of a large-scale polycrystalline diamond block material. The method comprises the following steps that the block material is placed in a vacuum heat treatment furnace; carrying out vacuumizing and gas washing operation on the furnace chamber so as to remove residual active gas; introducing high-purity protective gas into the furnace and maintaining positive pressure; executing a stepped heating and heat preservation process: firstly, heating to a first heat preservation temperature T1 at a first heating rate and preserving heat, and then heating to a higher second heat preservation temperature T2 at a second heating rate and preserving heat; and after heat preservation is completed, the controlled cooling process is executed till the furnace temperature is reduced to the room temperature. A strategy of'stepped heating + long-time heat preservation 'is adopted, firstly, the stress of a part of a high-energy area is preliminarily relaxed at a low temperature T1, and cracking caused by stress concentration due to rapid heating is avoided; then, at a higher temperature T2, sufficient energy is provided for atomic diffusion and grain boundary slippage, and deep and uniform release of the internal stress is achieved. And the method is particularly suitable for large-scale blocks.

Bearing assemblies that include a plurality of polycrystalline diamond (“PCD”) bearing elements, bearing apparatuses including such bearing assemblies, and methods of operating and fabricating such bearing assemblies and apparatuses are disclosed. In an embodiment, the plurality of PCD bearing elements of one or more of the bearing assemblies disclosed herein include at least one first PCD bearing element. At least a portion of the first PCD bearing element exhibits a coercivity of about 125 Oersteds or more and a specific magnetic saturation of about 14 Gauss cm3 / gram or less. The first PCD bearing element includes a bearing surface with at least one groove formed therein. In an embodiment, the plurality of PCD bearing elements also include at least one second PCD bearing element. The second PCD bearing element exhibits a coercivity that is less than and a specific magnetic saturation that is greater than the first PCD bearing element.