218 results about "Superhard material" patented technology

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.

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 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 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 relates to the field of intelligent welding processes and control, and discloses a welding method for a superhard material sealing body multilayer structure. Comprising the steps of obtaining multilayer structure data, and generating a three-dimensional digital model; energy input parameters are optimized according to the heat affected zone and the stress concentration zone, and an initial energy tuning parameter set is generated; according to the initial energy tuning parameter set, temperature field data and stress field data in the welding process are collected, and the dynamic heat affected zone change trend is obtained; according to the change trend of the dynamic heat affected zone, adjusting energy input and a scanning path, and generating a corrected energy tuning parameter; controlling depth distribution of energy in the multilayer structure according to the corrected energy tuning parameters to obtain fusion depth and heat affected zone distribution; energy input and scanning speed are adjusted according to the fusion depth and the heat affected zone distribution, and an energy input parameter set is generated. The precision of energy control in the welding process 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.

A method of leaching an element may include exposing an electrode and at least a portion of an element body comprising at least one of a superabrasive or a superhard material to a processing solution; while the electrode and the at least a portion of the element body are exposed to the processing solution in an electrochemical leaching process, applying an electrical potential between the electrode and the element body; and preferentially removing the metallic material from a portion of the element body in the electrochemical leaching process.

Herein is disclosed a friction stir welding tool comprising: a probe with a height Hp extending along a longitudinal axis of rotation, wherein the probe comprises a base portion and an apex; wherein the probe comprises a superhard material; wherein a surface of the probe comprises a helical path with a width W, wherein the helical path extends from the base portion towards the apex; and wherein a ratio between the height Hp of the probe and the width W is 15 or less and use of the same in a process of friction stir welding a non-ferrous metal. Herein is further disclosed a method of friction stir welding a workpiece which comprises aluminium.

The utility model relates to a superhard material guide rail machining device which comprises a lathe bed. The working table is arranged above the machine body; the two ends of the cross beam are arranged on the workbench through stand columns; the X-axis linear motor module is arranged on the cross beam; the Z-axis linear module is arranged on the X-axis linear motor module; the spindle box is arranged on the Z-axis linear module, an electric spindle is arranged in the spindle box, and a grinding tool or a polishing tool is installed on the electric spindle; the Y-axis linear motor module is arranged on the workbench; and the workpiece carrying plate is arranged above the Y-axis linear motor module. Through multi-axis linkage of the X-axis linear motor module, the Y-axis linear motor module and the Z-axis linear motor module, the long guide rail is pressurized and polished through a small tool, the grinding amount is controlled through the dwell time and the polishing pressure, and high-precision machining of the long guide rail is achieved.

The invention relates to the technical field of laser cutting, in particular to a laser cutting control system for a superhard material clad sheet, which comprises a monitoring module used for acquiring an initial scanning path of a laser beam for the superhard material clad sheet, dividing a plurality of nodes in the initial scanning path, dividing adjacent nodes into a scanning section, the monitoring module respectively records the cutting speed of each scanning section and the cutting degree parameter of each node in the scanning process; the path control unit generates a supplementary scanning path based on the cutting degree parameter of each node; the speed control unit determines the scanning speed of each scanning section in the supplementary scanning path based on the cutting degree parameters of the nodes at the two ends of the scanning section, and the cutting degree of each node can be effectively quantified and represented through parallel configuration collection of the photoelectric detector array. Therefore, the optimization of the path and the speed determined based on the cutting degree of each node is better matched with the actual working condition, and the forming precision of the superhard material clad sheet in the laser cutting process is effectively improved.

The invention discloses a manufacturing method of a grinding wheel for a high-uniformity and easy-to-sharpen grinding single crystal diamond cutter, and belongs to the field of superhard materials and products in machining, the manufacturing method mainly comprises the steps of wet mixing, tape casting, laser cutting, lamination, matrix surface treatment, integrated sintering, size processing, sharpening and the like, and finally the grinding wheel with the total thickness of an abrasive layer being 7-15 mm is formed. The grinding wheel layer is formed by intersecting and laminating a piece a and a piece b, the height of diamonds at the junction of the piece a and the piece b tends to be consistent, the diamond exposure height and smoothness are better compared with direct feeding sintering, meanwhile, the piece a can be designed to be of a porous structure through proper binder selection, and therefore the dressing efficiency is further improved, and the dressing effect is better. And higher processing quality and efficiency of the diamond cutter are indirectly improved.

Herein is disclosed a friction stir welding tool assembly comprising: a substrate having a substrate end; a tip having a tip end; and an interlayer between the substrate end and the tip end; wherein the tip further comprises a stirring pin, the stirring pin being located at a distal end to the tip end; and wherein the tip is formed of a first superhard material, and a use of the friction stir welding tool assembly in a friction stir welding process.

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 discloses a wafer precision grinding method based on laser subsurface modification softening, and belongs to the technical field of semiconductor manufacturing. The method is used for carrying out final damage layer removal and surface finish machining on the hard and brittle wafers (such as silicon carbide and diamond) subjected to preliminary mechanical polishing. The method comprises the following steps: (1) detecting the depth of a damaged layer on the subsurface of a wafer; (2) focusing ultrafast laser on the subsurface of the wafer, scanning to form a continuous and compact softened modified layer, controlling the modified layer to extend upwards in the vertical direction, so that the modified layer covers most of the volume of the material to be removed, and only retaining a micron or submicron original hard thin layer on the top layer of the wafer; (3) carrying out nondestructive testing on the modified layer; and (4) an ultra-precision grinding process (such as CMP or PAP) is adopted, the supporting weakening effect of the modified layer on the top hard thin layer and the characteristic that the modified layer is easy to remove are utilized, and all the to-be-machined allowances are rapidly removed at a time. According to the method, on the premise that the high-quality surface is not damaged, the finish machining efficiency of the superhard material is remarkably improved through the mechanism of internal softening and top layer collapse removal.

The invention discloses a modular cup-shaped grinding wheel for curved surface diamond grinding and a using method, and relates to the field of superhard material machining, the grinding wheel comprises a base body, the base body is of a cup-shaped structure, the outer wall of the base body is provided with a plurality of inserting grooves which are evenly distributed at intervals in the circumferential direction, each inserting groove sinks in the normal direction of the outer wall, and the two side faces of each inserting groove can extend downwards and intersect; included angles are formed between the two side surfaces and the bottom surface of the slot; the grinding block is matched with the slot and is mounted in the slot; the pressing plate is of an annular structure, sleeves the outer wall of the base body and is detachably connected with the base body, and the grinding block is pressed by the pressing plate and is detachably connected with the pressing plate; and the grinding material layer is mounted on the lower surface of the grinding block and used for grinding the curved-surface diamond. The brittle fracture process can be regulated and controlled, the grinding capacity of the grinding wheel is improved, the temperature of a grinding area is reduced, the grinding quality is improved, and the method is suitable for manufacturing high-end equipment such as high-power laser windows and spaceflight infrared optical systems.

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 invention discloses a composite laser cutting device which comprises a first light source, a second light source, a first reflecting mirror, a spectroscope, a focusing mirror, a first energy distribution adjusting assembly and a second energy distribution adjusting assembly, and further discloses a composite laser cutting method which comprises the following steps that a light beam is emitted, and energy distribution of the composite light beam is controlled. The method has the beneficial effects that distribution control and application of multi-level energy are achieved, and the efficiency and quality of composite beam laser cutting can be rapidly improved by controlling the energy density of the whole body and the center. The laser cutting machine can be well applied to laser cutting, is particularly suitable for cutting thick plates and composite plates, can cut transparent materials with high efficiency, and can overcome the technical problem that a laser cutting machine in the prior art is difficult to effectively cut the transparent materials and superhard materials.

A polycrystalline superhard material blank convenient for grinding and a preparation method thereof, comprising a polycrystalline superhard material blank formed by high temperature and high pressure. The polycrystalline superhard material blank includes a polycrystalline superhard material product body, a machining allowance grinding layer and an easy-to-grind grinding layer. It is characterized in that: the polycrystalline superhard material product body is a finished product that meets the specification requirements after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer is the same as that of the polycrystalline superhard material product body, and is a fine-grained polycrystalline superhard material with exactly the same particle size; the easy-to-grind grinding layer is the grinding layer on the pressure-receiving surface, and there are two types: a coarse-grained easy-to-grind grinding layer of the same quality as the polycrystalline superhard material and an easy-to-grind grinding layer of different quality from the polycrystalline superhard material. The raw material of the easy-to-grind grinding layer is a coarse-grained polycrystalline superhard material product body homogeneous fine powder, the particle size of which is coarser than that of the polycrystalline superhard material product body, and the porosity is larger than that of the polycrystalline superhard material product body. The larger the porosity, the worse the wear resistance, the easier it is to grind, the processing cost is reduced, and the processing efficiency is improved; the gas absorption effect of the metal powder can also reduce the content of impurity gases in the product body to achieve the above effects.

The invention provides intelligent self-adaptive precision grinding equipment and method for a superhard material. The intelligent self-adaptive precision grinding equipment comprises a frame body, a mortar rotating mechanism arranged on the frame body and used for driving a mortar to rotate, and a self-adaptive grinding mechanism used for driving a grinding rod to be rotationally matched with the mortar; the self-adaptive grinding mechanism comprises a flexible grinding rod assembly connected with the grinding rod and a moving module used for driving the flexible grinding rod assembly to move. The flexible grinding rod assembly is connected with the moving module through the three-dimensional torque feedback assembly. The three-dimensional torque feedback assembly feeds back the torque value in real time, the position of the sliding block, namely the moving end, of the moving module is rapidly adjusted, and then the three-dimensional torque feedback assembly and the flexible grinding rod assembly are driven to move; in addition, the flexible grinding rod assembly eliminates the instant change of grinding force caused by the irregularity of part of grinding rods and grinding bowls and different powder accumulation thicknesses, so that the pressure value of the grinding rods for pressing the inner wall is kept within a certain range, and the self-adaptive precise grinding is ensured.

The invention belongs to the technical field of superhard material tool manufacturing, and particularly relates to a functionally gradient enhanced diamond thin-wall drill and a preparation method and application thereof. The functionally gradient enhanced diamond thin-wall drill comprises a steel base body, the outer end of the steel base body is a drilling part of a cylindrical structure, and inclined grooves and drilling units are formed in the periphery of the drilling part at equal intervals; an anti-friction heat-conducting coating is cladded on the wall surface of the inclined groove; the drilling unit comprises a functional gradient nano-reinforced brazing filler metal layer and diamond abrasive particles brazed on the surface of the functional gradient nano-reinforced brazing filler metal layer through laser; the functional gradient nano-reinforced brazing filler metal layer comprises a transition layer, a reinforcing layer and a bonding layer which are sequentially arranged in the direction from the steel base body to the diamond abrasive particles. According to the diamond thin-wall drill, by designing the functional gradient nanometer enhanced brazing filler metal layer and the antifriction heat conduction coating and adopting the laser welding technology, multi-performance collaborative optimization of impact resistance, high abrasion resistance, strong heat dissipation and low friction of the diamond thin-wall drill can be achieved, and the service life of the diamond thin-wall drill is remarkably prolonged.

The utility model discloses a cubic press device for superhard material synthesis. The cubic press device comprises a cubic press body, a plurality of hinge beams are installed on the cubic press body, the hinge beams are connected through pin rods, the hinge beams are connected with a plurality of beam bottom protection belts, and the pin rods are connected with pin rod protection belts. According to the cubic press device for synthesis of the superhard materials, the beam bottom protection belt, the pin rod protection belt, the oil pipe protection cover, the protection baffle and the beam bottom displacement sensor are arranged, so that the risk of a cubic press in the using process is reduced, crack breakage is prevented, and the using safety of the cubic press 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 utility model discloses a diamond drilling device which comprises a machine box, a machine frame connected to the machine box, a lifting base connected to the machine frame through a lifting mechanism, a pull rod connected to the bottom face of the lifting base, a bearing plate connected to the lower end of the pull rod, a through hole formed in the center of the bearing plate, and a first sleeve connected to the bottom face of the bearing plate. The periphery of the first sleeve is rotatably connected with a second sleeve, the lower end of the second sleeve is connected with a pre-drill bit, and the bottom surface of the bearing plate is provided with a first driving mechanism for driving the second sleeve to rotate; the center of the bottom face of the lifting base is connected with a first air cylinder, the telescopic end of the first air cylinder is connected with a telescopic rod through a rotary connector, the top face of the bearing plate is rotationally connected with a third sleeve, and the telescopic rod is in spline connection in the third sleeve. And a second driving mechanism for driving the third sleeve to rotate is arranged on the top surface of the bearing plate. Through pre-drilling, rapid drilling, rough machining and stress release are achieved, and the problem of edge breakage of superhard material drilling is solved.

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 utility model provides a trepanning drill for one-step forming of a taper hole, which comprises a drillstock and a drill bit, the drill bit is symmetrically provided with a pair of cutter bodies extending along the axis direction, each cutter body is provided with a top surface and an end surface, the top surfaces of the pair of cutter bodies are enveloped by a conical contour along the axis direction, and the end surface is provided with a plurality of end surfaces. A notch groove is formed between the pair of cutter bodies in the circumferential direction of the cone, and each notch groove is composed of the short cutter face of one cutter body and the long cutter face of the other cutter body. According to the utility model, cuttings are continuously extruded and broken off by the long cutter face, are simultaneously supported and accumulated in the notch groove by the short cutter face and are then discharged along the bottom of the notch groove, and the cuttings are extruded and broken off to require higher structural strength, so that the long cutter face is used for providing enough structural strength, and the short cutter face can release more structural sizes to the long cutter face; the tapping drill can meet the strength requirement of one-time forming of the taper hole made of the superhard material.

The invention provides a blank molding assembly block of diamond large single crystals and a plastic growth method, and belongs to the technical field of superhard material synthesis. The blank molding assembly block comprises a mutually-embedded metal catalyst layer formed by mutually embedding a plurality of prismatic table metal catalyst structures, the whole mutually-embedded metal catalyst layer is in a prismatic table shape, one of the upper end face and the lower end face of each prismatic table metal catalyst structure is in contact with the high-purity graphite carbon source layer, and the other one of the upper end face and the lower end face of each prismatic table metal catalyst structure is in contact with the seed crystal; the adjacent prismatic table metal catalyst structures are separated by an insulating layer, and the insulating layer is a Ca coating or a BN coating. A mutually-embedded prismatic-table-shaped metal catalyst structure with an axial temperature gradient and a carbon diffusion channel is constructed in a blank assembly block, diamond is induced to grow in a preset direction in an HPHT environment, directional shaping growth of the diamond is achieved under the condition that the process complexity is not improved, and the quality of the diamond is improved. The crystal morphology controllability, the catalytic agent utilization efficiency and the final drilling rate are remarkably improved, and the single-cavity yield is increased.

A cutting element may include a substrate; and an ultrahard layer on the substrate, the substrate and the ultrahard layer defining a non-planar working surface of the cutting element such that the ultrahard layer forms a cutting portion and the substrate is at least laterally adjacent to the ultrahard layer. Another cutting element includes a pointed region having a side surface extending from the pointed region outer perimeter to a peak. An ultrahard material body forms a portion of the pointed region including the peak, and a base region extends a depth from the pointed region outer perimeter. The ultrahard material body has a height to width aspect ratio with the height and width measured between two points of the body having the greatest distance apart along a dimension parallel with a longitudinal axis (i.e., height) along a dimension perpendicular to the longitudinal axis (i.e., width).

The invention relates to the technical field of hard alloy for synthesis of superhard materials, and particularly discloses a hard alloy holding-up hammer for synthesis of high-purity large single crystal diamond and a preparation method of the hard alloy holding-up hammer. The holding-up hammer material is composed of the following components in percentage by weight: 80%-88% of WC, 4%-8% of Co, 2%-5% of TaC, 3%-7% of TiC and 0.5%-2% of Cr3C. Wherein WC serves as a hard phase, Co serves as a binding phase, TaC inhibits grain growth, TiC nanoparticles are dispersed and distributed to form a pinning effect, and Cr3C2 improves the wettability of the binding phase and improves the oxidation resistance. The preparation method comprises the steps of raw material selection and ball-milling mixing, vacuum drying and sieving, cold pressing and cold isostatic pressing forming, gradient sintering and grinding and subzero treatment.

A milling cutter comprising: a tool shank (12) having a longitudinal axis of rotation; and a tool head (16) attached to one end of the tool shank, the tool head comprising first, second and third tiers (18a, 18b, 18c) extending around an outer surface of the tool head; wherein the tiers are axially displaced from each other along the longitudinal axis; wherein the first tier of the tool head comprises a plurality of axially extending first cutting surfaces, each first cutting surface having a first profile; the second tier of the tool head comprises a plurality of axially extending second cutting surfaces, each second cutting surface having a second profile; and the third tier of the tool head comprises a plurality of axially extending third cutting surfaces, each third cutting surface having a third profile; wherein the first tier is closer to the tool shank than the second tier; and wherein the third tier is further from the tool shank than the first tier and the second tier; wherein, when the first, second and third profiles are superimposed, the first profile nests within the second profile, and the second profile nests within the third profile; wherein the first profile differs from the second profile, and wherein the third profile differs from the first profile and the second profile; and wherein the first, second and third cutting surfaces comprise superhard material.

The present disclosure relates to a friction stir welding tool assembly (10) comprising a base (12) having a base end (12a), the base end (12a) comprising a convex portion, and a tip end (14) having a tip end (14a), the tip end (14a) comprising a concave portion, the tip end further comprising a stir pin (20), the stir pin (20) being located distally relative to the tip end (14a). The tip end (14) is formed of a superhard material, and the base end (12a) is joined to the tip end (14a) at corresponding convex portions and concave portions.