Abstract: In one aspect of the present invention, a high impact wear resistant tool has a superhard material bonded to a cemented metal carbide substrate at a non-planar interface. The superhard material has a thickness of at least 0.100 inch and forms an included angle of 35 to 55 degrees. The superhard material has a plurality of substantially distinct diamond layers. Each layer of the plurality of layers has a different catalyzing material concentration. A diamond layer adjacent the substrate of the superhard material has a higher catalyzing material concentration than a diamond layer at a distal end of the superhard material.

Abstract: A hardfacing composition for downhole well tools, such as earth-boring bits, contains sintered ultrahard particles. The ultrahard particles consist of tungsten carbide grains, cobalt and vanadium. The ultrahard particles are dispersed within a matrix metal of iron, nickel or alloys thereof. The composition may also have sintered tungsten carbide particles of a larger size than the ultrahard particles. The ultrahard particles have a greater hardness than the sintered tungsten carbide particles. The ultrahard particles and the sintered tungsten carbide particles may be in a spherical pellet form. Other hard metal particles may be in the composition.

Abstract: Polycrystalline compacts include non-catalytic nanoparticles in interstitial spaces between interbonded grains of hard material in a polycrystalline hard material. Cutting elements and earth-boring tools include such polycrystalline compacts. Methods of forming polycrystalline compacts include sintering hard particles and non-catalytic nanoparticles to form a polycrystalline material. Methods of forming cutting elements include infiltrating interstitial spaces between interbonded grains of hard material in a polycrystalline material with a plurality of non-catalytic nanoparticles.

Abstract: A polycrystalline diamond (PCD) material 10 comprising at least 88 volume percent and at most 99 volume percent diamond grains 12, the mean diamond grain contiguity being greater than 60.5 percent. The PCD material 10 is particularly but not exclusively for use in boring into the earth.

Abstract: A polycrystalline diamond abrasive element, particularly a cutting element, comprises a table of polycrystalline diamond bonded to a substrate, particularly a cemented carbide substrate, along a non-planar interface. The non-planar interface typically has a cruciform configuration. The polycrystalline diamond has a high wear-resistance, and has a region adjacent the working surface lean in catalysing material and a region rich in catalysing material. The region lean in catalysing material extends to a depth of 40 to 90 microns, which is much shallower than in the prior art. Notwithstanding the shallow region lean in catalysing material, the polycrystalline diamond cutters have a wear resistance, impact strength and cutter life comparable to that of prior art cutters, but requiring only 20% of the treatment times of the prior art cutters.

Abstract: A method of forming a thermally stable cutting element that includes disposing at least a portion of a polycrystalline abrasive body containing a catalyzing material to be leached into a leaching agent; and subjecting the polycrystalline abrasive object to an elevated temperature and pressure is disclosed. Thermally stable cutting elements and systems and other methods for forming thermally stable cutting elements are also disclosed.

Abstract: A front face of a diamond table mounted to a substrate is processed to introduce a material which comingles with or semi-alloys with or partially displaces interstitial catalyst binder in a thermal channel to a desired depth. The material is selected to be less thermally expandable than the catalyst binder and/or more thermally conductive than the catalyst binder and/or having a lower heat capacity than the catalyst binder.

Abstract: A method for a down hole cutting tool is disclosed, wherein the cutting tool includes a cutting element support structure having at least one cutter pocket to support a cutting element comprising a substrate and an ultrahard layer. The method includes inserting a base portion of the cutting element into the cutter pocket; locating a first braze alloy such that when heated the first braze alloy melts and fills a space in the cutter pocket between the cutting element and the cutting element support structure adjacent the ultrahard layer; locating a second braze alloy such that when heated the second braze alloy melts and fills a space in the cutter pocket between the cutting element and the cutting element support structure non-adjacent the ultrahard layer; and heating the first and second braze alloy such that they melt.

Abstract: In various embodiments, a polycrystalline diamond compact (“PDC”) comprises a substrate including an interfacial surface having a raised region. The PDC comprises a polycrystalline diamond (“PCD”) table bonded to the interfacial surface of the substrate. The PCD table defines an upper surface and exhibits a thickness over the raised region. The PCD table includes a plurality of bonded diamond grains defining a plurality of interstitial regions. A first region of the PCD table adjacent to the substrate includes metal-solvent catalyst disposed interstitially between the bonded diamond grains thereof, and a leached second region of the PCD table extends inwardly from the upper surface. The interstitial regions of the leached second region are depleted of metal-solvent catalyst. The geometry of the PCD table and raised region may be selected so that residual compressive stresses therein are retained to a sufficient level after leaching to provide a damage tolerant/thermally-stable PCD table.

Abstract: Embodiments of the invention relate to polycrystalline diamond (“PCD”) exhibiting enhanced diamond-to-diamond bonding. In an embodiment, polycrystalline diamond compact (“PDC”) includes a PCD table having a maximum thickness. At least a portion of the PCD table includes a plurality of diamond grains defining a plurality of interstitial regions. A metal-solvent catalyst occupies at least a portion of the plurality of interstitial regions. The plurality of diamond grains and the metal-solvent catalyst collectively exhibit a coercivity of about 115 Oersteds (“Oe”) or more and a specific magnetic saturation of about 15 Gauss·cm3/grams (“G·cm3/g”) or less. The PDC includes a substrate having an interfacial surface that is bonded to the PCD table. The interfacial surface exhibits a substantially planar topography. Other embodiments are directed to methods of forming PCD and PDCs, and various applications for such PCD and PDCs in rotary drill bits, bearing apparatuses, and wire-drawing dies.

Abstract: Embodiments relate to PDCs, methods of fabricating PDCs, and applications for such PDCs. In an embodiment, a PDC includes a substrate and a pre-sintered PCD table including an interfacial surface that is bonded to the substrate. The pre-sintered PCD table may be substantially free of leaching by-products in a region at least proximate to the interfacial surface. In an embodiment, a method of fabricating a PDC includes providing an at least partially leached PCD including an interfacial surface. The method includes removing at least some leaching by-products from the at least partially leached PCD table. After removing the at least some leaching by-products, the method includes bonding the interfacial surface of the at least partially leached PCD table to a substrate to form a PDC.

Abstract: An insert comprises a sintered polycrystalline diamond body bonded to a cemented metal carbide substrate. The diamond body comprises a substantially conical shape with conical side wall terminating at an apex. The diamond body comprises a first region with a metallic catalyst dispersed through interstices between the diamond grains and a second region proximate the apex with the characteristic of higher thermal stability than the first region.

Abstract: Methods of forming cutting elements for earth-boring tools include providing a barrier material between a first powder and a second powder each comprising diamond grains, and subjecting the powders and barrier material to high temperature and high pressure conditions to form polycrystalline diamond material. The formation of the polycrystalline diamond material is catalyzed, and catalytic material may be hindered from migrating across the layer of barrier material. Cutting elements for use in earth-boring tools include a barrier material disposed between a first layer of polycrystalline diamond material and a second layer of polycrystalline diamond material. Earth-boring tools include one or more such cutting elements for cutting an earth formation.

Abstract: Embodiments of the invention relate to methods of fabricating polycrystalline diamond (“PCD”) exhibiting enhanced diamond-to-diamond bonding by carbon pumping, and PCD and polycrystalline diamond compacts formed by such methods. In an embodiment of a method of fabricating PCD, a plurality of diamond crystals and a metal-solvent catalyst may be provided. The diamond crystals and metal-solvent catalyst may be subjected to a first pressure-temperature condition during which carbon is dissolved in the metal-solvent catalyst. After subjecting the diamond crystals and metal-solvent catalyst to the first pressure-temperature condition, the diamond crystals and metal-solvent catalyst may be subjected to a second pressure-temperature condition at which diamond is stable.

Abstract: A mixture for fabricating a cutting table, the cutting table, and a method of fabricating the cutting table. The mixture includes a cutting table powder and a binder. The binder includes at least one carbide formed from an element selected from at least one of Groups IV, V, and VI of the Periodic Table. The carbide is in its non-stoichiometric and/or stoichiometric form. The binder can include the element. In certain embodiments, the binder includes one or more of the cutting table powder and a catalyst. The cutting table is formed by sintering the mixture using a solid phase sintering process or a near solid phase sintering process. When forming or coupling the cutting table to a substrate, a divider is positioned and coupled therebetween to ensure that the sintering process that forms the cutting table occurs using the solid phase sintering process or the near solid phase sintering process.

Abstract: A drill bit that includes a body having a lower end face for engaging a rock formation, the end face having a plurality of raised ribs extending from the face of the bit body and separated by a plurality of channels therebetween; and at least one of the plurality of ribs having a cutting portion of the at least one rib comprising a first diamond impregnated matrix material and at least a portion of a gage surface region thereof comprising a second diamond impregnated matrix material, the gage surface region backed by a third matrix material is disclosed.

Abstract: A cutting element is provided including a substrate and a TSP material layer over the substrate. The TSP material layer includes at least a property having a value that varies through the layer.

Abstract: Embodiments of the invention relate to polycrystalline diamond (“PCD”) exhibiting enhanced diamond-to-diamond bonding. In an embodiment, PCD includes a plurality of diamond grains defining a plurality of interstitial regions. A metal-solvent catalyst occupies at least a portion of the plurality of interstitial regions. The plurality of diamond grains and the metal-solvent catalyst collectively exhibit a coercivity of about 115 Oersteads (“Oe”) or more and a specific magnetic saturation of about 15 Gauss·cm3/grams (“G·cm3/g”) or less. Other embodiments are directed to polycrystalline diamond compacts (“PDCs”) employing such PCD, methods of forming PCD and PDCs, and various applications for such PCD and PDCs in rotary drill bits, bearing apparatuses, and wire-drawing dies.

Abstract: Ultra-hard constructions include an ultra-hard body having a first region including a polycrystalline matrix first phase and a second phase material interposed therein. The first region is substantially free of a catalyst material used to form the first phase. The body is formed by removing the catalyst material and then replacing it with the second phase material. A second region is disposed within the body and includes the polycrystalline matrix first phase and a catalyst material used to form the first phase. The second phase material has a thermal characteristic that is more closely matched to the matrix first phase than the catalyst material. The body may be joined to a substrate, and the ultra-hard body may consist entirely of the first region. The second phase material can include non-refractory metals, ceramics, silicon, silicon-containing compounds, diamond, cubic boron nitride, polycrystalline diamond, polycrystalline cubic boron nitride, and mixtures thereof.

Abstract: A polycrystalline diamond abrasive element, particularly a cutting element, comprises a table of polycrystalline diamond bonded to a substrate, particularly a cemented carbide substrate, along a non-planar interface. The non-planar interface typically has a cruciform configuration. The polycrystalline diamond has a high wear-resistance, and has a region adjacent the working surface lean in catalysing material and a region rich in catalysing material. The region lean in catalysing material extends to a depth of 40 to 90 microns, which is much shallower than in the prior art. Notwithstanding the shallow region lean in catalysing material, the polycrystalline diamond cutters have a wear resistance, impact strength and cutter life comparable to that of prior art cutters, but requiring only 20% of the treatment times of the prior art cutters.

Abstract: A method of forming a thermally stable cutting element that includes disposing at least a portion of a polycrystalline abrasive body containing a catalyzing material to be leached into a leaching agent; and subjecting the polycrystalline abrasive object to an elevated temperature and pressure is disclosed. Thermally stable cutting elements and systems and other methods for forming thermally stable cutting elements are also disclosed.

Abstract: Polycrystalline ultra-hard compact constructions comprise a polycrystalline ultra-hard compact having a polycrystalline ultra-hard body attached to a substrate. A support member is attached to the compact by a braze material. The support member can have a one-piece construction including one or more support sections. The support member has a first section extending axially along a wall surface of the compact, and extending circumferentially along a portion of the compact. The support member can include a second section extending radially along a backside surface of the compact, and/or a third section extending radially along a front side surface of the compact. In one embodiment, the support member includes a second and/or third section and the compact disposed therein is in an axially compressed state. The support member is interposed between the compact and an end-use device.

Abstract: Embodiments of the invention relate to polycrystalline diamond (“PCD”) exhibiting enhanced diamond-to-diamond bonding. In an embodiment, PCD includes a plurality of diamond grains defining a plurality of interstitial regions. A metal-solvent catalyst occupies at least a portion of the plurality of interstitial regions. The plurality of diamond grains and the metal-solvent catalyst collectively exhibit a coercivity of about 115 Oersteads (“Oe”) or more and a specific magnetic saturation of about 15 Gauss·cm3/grams (“G·cm3/g”) or less. Other embodiments are directed to polycrystalline diamond compacts (“PDCs”) employing such PCD, methods of forming PCD and PDCs, and various applications for such PCD and PDCs in rotary drill bits, bearing apparatuses, and wire-drawing dies.

Abstract: Embodiments relate to PDCs, methods of fabricating PDCs, and applications for such PDCs. In an embodiment, a PDC includes a substrate and a pre-sintered PCD table including an interfacial surface that is bonded to the substrate. The pre-sintered PCD table may be substantially free of leaching by-products in a region at least proximate to the interfacial surface. In an embodiment, a method of fabricating a PDC includes providing an at least partially leached PCD including an interfacial surface. The method includes removing at least some leaching by-products from the at least partially leached PCD table. After removing the at least some leaching by-products, the method includes bonding the interfacial surface of the at least partially leached PCD table to a substrate to form a PDC.

Abstract: A front face of a diamond table mounted to a substrate is processed to introduce a material which comingles with or semi-alloys with or partially displaces interstitial catalyst binder in a thermal channel to a desired depth. The material is selected to be less thermally expandable than the catalyst binder and/or more thermally conductive than the catalyst binder and/or having a lower heat capacity than the catalyst binder.

Abstract: Earth-boring tools comprising bodies with one or more thermally conductive insert support regions and one or more inserts secured to the one or more insert support regions are disclosed. The inserts may each comprise an insert body, which may be secured to the one or more insert support regions of the body. In some embodiments, one or more insert support regions of the body may have a thermal conductivity similar to the thermal conductivity of the insert body of the one or more inserts. In additional embodiments, one or more insert support regions of the body may have a thermal conductivity that is greater than the thermal conductivity of the insert body of the one or more inserts. In further embodiments, methods of forming earth-boring tools comprising bodies with one or more thermally conductive insert support regions are disclosed.

Abstract: Thermally stable polycrystalline constructions comprise a body having a polycrystalline ultra-hard phase and a plurality of empty voids. A population of the voids can be filled with a reaction product. The body is substantially free of a catalyst material. The construction comprises a first support member attached to the body by a first braze material. A second support member is attached to the body and the first support member by a second braze material. The construction may include a third support member attached to the body that is integral or separate from one of the other support members. The braze materials used to attached the support members can be the same or different, as can be the materials used to form the different support members.

Abstract: A cutting element is provided including a substrate and a TSP material layer over the substrate. The TSP material layer includes at least a property having a value that varies through the layer.

Abstract: Thermally stable diamond bonded materials and compacts include a diamond body having a thermally stable region and a PCD region, and a substrate integrally joined to the body. The thermally stable region has a microstructure comprising a plurality of diamond grains bonded together by a reaction with a reactant material. The PCD region extends from the thermally stable region and has a microstructure of bonded together diamond grains and a metal solvent catalyst disposed interstitially between the bonded diamond grains. The compact is formed by subjecting the diamond grains, reactant material, and metal solvent catalyst to a first temperature and pressure condition to form the thermally stable region, and then to a second higher temperature condition to both form the PCD region and bond the body to a desired substrate.

Abstract: High energy cutting elements and bits incorporating the same are provided. The cutting elements have at least a portion of their cutting layers which will be exposed to high temperatures during drilling formed from a PCBN material capable of operating at temperatures of at least 1000° C.

Abstract: An abrasive-impregnated cutting structure for use in drilling a subterranean formation is disclosed. The abrasive-impregnated cutting structure may comprise a plurality of abrasive particles dispersed within a substantially continuous matrix, wherein the abrasive-impregnated cutting structure exhibits an anisotropic wear resistance. One or more of the amount, average size, composition, properties, shape, quality, strength, and concentration of the abrasive particles may vary within the abrasive-impregnated cutting structure. Anisotropic wear resistance may relate to a selected direction, such as, for example, one or more of an expected direction of engagement of the abrasive-impregnated cutting structure with the subterranean formation and an anticipated wear direction. Anisotropic wear resistance of an abrasive-impregnated cutting structure may be configured for forming or retaining a formation-engaging leading edge thereof.

Abstract: A hard composite member produced by a rapid omni-directional compaction process that includes the steps of: providing a pre-compaction composite comprising a substrate, a superhard member and a layer of braze between the substrate and the superhard member; placing the pre-compaction composite in a pressure transmitting material contained within a shell to form an isostatic die assembly; heating the isostatic die assembly to a temperature at which the pressure-transmitting material is capable of fluidic flow and wherein the temperature ranges between greater than the melting point of the braze layer and less than or equal to about 1200° C.; and in a forging press, compressing the isostatic die assembly to consolidate the pre-compaction composite under omnidirectional pressure at a pressure equal to or greater than about 60,000 psi into a dense, consolidated body.

Abstract: A method of forming a thermally stable cutting element that includes disposing at least a portion of a polycrystalline abrasive body containing a catalyzing material to be leached into a leaching agent; and subjecting the polycrystalline abrasive object to an elevated temperature and pressure is disclosed. Thermally stable cutting elements and systems and other methods for forming thermally stable cutting elements are also disclosed.

Abstract: In one embodiment, a method of increasing a durability of a drill bit having a bit body with at least one blade disposed thereon, at least one cutter pocket disposed on the blade, and at least one cutter disposed in the cutter pocket is disclosed. The method includes brazing the at least one cutter to the at least one cutter pocket so that a braze material disposed between the at least one cutter pocket and the at least one cutter comprises an exposed surface, and overlaying at least a portion of the exposed surface with a hardfacing material, wherein the hardfacing material includes a binder having a melting point selected to avoid damaging the cutter.

Abstract: A laminated cutting element for use on a rotary-type earth-boring drill bit for drilling subterranean formations preferably including at least one first segment formed of a hard, continuous-phase material impregnated with a particulate superabrasive material laminated to and including at least one second segment formed of a continuous-phase material having essentially no particulate superabrasive material impregnated therein. Alternatively, the at least one second segment may have superabrasive and/or abrasive material impregnated therein which is less abrasive than the superabrasive material impregnated in the at least one first segment. Preferably, the continuous-phase material in which the at least one first segment and the at least one second segment are made is a metal matrix material. A further alternative of the present invention includes a single segment formed of a continuous-phase material in which a particulate superabrasive material is impregnated.

Abstract: Cutting elements for incorporation in a drill bit are provided having a body and an ultra hard material cutting layer over an end face of the body. A plurality of abutting shallow depressions are formed on the end face of the body. A transition layer may be incorporated between the body and the ultra hard material layer. The transition layer preferably has material properties intermediate between the properties of the body and the ultra hard material layer.

Abstract: A rotary drill bit includes cutters arranged in a series of concentric rings, the cutters of one of the rings having a different wear resistance to the cutters of another of the rings with the result that the stability of the drill bit improves with wear. Although the wear resistance is different, the cutters have substantially the same impact toughness.

Abstract: An earth-boring bit comprises a bit body bit body in which are mounted a plurality of cutting structures inserts, wherein at least a portion of the cutting structures comprise diamond-impregnated inserts having a total thermal exposure of less than 25 minutes above 1500° F. The diamonds can be natural or synthetic diamond. The bit body itself may be diamond-impregnated, in which case it is preferred that the diamonds in the inserts make up at least 40% of the total diamond in the bit.

Abstract: A preform cutting element, for a rotary drill bit, and a rotary drill bit with prefrom cutting elements including a facing table of superhard material having a front face, a rear surface is bonded to the front surface of a substrate which is less hard than the superhard material and has a rim or edge section of the superhard material at least partially covered by a metallic material different from the substrate material. The metallic material is bonded to the edge section of the superhard material through a high pressure bonding step. The superhard material covered by the compliant metallic material is protected from impact forces occurring in drill bit operations such as tripping.

Abstract: The present invention relates to cutting tool insert consisting of a tungsten carbide based hard metal substrate and a coating. The hard metal consists of about 4-15 wt-% binder phase with face centered cubic structure and a composition of 35-65 wt-% Fe and 35-65 wt-% Ni in addition to dissolved elements. As a result, inserts have been produced with at least as good performance in machining as conventional state-of-the-art inserts with Co-based binder phase. The insert can be applied in milling and turning of low and medium alloyed steels as well as stainless steels.

Abstract: Cutting elements for incorporation in a drill bit are provided having a body and an ultra hard material cutting layer over an end face of the body. A plurality of abutting shallow depressions are formed on the end face of the body. A transition layer may be incorporated between the body and the ultra hard material layer. The transition layer preferably has material properties intermediate between the properties of the body and the ultra hard material layer.

Abstract: An insert for a rolling cone earth-boring bit has a cylindrical base that interferingly presses into a mating hole formed in a cone of the bit. The insert has a convex end that extends from the base. A polycrystalline diamond cap is bonded to the convex end. The body is formed of at least two layers of carbide material having different mechanical properties, particularly a different modulus of elasticity. The first layer may have a metallic binder with a lesser percentage than the binder of the second layer to reduces the stress at the interface between the first layer and the diamond cap. The layers may have different average carbide average grain sizes, with finer average grain sizes adjoining the diamond cap. Further, the layers may have different binders, with cobalt being the binder in the layer adjoining the diamond cap and either nickel or a nickel-cobalt alloy in another layer.

Abstract: An earth-boring device such as a drill bit is disclosed. The earth boring device includes a rotary main cutting structure, an insert on the main cutting structure. The insert is formed of a composition having tungsten carbide and cobalt. The cobalt makes up less than approximately 9% by weight of the composition. The composition has a Rockwell A hardness greater than approximately an Hmin as determined by the following formula: Hmin=91.1−0.63X, where X represents a cobalt content by weight of the composition.

Abstract: A rock drilling bit for drilling bores in rock, more particularly to a percussion rock drilling bit. Specifically, a rock drilling bit having hard material cutting inserts affixed to an austempered ductile iron (ADI) drill body, and a method of drilling rock using said bit.

Abstract: An earth boring bit is shown of the type used to drill subterranean formations. The bit body has an upper extent which is threaded for connection in a drill string extending to the earth's surface. A lower extent of the bit body has a number of cutting elements mounted thereon which engage an earthen formation and cut the formation. At least selected ones of the cutting elements incorporate a nanocrystalline diamond material.

Abstract: A polycrystalline diamond cutter having a coating of refractory material applied to the polycrystalline diamond surface increases the operational life of the cutter. The coating typically has a thickness in the range of from 0.1 to 30 .mu.m and may be made from titanium nitride, titanium carbide, titanium carbonitride, titanium aluminum carbonitride, titanium aluminum nitride, boron carbide, zirconium carbide, chromium carbide, chromium nitride, or any of the transition metals or Group IV metals combined with either silicon, aluminum, boron, carbon, nitrogen or oxygen. The coating can be applied using conventional plating or other physical or chemical deposition techniques.

Abstract: A cutting element suitable for incorporation in a drill bit used for earth drilling is disclosed which comprises an abrasive layer of superhard material formed on a substrate support, the substrate and/or the abrasive layer being structurally modified to reduce and/or redistribute detrimental tensile stresses which occur at the periphery of the abrasive layer and at or near the interface between the abrasive layer and the substrate, and within the body of the substrate. The modified cutting element structure reduces the occurrence of fracturing and cutter degradation.

Abstract: A method of forming a cutter assembly for a rotary drill bit comprises locating in a mould a preform polycrystalline diamond cutting element of a non-thermally stable type, packing powdered matrix-forming material, such as powdered tungsten carbide, around at least part of the cutting element within the mould, and then infiltrating the powdered material with a metal alloy in a furnace to form a body of solid infiltrated matrix in which the cutting element is at least partly embedded. The metal alloy is selected to provide an infiltration temperature, for example of up to about 850.degree., which is not greater than the temperature at which significant thermal degradation of the cutting element would occur.

Abstract: A well pipe perforating gun (10) is improved by the utilization of a pulverable support structure (14) to hold the explosive shaped charges (18a, 18b, etc.) and the fireset (20). When the gun (10) is fired, the support structure (14) disintegrates substantially into fragments too small to obstruct the flow of oil or natural gas from a surrounding earth formation into or through the well pipe (12) within which the gun is disposed. Optionally, the support structure (14) is assembled from a number of segments (14a, 14b, etc.) linked together in sequential fashion.

Abstract: The present invention relates to a rock bit insert of cemented carbide for cutting rock drilling. The insert is provided with one or more bodies or layers of diamond or cBN produced at high pressure and high temperature in the diamond or cBN stable area.The body of cemented carbide has a multi-structure containing eta-phase surrounded by a surface zone of cemented carbide free of eta-phase and having a low content of cobalt in the surface and a higher content of cobalt next to the eta-phase zone.