Abstract: A welding rod for use in applying hardfacing to a surface of a tool includes an elongated, generally cylindrical body including a metal matrix material. The welding rod also includes particles of polycrystalline diamond material carried by the elongated, generally cylindrical body. The particles of polycrystalline diamond material include a plurality of inter-bonded diamond grains.

Abstract: Rotary drag bits comprise a body comprising a face at a leading end of the body. An abrasive-impregnated cutting structure is located at the face of the bit body. The abrasive-impregnated cutting structure comprises abrasive particles dispersed within a matrix material. The abrasive-impregnated cutting structure exhibits an anisotropic wear resistance. The wear resistance varies at least substantially continuously within the abrasive-impregnated cutting structure.

Abstract: A polycrystalline diamond compact comprising a diamond table is formed in a high-pressure, high-temperature process using a catalyst, the catalyst being substantially removed from the entirety of the diamond table, and the diamond table attached to a supporting substrate in a subsequent high-pressure, high-temperature process using a binder material differing at least in part from a material of the catalyst. The binder material is permitted to penetrate substantially completely throughout the diamond table from an interface with the substrate to and including a cutting surface, and the binder material is selectively removed from a region or regions of the diamond table by a conventional technique (e.g., acid leaching). Cutting elements so formed and drill bits equipped with such cutting elements are also disclosed.

Abstract: A method of forming an instrumented cutting element comprises forming a free standing sintered diamond table having at least one chamber in the free standing sintered diamond table, providing a doped diamond material within the at least one chamber, and attaching a substrate to the free standing sintered diamond table to form an instrumented cutting element. The instrumented cutting element includes the doped diamond material disposed within the sintered diamond table on the substrate. A method of forming an earth-boring tool comprises attaching at least one instrumented cutting element to a body of an earth-boring tool. The at least one instrumented cutting element has a diamond table bonded to a substrate. The diamond table has at least one sensing element disposed at least partially within the diamond table. The at least one sensing element comprises a doped diamond material.

Abstract: A cutting element for an earth-boring drill bit may include a thermally stable cutting table comprising a polycrystalline diamond material. The polycrystalline diamond material may consist essentially of a matrix of diamond particles bonded to one another and a silicon, silicon carbide, or silicon and silicon carbide material located within interstitial spaces among interbonded diamond particles of the matrix of diamond particles. The cutting table may be at least substantially free of Group VIII metal or alloy catalyst material. The cutting element may further include a substrate and an adhesion material between and bonded to the cutting table and the substrate. The adhesion material may include diamond particles bonded to one another and to the cutting table and the substrate after formation of the preformed cutting table.

Abstract: Methods of forming composite particles include forming a source material over a plurality of nucleation cores and forming a catalyst material over the source material. Compositions of matter include a plurality of composite particles, each particle of the plurality comprising a plurality of nucleation cores, a source material disposed over the nucleation cores, and a catalyst material disposed over the source material. Methods of forming earth-boring tools include forming a plurality of composite particles, combining the plurality of composite particles with a plurality of grains of hard material, and catalyzing the formation of inter-granular bonds between the composite particles and the grains of hard material to faun a polycrystalline material. The plurality of in situ nucleated grains of hard material and the plurality of grains of hard material may be interspersed and inter-bonded.

Abstract: Polycrystalline compacts include hard polycrystalline materials comprising in situ nucleated smaller grains of hard material interspersed and inter-bonded with larger grains of hard material. The average size of the larger grains may be at least about 250 times greater than the average size of the in situ nucleated smaller grains. Methods of forming polycrystalline compacts include nucleating and catalyzing the formation of smaller grains of hard material in the presence of larger grains of hard material, and catalyzing the formation of inter-granular bonds between the grains of hard material. For example, nucleation particles may be mixed with larger diamond grains, a carbon source, and a catalyst. The mixture may be subjected to high temperature and high pressure to form smaller diamond grains using the nucleation particles, the carbon source, and the catalyst, and to catalyze formation of diamond-to-diamond bonds between the smaller and larger diamond grains.

Abstract: An earth-boring tool having at least one cutting element with a multi-friction cutting face provides for the steering of formation cuttings as the cuttings slide across the cutting face. The multi-friction cutting element includes a diamond table bonded to a substrate of superabrasive material. The diamond table has a cutting face formed thereon with a cutting edge extending along a periphery of the cutting face. The cutting face has a first area having an average surface finish roughness less than an average surface finish roughness of a second area of the cutting face, the two areas separated by a boundary having a proximal end proximate the tool crown and a distal end remote from the tool crown.

Abstract: A cutting element for use with an earth-boring drill bit includes a diamond cutting table that is substantially free of a metallic binder. The cutting table may include polycrystalline diamond and a carbonate binder or polycrystalline diamond with silicon and/or silicon carbide dispersed therethrough. A base of the cutting table is secured to a substrate by way of an adhesion layer. The adhesion layer includes diamond. The adhesion layer may also include cobalt or another suitable binder material, which may be mixed with diamond particles from which the adhesion layer is formed, or may leach from the substrate into the adhesion layer as the cutting element is bonded to the substrate. Alternatively, the cutting table may be formed from and consist essentially of chemical vapor deposited diamond that has been diamond bonded to an underlying polycrystalline diamond compact. Processes may include securing substantially metallic binder-free cutting elements to substrates.

Abstract: A polycrystalline diamond compact comprising a diamond table is formed in a high-pressure, high-temperature process using a catalyst, the catalyst being substantially removed from the entirety of the diamond table, and the diamond table attached to a supporting substrate in a subsequent high-pressure, high-temperature process using a binder material differing at least in part from a material of the catalyst. The binder material is permitted to penetrate substantially completely throughout the diamond table from an interface with the substrate to and including a cutting surface, and the binder material is selectively removed from a region or regions of the diamond table by a conventional technique (e.g., acid leaching). Cutting elements so formed and drill bits equipped with such cutting elements are also disclosed.

Abstract: A cutting element for an earth-boring drilling tool comprises a cutting body having a cutting surface thereon, and a sensor coupled with the cutting surface, the sensor configured to determine resistivity of a contacting formation. An earth-boring drilling tool comprises a bit body and an instrumented cutting element coupled with the bit body. The cutting element includes a cutting body having a cutting surface thereon, and at least one sensor located proximate the cutting surface. The at least one sensor is oriented and configured to determine resistivity of a contacting formation. A method of determining resistivity of a subterranean formation during a drilling operation comprises energizing a sensor of an instrumented cutting element of a drill bit, sensing a return signal flowing on or through the subterranean formation through the instrumented cutting element, and determining a resistivity of the subterranean formation based, at least in part, on the return signal.

Abstract: An earth-boring drilling tool comprises a cutting element. The cutting element comprises a substrate, a diamond table, and at least one sensing element formed from a doped diamond material disposed at least partially within the diamond table. A method for determining an at-bit measurement for an earth-boring drill bit comprises receiving an electrical signal generated within a doped diamond material disposed within a diamond table of a cutting element of the earth-boring drill bit, and correlating the electrical signal with at least one parameter during a drilling operation.

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 faun 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: Cutting elements for earth-boring tools comprise a substrate including at least one material selected from the group consisting of CoCr, CoCrMo, CoCrW, Ti. A polycrystalline superabrasive material may be attached to the substrate. Earth-boring tools comprise a body. At least one cutting element is attached to the body. The cutting element comprises a substrate including at least one material selected from the group consisting of CoCr, CoCrMo, CoCrW, and Ti. A polycrystalline superabrasive material may be attached to the substrate. Methods of forming cutting elements for earth-boring tools comprise disposing a substrate including at least one material selected from the group consisting of CoCr, CoCrMo, CoCrW, and Ti in a container. Particles of superabrasive material may be disposed in the container. The particles of superabrasive material may be sintered with the substrate in the container to form a polycrystalline superabrasive material attached to the substrate.

Abstract: Cutting elements for use in earth-boring applications include a substrate, a transition layer, and a working layer. The transition layer and the working layer comprise a continuous matrix phase and a discontinuous diamond phase dispersed throughout the matrix phase. The concentration of diamond in the working layer is higher than in the transition layer. Earth-boring tools include at least one such cutting element. Methods of making cutting elements and earth-boring tools include mixing diamond crystals with matrix particles to form a mixture. The mixture is formulated in such a manner as to cause the diamond crystals to comprise about 50% or more by volume of the solid matter in the mixture. The mixture is sintered to form a working layer of a cutting element that is at least substantially free of polycrystalline diamond material and that includes the diamond crystals dispersed within a continuous matrix phase formed from the matrix particles.

Abstract: Earth-boring tools include combinations of shearing cutting elements and gouging cutting elements on a blade of the earth-boring tools. In some embodiments, a gouging cutting element may be disposed adjacent to a shearing cutting element on a blade of an earth-boring tool. Methods of forming earth-boring tools include providing such combination of at least one shearing cutting element and at least one gouging cutting element on a blade of an earth-boring tool.

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: Methods for forming cutting elements, methods for forming polycrystalline compacts, and related polycrystalline compacts are disclosed. Grains of a hard material are subjected to a high pressure, high temperature process to form a polycrystalline compact. Inclusion of at least one relatively quick spike in system pressure or temperature during an otherwise plateaued temperature or pressure stage accommodates formation of inter-granular bonds between the grains. The brevity of the peak stage may avoid undesirable grain growth. Embodiments of the methods may also include at least one of oscillating at least one system condition (e.g., pressure, temperature) and subjecting the grains to ultrasonic or mechanical vibrations.

Abstract: Cutting elements for earth-boring tools include one or more recesses and/or one or more protrusions in a cutting face of a volume of superabrasive material. The superabrasive material may be disposed on a substrate. The cutting face may be non-planar. The recesses and/or protrusions may include one or more linear segments. The recesses and/or protrusions may comprise discrete features that are laterally isolated from one another. The recesses and/or protrusions may have a helical configuration. The volume of superabrasive material may comprise a plurality of thin layers, at least two of which may differ in at least one characteristic. Methods of forming cutting elements include the formation of such recesses and/or protrusions in and/or on a cutting face of a volume of superabrasive material. Earth-boring tools include such cutting elements, and methods of forming earth-boring tools include attaching such a cutting element to a tool body.

Abstract: Methods of forming a hardfacing material include subjecting diamond grains to elevated temperatures and pressures to form diamond-to-diamond bonds between the diamond grains and form a PCD material. The PCD material is broken down to form PCD particles that include a plurality of inter-bonded diamond grains.