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.

The present disclosure provides a sintering assembly and a polycrystalline diamond compact (PDC) including a acid-labile leach-enhancing material, a PDC including cavities formed by removal of an acid-labile leach-enhancing material, and a method of forming a leached PDC using an acid-labile leach-enhancing material. The present disclosure further includes drill bits using PDCs formed suing an acid-labile leach-enhancing material.

A superabrasive element includes a substrate and a superabrasive table bonded to the substrate, the superabrasive table including a polished surface having a polished finish, the polished surface extending over at least a central, apical region of the superabrasive table, and an unpolished surface including an unpolished finish, the unpolished surface surrounding a majority of the polished surface. A method of manufacturing a superabrasive element includes providing a superabrasive element having a substrate and a superabrasive table bonded to the substrate and polishing at least a central, apical region of the superabrasive table to form a polished surface, without polishing an unpolished surface of the superabrasive table, the unpolished surface surrounding a majority of the polished surface.

A method of making a polycrystalline diamond compact includes forming a first layer of polycrystalline diamond precursor materials comprising diamond particles and a first concentration of catalyst, forming a second layer of polycrystalline diamond precursor materials comprising diamond particles and a second concentration of catalyst, and placing a layer of an infiltrant material in the proximity of the first or the second layer of polycrystalline diamond precursor materials. The second concentration of catalyst is greater than the first concentration of catalyst. The infiltrant material is a catalyst. The first layer and the second layer are sintered under high-pressure high-temperature conditions in the presence of the infiltrant material to form the polycrystalline diamond compact. At least a portion of the catalyst is leached from the polycrystalline diamond compact.

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.

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.

Earth-boring tools may comprise rotatable cutting elements rotatably connected to protruding journals, which may be at least partially located within inner bores extending through the rotatable cutting elements. A rotationally leading end of one of the protruding journals may not extend beyond a cutting face of its associated rotatable cutting element. Alternatively, a protruding journal may comprise a chip breaker protruding from a cutting face of a rotatable cutting element. Methods of removing an earth formation may include directing cuttings forward, away from a cutting face of a rotatable cutting element when the cuttings reach an inner bore of the rotatable cutting element, and rotating the rotatable cutting element around a protruding journal at least partially located in the inner bore.

Earth-boring tools may comprise rotatable cutting elements rotatably connected to protruding journals, which may be at least partially located within inner bores extending through the rotatable cutting elements. A rotationally leading end of one of the protruding journals may not extend beyond a cutting face of its associated rotatable cutting element. Alternatively, a protruding journal may comprise a chip breaker protruding from a cutting face of a rotatable cutting element. Methods of removing an earth formation may include directing cuttings forward, away from a cutting face of a rotatable cutting element when the cuttings reach an inner bore of the rotatable cutting element, and rotating the rotatable cutting element around a protruding journal at least partially located in the inner bore.

Roller cutters comprise a diamond-bonded body joined to an infiltration substrate. An extension is joined to the substrate and includes first section having a diameter sized the same as the substrate, and an integral second section having a diameter smaller than the substrate. The extension is joined to the substrate during an HPHT process. The first section has a thickness greater than that of the infiltration substrate. The second section has an axial length greater than the combined thickness of the substrate and the first section. The extension has a strength and/or toughness greater than the substrate as a result of its material composition, e.g., the amount of binder phase material and/or the size of hard phase material. The roller cutter is rotatably disposed within a pocket internal cavity, wherein the pocket is attached to a

Roller cutters comprise a diamond-bonded body joined to an infiltration substrate. An extension is joined to the substrate and includes first section having a diameter sized the same as the substrate, and an integral second section having a diameter smaller than the substrate. The extension is joined to the substrate during an HPHT process. The first section has a thickness greater than that of the infiltration substrate. The second section has an axial length greater than the combined thickness of the substrate and the first section. The extension has a strength and/or toughness greater than the substrate as a result of its material composition, e.g., the amount of binder phase material and/or the size of hard phase material. The roller cutter is rotatably disposed within a pocket internal cavity, wherein the pocket is attached to a