Method of fabricating polycrystalline diamond include functionalizing surfaces of diamond nanoparticles with fluorine, combining the functionalized diamond nanoparticles with a polymer to form a mixture, and subjecting the mixture to high pressure and high temperature (HPHT) conditions to form inter-granular bonds between the diamond nanoparticles. A green body includes a plurality of diamond nanoparticles functionalized with fluorine, and a polymer material interspersed with the plurality of diamond nanoparticles. A method of forming cutting element includes functionalizing surfaces of diamond nanoparticles with fluorine, and combining the functionalized diamond nanoparticles with a polymer to form a mixture. The mixture is formed over a body, and the mixture and the body are subjected to HPHT conditions to form inter-granular bonds between the diamond nanoparticles and secure the bonded diamond nanoparticles to the body.

A method for making a carbonate polycrystalline diamond body includes combining a first quantity of diamond with a first quantity of magnesium carbonate to form a first layer for forming a working surface, and combining a second quantity of magnesium carbonate to form a second layer adjacent to the first layer, forming an assembly. The method includes placing a quantity of silicon or aluminum in or adjacent to at least a portion of the assembly and sintering the assembly including the silicon or aluminum at high pressure and high temperature, causing the silicon or aluminum to infiltrate at least one layer of the assembly.

Polycrystalline diamond cutting elements having enhanced thermal stability, drill bits incorporating the same, and methods of making the same are disclosed herein. In one embodiment, a cutting element includes a substrate having a metal carbide and a polycrystalline diamond body bonded to the substrate. The polycrystalline diamond body includes a plurality of diamond grains bonded to adjacent diamond grains by diamond-to-diamond bonds and a plurality of interstitial regions positioned between adjacent diamond grains. At least a portion of the plurality of interstitial regions comprise lead or lead alloy, a catalyst material, metal carbide, or combinations thereof. At least a portion of the plurality of interstitial regions comprise lead or lead alloy that coat portions of the adjacent diamond grains such that the lead or lead alloy reduces contact between the diamond and the catalyst.

Polycrystalline diamond cutting elements having enhanced thermal stability, drill bits incorporating the same, and methods of making the same are disclosed herein. In one embodiment, a cutting element includes a substrate having a metal carbide and a polycrystalline diamond body bonded to the substrate. The polycrystalline diamond body includes a plurality of diamond grains bonded to adjacent diamond grains by diamond-to-diamond bonds and a plurality of interstitial regions positioned between adjacent diamond grains. At least a portion of the plurality of interstitial regions comprise lead or lead alloy, a catalyst material, metal carbide, or combinations thereof. At least a portion of the plurality of interstitial regions comprise lead or lead alloy that coat portions of the adjacent diamond grains such that the lead or lead alloy reduces contact between the diamond and the catalyst.

Polycrystalline diamond constructions comprise a diamond body attached with a substrate during high pressure/high temperature processing, and include a modified reaction zone interposed between the body and substrate that is engineered to minimize or eliminate unwanted back diffusion of carbon from the diamond body into the substrate during the high pressure/high temperature processing.

The rate of leaching of a polycrystalline diamond (PCD) cutting layer for cutting elements or other wear parts is varied by introduction into the PCD of an additive prior to leaching. Selective introduction of the additive into one or more regions of a PCD cutting structure allows controlling leaching rates of selective leaching of parts of the PCD structure, which allows for creating of a boundary between the leached and non-leached regions of a PCD structure to be made so that is not parallel to the surface or surfaces exposed to the leaching solution. The additive is comprised of a material that increases the permeability of the PCD or acceptance of the PCD to the leaching solution, such as a hydrophile.

Embodiments of the invention relate to polycrystalline diamond compacts (PDCs) comprising a polycrystalline diamond (PCD) table including at least a portion having aluminum carbide disposed interstitially between bonded-together diamond grains thereof, and methods of fabricating such PDCs. In an embodiment, a PDC includes a substrate, and a PCD table bonded to the substrate. The PCD table includes a plurality of bonded-together diamond grains defining a plurality of interstitial regions. The PCD table further includes aluminum carbide disposed in at least a portion of the plurality of interstitial regions.

A method of forming polycrystalline diamond includes encapsulating diamond particles, carbon monoxide, and carbon dioxide in a container. The encapsulated diamond particles, carbon monoxide, and carbon dioxide are subjected to a pressure of at least 4.5 GPa and a temperature of at least 1,400 C. to form inter-granular bonds between the diamond particles. A cutting element includes polycrystalline diamond material comprising inter-bonded grains of diamond. The polycrystalline diamond material is substantially free of graphitic carbon and metallic compounds. The polycrystalline diamond material exhibits a density of at least about 3.49 g/cm.sup.3 and a modulus of at least about 1,000 GPa. An earth-boring tool may include such a cutting element secured to a body.

Cutting elements include a substrate, a thermally stable polycrystalline table comprising a superhard material secured to the substrate, and a layer of metal interposed between, and attaching the substrate and the thermally stable polycrystalline table. Methods of forming a cutting element include providing a thermally stable polycrystalline table in a mold, providing a layer of metal on the thermally stable polycrystalline table, distributing a mixture of particles comprising a plurality of hard particles and a plurality of particles comprising a matrix material on the layer of metal, and heating the mold while applying pressure to the mixture of particles to cause the mixture of particles to coalesce and form a substrate and at least partially melt the layer of metal to flow and wet the thermally stable polycrystalline table and the substrate to form an attachment therebetween.

A polycrystalline diamond construction may be made by subjecting diamond grains to a high pressure/high temperature condition in the presence of a catalyst material to form a polycrystalline diamond material comprising a matrix phase of bonded together diamond grains and interstitial regions disposed between the diamond grains including the catalyst material, treating the polycrystalline diamond material to remove the catalyst material therefrom to form a diamond body that is substantially free of the catalyst material, and attaching a substrate to the diamond body with a layer of eruption minimization material having a thickness from about 2 m to 8 m on at least one attachment interface surface of the substrate and/or diamond body.