Polycrystalline compacts including nanoparticulate inclusions, cutting elements and earth-boring tools including such compacts, and methods of forming same
View Patent ↗A polycrystalline compact comprises a plurality of grains of hard material and a plurality of nanoparticles disposed in interstitial spaces between the plurality of grains of hard material. The nanoparticles have cores of a first material and at least one oxide material on the cores. An earth-boring tool comprises such a polycrystalline compact. A method of forming a polycrystalline compact comprises combining a plurality of hard particles with a plurality of nanoparticles to form a mixture and sintering the mixture to form a polycrystalline hard material comprising a plurality of interbonded grains of hard material. A method of forming a cutting element comprises infiltrating interstitial spaces between interbonded grains of hard material in a polycrystalline material with a plurality of nanoparticles.
1. A polycrystalline compact, comprising:
a plurality of grains of hard material; and
a plurality of nanoparticles disposed in interstitial spaces between the plurality of grains of hard material, wherein each nanoparticle of the plurality comprises:
a core comprising a first material; and
at least one oxide material on the core, the at least one oxide material different from the first material.
2. The polycrystalline compact of claim 1 , wherein the plurality of grains of hard material comprises a plurality of grains of diamond.
3. The polycrystalline compact of claim 1 , wherein the grains of hard material exhibit a first thermal conductivity at 23° C. and the nanoparticles exhibit a second thermal conductivity at 23° C., and wherein the second thermal conductivity is less than about 50 Wm −1 K −1 .
4. The polycrystalline compact of claim 1 , further comprising a catalyst material in the interstitial spaces between the plurality of grains of hard material.
5. The polycrystalline compact of claim 1 , wherein the grains of hard material exhibit a first thermal conductivity at 23° C. and the nanoparticles exhibit a second thermal conductivity at 23° C., wherein the second thermal conductivity is less than about 0.2 times the first thermal conductivity.
6. The polycrystalline compact of claim 1 , wherein the core comprises at least two particles.
7. The polycrystalline compact of claim 1 , wherein the core comprises tungsten carbide and the at least one oxide material on the core comprises alumina.
8. The polycrystalline compact of claim 5 , wherein the at least one oxide material on the core comprises a first oxide material comprising alumina, a second oxide material comprising zirconia, and a third oxide material comprising alumina.
9. The polycrystalline compact of claim 1 , wherein the plurality of nanoparticles occupies from about 0.01% to about 50% by volume of the polycrystalline compact.
10. The polycrystalline compact of claim 1 , further comprising a substrate bonded to the plurality of grains of hard material.
11. An earth-boring tool comprising the polycrystalline compact of claim 1 .
12. The earth-boring tool of claim 11 , wherein the earth-boring tool is a fixed-cutter rotary drill bit.
13. A method of forming a polycrystalline compact, comprising:
combining a plurality of hard particles with a plurality of nanoparticles to form a mixture, each nanoparticle of the plurality of nanoparticles comprising:
a core comprising a first material and;
at least one oxide material on the core, the at least one oxide material different from the first material; and
sintering the mixture to form a polycrystalline hard material comprising a plurality of interbonded grains of hard material.
14. The method of claim 13 , wherein combining a plurality of hard particles with a plurality of nanoparticles to form a mixture comprises combining a plurality of diamond particles with a plurality of nanoparticles to form the mixture.
15. The method of claim 13 , wherein combining a plurality of hard particles with a plurality of nanoparticles to form a mixture comprises combining a plurality of hard particles exhibiting a first thermal conductivity at 23° C. with nanoparticles exhibiting a second thermal conductivity at 23° C., wherein the second thermal conductivity is less than about 0.2 times the first thermal conductivity.
16. The method of claim 15 , wherein combining a plurality of hard particles having a first thermal conductivity at 23° C. with a plurality of nanoparticles having a second thermal conductivity at 23° C. to form a mixture comprises combining a plurality of hard particles with nanoparticles comprising a material having a thermal conductivity less than about 50 Wm −1 K −1 .
17. The method of claim 13 , further comprising adding a catalyst to the mixture, the catalyst selected to promote formation of inter-granular bonds between the grains of hard material.
18. A method of forming a cutting element comprising a polycrystalline compact, the method comprising infiltrating interstitial spaces between interbonded grains of hard material in a polycrystalline material with a plurality of nanoparticles, each nanoparticle of the plurality of nanoparticles comprising:
a core comprising a first material and;
at least one oxide material on the core, the at least one oxide material different from the first material.
19. The method of claim 18 , wherein infiltrating interstitial spaces between interbonded grains of hard material in a polycrystalline material with a plurality of nanoparticles comprises infiltrating interstitial spaces between interbonded diamond grains with a plurality of nanoparticles.
20. The method of claim 18 , wherein infiltrating interstitial spaces between interbonded grains of hard material in a polycrystalline material with a plurality of nanoparticles comprises infiltrating interstitial spaces between interbonded grains of hard material in a polycrystalline material with a material having a thermal conductivity of less than about 50 Wm −1 K −1 .