Methods of attaching a polycrystalline diamond compact to a substrate

1. A method of attaching a polycrystalline diamond compact element to a substrate, the method comprising:

positioning a polycrystalline diamond compact element adjacent a substrate;

maintaining a gap between the polycrystalline diamond compact element and the substrate; and

at least substantially filling the gap with an adhesion material using at least one of a chemical vapor deposition process, a plasma deposition process, a plasma-enhanced chemical vapor deposition process, a plasma arc deposition process, and a physical vapor deposition process.

2. The method of claim 1 , further comprising forming the substrate to include a particulate carbide material and a metal matrix material.

3. The method of claim 1 , wherein at least substantially filling the gap comprises subjecting the polycrystalline diamond compact element and the substrate adjacent thereto to a chemical vapor deposition process.

4. The method of claim 3 , wherein subjecting the polycrystalline diamond compact element and the substrate adjacent thereto to a chemical vapor deposition process comprises subjecting the polycrystalline diamond compact element and the substrate adjacent thereto to a chemical vapor deposition process operating at a temperature of less than about 600° C.

5. The method of claim 4 , wherein subjecting the polycrystalline diamond compact element and the substrate adjacent thereto to a chemical vapor deposition process operating at a temperature of less than about 600° C. comprises placing the polycrystalline diamond compact and the substrate adjacent thereto in a plasma-enhanced chemical vapor deposition chamber and operating the plasma-enhanced chemical vapor deposition chamber with a maximum temperature of less than about 150° C.

6. The method of claim 1 , wherein at least substantially filing the gap with an adhesion material comprises at least substantially filling the gap with at least one of a diamond material, a diamond-like carbon material, a cubic boron nitride material, a carbide material, and a nitride material.

7. The method of claim 1 , further comprising masking surfaces of the polycrystalline diamond compact element and of the substrate outside the gap to reduce formation of the adhesion material on surfaces outside the gap.

8. The method of claim 7 , wherein masking surfaces comprises positioning an aluminum material over the surfaces.

9. The method of claim 1 , further comprising forming the substrate to include at least one of a cemented carbide material and a portion of a bit body.

10. The method of claim 1 , further comprising forming the polycrystalline diamond compact element to include a silicon catalyst.

11. The method of claim 1 , further comprising maintaining a distance between the polycrystalline diamond compact element and the substrate to be smaller in a central region of the gap than in an outer region of the gap.

12. The method of claim 1 , wherein positioning a polycrystalline diamond compact element adjacent a substrate comprises touching a surface or point of the substrate with a surface or point of the polycrystalline diamond compact element.

13. The method of claim 1 , wherein at least substantially filling the gap with an adhesion material comprises forming the adhesion material on a surface of the polycrystalline diamond compact facing the gap.

14. The method of claim 1 , further comprising providing through holes in at least one of the polycrystalline diamond compact and the substrate and at least partially filling the through holes with the adhesion material.

15. A method of forming a cutting element for an earth-boring tool, the method comprising:

forming a polycrystalline diamond compact element by sintering and bonding diamond crystals together;

forming a substrate comprising a particulate carbide material and a matrix material;

positioning the polycrystalline diamond compact element adjacent the substrate leaving a gap between at least portions of the polycrystalline diamond compact element and the substrate;

masking surfaces of the polycrystalline diamond compact element and surfaces of the substrate that do not face the gap; and

forming an adhesion material on a surface of the polycrystalline diamond compact and on a surface of the substrate that face the gap to at least substantially fill the gap with the adhesion material.

16. The method of claim 15 , wherein forming an adhesion material comprises forming the adhesion material by at least one of growing and depositing the adhesion material with a low temperature deposition process.

17. The method of claim 16 , wherein forming the adhesion material by at least one of growing and depositing the adhesion material with a low temperature deposition process comprises forming the adhesion material by at least one of growing and depositing the adhesion material with a deposition process at a maximum temperature of less than about 600° C.

18. The method of claim 15 , further comprising:

forming another polycrystalline diamond compact element;

positioning the another polycrystalline diamond compact element adjacent the polycrystalline diamond compact element; and

forming another adhesion material between the another polycrystalline diamond compact element and the polycrystalline diamond compact element by at least one of growing and depositing the another adhesion material with a low temperature deposition process.

19. The method of claim 15 , wherein forming an adhesion material comprises forming at least one of a diamond material, a diamond-like carbon material, a cubic boron nitride material, a carbide material, a nitride material, and a catalyst material selected to catalyze formation of inter-granular bonds in diamond material.

20. The method of claim 15 , wherein forming an adhesion material comprises using a deposition process selected from the group consisting of a chemical vapor deposition process, a plasma deposition process, a plasma-enhanced chemical vapor deposition process, a plasma arc deposition process, and a physical vapor deposition process.