Chemically strengthened bond between thermally stable polycrystalline hard materials and braze material

1. A method of making a drill bit cutter, comprising:

forming, by chemical vapor deposition, a bonding layer on a bonding surface of a polycrystalline material body that comprises a hard material, the bonding surface opposing a contact surface of the polycrystalline material body, and the bonding layer substantially formed by the chemical vapor deposition to have a [111] crystal structure of the hard material, a [100] crystal structure of the hard material, or a combination thereof; and

brazing the bonding layer to a hard composite using a braze material to make the drill bit cutter.

2. The method of claim 1 further comprising:

forming the bonding layer to have a thickness of 10 microns to 250 microns at the bonding surface.

3. The method of claim 1 further comprising:

masking the bonding surface of the polycrystalline material body before forming the bonding layer; and

removing the mask after forming the bonding layer and before brazing the bonding layer to the hard composite.

4. The method of claim 1 , wherein the hard material is diamond, the bonding layer is substantially formed by the [111] crystal structure of the diamond, and forming the bonding layer involves:

treating the bonding surface with a hydrogen plasma in the presence of oxygen and a carbon-containing gas at 600° C. to 1100° C. at a total pressure 30 torr or greater and a gas composition of 200 parts to 250 parts hydrogen, 0.5 parts to 3 parts oxygen, and 3 parts to 8 parts carbon-containing gas.

5. The method of claim 1 , wherein the hard material is diamond, the bonding layer is substantially formed by the [100] crystal structure of the diamond, and forming the bonding layer involves:

treating the bonding surface with a hydrogen plasma in the presence of oxygen and a carbon-containing gas at 600° C. to 1100° C. at a total pressure less than 30 torr and a gas composition of 200 parts to 250 parts hydrogen, 0.5 parts to 3 parts oxygen, and 3 parts to 8 parts carbon-containing gas.

6. The method of claim 1 , wherein the hard material is cubic boron nitride.

7. A drilling assembly comprising:

a drill string extendable from a drilling platform and into a wellbore;

a pump fluidly connected to the drill string and configured to circulate a drilling fluid into the drill string and through the wellbore; and

a drill bit attached to an end of the drill string, the drill bit having a matrix bit body and a plurality of cutting cutters according to claim 6 coupled to an exterior portion of the matrix bit body.

8. The method of claim 1 , wherein the hard material is silicon carbide.

9. A method of making a drill bit cutter, comprising:

depositing a refractory nitride layer on a bonding surface of a polycrystalline material body that comprises a hard material, the bonding surface opposing a contact surface of the polycrystalline material body;

forming, by chemical vapor deposition, a bonding layer on the refractory nitride layer, the bonding layer substantially formed by the chemical vapor deposition to have a [111] crystal structure of the hard material, a [100] crystal structure of the hard material, or a combination thereof; and

brazing the bonding layer to a hard composite using a braze material to make the drill bit cutter.

10. The method of claim 9 further comprising:

forming the bonding layer to have a thickness of 10 microns to 250 microns at the bonding surface.

11. The method of claim 9 further comprising:

masking the refractory nitride layer before forming the bonding layer; and

removing the mask after forming the bonding layer and before brazing the bonding layer to the hard composite.

12. The method of claim 9 , wherein the hard material is diamond, the bonding layer is substantially formed by the [111] crystal structure of the diamond, and forming the bonding layer involves:

treating the refractory nitride layer with a hydrogen plasma in the presence of oxygen and a carbon-containing gas at 600° C. to 1100° C. at a total pressure 30 torr or greater and a gas composition of 200 parts to 250 parts hydrogen, 0.5 parts to 3 parts oxygen, and 3 parts to 8 parts carbon-containing gas.

13. The method of claim 9 , wherein the hard material is diamond, the bonding layer is substantially formed by the [100] crystal structure of the diamond, and forming the bonding layer involves:

treating the refractory nitride layer with a hydrogen plasma in the presence of oxygen and a carbon-containing gas at 600° C. to 1100° C. at a total pressure less than 30 torr and a gas composition of 200 parts to 250 parts hydrogen, 0.5 parts to 3 parts oxygen, and 3 parts to 8 parts carbon-containing gas.

14. The method of claim 9 , wherein the hard material is cubic boron nitride.

15. The method of claim 9 , wherein the hard material is silicon carbide.