Shear cutter with improved wear resistance of WC-CO substrate

1. A cutting element, comprising:

a substrate;

an abrasive layer mounted to the substrate at an interface; and

a longitudinal axis extending through the abrasive layer and the substrate;

wherein the substrate comprises:

a binder material;

a plurality of metal carbide grains bonded together by an amount of the binder material;

an upper region extending from the interface to a depth of the substrate, wherein the amount of binder material decreases along at least one direction of the longitudinal axis to form a first binder gradient; and

a lower region extending from the upper region toward the bottom of the substrate, wherein the lower region comprises a radial binder gradient and a constant binder concentration along the longitudinal axis.

2. The cutting element of claim 1 , wherein the amount of binder material in the lower region decreases from a second depth below an outer surface of the substrate to the outer surface of the substrate to form the radial binder gradient.

3. The cutting element of claim 2 , wherein the second depth ranges from 1 to 3 mm.

4. The cutting element of claim 1 , wherein the amount of binder material in the lower region decreases from the longitudinal axis to an outer surface of the substrate to form the radial binder gradient.

5. The cutting element of claim 4 , wherein the lower region extends the from the upper region to the bottom of the substrate.

6. The cutting element of claim 1 , wherein the upper region of the substrate comprises a substantially uniform amount of binder material from the longitudinal axis to the outer surface of the substrate.

7. The cutting element of claim 1 , wherein the amount of binder material in the upper region decreases from the first depth of the substrate to the interface to form an axial binder gradient.

8. The cutting element of claim 1 , wherein the abrasive layer is selected from the group consisting of polycrystalline diamond and thermally stable polycrystalline diamond.

9. The cutting element of claim 1 , wherein the total amount of binder material throughout the substrate comprises 12% to 14% by weight of the substrate.

10. The cutting element of claim 1 , wherein the total amount of binder material throughout the substrate comprises less than 12% by weight of the substrate.

11. The cutting element of claim 1 , wherein the abrasive layer is brazed to the substrate.

12. A shear cutter drill bit, comprising:

a bit body comprising a cutting end;

a plurality of blades extending outwardly from the bit body;

a plurality of shear cutters disposed along the length of each blade, wherein at least one shear cutter comprises:

a substrate;

an abrasive layer mounted to the substrate at an interface; and

a longitudinal axis extending through the abrasive layer and the substrate;

wherein the substrate comprises:

a binder material; and

a plurality of metal carbide grains bonded together by an amount of the binder material;

an upper region extending from the interface to a depth of the substrate, wherein the amount of binder material decreases along at least one direction of the longitudinal axis to form a first binder gradient; and

a lower region extending from the upper region toward the bottom of the substrate, wherein the lower region comprises a radial binder gradient and a constant binder concentration along the longitudinal axis.

13. The drill bit of claim 12 , wherein the amount of binder material in the lower region decreases from a second depth from an outer surface of the substrate to the outer surface of the substrate to form the radial binder gradient.

14. The drill bit of claim 13 , wherein the second depth ranges from 1 to 3 mm.

15. The drill bit of claim 12 , wherein the amount of binder material in the lower region decreases from the longitudinal axis to an outer surface of the substrate to form the radial binder gradient.

16. The drill bit of claim 15 , wherein the radial binder gradient extends from a bottom of the substrate to the upper region of the substrate.

17. The drill bit of claim 12 , wherein the upper region of the substrate comprises a substantially uniform amount of binder material from the longitudinal axis to the outer surface of the substrate.

18. The drill bit of claim 12 , wherein the amount of binder material in the upper region decreases from the depth of the substrate to the interface to form an axial binder gradient.

19. The drill bit of claim 12 , wherein the total amount of binder material throughout the substrate comprises 12% to 14% by weight of the substrate.

20. The drill bit of claim 12 , wherein the total amount of binder material throughout the substrate comprises less than 12% by weight of the substrate.

21. The drill bit of claim 12 , wherein the abrasive layer is brazed to an interface surface of the substrate.

22. A cutting element, comprising:

a substrate; and

an abrasive layer brazed to the substrate at an interface;

wherein the substrate comprises:

a binder material;

a plurality of metal carbide grains bonded together by an amount of the binder material;

a first binder gradient formed at the interface to a first depth; and

a lower region extending from the first depth to a bottom surface of the substrate, wherein the lower region comprises a radial binder gradient and a constant binder concentration along a longitudinal axis of the cutting element.

23. The cutting element of claim 22 , wherein the amount of binder material at the interface is less than the total amount of binder material throughout the substrate.

24. The cutting element of claim 22 , wherein the amount of binder material at the interface is larger than the total amount of binder material throughout the substrate.

25. The cutting element of claim 22 , wherein the amount of binder material in the lower region increases from an outer surface of the substrate to a depth from the outer surface of the substrate.