Diamond-coated substrates

Patent metadata

Field	Value
Publication number	US-9487856-B2
Application number	US-201314416388-A
Country	US
Kind code	B2
Filing date	Jul 22, 2013
Priority date	Jul 22, 2012
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A composite structure, comprising a cemented carbide substrate (e.g., tungsten carbide substrate cemented with cobalt, such as WC—Co), a thin interlayer disposed over the substrate, and a contiguous diamond film disposed over the interlayer, as well as processes of preparing such a composite structure and uses thereof, are provided. The composite structure is characterized by at least one of a substrate binder concentration of at least 2 percents by weight, interlayer thickness less than 20 microns, a homogenous interlayer made substantially of crystalline chromium nitride, a low to null binder concentration in the interlayer, and a high co-adhesion of the diamond film to the interlayer and the interlayer to the substrate.

First claim

What is claimed is:

1. A composite structure, comprising a cemented carbide substrate, an interlayer disposed over said substrate and a contiguous diamond film disposed over said interlayer, wherein said cemented carbide substrate comprises a binder, and said interlayer comprises crystalline chromium nitride, the composite structure being characterized by at least one of:
a thickness of said interlayer which is lower than 20 microns;
a concentration of said binder in said interlayer which is lower than 0.5 percent by weight;
a concentration of amorphous carbon in said interlayer which is lower than 0.5 percent by weight; and
a co-adhesion of said diamond film to said interlayer and of said interlayer to said substrate, which is exhibited by a microhardness test at a load of at least 20 kg.

2. The composite structure of claim 1 , being characterized by exhibiting at least three of the peaks of an X-Ray diffraction pattern selected from the group consisting of the X-Ray diffraction patterns as presented in FIG. 36C , FIG. 37C , FIG. 38C , FIG. 39C , FIG. 40C , FIG. 41C , FIG. 42C and FIG. 43C .

3. The composite structure of claim 1 , wherein a concentration of said binder in said substrate is at least 2 percents by weight.

4. The composite structure of claim 1 , wherein a concentration of said binder in said cemented carbide substrate near an interface with said interlayer is substantially the same as a concentration of said binder in deeper regions of said cemented carbide substrate.

5. The composite structure of claim 1 , wherein a chemical composition of said interlayer is substantially homogenous with respect to a perpendicular axis of said interlayer.

6. The composite structure of claim 1 , wherein a ratio of chromium to nitrogen in said interlayer ranges from 0.90 to 1.50.

7. The composite structure of claim 1 , wherein said cemented carbide substrate comprises tungsten carbide and said binder.

8. The composite structure of claim 7 , wherein said binder comprises cobalt.

9. The composite structure of claim 8 , being characterized by a secondary ion mass spectrogram (SIMS) exhibiting at least one of:
a concentration of carbon;
a concentration of chromium nitride;
a concentration of cobalt; and
a concentration of tungsten
as determined by a SIMS spectrum selected from the group consisting of the SIMS spectra as presented in FIG. 34D and FIG. 34E .

10. The composite of claim 9 , being characterized by a secondary ion mass spectrogram (SIMS) exhibiting at least three of:
a concentration of carbon;
a concentration of chromium nitride;
a concentration of cobalt; and
a concentration of tungsten
as determined by a SIMS spectrum selected from the group consisting of the SIMS spectra as presented in FIG. 34D and FIG. 34E .

11. The composite of claim 9 , being characterized by a secondary ion mass spectrogram (SIMS) exhibiting any of:
a concentration of carbon;
a concentration of chromium nitride;
a concentration of cobalt; and
a concentration of tungsten
as determined by a SIMS spectrum selected from the group consisting of the SIMS spectra as presented in FIG. 34D and FIG. 34E .

12. The composite of claim 1 , wherein a thickness of said interlayer is lower than 10 microns.

13. The composite of claim 1 , comprising a single interlayer between said substrate and said diamond film.

14. An article of manufacture comprising the composite structure of claim 1 .

15. A process of preparing a composite structure which comprises a cemented carbide substrate, an interlayer disposed over said substrate and a contiguous diamond film disposed over said interlayer, wherein said cemented carbide substrate comprises a binder, and said interlayer comprises crystalline chromium nitride, the process comprising:
depositing a layer of metallic chromium having a thickness lower than 20 microns onto a surface of said cemented carbide substrate, to thereby form a cemented carbide substrate having a layer of metallic chromium deposited onto its surface;
nitiridizing said layer of metallic chromium by exposing said cemented carbide substrate having said layer of metallic chromium deposited onto its surface to gaseous ammonia, at a temperature of at least 700° C., to thereby form said cemented carbide substrate having a layer of chromium nitride deposited on its surface; and
depositing said contiguous diamond film onto said layer of chromium nitride, thereby preparing the composite structure.

16. The process of claim 15 , wherein depositing said layer of metallic chromium is effected by a physical vapor deposition method selected from the group consisting of sputter deposition, magnetron sputtering and cathodic arc.

17. The process of claim 15 , wherein said exposing to ammonia comprises exposing said cemented carbide substrate having said layer of metallic chromium deposited onto its surface to ammonia at a flow ranging from 200 sccm to 500 sccm.

18. The process of claim 15 , wherein said exposing to ammonia comprises exposing said cemented carbide substrate having said layer of metallic chromium deposited onto its surface to ammonia at a pressure that ranges from 100 to 300 Torr.

19. The process of claim 15 , wherein said exposing to ammonia comprises exposing said cemented carbide substrate having said layer of metallic chromium deposited onto its surface to ammonia at a temperature that ranges from 600° C. to 1000° C.

20. The process of claim 15 , wherein said exposing to ammonia is effected for a time period that ranges from 30 minutes to 90 minutes.

21. The process of claim 20 , wherein said exposing to ammonia is effected for a time period of 60 minutes.

22. The process of claim 15 , further comprising, prior to said depositing said contiguous diamond film onto said layer of chromium nitride,
carbidizing said layer of chromium nitride.

23. The process of claim 22 , wherein said carbidizing said layer of chromium nitride comprises:
heating said cemented carbide substrate having a layer of chromium nitride deposited on its surface to a temperature that ranges from 500° C. to 800° C.;
exposing said substrate to a thermally activated gas mixture of methane and hydrogen at a volume ratio that ranges from 1:90 to 1:99 for a time period that ranges from 10 minutes to 20 minutes.

24. The process of claim 15 , further comprising, prior to depositing said diamond film, seeding said layer of chromium nitride with diamond particles by contacting said layer of chromium nitride with an abrasive slurry that comprises said diamond particles.

25. The process of claim 15 , wherein depositing said contiguous diamond film onto said layer of chromium nitride comprises:
heating said cemented carbide substrate having said layer of chromium nitride deposited on its surface to a temperature that ranges from 500° C. to 800° C.; and
exposing said substrate to a thermally activated gas mixture of methane and hydrogen at a volume ratio that ranges from 1:90 to 1:99.

26. The process of claim 15 , wherein said cemented carbide substrate comprises tungsten carbide and a binder.

27. The process of claim 26 , wherein said binder comprises cobalt.

28. A composite structure prepared by the process of claim 15 .

29. An article of manufacture comprising the composite structure of claim 28 .

Assignees

• Technion Res & Dev Foundation

Inventors

• Hoffman Alon

Classifications

• C23C16/271

  using hot filaments · CPC title

• C23C16/0272 Primary

  Deposition of sub-layers, e.g. to promote the adhesion of the main coating · CPC title

• C23C8/24

  Nitriding · CPC title

• Y10T428/265

  1 mil or less · CPC title

• C23C14/025 Primary

  Metallic sublayers · CPC title