Carbon-containing hard coating and a method for depositing a hard coating onto a substrate

1. A carbon-containing hard coating comprising nano-crystalline grains separated from each other by grain boundaries, said hard coating comprising aluminum, at least one additional metal (Me1, Me2), carbon and at least one further element (E1, E2) and having the chemical composition:

(Al x Me1 y Me2 z )C u E1 v E2 w

wherein Me1 is a metal and Me2 is a metal and

with x>0.4 and x+y+z=1 and y,z≧0 and

with 1>u>0 and u+v+w=1 and v,w≧0

characterized in that the grain boundaries have a higher concentration of carbon atoms than the nano-crystalline-grains.

2. A hard coating according to claim 1 , wherein the full width at half maximum (FWHM) of the carbon Raman-lines (G, D) between 1700 cm −1 and 1000 cm −1 is less than 150 cm −1 .

3. A hard coating according to claim 1 , wherein the hard coating includes a metal carbo-oxide wherein E1 is oxygen and v>0.

4. A hard coating according to claim 1 , wherein the hard coating includes a metal carbo-nitride wherein E2 is nitrogen and w>0.

5. A hard coating according to claim 1 , wherein E1 and/or E2 is an element of the 6 th or 7 th main-group of the periodic table of the elements.

6. A hard coating according to claim 1 , wherein Me1 and/or Me2 is lithium and/or beryllium and/or an element of the 3 rd or 4 th main-group of the periodic table of the elements.

7. A hard coating according to claim 1 , wherein Me1 and/or Me2 is a transition metal.

8. A hard coating according to claim 1 , wherein the nano-crystalline grains have a cubic structure.

9. A hard coating according to claim 1 , wherein the nano-crystalline grains have a hexagonal structure.

10. A hard coating according to claim 1 , wherein the grain boundaries are substantially of highly disordered structure.

11. A hard coating according to claim 1 , wherein a characteristic diameter of the nano-crystalline grains is greater than 1 nm and less than 50 nm.

12. A hard coating according to claim 1 , having a multi-layer structure including at least 2 layers and at the most 2000 layers.

13. A hard coating according to claim 8 , wherein the thickness of each layer is at least 2 nm and at the most 2000 nm.

14. A hard coating according to claim 1 , having a multi-layer structure including an A-layer (A) and a B-layer (B) wherein the A-layer (A) has a lower atomic concentration of carbon (C) than the B-layer (B).

15. A hard coating according to claim 10 , wherein the B-layer has a multi-layer structure including a C-layer (BC) and a D-layer (BD) wherein the C-layer (BC) has a lower atomic concentration of carbon (C) than the D-layer (BD).

16. A hard coating according to claim 11 , wherein the thickness of the C-layer (BC) and the D-layer (BD) is at least 2 nm and at the most 100 nm.

17. A hard coating according to claim 1 , having at least one layer and one amorphous-like top layer (T) with a higher atomic concentration of carbon (C) than said one layer.

18. A hard coating according to claim 1 , wherein the full width at half maximum of the (200) x-ray diffraction peak caused by an (200)-plane is at least 1° and at the most 4° at 2θ.

19. A hard coating according to claim 1 , wherein an (200)-intensity (I[200]) of an (200)-peak caused by an (200)-plane, and an (111)-Intensity (I[111]) of the (111)-peak caused by an (111) plane, have a intensity-ratio (I[200]/I[111]) of at least 1 and at the most of 15.

20. A method for depositing a hard coating (1) according to claim 1 , wherein said method is a physical vapor-deposition technique.

21. A method for depositing a hard coating (1) according to claim 20 , wherein the hard coating (1) is sputtered onto a substrate (S) by using a carbon-containing sputter-target.

22. A method for depositing a hard coating (1) according to claim 20 , wherein the hard coating (1) is deposited onto the substrate (S) by using an arc-plasma-deposition technique.

23. A method for depositing a hard coating (1) according to claim 20 , wherein the hard coating (1) is deposited onto the substrate (S) by using an electron-beam-evaporation technique.

24. A method for depositing a hard coating (1) according to claim 20 , wherein the hard coating (1) is deposited onto the substrate (S) by a chemical-vapor-deposition technique.

25. A method for depositing a hard coating (1) according to claim 20 , wherein the hard coating (1) is deposited onto the substrate (S) by a plasma-enhanced-chemical-vapor-deposition technique.

26. A method for depositing a hard coating (1) according to claim 20 , wherein the atomic concentration of carbon (C) in the hard coating (1) is controlled by varying the flow rate of an oxygen (O) and/or carbon (C) containing gas in the course of the coating process.

27. A hard coating according to claim 2 , wherein the full width at half maximum (FWHM) of the carbon Raman-lines (G, D) between 1700 cm −1 and 1000 cm −1 is less than 100 cm −1 .

28. A hard coating according to claim 5 , wherein E1 and/or E2 is sulphur and/or fluorine and/or chlorine.

29. A hard coating according to claim 6 , wherein Me1 and/or Me2 is boron and/or silicon, or a lanthanide.

30. A hard coating according to claim 7 , wherein Me1 and/or Me2 is iron and/or copper and/or chromium and/or manganese and/or scandium and/or yttrium and/or lanthanum and/or molybdenum and/or tungsten and/or titanium and/or tantalum and/or niobium and/or vanadium and/or zirconium and/or hafnium.

31. A hard coating according to claim 9 , wherein the nano-crystalline grains have a minor-hexagonal structure.

32. A hard coating according to claim 11 , wherein a characteristic diameter of the nano-crystalline grains is greater than 2 nm and less than 10 nm.

33. A hard coating according to claim 18 , wherein the full width at half Maximum of the (200) x-ray diffraction peak caused by an (200)-plane is at least 1.2° and at the most 1.9° at 2θ.

34. A hard coating according to claim 11 , wherein a characteristic diameter of the nano-crystalline grains is greater than 2 nm and less than 10 nm.