Multilayer hard coating for tools

1. A hard multilayer coating for improving the wear resistance of workpieces, said multilayer coating comprising:

at least one layer selected from the group consisting of:

an (Al y Cr 1-y )X layer, wherein 0.2≦y≦0.7 and X is selected from the group consisting of N, C, B, CN, BN, CBN, NO, CO, BO, CNO, BNO, and CBNO, and

a (Ti z Si 1-z )X layer, wherein 0.99≧z≧0.7, and

at least one layer stack comprising the following layers:

one (AlCrTiSi)X mixed layer

followed by another (Ti z Si 1-z )X layer

followed by another (AlCrTiSi)X mixed layer

followed by another (Al y Cr 1-y )X layer,

wherein X, y and z are as previously defined.

2. The hard coating in claim 1 , characterized by the fact that the at least one (Al y Cr 1-y ) X layer, the other (Al y Cr 1-y )X layer and the (AlCrTiSi)X mixed layers contain at least one other element from Group IVb, Vb and/or VIb of the Periodic Table of the Elements, or silicon.

3. The hard coating in claim 2 , characterized by the fact that the at least one (Al y Cr 1-y ) X layer and the other (Al y Cr 1-y )X layer contain 0.5 to 25 atom % of the other element or silicon, setting the concentration of the elements and of the silicon in the other (AlCrTiSi)X mixed layers.

4. The hard coating in claim 1 , characterized by the fact that the layers in the layer stack have the following thickness:

Al y Cr 1-y N layer between 75 nm and 200 nm

Ti z Si 1-z N layer between 50 and 150 nm

(AlCrTiSi)X mixed layer 20±10 nm.

5. The hard coating in claim 1 , characterized by the fact that the coating includes several layer stacks in a row.

6. The hard coating in claim 5 , characterized by the fact that the coating contains 4, 8 or 12 layer stacks.

7. The hard coating in claim 1 , characterized by the fact that at least one (Al y Cr 1-y )X layer is deposited directly on the workpiece or on an adhesive layer.

8. The hard coating in claim 1 , characterized by the fact that a (Al y Cr 1-y )X cover layer or a (Ti z Si 1-z )X layer forms the outer last layer of the hard coating.

9. The hard coating in claim 1 , characterized by the fact that an additional sliding layer is deposited on the hard coating.

10. A hard multilayer coating for improving the wear resistance of workpieces, said multilayer coating comprising:

at least one layer selected from the group consisting of:

an (Al y Cr 1-y )X layer, wherein 0.2≦y≦0.7 and X is selected from the group consisting of N, C, B, CN, BN, CBN, NO, CO, BO, CNO, BNO, and CBNO, and

a (Ti z Si 1-z )X layer, wherein 0.99≧z≧0.7, and

at least one layer stack comprising the following layers:

one (AlCrTiSi)X mixed layer

followed by another (Al y Cr 1-y )X layer

followed by another (AlCrTiSi)X mixed layer

followed by another (Al y Cr 1-y )X layer,

wherein X, y and z are as previously defined.

11. The hard coating in claim 1 or 10 , characterized by the fact that the mixed layers contain a multilayer structure.

12. A workpiece, characterized by the fact that the workpiece includes the coating in claim 1 or 10 .

13. The workpiece in claim 12 , characterized by the fact that the workpiece is a component for machining and forming, a tool, a machining tool, a cutting or forming tool.

14. The workpiece in claim 13 , said workpiece being a drill.

15. The hard coating in claim 1 , wherein X is selected from the group consisting of N and CN.

16. The hard coating in claim 6 , said coating containing 8 layer stacks.

17. The hard coating in claim 1 , wherein:

X in said at least one layer is N or CN,

X in said (Ti z Si 1-z )X layer is N or CN, and

0.95≧z≧0.85.

18. The hard coating in claim 1 , wherein X is N or CN in every recited layer.

19. The hard coating in claim 1 , wherein:

X in said at least one layer is N,

X in said (Ti z Si 1-z )X layer is N, and

0.95≧z≧0.85.

20. The hard coating in claim 1 , wherein 0.3≦y≦0.5.

21. the hard coating in claim 10 wherein 0.3≦y≦0.5.