Coating for a titanium alloy substrate

1. A surgical implant comprising:

a metallic substrate;

a tantalum interlayer disposed adjacent to the metallic substrate and comprising α-tantalum and amorphous tantalum;

at least one diamond like carbon (“DLC”) layer disposed adjacent the tantalum interlayer;

wherein the tantalum interlayer has a phase gradient from β-tantalum to α-tantalum or from amorphous tantalum to α-tantalum between a metallic substrate side and a DLC side;

wherein the DLC layer has a hardness value and an elastic modulus value; and wherein the hardness value has a gradient increasing away from the tantalum side; and wherein the elastic modulus value has a gradient increasing away from the tantalum side.

2. The surgical implant according to claim 1 , wherein the metallic substrate is titanium or a titanium based alloy.

3. The surgical implant according to claim 1 , wherein the metallic substrate is a cobalt based alloy.

4. The surgical implant according to claim 1 , wherein the metallic substrate is steel.

5. The surgical implant according to claim 1 , wherein the tantalum interlayer has a thickness ranging from 1 nm to 2 μm.

6. The surgical implant according to claim 1 , wherein the tantalum interlayer further comprises a compound or element to promote alpha-tantalum growth.

7. The surgical implant according to claim 6 , wherein the compound is independently selected from the group consisting of: a titanium compound, a niobium compound, a tungsten compound and combinations thereof; and the element is independently selected from the group consisting of: titanium, niobium, tungsten and combinations thereof.

8. The surgical implant according to claim 5 , wherein the tantalum interlayer further comprises tantalum compound nanoparticles.

9. The surgical implant according to claim 8 , wherein the tantalum interlayer is a nanocomposite of tantalum-carbide and tantalum.

10. The surgical implant according to claim 1 , wherein the hardness value gradient increases from 12 GPa to 22 GPa.

11. The surgical implant according to claim 10 , wherein the elastic modulus value gradient increases from 120 GPa to 220 GPa.

12. The surgical implant according to claim 1 , wherein the at least one DLC comprises a plurality of alternating sub-layers comprising a DLC sub-layer and a metal doped DLC sub-layer.

13. The surgical implant according to claim 12 , wherein the metal doped DLC sub-layer is doped with titanium.

14. The surgical implant according to claim 1 , wherein the phase gradient extends from the metallic substrate side to the DLC side.