A novel functional layered diamond like carbon coating for orthopedics applications

Functional Layered "Diamond like Carbon (DLC)" coated interfaces for orthopedic load bearing applications were fabricated and assessed. They consisted of three layers, each designed for specific functions. The fabrication process was performed using magnetron sputtering at low temperatures on steel substrates. Structural investigations showed the layers possessed very fine grained, columnar microstructures with a very low density of inter columnar micro-cracks. The mechanical and surface properties such as micro hardness, wettability, roughness, modulus of elasticity, water contact angle and absorbed protein layer (γ-globulin) varied among the DLCs. The biotribological tests, conducted under simulated hip joint conditions (friction, wear, Raman intensity ratio and polyethylene wear debris) were correlated with their surface and material properties. The DLC (sample no #ML1), which were built with 0.6 μm thick tribological layer (a-C:H:Cr-a-C:16 bilayers, ratio: 1:1) and 0.15 μm thin (a-C:H) top layer was found to yield superior tribological performances at "DLC on Polyethylene" sliding pairs. On the other hand, DLC (sample no#GL3), which consist of 0.6 μm thick tribological layer (gradient layer a-C:H > a-C:N) and 0.15 μm thin (a-C:H) top layer was found to yield finest tribological performances at "DLC on DLC" sliding pairs.