The NanoTest was used to investigate diamond-like carbon films on silicon which were prepared by magnetron sputtering from a graphite target. The magnetron power was 700 W and the resulting film thickness was 250 nm.

The depth vs. load curves shown (courtesy of J.C. Pivin) were obtained using a 90° trigonal indenter (i.e. a cube corner). With this diamond geometry, relatively deep indentations are possible in DLC on silicon before substrate effects become apparent.

The film hardness, determined from the Depth vs. Load hysteresis curves, was about 45 GPa.

The discontinuities in the loading curves which can be clearly seen in the figure were reproducible and were indicative of adhesion failure. Radial film cracking was also observed, but this did not necessarily produce such effects on the loading curves. Using the indentation approach, it was clearly shown that DLC adhesion was strongly dependent on the particular deposition technique employed.