Nanoindentation measurements of amorphous carbon coatings

In this study, amorphous carbon coatings were deposited with thicknesses ranging from 20 nm to 100 nm on single-crystal silicon substrates by sputtering, ion beam, and cathodic arc deposition techniques. An indentation system with a three-plate transducer with electrostatic actuation and capacitive sensor has been used to make load displacement measurements and subsequently carry out in situ imaging of the indents. Indentation experiments were carried out using a three-sided pyramidal (Berkovich) diamond tip. Measurements include load-displacement curves and calculation of hardness and Young's modulus of elasticity at various indentation depths, studies of hysteresis behavior, creep behavior, and strain rate effect of various carbon coatings. The cathodic arc coating exhibited the highest hardness and elastic modulus followed by the sputtered and ion beam coatings.