Adhesion measurements of non-crystalline diamond films prepared by a laser plasma discharge source

Films of amorphic diamond can be deposited with a laser plasma discharge source of multiply-charged carbon ions in an ultrahigh vacuum (UHV) environment without the use of any catalyst in the growth mechanism. The beam from a pulsed Nd-YAG laser is focused at very high power densities onto a graphite feedstock and the resulting plasma ejects carbon ions carrying keV energies through a discharge space to the substrates to be coated. The high energies of condensation produce interfacial layers between the films and substrate materials, resulting in levels of adhesion which can support the protection of fragile and sensitive substrates subjected to harsh environmental conditions. Coatings of 2-5 μm thicknesses have extended the lifetimes of substrate materials such as Si, Ti, Ge, ZnS, and stainless steel against the erosive wear from high-speed particles and droplets by factors of tens to thousands. In this paper, we give details of the adhesion and mechanical properties of amorphic diamond films. Emphasis is placed on the quantitative methods to assess and measure the adhesion of films to a variety of substrates. Parameters such as the bonding of the films are examined by Rutherford backscattering spectrometry and nanoindentation techniques. Resistances to wear and debonding are estimated with a modified sand blaster which simulates erosive environments.