Noncrystalline films with the chemistry, bonding, and properties of diamond

Abstract

The energetic condensation of multiple charged ions of carbon at keV energies produces textured noncrystalline films having many of the properties of diamond. Prepared in vacuum by the laser ablation of graphite at intensities in excess of 1011 W cm−2, a variety of structural morphologies can result that depend upon the kinetic energies and charge states employed. The most promising is an amorphous ceramic called ‘‘amorphic diamond’’ for convenience. It consists of sp3-bonded nodules of carbon in a matrix of other carbons. The high energies of condensation provide both for the chemical bonding of such films to a wide variety of substrates and for low values of residual compressive stress, 0.7–0.8 GPa. On selected films, hardness cannot be measured because of deformations of the diamond indenter, but a lower limit for hardness has been found at 78 GPa. Coatings of 2–5 μm thicknesses have extended lifetimes of materials such as Si, Ti, and ZnS against the erosive wear from high-speed particles and droplets by factors of tens to thousands.