Protective coatings of nanophase diamond deposited directly on stainless steel substrates

Abstract

Composed of sp3 bonded nodules of carbon, nanophase diamond films are deposited in vacuum onto almost any substrate by condensing carbon ions carrying keV energies. These multiply charged ions are obtained from the laser ablation of graphite at intensities in excess of 1011 W cm−2. The high energy of condensation provides both the chemical bonding of such films to a wide variety of substrates and low values of residual compressive stress. Coatings of 2–5 μm thickness have extended lifetimes of materials such as Si, Ti, ZnS, ZnSe, and Ge against the erosive wear from high-speed particles by factors of tens to thousands. In this research emphasis has been placed on studies of the bonding and properties realized by the direct deposition of nanophase diamond films on stainless steel substrates. Examinations of interfacial layers showed deep penetrations of carbon atoms into steel substrates. Resistances to low and high impact wear estimated by a tumbler device and a modified sand blaster, respectively, and results indicated significant increases in the lifetime of stainless steel samples. The characterization studies in this work demonstrated nanophase diamond as an attractive material for use as a protective coating in current industrial applications.