Diamond-like a-C:H coatings deposited in a non-self-sustained discharge with plasma cathode

Abstract

Hydrogenated amorphous carbon (a-C:H) coatings have been obtained by means of acetylene decomposition in a non-self-sustained periodic pulse discharge (2A, 50 kHz, 10 μs) with hollow cathode. The discharge operation was maintained by plasma cathode emission with grid stabilization based on dc glow discharge. Using the proposed method, it is possible to control the deposition conditions (total pressure of the Ar + C₂H₂ mixture, partial pressure of C₂H₂, ion current density, carbon ion energy) within broad limits, to apply a-C:H coatings onto large-area articles, and to perform deposition in one technological cycle with ion etching and ion implantation treatments aimed at improving the adhesion of coatings to substrates (Ti, Al, stainless steel, VK8 hard alloy) at temperatures below 150°C. Results of determining the deposition rate (1–8 μm), the nanohardness of coatings (up to 70 GPa), and the fraction of sp ³ bonds (25–70%) in the diamond-like coating material are presented.