Effect of reactive gas pressure on the plasma parameters during triode ion plating of Cr−C films

Abstract

Mechanical properties and the average chemical composition of Cr−C hard coatings deposited by means of triode ion plating strongly depends on the partial pressure of the reactive gas (C₂H₂) during the deposition. The partial pressure of the acetylene has to be higher ($p_{C_2 H_2 } = 1.5 \times 10^{ - 3} mbar$) and much tighly controlled than the partial pressure of N₂ during the deposition of CrN. The shape of energy spectra measured by PPM 421 are similar in both cases, with the energy peak at about 50 eV. This energy corresponds to theU _pl and to the potential measured on the crucible. The intensity of ions originating from the C₂H₂ is much lower than the intensity of nitrogen ions. Only the¹²C⁺, CH ^Emphasis>+ _x group and C ⁺₂ ions were definitely detected.