Vanadium carbide films produced by plasma-assisted metal-organic chemical vapour deposition

Abstract
Vanadium carbide films as wear-resistant coatings produced by salt bath immersion at high temperatures have found wide technological application in manufacturing industries. In order to reduce the substrate temperature, the deposition of VC-films by plasma-assisted chemical vapour deposition using a metal-organic compound as precursor was investigated. Bis(cyclopentadienyl)-vanadium, a purple solid compound showing a sufficient sublimation rate at relatively low evaporator temperatures, was used together with hydrogen and argon to deposite VC-films in a d.c. glow discharge. As one of the most important parameters the substrate temperature was varied from 200 °C to 400 °C . The compound decomposed into films and gaseous by-products like C₅H₆ and other hydrocarbons which could be detected by quadrupole mass spectrometer. The deposition efficiency of the coatings was almost independent of the substrate temperature. It was established by means of EDX and XRD that cubic vanadium carbide coatings were obtained. The morphology of these layers was examined by scanning electron microscopy. In the entire temperature range dense, polycrystalline layers were created, whose hardness measured between 2200-3300 HV. With the increase of the substrate temperature the adhesive strength of the coatings increased, too.