Alain Weymeersch

Electron conducting organic coating of mild steel by electropolymerization

The aim was to coat mild steel with an electron conducting polymer in order to replace any possible electrochemical corrosion of the metal by another electrochemical reaction occurring on top of the film. In view of potential industrialization, electropolymerization of a water soluble monomer was studied. In most cases, this was achieved by oxidation, and the substrate had to be passivated. Polyaniline, was obtained in nitric acid solution. Films had a good structure but were brittle and powdery on the surface. Except on tin free steel, they were insulating. Polypyrrole was a better candidate. Prepared from a Na2SO4 solution, films were conductive, ensured good corrosion resistance of the substrate but they were brittle and adhesion to the substrate was not high. Furance, thiophene and iron substituted vinylpyridine complex were tried without success. Further, research should consider copolymerization of pyrrole with other monomers.

Determination of the chemical and physical properties of hydrogenated carbon deposits produced by d.c. magnetron reactive sputtering

Abstract Hydrogenated carbon deposits on silicon substrate have been prepared by magnetron-enhanced reactive sputtering in a C 2 H 2 -Ar gas mixture with a carbon autofeeding target system. The hydrogen content and the density of the hydrogenated carbon deposits have been determined by elastic recoil detection analysis and related to the C 2 H 2 : Ar gas flow ratio. The characteristics of carbon-hydrogen and carbon-carbon bonds have been investigated by Fourier transform IR spectrometry. The mechanical properties were investigated by nanoindentation. This systematic study reveals a dependence of film properties on gas composition. This dependence can be used to tune film properties to specific applications. As the acetylene flow increases, the hydrogen concentration increases, and films have a decreasing density, decreasing hardness and decreasing Youngs modulus.

Study of the formation of a carbon layer on a sputtering target during magnetron-enhanced reactive sputtering

Abstract The goal of this work is to estimate and to discuss the optimum conditions for the realization of hydrogenated carbon deposits obtained by magnetron-enhanced reactive sputtering in a C 2 H 2 -Ar gas mixture with a carbon autofeeding target system. Hydrogenated carbon layers can be obtained by reactive sputtering of a copper target poisoned by carbon compounds during the deposition process. It is shown that the target poisoning rate, composition and structure depend on the gas composition (C 2 H 2 -Ar) and on the sputtering conditions (target current). The target poisoning rate is compared with the deposition rate of the hydrogenated carbon deposit on a silicon substrate and related to an analysis of the gas discharge by emission spectroscopy for different experimental conditions. The structure of the carbon-poisoning layer is also compared with the structure of the carbon layer deposited on a substrate. The hydrogen-to-carbon ratio is determined on both the target and the substrate by elastic recoil detection analysis.

Influence of the plasma pretreatment of a steel substrate on the development of an hydrogenated carbon deposit

The first stages of the growth of a hydrogenated carbon deposit have been investigated by Auger electron spectroscopy on plasma-etched steel substrates. The deposit-to-substrate Auger peak-to-peak intensity curves vs. the quantity of deposited matter are characteristics of the growth mode which is itself very dependent on the plasma cleaning procedure. Substrate cleaning promotes a layer-by-layer growth mode whereas its absence induces an island growth mode. The steel substrate decontamination not only increases the adhesion between the carbonaceous film and the steel surface but also improves the protective properties of the coating. Finally it is shown that on a decontaminated steel sheet, a film of 1.2 nm can be a perfect covering.