Nitruvid

Patrick Choquet

Jean-Francois Nowak

Francois Cellier

The process with a view to imparting to the treated article a resistance to frictional wear, a corrosion resistance, and a color, is characterized according to the invention in that the surface of the article is subjected to a thermochemical pretreatment under electric plasma in a vessel under an atmosphere containing reactive species such as N.sub.2 and hydrogen, the reactive species diffusing into and precipitating in the metal matrix of the article to form a diffusion sublayer and in that a layer of carbon in vapor phase is deposited under electric plasma on the surface thus treated, in the same vessel, the composition of the atmosphere for the pretreatment being gradually modified, on the one hand, by the introduction of a hydrocarbon and/or of a silane in the gaseous state and, on the other hand, by progressive reduction of the partial pressures of the reactive species employed during the pretreatment, and the maintenance of the hydrocarbon atmosphere for the carbon deposition.

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Saint-Etienne, France

Patrick Choquet