Indirect Production of Chromium Carbides Film on Low Alloy Steel

Chromium carbide coatings deposited on mechanical parts by different techniques have an interesting hardness, wear-resistant and corrosion resistance. Some studies show that chromium carbides produced by physical vapor deposition methods and revealed a superior hardness present a poor adherence to their substrates. The objective of this study is to indirectly obtain a hard, and adherent coating of chromium carbide by using a conversion treatment including carburizing treatment of steel substrate, deposition of a pure chromium layer, and annealing treatment of coated carburized steel under a carbonic gas atmosphere. Treatment temperature has an effect on the partial or complete conversion of chromium film as a result of the diffusion and precipitation process. The transformation rate of chromium into both chromium carbide layers was investigated. For 1 h of holding treatment, chromium film was totally transformed at 900 °C into chromium carbide film which presented high hardness and excellent adhesion.