A Novel Approach of Plasma Nitrocarburizing Using a Solid Carbon Active Screen – a Proof of Concept

Abstract

Abstract The feasibility of a novel approach of plasma nitrocarburizing with active screen (AS) made of carbon-fiber reinforced carbon (CFC) has been demonstrated in a comparative study of two types of AS material, steel and CFC, under similar process conditions. Besides the excellent thermo-mechanical properties of the CFC material against the conventional steel, an uncontrollable sputter deposition of the steel screen material during the nitriding can be avoided by the use of the CFC material. Furthermore, a solid-carbon-source concept based on the generation of highly reactive precursor gases, in particular of the unsaturated hydrocarbons HCN and C2H2 directly in the process, avoiding external supply of gaseous hydrocarbons, has been realized in the plasma-enhanced thermochemical treatment. The high nitriding effect of the process atmosphere obtained with the CFC AS yielded a significant improvement of nitriding results for different treated steels.