Active screen plasma nitriding and nitrocarburizing are relatively new processes in which a plasma discharge is applied to a metal screen surrounding the workload, generating highly reactive gas species that flow to the component surface. The active screen also radiates heat, resulting in a uniform temperature throughout the load. This article provides an overview of the two processes and presents examples of their use on stainless steel piston rings (nitriding) and 4142 and 1045 steels (nitrocarburizing).

Chemical vapor deposition (CVD) of pyrolytic chromium carbide coatings (PCCCs) is proving to be a viable alternative to hard chrome plating used on cylinder piston group components. This article discusses the development and optimization of a CVD process for depositing PCCCs on piston rings and cylinder sleeves. It evaluates the coatings based on friction, wear, and adhesion properties in comparison with coatings produced by other methods.