Alternatives to Chromium Coatings: Dry Deposition Technologies

摘要

The electrodeposition of chromium involves hazardous and/or toxic chemicals. With the proposed new OSHA exposure limit for hexavalent chromium, plating shops will find it harder to remain in compliance with the environmental, health and safety regulations. Consequently, alternatives that have the ability to offer comparable performance, reduce compliance burdens and worker safety concerns, and decrease life cycle operating costs are of considerable interest. There are a number of approaches to depositing alternative coatings or modifying surfaces to provide the desired engineering and aesthetic properties. This paper focuses on some of the "dry" processes that are available, including physical or chemical vapor deposition, thermal diffusion, laser alloying, and ion implantation. Properties - such as deposit quality, surface finish, thickness, porosity, hardness, and wear resistance - will be discussed and compared to those for decorative and hard chromium. Advantages and limitations of the various processes will be presented.