Surface Hardening with LAPPS
NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
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LAPPS Large Area Plasma Processing System was invented in NRLs Plasma Physics Division and Materials Science and Technology Directorate. It uses a 2-5 keV electron beam to ionize and dissociate gas molecules, species that are then used to modify the surface properties of various materials. This novel approach to plasma generation provides a direct scalability of the system and higher control over reactive chemical species compared to conventional plasma processing systems used in the semiconductor and coatings industries. The scalability is simply dictated by the dimensions of the electron beam, allowing unprecedented surface areas to be treated uniformly. The processchemical control is provided by the electron beammolecule interactions, which ensures that all chemical reaction pathways are accessible, as opposed to conventional plasma systems. The ability to increase the hardness of a material while preserving its intrinsic properties provides tremendous advantages in choosing materials for demanding applications. Thin layers of well-known hard coatings are frequently used, but adhesion problems lattice and temperature coefficient matching limit their utility. For metals, incorporating nitrogen into the surfaces lattice surface nitriding is highly desirable because the nitrided layer is physically part of, yet significantly harder than, the bulk material. Equally important in surface nitriding is maintaining sufficiently low temperatures to preserve the properties of the bulk material.
- Plasma Physics and Magnetohydrodynamics