NOVEL REACTIVE PLASMA PROCESSING FOR TRANSFORMING SURFACES OF METALS AND INTERMETALLICS TO CERAMICS

Abstract

The surface of Ti, Zr, and TiAl was directly transformed to ceramics with a graded composition by carburizing, nitriding, and oxidizing using novel reactive plasma processing that has been developed by the present authors. Thick modified layers which consist of TiC, TiN, ZrC, ZrN (Zr₂N), ZrO₂, and Ti₂AlN were successfully synthesized by this plasma process. The ceramic layers exhibited higher hardness and elastic modulus than the substrates. The formation behavior of these ceramic layers was analyzed with ab initio molecular orbital simulation and thermodynamic calculation. The chemical interaction of the interstitial atoms with the lattice of substrate materials was found to govern the diffusion and ordering processes to form the ceramic layers.

Keywords:

• Surface modification
• Carburization
• Nitridation
• Oxidation
• Plasma process
• RF plasma
• Chemical reaction
• Diffusion
• Ordering
• Thermodynamics
• Molecular orbital simulation
• Ceramics
• Metals
• Intermetallics
• Hardness

Acknowledgments