Simulations of Erosion/Corrosion Surface Chemical Reactions with a Laser Beam,
LAWRENCE LIVERMORE NATIONAL LAB CA
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Surface chemical reactions in highly transient reactive environments frequently contribute to material degradation and subsequent loss by erosioncorrosion mechanisms. An attempt was made to simulate these reactions with a pulsed laser system in a pressure chamber. Gaseous carburizing and nitriding reactions were studied because of their frequent occurrence in erosioncorrosion environments. Reactions in pure iron and AISI 4340 steel were characterized by secondary ion mass spectroscopy SIMS, optical metallograpy, and scanning electron microscopy SEM. Gases used for laser-pulsing included argon, methane, carbon monoxide, ammonia, and nitrogen. The effect of gas pressure also was investigated. The results demonstrate that significant amounts of the reactive species can be driven into metal surfaces if the energy of the laser pulse exceeds the threshold for surface melting to occur. Test also were performed on steel specimens coated with tungsten to demonstrate the capability of the laser system to test candidate coating materials.
- Physical Chemistry
- Properties of Metals and Alloys