Application of scanning SIMS techniques for the evaluation of the oxidation behavior of high-purity molybdenum

Refractory metals are primarily characterized by a high melting point combi ned with a rather poor corrosion resistance under oxidizing atmosphere and therefore are mainly used in high temperature processes under reducing atmo sphere or in vacuum. Exposure to an atmosphere of high humidity can lead to oxidation of the material even at room temperature. Different methods of s urface pre-treatment have been applied to investigate their influence on th e oxidation behavior of high-purity molybdenum. Within the scope of this wo rk molybdenum foils and molybdenum discs consisting of the same base materi al were investigated. Since lateral surface structure as well as the in-dep th distribution of contaminants are expected to play an important role in t he oxidation process, both the in-depth distribution of the constituents wi thin the oxide layer and the lateral distribution at the surface level of t he oxide have been analyzed. Scanning SIMS has been engaged to analyze the uppermost structures of the oxide layer. In order to achieve maximum detect ion power and to gain the in-depth information, stigmatic SIMS has been app lied to investigate the in-depth distribution of the interesting specimen c onstituents.