Internal oxidation of laminated Nb-Ru coatings

A direct current magnetron cosputtering system was used to deposit Nb-Ru coatings with various chemical compositions onto silicon wafers. The Nb-Ru coatings exhibited distinct nanolaminated structures because of the cyclical gradient concentration deposition. The oxidized Nb-Ru coatings formed oxide and metal multilayers when they experienced internal oxidation at 400-600 °C in a 1% O2-99% Ar atmosphere. A two-stage parabolic-rate law was obeyed for the Nb0.49Ru0.51 coatings oxidized at 350-550 °C in 1% O2-99% Ar. The activation energies in the two-stage oxidation, dominated by oxygen dissolution and oxide formation, were calculated at 88 and 127 kJ/mol, respectively.