Thermal stability of reactive sputtered tungsten oxide coatings

• Main Author: Parreira, N. M. G.
• Publication Date: 2007
• Other Authors: Polcar, T., Cavaleiro, A.
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: https://hdl.handle.net/10316/4205; https://doi.org/10.1016/j.surfcoat.2007.01.019
• topic: Tungsten oxide; Reactive sputtering; Structural characterization; Thermal stability

The thermal stability of different W-O coatings, W100, W90O10, W54O46, W30O70 and W25O75, were studied by in-situ X-ray diffraction at elevated temperatures up to 900 °C. The coatings were deposited by DC reactive magnetron sputtering from a pure tungsten target in an Ar + O2 atmosphere onto Fecralloy alloy. The evolution of the structure of the coatings was studied in both protective and oxidant atmospheres. Three groups of films were identified: (1) W25O75 which showed structural evolution following the W-O phase diagram; (2) amorphous O-deficient WO3 whose structure followed the W-O phase diagram either as WO3 or as its chemical composition depending on annealing in oxidant or protective atmospheres, respectively; and (3) low O-content crystalline films that oxidized from 500 °C.