Synthesis and characterization of metal oxide multilayers obtained via MOCVD as protective coatings of graphite against oxidation

Zirconia (ZrO2) titania (TiO2), and alumina (Al2O3) thin films were deposited on a graphite substrate both in mono- and in multi-layer systems, using the metal organic chemical vapor deposition technique, to test their practical qualities as protective coatings against oxidation at high temperatures. The depositions were performed using a hot wall reactor at reduced pressure (0.6 Torr) in the temperature range 350-500 degreesC, using, as precursors, (eta(5)-C5H5)(2)Zr(CH2C(CH3)(3))(2), Ti(OCH(CH3)(2))(4), and (CH3CH2)(2)Al(OCCH3CHCCH3O), respectively Surface and topographical analysis of the deposits using X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy techniques as well as thermogravimetric measurements (TG and DTA) in an oxygen flux of mono- and multi-layer systems are reported and examined.