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 °C, using, as precursors, (η5-C5H5)2Zr(CH2C(CH3)3)2, Ti(OCH(CH3)2)4, and (CH3CH2)2Al(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.