Direct liquid injection chemical vapor deposition of ZrO2 films from a heteroleptic Zr precursor: interplay between film characteristics and corrosion protection of stainless steel

The direct liquid injection chemical vapor deposition (DLI-CVD) of uniform and dense zirconium oxide (ZrO2) thin films applicable as corrosion protection coatings (CPCs) is reported. We present the entire development chain from the rational choice and thermal evaluation of the suitable heteroleptic precursor [Zr((OPr)-Pr-i)(2)(tbaoac)(2)] over the detailed DLI-CVD process design and finally benchmarking the CPC behavior using electrochemical impedance spectroscopy (EIS). For a thorough development of the growth process, the deposition temperature (T-dep) is varied in the range of 400 - 700 degrees C on Si(100) and stainless steel (AISI 304) substrates. Resulting thin films are thoroughly analyzed in terms of structure, composition, and morphology. Grazing incidence X-ray diffractometry (GIXRD) reveals an onset of crystallization at T-dep >= 500 degrees C yielding monoclinic and even cubic phase at low temperatures. At T-dep = 400 degrees C, isotropic growth of XRD amorphous material is shown to feature cubic crystalline domains at the interfacial region as revealed by electron diffraction. Corrosion results obtained through EIS measurements and further immersion tests revealed improved CPC characteristic for the 400 degrees C processed ZrO2 coatings compared to the ones deposited at T-dep >= 500 degrees C, yielding valuable insights into the correlation between growth parameter and CPC performance which are of high relevance for future exploration of CPCs. (C) 2021 The Author(s). Published by Elsevier B.V.