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Influence of oxide layer promoted by d.c. plasma preheating on the adhesion coating and role of the initial surface pretreatment
Author(s) -
Pech J.,
Hannoyer B.
Publication year - 2000
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/1096-9918(200008)30:1<585::aid-sia844>3.0.co;2-y
Subject(s) - materials science , coating , oxide , layer (electronics) , spinel , substrate (aquarium) , ceramic , spallation , composite material , adhesion , phase (matter) , deposition (geology) , metallurgy , chemical engineering , chemistry , physics , organic chemistry , quantum mechanics , engineering , paleontology , oceanography , sediment , neutron , biology , geology
A preheating procedure of metallic substrates inducing surface oxidation is required for the deposition of d.c. plasma‐sprayed ceramic coatings. The intermediate oxide layers, depending on their composition and thickness, enhance or decrease the ceramic coating adhesion. To study the formed oxide layers, different thermal treatments have been carried out on polished or grit‐blasted stainless steel 304L. The oxide layers have been investigated using low‐incidence x‐ray diffraction and conversion electron Mössbauer spectroscopy. The preheating stage induces thin scales mainly consisting of a paramagnetic Ni x Cr y Fe 3− x − y O 4 spinel phase (polished surfaces) or an Fe 2− x Cr x O 3 hexagonal phase (grit‐blasted surfaces). On each oxide layer, an alumina coating has been deposited according to optimized deposition conditions. After spallation of the coating in the case of polished surfaces, two surfaces have been identified, the first one corresponding to the coating surface initially in contact with the substrate (S 1 ) and the second one being the self‐substrate surface (S 2 ). The FeAlO 3 and Fe 2− x − y Cr x Al y O 3 phases have been identified on S 1 , whereas S 2 is overlaid only by Fe 2− x − y Cr x Al y O 3 . In the case of grit‐blasted surfaces, the coating adhesion seems to be proportional to the initial oxide thickness. The minimum value is ∼25 MPa for a 17 nm thick layer and the maximum one reaches 33 MPa for a 59 nm thick scale. Copyright © 2000 John Wiley & Sons, Ltd.