Tuning Adhesion at Metal/Oxide Interfaces by Surface Hydroxylation

Abstract

The control of adhesion at metal/oxide interfaces is of key importance in modern applications, whenever three-dimensional metal clusters or two-dimensional metal overlayers are to be synthesized on an oxide support. By focusing on the zinc/alumina system, we address here one of the long-standing issues in this context, which is the poor wetting of wide bandgap oxides by noble and post-transition metals. It has recently been recognized to have detrimental industrial consequences for the adhesion of anti-corrosive zinc coatings to new high strength steels grades. We have combined photoemission, thermal desorption and plasmonics with atomistic simulation to describe the energetics of zinc deposits on dry and hydroxylated α-Al 2 O 3 (0001) surfaces. Both experimental and computational results show that an activated reaction of the metal with the OHcovered surface, followed by hydrogen desorption, produces dispersed interfacial moieties involving both oxidized Zn species and undercoordinated oxygen ions, that lead to a significant improvement of adsorption/adhesion characteristics on the hydroxylated surface. In particular, the key role of interfacial undercoordinated anions, remnants of the hydroxylation layer, is highlighted for the first time, pointing to a general mechanism by which surface hydroxylation appears as a promising route towards a systematic improvement of wide band gap oxide wetting by metals. 1

Aluminium segregation profiles in the (110), (100) and (111) surface regions of the Fe0.85Al0.15 random body-centered cubic alloy

“…[4] and references therein) and the oxygen-induced segregation of alumina at the steel surface, degrading the quality of the anti-corrosion zinc coating, commonly referred to as galvanization [10,11,12,13,14,15,16]. To be more specific, despite a reducing atmosphere that prevents iron oxidation, segregation occurs during the recrystallization annealing of the Al-alloyed steel at 1070 K, which is the last production stage of steel sheets prior to galvanization [10,11,12,14,15,16].) Indeed, the formation of both surface alumina films [13] and brittle compounds [4,17,18] originates from the aluminium segregation at either the surface or the grain boudaries and shear bands.…”

Self-organized carbon-rich stripe formation from competitive carbon and aluminium segregation at Fe0.85Al0.15(1 1 0) surfaces

“…However, during steel processing, complex phenomena of segregation due to alloying elements occur at surfaces or grain boundaries. These latter impact material properties [3,4] such as corrosion resistance and mechanical behaviour; above all, wettability during galvanization becomes a major concern that refers to questions related to metal-oxide interfaces [5,6,7,8]. Either as an alloying element or as an impurity, carbon is commonly present on iron and steel surfaces since the range of bulk solubility of carbon in iron is low ( 200 ppm) [9]; the precipitation of carbides (Fe 3 C -cementite or Fe 5 C 2 κ-Hägg carbides) in the bulk embrittles steel.…”

Chemical nature and thermal decomposition behavior of tartaric acid multilayers on rutile TiO2(110)

“…The activation energy and order of desorption in the multilayer regime can be estimated using the leading edge analysis. 28,30,31 The method is based on the ansatz of desorption rate of Polanyi and Wigner, 28,31…”