Optimization of Anticorrosive Zinc Coatings: Tuning the Adhesion of Zinc/Silica Contact by Interfacial Ternary Oxide Formation

Abstract

Formation of mixed compounds at interfaces between materials often has significant impact on the properties of the junction. With the goal of assessing if interfacial oxide mixing improves the adhesion of anti-corrosive zinc coatings on silica, we report an ab initio study of the structural, electronic, and adhesion characteristics of interfaces between zinc and zinc silicate. We show that, regardless the precise thermodynamic conditions, ZnO-rich zinc silicate interfaces are more stable than SiO 2-rich ones because their formation does not require breaking strong Si-O bonds. Moreover, we find that zinc adhesion at such ZnO-rich interfaces is by at least a factor two larger than that of the zinc/silica contact. Due to a dense network of interfacial Zn-O bonds, this improvement does not produce any unfavorable decohesion effects in the zinc deposit. The formation of an interfacial silicate layer enables the suppression of the weak zinc/silica interface, which is responsible for the poor zinc adhesion. The cohesive cleavage within zinc predicted for the complex zinc/silicate/silica junction offers a promising improvement of performances of anti-corrosive zinc coatings of Si-rich steel grades, of crucial importance in steel-making and automotive industries.

Theoretical study of metal/silica interfaces: Ti, Fe, Cr and Ni on β-cristobalite

“…34 Therefore, we have estimated to what extent the interfacial charge transfer and the partial metal ionization impact the bonding within the different metal deposits. In previous studies, this effect was found to be significant only at oxygen-rich interfaces 37 , and the minimal separation energy was reached when a number of metal atoms close to that needed to compensate the surface polarity was left on the oxide surface. 34 Therefore, we have tested whether the separation energies decrease when one metal atom per O 2− 2 group is left on the silica surface, breaking the peroxo group and compensating the surface polarity.…”

“…We recall here that the interface energies between TMOs and metals E , but considering the low values normally found for oxide/oxide interface energies 37,39 (often in the range 0.5-1.0 J m −2 ) we expect ∆E buf to be significantly negative. As a consequence, the segregation of TMOs near silica will be thermodynamically favored.…”

“…As a consequence, the segregation of TMOs near silica will be thermodynamically favored. As oxide/oxide interfaces have strong adhesion properties, 28,37,39 and the remainder of the buffer will behave as in the case of alumina substrates, formation of chromium or iron oxides is not expected to degrade the performance of the multicomponent buffer.…”

“…However, since this requires to overcome a large energy barrier, it may not be feasible in normal conditions. In this respect, we have proposed surface pre-hydroxylation 35 or formation of interfacial ternary compounds 36,37 as possible routes for removing the surface reconstruction and enhancing adhesion.…”

Improving the Anticorrosion and Self-Healing Properties of the Epoxy Coating Using the Mn–Zn2SiO4/PDA Composite

“…Zinc silicate (Zn 2 SiO 4 ) exhibits several desirable characteristics, such as low toxicity, cost-effectiveness, and excellent physical and chemical stability. , Owing to these attributes, Zn 2 SiO 4 commonly acts as a protective barrier between metal surfaces and corrosive environments, , and is widely used as a corrosion-resistant filler of epoxy resin in the field of metal corrosion protection. , However, the presence of micro gaps in Zn 2 SiO 4 coatings reduced their shielding performance, leading to decreased long-term corrosion resistance. − In recent years, the scientific community has shown significant interest in nanocomposites that incorporate materials such as graphene, graphene oxide (GO), polyaniline, and polydopamine (PDA) to fill the micropores of Zn 2 SiO 4 material.…”