Abdulrahman Altin
Max Planck Society
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Featured researches published by Abdulrahman Altin.
ACS Applied Materials & Interfaces | 2014
Danish Iqbal; Julian Rechmann; Adnan Sarfraz; Abdulrahman Altin; Georgi Genchev; Andreas Erbe
Polymer coatings are widely used to protect metals from corrosion. Coating adhesion to the base material is critical for good protection, but coatings may fail because of cathodic delamination. Most of the experimental studies on cathodic delamination use polymers to study the corrosion behavior under conditions where the interfacial chemistry at the metal(oxide)/polymer interface is not well-defined. Here, ultrathin linear and cross-linked poly(methyl methacrylate) [PMMA] coatings that are covalently bound to oxide-covered zinc via a silane linker have been prepared. For preparation, zinc was functionalized with vinyltrimethoxysilane (VTS), yielding a vinyl monomer-covered surface. These samples were subjected to thermally initiated free radical polymerization in the presence of methyl methacrylate (MMA) to yield surface-bound ultrathin PMMA films of 10-20 nm thickness, bound to the surface via Zn-O-Si bonds. A similar preparation was also carried out in the presence of different amounts of the cross-linkers ethylene glycol diacrylate and hexanediol diacrylate. Functionalized and polymer-coated zinc samples were characterized by infrared (IR) spectroscopy, secondary ion mass spectrometry (SIMS), ellipsometry, and X-ray photoelectron spectroscopy (XPS). Coating stability toward cathodic delamination has been evaluated by scanning Kelvin probe (SKP) experiments. In all cases, the covalently linked coatings show lower delamination rates of 0.02-0.2 mm h(-1) than coatings attached to the surface without covalent bonds (rates ∼10 mm h(-1)). Samples with a higher fraction of cross-linker delaminate slower, with rates down to 0.03-0.04 mm h(-1), compared to ∼0.3 mm h(-1) without cross-linker. Samples with longer hydrophobic alkyl chains also delaminate slower, with the lowest observed delamination rate of 0.028 mm h(-1) using hexanediol diacrylate. For the coatings studied here, delamination kinetics is not diffusion limited, but the rate is controlled by a chemical reaction. Several possibilities for the nature of this reaction are discussed; radical side reactions of the oxygen reduction are the most likely path of deadhesion.
Archive | 2016
Christian David Fernández Solis; Ashokanand Vimalanandan; Abdulrahman Altin; Jesus S. Mondragon Ochoa; Katharina Kreth; Patrick Keil; Andreas Erbe
This chapter introduces the basics of electrochemistry, with a focus on electron transfer reactions. We will show that the electrode potential formed when a metal is immersed in a solution is most of the time not an equilibrium potential, but a mixed potential in a stationary state. This mixed potential formation is the basis of corrosion of metals in aqueous solutions. Organic coatings are introduced as protecting agents, and several types of coatings are discussed: classical passive coatings, and active coatings as modern developments. Three electrochemical techniques, which are commonly used to asses the protecting properties of coatings, are shortly introduced as well: linear polarisation measurements, electrochemical impedance spectroscopy, and scanning Kelvin probe measurements.
Beilstein Journal of Nanotechnology | 2018
Abdulrahman Altin; Maciej Krzywiecki; Adnan Sarfraz; Cigdem Toparli; Claudius Alexander Laska; Philipp Kerger; Aleksandar R. Zeradjanin; Karl Johann Jakob Mayrhofer; Michael Rohwerder; Andreas Erbe
Corrosion inhibitors are added in low concentrations to corrosive solutions for reducing the corrosion rate of a metallic material. Their mechanism of action is typically the blocking of free metal surface by adsorption, thus slowing down dissolution. This work uses electrochemical impedance spectroscopy to show the cyclic oligosaccharide β-cyclodextrin (β-CD) to inhibit corrosion of zinc in 0.1M chloride with an inhibition efficiency of up to 85%. Only a monomolecular adsorption layer of β-CD is present on the surface of the oxide covered metal, with Raman spectra of the interface proving the adsorption of the intact β-CD. Angular dependent X-ray photoelectron spectroscopy (ADXPS) and ultraviolet photoelectron spectroscopy (UPS) were used to extract a band-like diagram of the β-CD/ZnO interface, showing a large energy level shift at the interface, closely resembling the energy level alignment in an n–p junction. The energy level shift is too large to permit further electron transfer through the layer, inhibiting corrosion. Adsorption hence changes the defect density in the protecting ZnO layer. This mechanism of corrosion inhibition shows that affecting the defect chemistry of passivating films by molecular inhibitors maybe a viable strategy to control corrosion of metals.
Journal of Materials Processing Technology | 2014
Peter Groche; Simon Wohletz; Andreas Erbe; Abdulrahman Altin
Journal of The Electrochemical Society | 2016
Dandapani Vijayshankar; Abdulrahman Altin; Claudia Merola; Asif Bashir; Eberhard Heinen; Michael Rohwerder
Materials and Corrosion-werkstoffe Und Korrosion | 2017
J. S. Mondragón Ochoa; Abdulrahman Altin; Andreas Erbe
Journal of The Electrochemical Society | 2017
Abdulrahman Altin; Michael Rohwerder; Andreas Erbe
Advanced Materials Research | 2014
Abdulrahman Altin; Simon Wohletz; Waldemar Krieger; Aleksander Kostka; Peter Groche; Andreas Erbe
Materials and Corrosion-werkstoffe Und Korrosion | 2018
Danish Iqbal; Julian Rechmann; Asif Bashir; Adnan Sarfraz; Abdulrahman Altin; Andreas Erbe
Energy and Environmental Science | 2018
Chang Hyuck Choi; Hyung-Kyu Lim; Min Wook Chung; Gajeon Chon; Nastaran Ranjbar Sahraie; Abdulrahman Altin; Moulay-Tahar Sougrati; Lorenzo Stievano; Hyun Seok Oh; Eun Soo Park; Fang Luo; Peter Strasser; Goran Dražić; Karl Johann Jakob Mayrhofer; Hyungjun Kim; Frédéric Jaouen