Showing papers on "Corrosion published in 2011"

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation

Abstract: A leading approach for large-scale electrochemical energy production with minimal global-warming gas emission is to use a renewable source of electricity, such as solar energy, to oxidize water, providing the abundant source of electrons needed in fuel synthesis. We report corrosion-resistant, nanocomposite anodes for the oxidation of water required to produce renewable fuels. Silicon, an earth-abundant element and an efficient photovoltaic material, is protected by atomic layer deposition (ALD) of a highly uniform, 2 nm thick layer of titanium dioxide (TiO(2)) and then coated with an optically transmitting layer of a known catalyst (3 nm iridium). Photoelectrochemical water oxidation was observed to occur below the reversible potential whereas dark electrochemical water oxidation was found to have low-to-moderate overpotentials at all pH values, resulting in an inferred photovoltage of ~550 mV. Water oxidation is sustained at these anodes for many hours in harsh pH and oxidative environments whereas comparable silicon anodes without the TiO(2) coating quickly fail. The desirable electrochemical efficiency and corrosion resistance of these anodes is made possible by the low electron-tunnelling resistance (<0.006 Ω cm(2) for p(+)-Si) and uniform thickness of atomic-layer deposited TiO(2).

Corrosion mechanism applicable to biodegradable magnesium implants

Abstract: Much of our understanding of the Mg corrosion mechanism is based on research using aggressive chloride based solutions like 3% NaCl, which are appropriate for understand the corrosion for applications such as auto construction. The chloride ions tend to cause break down of the partly protective surface film on the Mg alloy surface. The corrosion rate increases with exposure time until steady state is reached, which may take several weeks. An overview is provided of the aspects which determine the corrosion of Mg alloys: (i) measurement details; (ii) impurity elements Fe, Ni, Cu and Co; (iii) second phases; (iv) surface films and surface condition and (v) stress corrosion cracking (SCC). This understanding is used to help understand Mg corrosion for Mg as a biodegradable implant for medical applications. Solutions that elucidate these applications tend to form surface films and the corrosion rate tends to decrease with immersion time.

Biodegradable Mg and Mg alloys: Corrosion and biocompatibility

Abstract: This review discusses the current state and challenges in understanding Mg alloy corrosion behavior, in view of use of these materials for biodegradable implants. After the description of some basic and specific aspects of Mg alloy corrosion, the influence of specific biological environments on the corrosion behavior of Mg alloys is summarized. Interactions between corroding Mg surfaces and cells are shortly discussed. Moreover, approaches to control the corrosion and biological performance of Mg alloys by surface modification are presented. The article tries to provide general, instead of alloy specific, information on the topics covered.

Electrochemical behavior and passivation of current collectors in lithium-ion batteries

Abstract: This paper examines several metals that are commonly employed as current collectors of positive and negative electrodes for rechargeable lithium batteries. Current collectors must be electrochemically stable when in contact with the cell component during the potential operation window of an electrode. Various electrochemical techniques have been used to investigate the corrosion of current collector materials. In practice, continued corrosion of current collectors leads to a gradual increase in the internal resistance of cells, which causes the capacity to fade gradually. Corrosion of the current collector may induce a short-circuit, affecting its safety. Thus, the formation of thick and compact, protective passive film on the metal surface is highly important so as to ensure battery performance and safety. Depending on the salts and additives, different types of protective films are formed. The solubility of these surface layers in the electrolyte is a determining factor in the overall stability of the current collector. In this review, we introduce the electrochemical behavior and protective film formation processes of various metallic current collectors in representative electrolytes.

Mesoporous silica nanoparticles for active corrosion protection

Abstract: This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol−gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g−1), narrow pore size distribution (d ∼ 3 nm), and large pore volume (∼1 mL·g−1). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol−gel coating was observed during a simulated corrosion process by the ...

Review of Corrosion-Resistant Conversion Coatings for Magnesium and Its Alloys

Abstract: The corrosion susceptibility of Mg and its alloys in humid and aqueous environments limits their widespread application. The performance of several conversion coating technologies is reviewed herein. In addition to the assessment of performance based on the literature to date, thermodynamic analysis has been used to compare coating processes. Ongoing research reveals that the search for appropriate conversion coatings to replace toxic Cr-based coatings continues. It is seen that the variability between coatings of the same technology was greater than the averages between coating technologies. Additionally, coating pretreatment also appears to be more significant than the choice of coating technology itself.

Corrosion resistance and durability of superhydrophobic surface formed on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution

Abstract: The corrosion resistant performance and durability of the superhydrophobic surface on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution were investigated using electrochemical and contact angle measurements. The durability of the superhydrophobic surface in corrosive 5 wt % NaCl aqueous solution was elucidated. The corrosion resistant performance of the superhydrophobic surface formed on magnesium alloy was estimated by electrochemical impedance spectroscopy (EIS) measurements. The EIS measurements and appropriate equivalent circuit models revealed that the superhydrophobic surface considerably improved the corrosion resistant performance of magnesium alloy AZ31. American Society for Testing and Materials (ASTM) standard D 3359−02 cross cut tape test was performed to investigate the adhesion of the superhydrophobic film to the magnesium alloy surface. The corrosion formation mechanism of the superhydrophobic surface formed on th...

Magnesium, Magnesium Alloys, and Magnesium Composites

Abstract: PREFACE. ACKNOWLEDGMENTS. 1 INTRODUCTION TO MAGNESIUM. 1.1 Introduction. 1.2 Characteristics of Pure Magnesium. 1.3 Applications. 1.4 Summary. References. 2 SYNTHESIS TECHNIQUES FOR MAGNESIUM-BASED MATERIALS. 2.1 Introduction. 2.2 Liquid Phase Processes. 2.3 Solid Phase Process. 2.4 Disintegrated Melt Deposition Method. 2.5 Mechanical Disintegration and Deposition Method. 2.6 Summary. References. 3 MAGNESIUM ALLOYS. 3.1 Introduction. 3.2 Casting Alloys. 3.3 Wrought Alloys. 3.4 Magnesium Elektron Series Alloys. 3.5 Magnesium Alloys for Elevated Temperature Applications. 3.6 Magnesium-Based Bulk Metallic Glasses. References 81 4 FUNDAMENTALS OF METAL MATRIX COMPOSITES. 4.1 Introduction. 4.2 Materials. 4.3 Interface Between Matrix and Reinforcement. 4.4 Theoretical Prediction of Properties. 4.5 Summary. References. 5 MAGNESIUM COMPOSITES. 5.1 Introduction. 5.2 Materials. 5.3 Magnesium-Based Composites with Al2O3. 5.4 Magnesium-Based Composites with MgO. 5.5 Magnesium-Based Composites with SiC. 5.6 Magnesium-Based Composites with Y2O3. 5.7 Magnesium-Based Composites with ZrO2. 5.8 Magnesium-Based Composites with CNT. 5.9 Magnesium-Based Composites with Metallic Additions. 5.10 Bimetal Mg/Al Macrocomposite. 6 CORROSION ASPECTS OF MAGNESIUM-BASED MATERIALS. 6.1 Introduction. 6.2 Types of Corrosion. 6.3 Influence of Impurity. 6.4 Corrosion Behavior of Magnesium-Based Materials. 6.5 Ways to Reduce Corrosion. 6.6 Summary. References. 7 STRENGTH-DUCTILITY COMBINATIONS OF MAGNESIUM-BASED MATERIALS. 7.1 0.2% Yield Strength "/i> 100 MPa and Ductility Matrix. 7.2 0.2% Yield Strength 100-150 MPa and Ductility Matrix. 7.3 0.2% Yield Strength 150-200 MPa and Ductility Matrix. 7.4 0.2% Yield Strength 200-250 MPa and Ductility Matrix. 7.5 0.2% Yield Strength 250-300 MPa and Ductility Matrix. 7.6 0.2% Yield Strength 300 MPa and Ductility Matrix. APPENDIX: LIST OF SOME MAGNESIUM SUPPLIERS. ABOUT THE AUTHORS. INDEX.

Steel Corrosion in Concrete: Fundamentals and civil engineering practice

Abstract: Introduction. Mechanisms of Steel Corrosion. Relations Between Corrosion and the Structure and Properties of Concrete. Corrosion Measurements. Corrosion Damage. Corrosion Measurements. Corrosion Control. Specificaitons and Design. Repair and Rehabilitation. Index.