The metallurgy of zinc-coated steel

Introduction 1. Aqueous Corrosion 2. Environments and Application Examples 3. high-Temperature Corrosion 4. Modeling, Life Prediction, and Computer Applications 5. Corrosion Failures 6. Corrosion Maintenance Through Inspection And Monitoring 7. Acceleration and Amplification of Corrosion Damage 8. Materials Selection 9. Protective Coatings 10. Corrosion Inhibitors 11. Cathodic Protection 12. Anodic Protection

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Handbook of Corrosion Engineering

“Hydrothermal synthesis” usually refers to heterogeneous reactions in aqueous media above 100°C and 1 bar. The previously common distinction between hydrothermal conditions below and pneumatolytic conditions above the critical point is no longer made, since no discontinuities are observed upon exceeding the critical conditions. Under hydrothermal conditions, reactants otherwise difficult to dissolve go into solution as complexes, in whose formation water itself or very soluble “mineralizers” can participate. Thus, one can obtain the conditions of chemical transport reactions,[1] of which hydrothermal syntheses can be considered a special case. During recent decades in the geological sciences—in which the method is also historically rooted—it has received a strong impulse, whose effect on preparative solid state chemistry is discussed here.

The Role of Hydrothermal Synthesis in Preparative Chemistry

SUMMARY Raman spectroscopy uses the inelastic scattering of electromagnetic radiation by molecules. Monochromatic light of a laser interacts with phonons, the vibrational modes in the crystal lattice. The energy of the scattered light is shifted by the scattering. The shifts in energy yield the Raman spectrum that is specific for each mineral because the phonons are specific for each mineral. In this study, Raman spectroscopy of synthetic and natural iron (oxy)hydroxides and iron oxides was performed to test its potential in environmental magnetic studies and soil science. The main aim was to distinguish between the different iron oxides occurring in soils. Most of them can be identified by magnetic methods, but there are some minerals that are not easy to differentiate from each other. In these cases, the magnetic methods can be complemented by Raman spectroscopy. A major challenge is the fast transformation of many iron minerals if laser power is applied, especially if the material is poorly crystallized as often is the case in environmental material. In this study, very low laser powers were applied. Nevertheless, the investigated iron minerals could be distinguished from each other. Thus, a magnetic method to discern lepidocrocite and ferrihydrite in soil samples could be corroborated. It is also shown that Raman spectroscopy is an easy method to distinguish magnetite and maghemite. Due to the low laser powers applied, a wuestite band at about 595 cm −1 could be established enabling a non-ambiguous identification of this mineral by its Raman spectrum. Furthermore, the potential of the method to investigate magnetic material produced by soil bacteria is demonstrated.

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Raman spectroscopy of iron oxides and (oxy)hydroxides at low laser power and possible applications in environmental magnetic studies

Thin films of three iron oxide polymorphs, hematite, maghemite, and magnetite, were produced on KBr substrates using a conventional electron beam deposition technique coupled with thermal annealing. This method allowed for iron oxide thin films free from chemical precursor contaminants. The films were characterized using Fourier-transform infrared spectroscopy (FTIR), Raman microspectroscopy, and ellipsometry. These spectroscopic techniques allowed for a clear assignment of the phase of the iron oxide polymorph films produced along with an examination of the degree of crystallinity possessed by the films. The films produced were uniform in phase and exhibited decreasing crystallinity as the thickness increased from 40 to 250 nm.

Vibrational Spectroscopic Characterization of Hematite, Maghemite, and Magnetite Thin Films Produced by Vapor Deposition

For fundamental studies of the atmospheric corrosion of steel, it is useful to identify the iron oxide phases present in rust layers. The nine iron oxide phases, iron hydroxide (Fe(OH)2), iron trihydroxide (Fe(OH)3), goethite (α-FeOOH), akaganeite (β-FeOOH), lepidocrocite (γ-FeOOH), feroxyhite (δ-FeOOH), hematite (α-Fe2O3), maghemite (γ-Fe2O3) and magnetite (Fe3O4) are among those which have been reported to be present in the corrosion coatings on steel. Each iron oxide phase is uniquely characterized by different hyperfine parameters from Mossbauer analysis, at temperatures of 300K, 77K and 4K. Many of these oxide phases can also be identified by use of Raman spectroscopy. The relative fraction of each iron oxide can be accurately determined from the Mossbauer subspectral area and recoil-free fraction of each phase. The different Mossbauer geometries also provide some depth dependent phase identification for corrosion layers present on the steel substrate. Micro-Raman spectroscopy can be used to uniquely identify each iron oxide phase to a high spatial resolution of about 1 µm.

Characterization of Iron Oxides Commonly Formed as Corrosion Products on Steel

Atmospheric corrosion of different steels in marine, rural and industrial environments

From 1934 to 1938, Bethlehem Steel Corporation initiated a series of outdoor corrosion tests involving several hundred low-alloy steel compositions. These tests were conducted in the indus...

Effects of Alloying Elements on the Corrosion of Steel in Industrial Atmospheres

Potential-pH diagrams at elevatedtemperature for the system Fe-H2O

Weathering steel (ASTM A588, Grade B) and steels with 0.021 and 0.21 percent copper were tested for corrosion resistance in marine, rural, and two industrial environments. The results of these tests are represented well by kinetic equations of the form C = At B , where C is the corrosion loss, t is time, and A and B are constants. On the basis of the time required to achieve a 250-μm (0.01 in.) thickness loss that is calculated using these equations, the weathering steel is 6 to 19 times more durable than the 0.021 percent copper steel and 2 to 10 times more durable than the 0.21 percent copper steel.

Herbert E. Townsend

Papers

Characterization of Iron Oxides Commonly Formed as Corrosion Products on Steel

Atmospheric corrosion of different steels in marine, rural and industrial environments

Effects of Alloying Elements on the Corrosion of Steel in Industrial Atmospheres

Potential-pH diagrams at elevatedtemperature for the system Fe-H2O

Eight-Year Atmospheric Corrosion Performance of Weathering Steel in Industrial, Rural, and Marine Environments