The initial stages of lead oxidation in pH 9 to 14 aqueous solutions

1989 ◽  
Vol 67 (6) ◽  
pp. 1098-1104 ◽  
Author(s):  
V. I. Birss ◽  
W. Waudo
Keyword(s):  
Cyclic Voltammetry ◽  
Surface Film ◽  
Alkaline Solutions ◽  
Oxide Surface ◽  
Surface Films ◽  
Ion Content ◽  
Initial Product ◽  
Carbonate Solutions ◽  
Lead Hydroxide ◽  
Lead Oxidation

The initial stages of lead oxidation in a range of alkaline solutions of varying pH and ion content have been investigated with the use of cyclic voltammetry and potential step techniques. In both carbonate and borate buffered solutions (pH > 9), and in more alkaline solutions, Pb oxidation commences at a potential of ca. 140 mV vs. RHE. The initial product is considered to be Pb(OH)2, due to the proximity of this potential with the theoretically predicted one, and due to its invariance (vs. RHE) with pH. In pH 14 solutions, Pb(OH)2 is soluble, producing Pb(OH)3− and only a small amount of a stable surface film. At lower pH's, Pb(OH)2 is not predicted to be soluble, and in borate-buffered solutions, a stable, reducible film appears to form. In carbonate-buffered solutions, the surface film is very difficult to remove electrochemically. Although XPS analyses show the film to be essentially free of carbonate, it is clear that carbonate must be involved in some way in inhibiting film reduction. Keywords: lead, lead hydroxide, lead oxide, surface films, carbonate solutions, borate solutions, alkaline solutions, cyclic voltammetry.

Measurement of Thin Oxide Surface Film Thicknesses and Atomic Densities by the Analysis of Positive Ion Excited Soft X-Ray Spectral

1968 ◽  
Vol 12 ◽  
pp. 457-479 ◽  
Author(s):  
W. P. Saylor ◽  
C. L. Marks
Keyword(s):  
Thin Films ◽  
Surface Film ◽  
Target Material ◽  
High Sensitivity ◽  
Low Energy ◽  
Oxide Surface ◽  
Surface Films ◽  
Calibration Data ◽  
X Ray ◽  
Positive Ion

AbstractCharacteristic soft x-ray emission lines created as a result of low energy (10-100keV) positive ion excitation of a target material has been applied to the study of thin films of oxygen that form naturally on metal surfaces. The specific metals investigated were aluminum and nickel aa well as a number of their corresponding alloys.Low energy positive ions are well suited as projectiles for the study of thin films in that they have low penetrating powers, yet produce high x-ray yields for K-, L-, and M-shell elemental x-ray lines. Perhaps the most important feature is the fact that no background bremsstrahlung continuum x-radiation is generated in the slowing processes of the ions. Exploiting the advantages of these facts, a special high sensitivity detection technique has been developed for the soft x-ray analysis of the constituents that make up a particular thin surface film.The physical basis for thickness and atomic density measurements of thin surface films by positive ion excitation are discussed. Calibration data are presented for thin films of known thickness and composition establishing the sensitivity of the method for the measurement of the elemental atomic densities of thin films down to a few monolayers or approximately 10 Å in thickness. Finally, the results of the analysis of oxide surface films of aluminum, nickel and some of their alloys are presented and discussed.The objective of this continuing program is to gain an understanding of the mechanisms and principles governing the formation of oxide surface films on metals with the basic goal of producing new alloying techniques for metal passification in a saline environment.

Surface Films on Zircaloy-2 Samples Cracked in Neutral Aqueous NaCl by Stress Corrosion

1973 ◽  
Vol 31 ◽  
pp. 46-47
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Stress Corrosion ◽  
Zirconium Dioxide ◽  
Surface Film ◽  
Surface Films ◽  
Continuous Layer ◽  
Transmission Electron ◽  
Product Film

Samples of low-nickel Zircaloy-2 (material MLI-788-see(1)), when anodically polarized in neutral 5 wt% NaCl solutions, were found to be susceptible to pitting and stress corrosion cracking. The SEM revealed that pitting of stressed samples was occurring below a 2000Å thick surface film which behaved differently from normal zirconium dioxide in that it did not display interference colours. Since the initial film thickness was approximately 65Å, attempts were made to examine the product film by transmission electron microscopy to deduce composition and how the corrosion environment could penetrate the continuous layer.

Evaluation of a molybdenum sulfide reference electrode in hot alkaline solutions

TAPPI Journal ◽  
2010 ◽  
Vol 9 (7) ◽  
pp. 35-41
Author(s):  
OUTI A. HYÖKYVIRTA ◽  
TOM E. GUSTAFSSON
Keyword(s):  
Molybdenum Disulfide ◽  
Surface Film ◽  
Reference Electrode ◽  
Exposure Period ◽  
Molybdenum Sulfide ◽  
Alkaline Solutions ◽  
Internal Reference ◽  
Cell Potential ◽  
Pulp Digester ◽  
Alkaline Sulfide

This investigation evaluated the applicability of a molybdenum sulfide reference electrode (MSRE) as an internal reference electrode for use in alkaline sulfide solutions over a range of pulp digester liquors at 170°C. The electrode remained stable during the exposure period of two weeks. The experimentally determined half cell potential of the MSRE is E = -0.91 VSHE. The surface of the MSRE was examined by scanning electron microscope (SEM) and electron spectroscopy for chemical analysis (ESCA) to verify the chemical composition of the thin surface film. Based on ESCA studies, the surface film contained molybdenum disulfide and sodium disulfide. During storage of the specimens, sulfide was partly oxidized to sodium sulfite in air. Next to the metallic molybdenum, a mixed molybdenum disulfide and molybdenum hydroxide layer was detected.

ON THE MECHANISM OF THE DISSOLUTION OF MAGNESIUM IN ACIDIC SALT SOLUTIONS: I. PHYSICAL CONTROL BY SURFACE FILMS

1953 ◽  
Vol 31 (9) ◽  
pp. 849-867 ◽  
Author(s):  
E. J. Casey ◽  
R. E. Bergeron
Keyword(s):  
Ionic Strength ◽  
Chemical Control ◽  
Corrosion Potential ◽  
Surface Film ◽  
Surface Films ◽  
Salt Solutions ◽  
Acidic Solutions ◽  
Activity Temperature ◽  
Acidic Salt ◽  
High Concentrations

A kinetic study and analysis has been made of the effects of ionic strength, acid activity, temperature, and salt type on the dissolution of magnesium in acidic salt solutions. This is an example of the simplest type of corrosion involving hydrogen evolution. The results are interpreted in terms of the effects of the various factors on the structure of a surface film which must be magnesium oxide and/or hydroxide even in acidic solutions. The importance of internal dissolutions in the film at high concentrations of attacking reagent, for this and other cases, is shown. Owing to complex formation, under certain conditions an odd case of "chemical control" of the dissolution rate in this simplest case becomes evident. Corrosion potential measurements aid in the interpretation.

scholarly journals Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions

2021 ◽  
Author(s):  
Shishir Mundra ◽  
John L. Provis
Keyword(s):  
Mild Steel ◽  
Surface Film ◽  
Critical Role ◽  
Chloride Concentration ◽  
Alkaline Solutions ◽  
Sulfide Concentration ◽  
Chloride Induced Corrosion ◽  
Alkaline Sulfide ◽  
High Sulfide

AbstractThe pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer.

scholarly journals Elastic Properties of Natural Sea Surface Films Incorporated with Solid Dust Particles: Model Baltic Sea Studies

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Adriana Z. Mazurek ◽  
Stanisław J. Pogorzelski
Keyword(s):  
Baltic Sea ◽  
Surface Film ◽  
Contact Angles ◽  
Solid Particles ◽  
Sea Surface ◽  
Dust Particles ◽  
Surface Films ◽  
Particle Removal ◽  
Water Contact ◽  
Composite Surface

Floating dust-originated solid particles at air-water interfaces will interact with one another and disturb the smoothness of such a composite surface affecting its dilational elasticity. To quantify the effect, surface pressure (Π) versus film area (A) isotherm, and stress-relaxation (Π-time) measurements were performed for monoparticulate layers of the model hydrophobic material (of μm-diameter and differentiated hydrophobicity corresponding to the water contact angles (CA) ranging from 60 to 140°) deposited at surfaces of surfactant-containing original seawater and were studied with a Langmuir trough system. The composite surface dilational modulus predicted from the theoretical approach, in which natural dust load signatures (particle number flux, daily deposition rate, and diameter spectra) originated from in situ field studies performed along Baltic Sea near-shore line stations, agreed well with the direct experimentally derived data. The presence of seawater surfactants affected wettability of the solid material which was evaluated with different CA techniques applicable to powdered samples. Surface energetics of the particle-subphase interactions was expressed in terms of the particle removal energy, contact cross-sectional areas, collapse energies, and so forth. The hydrophobic particles incorporation at a sea surface film structure increased the elasticity modulus by a factor K (1.29–1.58). The particle-covered seawater revealed a viscoelastic behavior with the characteristic relaxation times ranging from 2.6 to 68.5 sec.

Rupture and Reformation of Ultra-Thin Surface Films

2010 ◽  
Author(s):  
William W. F. Chong ◽  
Mircea Teodorescu ◽  
Homer Rahnejat
Keyword(s):  
Thin Film ◽  
Data Storage ◽  
Surface Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Surface Films ◽  
Disk Drives ◽  
Film Rupture ◽  
Near Surface ◽  
Ultra Thin Film

In lubricated contact conjunctions film ruptures close to the exit boundary. This significantly affects the load carrying capacity and can lead to direct surface interactions. Nano-scale films (several molecular diameters of the lubricant) are no exception, a fact that has been observed using ellipsometry studies for ultra-thin film conjunctions representative for high storage capacity hard disk drives. Immediately beyond the film rupture an area of cavitation occurs and the continuity of flow condition is breached. It has been shown that for molecularly smooth surfaces solvation effect becomes dominant. This means that the contact exit is subject to discrete drainage of lubricant and may be devoid of a sufficient lubricant for film reformation to occur. This can be a stumbling block in an increasing quest to increase the data storage density of hard disk drives. Wear can become a problem as well as non-uniformity of free surface film at the inlet meniscus. It has been noted that peaks of lubricant can gather in some places, a phenomenon referred to as lubricant mogul. These localized piles of lubricant can exceed the nominally aimed for lubricant film thickness necessary for a given data storage level. This paper carries out an in-depth prediction of ultra thin film lubricant behavior through the contact. Hydrodynamic as well as near surface effects and intermolecular interactions responsible for the supply, formation, cavitation and reformation of thin films in the slider-disk conjunction have been considered.

Temperature and Orientation Dependence of Surface Film Effects in Single Crystal Nial

1986 ◽  
Vol 81 ◽  
Author(s):  
R.D. Noebe ◽  
J.T. Kim ◽  
R. Gibala
Keyword(s):  
Single Crystal ◽  
Crystallographic Orientation ◽  
Surface Film ◽  
Orientation Dependence ◽  
Surface Films ◽  
Temperature Dependent ◽  
Paper Surface ◽  
Bcc Metals ◽  
Coated Materials ◽  
Ordered Alloys

AbstractDuring deformation of bcc metals and bcc-based ordered alloys, conditions of elastic and plastic constraint associated with the presence of thin adherent surface films can be responsible for introducing increased densities of mobile dislocations in the metal, resulting in enhanced ductility and reduced yield and flow stresses of the film-coated materials. In the present paper, surface film effects were investigated as a function of temperature and crystallographic orientation for single crystal β-NiAl. Appreciable temperature-dependent and orientation-dependent surface film effects were observed, as were significant effects of film adherence on the observation of surface film softening.

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