Surface analysis corrosion

XPS has been used in almost every area in which the properties of surfaces are important. The most prominent areas can be deduced from conferences on surface analysis, especially from ECASIA, which is held every two years. These areas are adhesion, biomaterials, catalysis, ceramics and glasses, corrosion, environmental problems, magnetic materials, metals, micro- and optoelectronics, nanomaterials, polymers and composite materials, superconductors, thin films and coatings, and tribology and wear. The contributions to these conferences are also representative of actual surface-analytical problems and studies [2.33 a,b]. A few examples from the areas mentioned above are given below more comprehensive discussions of the applications of XPS are given elsewhere [1.1,1.3-1.9, 2.34—2.39]. 

Environmental tests have been combined with conventional electrochemical measurements by Smallen et al. [131] and by Novotny and Staud [132], The first electrochemical tests on CoCr thin-film alloys were published by Wang et al. [133]. Kobayashi et al. [134] reported electrochemical data coupled with surface analysis of anodically oxidized amorphous CoX alloys, with X = Ta, Nb, Ti or Zr. Brusic et al. [125] presented potentiodynamic polarization curves obtained on electroless CoP and sputtered Co, CoNi, CoTi, and CoCr in distilled water. The results indicate that the thin-film alloys behave similarly to the bulk materials [133], The protective film is less than 5 nm thick [127] and rich in a passivating metal oxide, such as chromium oxide [133, 134], Such an oxide forms preferentially if the Cr content in the alloy is, depending on the author, above 10% [130], 14% [131], 16% [127], or 17% [133], It is thought to stabilize the non-passivating cobalt oxides [123], Once covered by stable oxide, the alloy surface shows much higher corrosion potential and lower corrosion rate than Co, i.e. it shows more noble behavior [125]. 

Electrochemical impedance spectroscopy was used to determine the effect of isomers of 2,5-bis( -pyridyl)-l,3,4-thiadiazole 36 (n 2 or 3) on the corrosion of mild steel in perchloric acid solution <2002MI197>. The inhibition efficiency was structure dependent and the 3-pyridyl gave better inhibition than the 2-pyridyl. X-ray photoelectron spectroscopy helped establish the 3-pyridyl thiadiazoles mode of action toward corrosion. Adsorption of the 3-pyridyl on the mild steel surface in 1M HCIO4 follows the Langmuir adsorption isotherm model and the surface analysis showed corrosion inhibition by the 3-pyridyl derivative is due to the formation of chemisorbed film on the steel surface. 

This book systematically summarizes the researches on electrochemistry of sulphide flotation in our group. The various electrochemical measurements, especially electrochemical corrosive method, electrochemical equilibrium calculations, surface analysis and semiconductor energy band theory, practically, molecular orbital theory, have been used in our studies and introduced in this book. The collectorless and collector-induced flotation behavior of sulphide minerals and the mechanism in various flotation systems have been discussed. The electrochemical corrosive mechanism, mechano-electrochemical behavior and the molecular orbital approach of flotation of sulphide minerals will provide much new information to the researchers in this area. The example of electrochemical flotation separation of sulphide ores listed in this book will demonstrate the good future of flotation electrochemistry of sulphide minerals in industrial applications. 

The surface of a solid sample interacts with its environment and can be changed, for instance by oxidation or due to corrosion, but surface changes can occur due to ion implantation, deposition of thick or thin films or epitaxially grown layers.91 There has been a tremendous growth in the application of surface analytical methods in the last decades. Powerful surface analysis procedures are required for the characterization of surface changes, of contamination of sample surfaces, characterization of layers and layered systems, grain boundaries, interfaces and diffusion processes, but also for process control and optimization of several film preparation procedures. 

Various surface analysis techniques show that silicate glasses rapidly develop surface compositional profiles when exposed to water. When water is present as a vapor an alkali-rich layer (presumably a hydrated alkali carbonate) forms over the SiOj-rich layer. Water as a liquid dissolves the alkali and leaves the silica-rich film. As long as this SiC -rich film is stable the rate of corrosion due to diffusion is reduced with exposure time. Addition of multi-valent species to the glass or reactant results in formation of a complex protective surface layer in the glass which may be stable over a wide range of environmental conditions. 

Common concerns involving metal contacts include adhesion to the substrate, degradation due to corrosion, electromigration etc. and the tendency for some multilayered metallization schemes to undergo rapid interdiffusion. Surface analysis has been used to address a number of these problems. 

Corrosion necessarily involves a reaction of a material with its environment at a solid-gas, solid-liquid or solid-solid interface. One might think, therefore, that corrosion scientists would be among the most enthusiastic users of surface analytical techniques, which by their nature examine such interfaces (5). However, as McIntyre (5) notes about XPS, "the impact on corrosion science has been rather modest," and according to an editorial in Corrosion (6), any significance of surface science in solving corrosion problems is not obvious to many corrosion professionals and plant operators. Recent advances in surface science techniques have increased the usefulness of these methods in applied areas such as corrosion. To understand the current role of surface analysis in corrosion research and problem solving, it is necessary to know about the many forms of corrosion and the advantages and limitations of surface techniques in each area. 

Potential Problems. Most, but not all, of the surface sensitive techniques require measurements to be made in a vacuum, frequently near room temperature. Because these conditions are usually different from the corrosion conditions, the possibility that the desired information will be lost in the transfer from the corrosion chamber to surface analysis chamber is a major concern. There is also a possiblity that the measurement itself will alter the composition or chemistry of interest. Various aspects of those problems may apply to any method for which analysis occurs under conditions different from those in which the sample is generated, but they are of particular concern for surface methods that examine the very outer layers of the material. 

The null or non-informative result is a particular problem in surface analysis because it can occur for many reasons. For example, if a contaminant, such as Cl, is suspected of causing a corrosion problem and it is searched for and not found, there are several possible reasons. It may not be the problem and thus should not be found. However, there are several other less desirable possibilities including it was washed off as the samples were being prepared it caused the corrosion, but is not present in the corrosion layer being examined (the sample is being examined in wrong condition) it is present at concentrations below the sensitivity level of the technique it is removed by the analysis conditions (probe effect) it is at a location other than that being examined (in a different area of the sample or at an... 

The purpose of this section is to show, by example, how the concerns of technique selection, potential problems, data acquisition and analysis have been applied for several different corrosion problems and techniques. Examples of fundamental research work and industrial problem solving have been included to show the range of applicability of the techniques. In most cases, more than one technique was used to solve the problem. Frequently, a surface analysis technique was used in combination with one or more other types of analysis method. These examples are not comprehensive it is hoped that sufficient references have been supplied to enable the reader to find other work of relevant interest. 

In the past ten years the number of chemistry-related research problems in the nuclear industry has increased dramatically. Many of these are related to surface or interfacial chemistry. Some applications are reviewed in the areas of waste management, activity transport in coolants, fuel fabrication, component development, reactor safety studies, and fuel reprocessing. Three recent studies in surface analysis are discussed in further detail in this paper. The first concerns the initial corrosion mechanisms of borosilicate glass used in high level waste encapsulation. The second deals with the effects of residual chloride contamination on nuclear reactor contaminants. Finally, some surface studies of the high temperature oxidation of Alloys 600 and 800 are outlined such characterizations are part of the effort to develop more protective surface films for nuclear reactor applications. ... 

Electrochemical techniques alone cannot reveal all the relevant aspects of chromate inhibition, and key characterization experiments involving surface analysis, solution analysis, or other techniques are required to help understand inhibition. For this reason, several useful nonelectrochemical techniques are also discussed. These techniques provide a means for examining the effects of inhibition under free corrosion conditions where electrochemical methods are not well suited for measuring corrosion rate. 

Refs. [i] Briggs D, Seah MP (1983) Practical surface analysis. Wiley, New York [ii] Marcus P, Mansfeld F (eds) (2006) Analytical methods in corrosion science and engineering. Taylor and Francis, Boca Raton... 

In this review results from two surface science methods are presented. Electron Spectroscopy for Chemical Analysis (ESCA or XPS) is a widely used method for the study of organic and polymeric surfaces, metal corrosion and passivation studies and metallization of polymers (la). However, one major accent of our work has been the development of complementary ion beam methods for polymer surface analysis. Of the techniques deriving from ion beam interactions, Secondary Ion Mass Spectrometry (SIMS), used as a surface analytical method, has many advantages over electron spectroscopies. Such benefits include superior elemental sensitivity with a ppm to ppb detection limit, the ability to detect molecular secondary ions which are directly related to the molecular structure, surface compositional sensitivity due in part to the matrix sensitivity of secondary emission, and mass spectrometric isotopic sensitivity. The major difficulties which limit routine analysis with SIMS include sample damage due to sputtering, a poor understanding of the relationship between matrix dependent secondary emission and molecular surface composition, and difficulty in obtaining reproducible, accurate quantitative molecular information. Thus, we have worked to overcome the limitations for quantitation, and the present work will report the results of these studies. 

Over the past decade, a revolution has occurred in the field of electrochemistry with the development of in situ and ex situ surface analysis techniques capable of resolving important phenomena on both microscopic and short time scales. These techniques should be adapted and utilized to characterize local physicochemical corrosion events in situ. In addition, in situ techniques should be extended to provide on-line monitoring of real-world systems where reliability often requires detecting the onset and progress of corrosion phenomena (e.g., pit depth and crack length) as a function of time. 

The first consideration in defect analysis is whether the part has been handled after removal from service. Handling can alter the appearance or contaminate it to the point that either failure analysis could not be conducted or the root cause could not be determined. Surface analysis techniques are sensitive to handling and cannot distinguish between the changes caused by the failure and contamination. The best practice is to minimize handling the part and keep track of the history of the part. There are certain steps that frequently have to be taken such as decontamination of parts that have been in contact with corrosive, toxic, or flammable chemicals. A log should be considered to keep track of what has been done to the part, which may help explain any unforeseen consequences of part handling. 

Most of the surface spectroscopic techniques require a vacuum environment. High vacuum conditions ensure that the particles used have long mean free paths to interact with the surface of interest. The vacuum environment also keeps the surface free from adsorbed gases during the surface analysis experiment. The exceptions to the high vacuum requirement arc the photon-photon techniques given in the last three rows of Table 21-T These allow examination of surfaces under conditions more akin to those used in applications such as catalysis, sensing, and corrosion studies. 

This paper wiU build on previous reviews which have sought to explore the marmer in which surface analysis methods can be purposefully employed to understand adhesion phenomena [4—6], with an emphasis on the elucidation of interphase chemistry. The rationale behind such an approach is that it is this critical region of a polymer/metal or polymer/polymer couple that will influence the performance of the overall system, be it the durability of an adhesive joint or the corrosion protection performance of an organic coating. 

The term surface analysis is used to mean the characterization of the chemical and physical properties of the surface layer of solid materials. The surface layer of a solid usually differs in chemical composition and in physical properties from the bulk solid material. A common example is the thin layer of oxide that forms on the surface of many metals such as aluminum upon contact of the surface with oxygen in air. The thickness of the surface layer that can be studied depends on the instrumental method. This layer may vary from one atom deep, an atomic monolayer, to 100-1000 nm deep, depending on the technique used. Surface analysis has become increasingly important because our understanding of the behavior of materials has grown. The nature of the surface layer often controls important material behavior, such as resistance to corrosion. The various surface analysis methods reveal the elements present, the distribution of the elements, and sometimes the chemical forms of the elements in a surface layer. Chemical speciation is possible when multiple siuface techniques are used to study a sample. 

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