Corrosion methods, summarized

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. 

Although no ASTM ferrous metal corrosion specification exists now for gasoline, diesel fuel, and other fuels, many refiners and marketers have adopted the National Association of Corrosion Engineers (NACE) Corrosion Standard Method TM-01-72-93 as a specification. This method has also been utilized by most product pipeline companies and is an established requirement. The NACE corrosion method is summarized as follows ... 

In a description of the methods summarizing soldering flux corrosivity, it was concluded that a quantitative method to replace the qualitative visual assessments was needed. 

The best way to minimize corrosion in flowing water system is at the fabrication stage as discussed above. Other methods to minimize flow-induced corrosion are summarized below. 

Specifications for the principal LPG products are summarized in Table 4. Detailed specifications and test methods for LPG are pubHshed by the Gas Processor s Association (GPA) (3) and ASTM (4). The ASTM specification for special-duty propane and GPA specification for propane HD-5 apply to propane that is intended primarily for engine fuel. Because most domestic U.S. LPG is handled through copper tubing, which could fail if corroded, all products must pass the copper strip corrosion test. A test value of No. 1 represents a LPG noncorrosive to the copper. 

In most cases, except those in earlier comparative studies between the real-photon method and the dipole-simulation method, the absolute cross-section values obtained by both methods agree with each other [27]. Comparison of obtained cross-section values between the two methods were discussed in detail [27, 2, and references therein] and summarized in conclusion [5]. It should be noted, at least briefly, that it is essentially difficult to accurately obtain the absolute values of photoabsorption cross sections (u) in the dipole-simulation experiments, and it is necessary to use indirect ways in obtaining those values as the application of the TKR sum rule, Eq. (3), to the relative values of the cross sections obtained partly with theoretical assumptions. Moreover, in some cases, in relatively earlier dipole-simulation experiments, particularly of corrosive molecules upon their electron optics with poorer energy resolutions, serious discrepancy from the real-photon experiments was clearly pointed out in the obtained absolute values of photoabsorption cross sections [5,20,25-28]. 

Table 1 of a paper by Murr (2) lists problems and/or concerns related to specific interface materials and specific components of SECS. In Table 2 of the same work, he related topical study areas and/or research problems to S/S, S/L, S/G, L/L, and L/G interfaces. It is also useful to divide interface science into specific topical areas of study and consider how these will apply to interfaces in solar materials. These study areas are thin films grain, phase, and interfacial boundaries oxidation and corrosion adhesion semiconductors surface processes, chemisorption, and catalysis abrasion and erosion photon-assisted surface reactions and photoelectrochemistry and interface characterization methods. The actual or potential solar applications, research issues and/or concerns, and needs and opportunities are presented in the proceedings of a recent Workshop (4) and summarized in a recent review (3). 

Table 1 summarizes the most important surface analytical methods working in the UHV, with their characteristics and advantages, which have been applied successfully to the study of passivity and corrosion research as well as the solution of... 

The results of studies of copper surfaces by low-temperature adsorption isotherms may be summarized as follows. True surface areas of metallic specimens as small as 10 sq. cm. can be derived with a precision of 6% from low-temperature adsorption isotherms using vacuum microbalance techniques. This method is of special value in determining the average thickness of corrosion films formed by the reaction of gases or liquids with solids. The effect of progressive oxidation of a rough polycrystalline metal surface is to decrease the surface area to a point where the roughness factor approaches unity. 

Silverman has defined a number of useful expressions that allow one to utilize the rotating cylinder method with a variety of practical geometries (12,15). Both shear stresses and mass transfer coefficients are included in the derivations described (12). Table 1 in NACE standard TM-0270-72 summarized the various features of experimental systems for studying flow induced corrosion (22). 

Designing alloy electrocatalysts by the so-called ad-atom method, and by alloy sputtering for oxidation of CH3OH and CO, and for CO tolerance in H2 oxidation, respectively, as well as for O2 reduction are discussed. Many years of experience are summarized and collaborations with other groups are highlighted. The particle size effect in electrocatalysis by small particle electrodes, and the effect of corrosion of carbon-black supported nanoparticles on the electrocatalytic activity are also discussed. All these factors, as well as catalyst lifetimes, are very important in fuel cell performance and in the final cost estimates for the practical fuel cell applications. 

Various conditions of accelerated corrosion testing are summarized in Table 1.10. According to ISO 14993 [85], water condensation on the test specimens should not occur under wet conditions. The methods of testing organic coatings on metallic materials according to ISO 11997-1 under cyclic corrosion conditions include condensation of water on the test surface during the period of humidity [87]. 

Macdonald summarized the hmitations of EIS technique when used to measure the corrosion current (corrosion rates) of metals [79]. A high level of mathematics is required to analyze data and interpret properties of the corrosion system. Analysis of impedance data results in determination of the polarization resistance. However, it requires obtaining a large number of low-frequency data for an accurate estimate. It is necessary to extract the noise from the data obtained at low frequency ranges to obtain meaningful mechanistic information. To calculate the corrosion rate using the Stem-Geary equation, the Tafel method should be used to estimate the Tafel slopes as a function of time. Due to the variation of porosity of corrosion products on metals, the corrosion products (oxides and hydroxides) contributions to the overall impedance spectra are difficult to evaluate. 

Table 9.1 summarizes environmental alloy combinations that have been shown to produce see. The test temperature accelerates the See for most of the systems listed in Table 9.1. Electrochemical methods and stress corrosion tests should be performed to evaluate possible corrosion environments for a given alloy. More information on these and additional systems may be found in the ASM Metals Handbook [30]. Other significant alloys include nickel alloys [31], austenitic stainless steel [30], carbon steels [32], copper alloys [33], ferritic, martensitic, duplex [31,32], titanium alloys [33], and aluminum alloys [34].

The ASTM standard methods for evaluation of specimens subjected to accelerated tests are summarized in Table 13.7. The performance rating depends on subjective visual observation made by the operator. Also, high corrosion resistant coatings show no visual signs of deterioration after weathering. 

In part 9, structural repairs and corrosion repairs are covered separately. The corrosion methodology is summarized in Table 2 Principles and Methods Relating to Reinforcement Corrosion. This is reproduced as Table 8.3. 

In this section we briefly summarize the more traditional methods for controlling corrosion, including the use of barrier coatings, the use of inorganic and organic inhibitors, and the use of anodic and cathodic protection. More complete discussions of these methods can be found in Refs. [16,17]. 

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