Graphical analysis corrosion

One of the earliest NDT applications for laser-based profilometry systems was for the inspection of marine boiler tubes. Under funding from the U.S. Navy", several systems were developed that were capable of rapidly and accurately mapping the inside surface of 25 mm and 50 mm diameter boiler tubing. Features such as internal pitting and corrosion can be located and quantitatively assessed using computer-graphic analysis. The system employs an... 

Reactors should not dissolve in the reaction medium. Judging by spectro-graphic analysis of spent catalysts, some attack of the reactor is more common than is generally supposed. It may be a cause of catalyst failure. Reactors are commonly made of type 316 stainless steel, but other alloys may provide better resistance to spedhc corrosive agents. 

The corrosion current density and the potential are in this case most easily determined with a simple graphical analysis as shown in Figure 4.8. The thick curve shows the sum of cathodic current densities in the potential range where both reactions contribute. 

The numerical methods [32, 33, 34, 35, 36, 37] developed for the analysis of experimental polarization curves described by the current-voltage characteristic (2) with the aim of determining the electrochemical parameters a, /3 and h, are of considerable importance in the field of basic research as well as in corrosion rate monitoring. They permit, in fact, a more objective evaluation of these quantities with reference to a given potential difference interval AE, removing the degree of subjectivity that is inherent in the graphic determination of the Tafel slopes. 

In conditions where general corrosion occurs, metallo-graphic samples can be used to verify the extent of metal loss through microscopic measurements of sample thickness. Reduction of thickness coupled with weight loss information provides a checks and balances program into the analysis and reveals any corrosion rate differences due to anisotropy. 

Pitting and crevice corrosion tendencies of a material in a select environment may be determined by immersion testing or by electrochemical techniques. Immersion testing generally involves visual examination and dimensional analysis after exposure of a test specimen to a select environment. Electrochemical methods usually involve exposure of a test specimen to a select environment and graphical interpretation of data. 

The polarization curves (i/E) correspond to the graphic representation of this expression (Sastri, 1998). Analysis of these curves provides basic information on corrosion phenomena, which are very useful for studying sensitivity to corrosion from pitting, by determining the breakdown potential, also known as pitting nucleationpotential p and... 

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