Pitting corrosion description

In this sub-section, we present the available theoretical descriptions for the effect of convection on pitting corrosion and metal salt deposition. Three models described in the literature are relevant these are discussed in the next three sections. 

It is perhaps not a surprise to learn that most modem analytical instruments have their place in archaeo-metric and/or conservation research. Many techniques are used extensively to study ceramic and metallic specimens or to identify pitting, weathering crusts, inclusions, efflorescence, and corrosion products on the surface of samples taken from specimens. In addition, the homogeneity of materials of mixed composition is examined, the results of previous restorations are assessed, and the major, minor, and trace element compositions of samples are recorded. A selection of instruments commonly used in archaeology and conservation research is given below. Detailed descriptions of the instruments can be found in the relevant articles in this encyclopedia. 

General Description. Cavitation is a form of erosion-corrosion that is caused by the formation and collapse of vapor bubbles in a liquid against a metal surface. Cavitation occurs in hydraulic turbines, on pump impellers, on ship propellers, and on many surfaces in contact with high-velocity liquids subject to changes in pressure. The appearance of cavitation is similar to pitting except that surfaces in the pits are usually much rougher. The affected region is free of deposits and accumulated corrosion products if cavitation has been recent. 

Description and corrosion resistance. This alloy s high critical pitting crevice temperatures provide more resistance to pitting and crevice corrosion than lesser-alloyed materials. The very high yield strength of this alloy combined with good ductihty allows lower wall thickness in process equipment. 

Description and corrosion resistance. Incoloy 825 is a nickel-iron-chromium alloy with additions of molybdenum and copper. It has excellent resistance to both reducing and oxidizing acids, stress-corrosion cracking, and localized attack such as pitting and crevice corrosion. The alloy is especially resistant to sulfuric and phosphoric acids. 

The initiation of crevice corrosion by pitting inside the crevice gap is mainly invoked for stainless steels. Indeed, several investigators [23,46,63,64] have observed pitting and further coalescence of the pits inside stainless steel crevices. Eklund [64] showed that pitting on MnS inclusions near the mouth of the crevice may be the initial stage of crevice corrosion of stainless steels. Oldfield and Sutton [46] have given a detailed description of... 

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