A UNS S 32654 , A STAINLESS STEEL FOR CONDENSER TUBES
The new superaustenitic stainless steel UNS S32654 (Avesta Sheffield 654 SMO) is proposed for condenser tubes in desalination and power plants. A number of tests illustrating its corrosion resistance in a variety of chloride containing environments are being reviewed in terms of pitting, crevice corrosion and stress corrosion cracking. Relevant mechanical and physical properties are described. Health hazards and the impact on the environment are discussed as well as the cost benefits of using a stainless steel for this application.
Behaviour of High Strength Molybdenum Containing Stainless Steels in Arabian Gulf Water. Part 1: Oxide Film Thickening
AbstractThe variation with time of the open circuit potentials of six molybdenum containing stainless steels was measured in Arabian Gulf water under conditions simulating operation in multistage flash evaporation distillers. The effects of temperature in the range 22–70°C and of sea water concentrated by cold evaporation to between 100 and 150% were examined in detail. With all steels, plots of potential as a function of logarithm of immersion time consisted of two straight line segments: the first, characterised by a lower slope, was attributed to the formation of a very thin, barrier type oxide layer, whereas the second related to longer times of immersion, indicating the formation of a thicker film. The mean rates of thickening of both forms of oxide (δ¯1 and δ¯2) were computed according to open circuit transient theory. Depending on the type of steel, δ¯2/δ¯1 varied between 4·6 and 11·0 below 40°0C and 1·1 and 1·6 at 70°C. Curves representing the variation of δ¯1 and δ¯2 with temperature exhibited ma...
Measuring Sheet Resistances of Dielectrics Using Co‐Planar Hydrogel Electrochemical Cells with Practical Applications to Characterize the Protective Quality of Paints on Sculptures
Electrical properties of thin dielectric films at the solid-liquid phase boundary are an important performance characteristic of many devices, coatings and sensors. In this paper, co-polymeric hydrogels of polyacrylic acid co-sulfonic acid, swollen with a salt solution to act as the solid electrolyte, were used to assess interfaces using electrochemical impedance spectroscopy (EIS) in a co-planar geometry. Silane-modified glasses were characterized by the co-planar hydrogel EIS cell and found to be distinguishable based on their surface monolayer chemistry. EIS measurements were also made on primed and painted metal substrates, using both test panels and an outdoor sculpture, Tony Smith's Stinger. The panels were then exposed to accelerated and outdoor weathering and showed degradation on the surface paint layers, which was observable electrochemically using EIS and confirmed visually by SEM. Electrochemical spectral features were compared between data from a standard paint-test cell versus this co-planar hydrogel cell; both cell types were able to measure coating capacitance, providing useful information about the condition of the bulk coating. Yet, sheet resistance (Rs) was a spectral feature seen only by the co-planar hydrogel cell. Thus, it can be concluded that the use of such co-planar hydrogel cells can provide an earlier warning sign to coating degradation and such cells provide a new type of spectral information that is not assessable by the standard geometry.