Corrosion-induced fields

The structure of thin-film inductive recording heads results in the exposure to the environment of small areas of metal, often permalloy (Ni-20Fe), which is a relatively corrosion-resistant alloy. In fact, in-service corrosion of permalloy is not a problem and thin-film inductive heads have no history of corrosion-induced field failure. However, corrosion of permalloy can occur during manufacturing, leading to yield losses. 

It should be noted that even if there are no shorts detected by electrical testing, the onset of such corrosion induces topography and weakens the interface with the SiCN capping layer, causing reliability problems. Evidence of this is presented by Liniger et al. (2010) in Figure 4.27 through time-dependent dielectric breakdown (TDDB) characterization of the effect of queue time. It can be seen that as queue time is increased, the time required for 50% of the structures to fail with a short under the applied electric field decreases. 

The total global emissions of H2S are estimated to be 70-80 Gg-S-yr (S stands for sulfur). Corrosion induced by H2S is a major risk in oil field equipment. The adsorption of HiS on a metallic surface is shown in Fig. 10.5. 

Various newer and more corrosion-resistant alloys are now available for use, including low nickel alloys, such as Inconel 800 (35% Ni, 20% Cr, 45% Fe). Low nickel alloys, in particular those with with less than 0.03% cobalt, are required to limit the development of a cobalt-induced, outer-core radiation field within the SG. 

Henry White was born in Chapel Hill. North Carolina in 1956. He received a B.S. in Chemistry from the University of North Carolina in 1978 and a Ph.D. in Chemistry from the University of Texas at Austin in 1982. He held a postdoctoral appointment at the Massachusetts Institute of Technology from 1983 to 1984 and was on the faculty of the Department of Chemical Engineering and Materials Science at the University of Minnesota from 1984 to 1993. He is currently a Professor of Chemistry at the University of Utah. His research interests include magnetic-field-induced transport, oxide films and corrosion, iontophoretic transdermal drug delivery, and electrochemical phenomena at electrodes of nanometer dimensions. 

Jan. 26, 1927, Farnborough, Great Britain - July 9, 2005, Ottawa, Canada) Canadian electrochemist, 1946-1949 Imperial College, London University, thesis on -> electrocatalysis and corrosion inhibitors (supervisor J.O M. Bockris), 1949-1954 Chester-Beatty Cancer Research Institute with J.A.V. Butler on DNA, 1954-1955 post-doc at University of Pennsylvania with J.O M. Bockris (among other subjects -> proton -+ mobility, the effect of field-induced reorientation of the water molecule), since 1956 professor at the University of Ottawa (Canada), more than 400 publications on physical electrochemistry, electrode kinetics and mechanisms, - electrochemical capacitors. 

Although it has been reported that an external DC electric field can induce an electrophoretic back transport that can significantly enhance flux in crossflow membrane filtration, its commercial implementation appears to be restricted by several factors. These include lack of suitably inexpensive corrosion-resistant electrode materials, concerns about energy consumption, and the complexity of module manufacture. 

Recent interest in ion beam processing has focused on studies of ion implantation, ion beam mixing, ion-induced phase transformations, and ion beam deposition. These interests have been stimulated by the possibilities of synthesizing novel materials with potential applications in the semiconductor, tribological, corrosion, and optical fields. 

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