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For metals where the electrolytic hydrogen evolution reaction gives a Tafcl line of low slope, e.g., 2.3 RT/2F or 2.3 RUF, the formulation of the reaction kinetics oil the assumption that the adsorbed hydrogen atoms obey a Lzngmuir isotherm is not in good agreenient with espcriniental data on surfxe coverage and reaction rates. A more consistent kinetic scheme is obtained by taking into account the variation with coierage of the heat of adsorption and activation energies for adsorption and desorption of hydrogen 011 metals. A Tafel slope of 2.3 RT/2F corresponds to a fast discharge reactloii fdhwed by a ratedetermining combination reaction, where the chemisorption of hydrogeir by tile metal is not activated. A Tafel slope of 2.3 RTIF corresponds to a fast discharge reaction followed by either a rate-deterrninii2g combiiiation reaction, where the chemisorption of hydrogen by the metal is activated, or by a rate-deiermining ioniatom reaction. It

A model of the electrochemical conditions in a static crack has been developed for steel in the active state based on the steady-state mass transport of species by diffusion and ion migration. The main reactions considered were anodic dissolution, hydrolysis of ferrous ions, and cathodic reduction of hydrogen ions and water with the assumption that the electrode reactions were taking place both at the tip and on the walls of the crack. The reduction of oxygen in the crack was not included since it was demonstrated in a separate analysis that this reaction is insignificant in a static crack at steady state. The pH and potential drop in the crack have been evaluated as a function of external potential, crack -dimensions, and other parameters assuming a bulk solution of 3.5% ik!aCl. The effect of dissolution and hydrolysis of alloying elements and also the buffer reactions of seawater on the pH within a crack were also assessed, but mass transport by ion migration was neglected in these cases. The theoretical predictions of the potential drop and pH were in reasonable agreement with values determined experimentally in an artificial crevice of the structural steel BS 4360 5OD in 3.5% NaCi and in artificial seawater.The electrochemical conditions within cracks are important in governing the rate of crack propagation in stress corrosion cracking and in corrosion fatigue * Electrochemical Society Active Member. since this will depend on the rate of metal dissolution and/or the rate of production of hydrogen atoms af the crack tip. A problem in characterizing the rates of electrode reactions within a crack is the lack of knowledge of the local solution composition and the electrode potential, which because of the restricted geom-) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252

Background: There has been significant progress in implant research during last the 10 years. The increase in the old age population coupled with a lack of proper physical activities is a potential causes for the sudden increment in the implant usages. However, implant life is limited due to the corrosion and tribocorrosion of implant materials. There is currently a large need for research in this area. Whether this need is being met or not has not been studied. Along this line, there has been no recent systematic approach made to analyze the progress of research and published work in this area. The objective of this work is to present the published literatures in the corrosion and tribocorrosion area during last century, giving more emphasize over last 10 years. The objective of this paper is to report the current status of the corrosion and tribocorrosion research in bio-implants based on the literature reviews. The review demonstrate that during last 10 years, there is a significant progress in the implant research, particularly in tribocorrosion research.

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