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S. Ganesh Sundara Raman

Other affiliations: Indian Institutes of Technology
Bio: S. Ganesh Sundara Raman is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Fretting & Ultimate tensile strength. The author has an hindex of 30, co-authored 89 publications receiving 2264 citations. Previous affiliations of S. Ganesh Sundara Raman include Indian Institutes of Technology.


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TL;DR: The surface morphological features reveal that the oxide film formed on Ti6Al4V alloy is adherent to the substrate at 500 and 650°C irrespective of the oxidation time whereas it spalls off when the alloy is oxidized at 800°C for more than 8h as discussed by the authors.

178 citations

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TL;DR: In this article, the corrosion behavior of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys was evaluated using polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution while their passivation behaviour was studied in 1N sulphuric acid solution.
Abstract: The present work deals with evaluation of corrosion behaviour of electrodeposited nanocrystalline Ni–W and Ni–Fe–W alloys. Corrosion behaviour of the coatings deposited on steel substrates was studied using polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution while their passivation behaviour was studied in 1N sulphuric acid solution. The corrosion resistance of Ni–W alloys increased with tungsten content up to 7.54 at.% and then decreased. In case of Ni–Fe–W alloys it increased with tungsten content up to 9.20 at.% and then decreased. The ternary alloy coatings exhibited poor corrosion resistance compared to binary alloy coatings due to preferential dissolution of iron from the matrix. Regardless of composition all the alloys exhibited passivation behaviour over a wide range of potentials due to the formation of tungsten rich film on the surface.

145 citations

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TL;DR: In this article, the authors present synthesis, characterization and evaluation of hardness and sliding wear resistance of electrodeposited nanocrystalline Ni-W alloys with 9.33 at.
Abstract: The present work involves synthesis, characterization and evaluation of hardness and sliding wear resistance of electrodeposited nanocrystalline Ni–W alloys. Crystallite size reduced with an increase in current density due to an increase in the W content. Ni–W alloy with 9.33 at.% W plated at 75 °C exhibited the maximum hardness of 638 HV. Alloys plated at 75 °C followed direct Hall–Petch relation. However, alloys plated at 85 °C exhibited an inverse Hall–Petch relation below a crystallite size of 15 nm. Wear resistance of alloys plated at 75 °C increased due to an increase in hardness with a reduction in the crystallite size up to 20 nm. It reduced due to brittle fracture of the coating below 20 nm. Wear resistance of alloys plated at 85 °C increased with a reduction in the crystallite size in the direct Hall–Petch region and decreased in the inverse Hall–Petch region. Ni–W coatings with 6–8 at.% W exhibited superior wear resistance.

138 citations

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TL;DR: In this paper, commercially pure titanium (CP Ti) samples were oxidized thermally at three different temperatures (500, 650 and 800 °C) for 24 hours and evaluation of their morphological and structural characteristics, microhardness and corrosion resistance in Ringer's solution was done.

88 citations

Journal ArticleDOI
TL;DR: The study reveals that surface modification of CP-Ti by both anodizing and thermal oxidation improved the fretting-corrosion resistance ofCP-Ti and among them the performance of thermally oxidized CP- Ti is superior to that of the anodized one.

84 citations


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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
Abstract: This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

1,668 citations

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TL;DR: In this article, the authors discuss various issues associated with biological corrosion of different kinds of implants used as cardio stents, orthopedic and dental implants, which is considered to be the best solution to combat corrosion and to enhance the life span of the implants and longevity of the human beings.
Abstract: In the area of materials science, corrosion of biomaterials is of paramount importance as biomaterials are required for the survival of the human beings suffering from acute heart diseases, arthritis, osteoporosis and other joint complications. The present article discusses various issues associated with biological corrosion of different kinds of implants used as cardio stents, orthopedic and dental implants. As the materials used for these implants are manifold starting from metallic materials such as stainless steel (SS), cobalt chromium, titanium and its alloys, bioceramics, composites and polymers are in constant contact with the aggressive body fluid, they often fail and finally fracture due to corrosion. The corrosion behavior of various implants and the role of the surface oxide film and the corrosion products on the failure of implants are discussed. Surface modification of implants, which is considered to be the best solution to combat corrosion and to enhance the life span of the implants and longevity of the human beings is dealt in detail and the recent advances in the coating techniques which make use of the superior properties of nanomaterials that lead to better mechanical properties and improved biocompatibility are also presented.

584 citations

Journal ArticleDOI
TL;DR: This article focuses on biocompatible metals which favorably used as implants such as 316L stainless steel, cobalt-chromium-molybdenum, pure titanium and titanium-based alloys, and the mechanism to improve it.

440 citations