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Pauline S.A.,Anna University | Sahila S.,Anna University | Gopalakrishnan C.,SRM University | Nanjundan S.,PERI Institute of Technology | Rajendran N.,Anna University
Progress in Organic Coatings | Year: 2011

In this study the potential of the terpolymer synthesized from poly(maleic anhydride-co-methyl methacrylate) and hydroxymethylbenzimidazole as corrosion protective coating for 60-40 brass was evaluated using dip coating technique. The copolymer, poly(maleic anhydride-co-methyl methacrylate) synthesized using free radical solution polymerization was reacted with different feed ratios of hydroxymethylbenzimidazole (HMBD) to obtain terpolymers containing maleic anhydride, MMA and mono benzimidazolylmethyl ester of maleic acid (MBMEMA) units. Both the copolymer and the terpolymers were characterized using FT-IR, 1H NMR and 13C NMR spectroscopy. The thermal stability of the polymers was studied using thermogravimetric analysis (TGA) and the molecular weight of the polymer was analyzed using gel permeation chromatography (GPC). The effect of different concentrations of MBMEMA in the polymer for corrosion protection of brass in 3.5% NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. Effective corrosion protection was obtained when the mole fraction of MBMEMA was 0.24 in the terpolymer. The surface morphology of the polymer coated specimens was studied by scanning electron microscopy (SEM). Solution analysis was used to calculate the dezincification factor. © 2011 Elsevier B.V. Source

Balakrishnan G.,National Institute of Technology Tiruchirappalli | Balakrishnan G.,PERI Institute of Technology | Sundari S.T.,Indira Gandhi Center for Atomic Research | Kuppusami P.,Indira Gandhi Center for Atomic Research | And 5 more authors.
Thin Solid Films | Year: 2011

Thin films of cerium oxide (CeO2) have been deposited on (100) Si substrates using pulsed laser deposition technique at various substrate temperatures from room temperature (RT) to 973 K at an optimized oxygen partial pressure of 3 Pa. Structural, morphological and optical properties have been carried out using X-ray diffraction (XRD), Raman, ellipsometry and atomic force microscopy techniques. XRD results showed that the deposited films are polycrystalline with cubic structure. At room temperature, the film showed preferred orientation along (111) plane, while at higher temperatures, it exhibited preferred orientation along (200). The crystallite sizes were calculated and were found to be in the range 17-52 nm. The texture coefficient for (200) reflection increased until 573 K, and then decreased in the temperature range 673-973 K. The Raman peak appeared at 463 cm- 1 due to the F2g active mode also confirmed the formation of CeO 2 with a cubic structure. There was a systematic variation in the Raman peak intensity, frequency shift and line broadening with the increase of temperature. The ellipsometry studies showed that the refractive index and band gap increased from 2.2 to 2.6 and 3.4 to 3.6 eV, respectively with increasing substrate temperature from RT to 973 K. © 2010 Elsevier B.V.All rights reserved. Source

Balakrishnan G.,Changwon National University | Balakrishnan G.,PERI Institute of Technology | Kuppusami P.,Sathyabama University | Sastikumar D.,National Institute of Technology Tiruchirappalli | Song II J.,Changwon National University
Nanoscale Research Letters | Year: 2013

Alumina/zirconia (Al2O3/ZrO2) multilayer thin films were deposited on Si (100) substrates at an optimized oxygen partial pressure of 3 Pa at room temperature by pulsed laser deposition. The Al2O3/ZrO2multilayers of 10:10, 5:10, 5:5, and 4:4 nm with 40 bilayers were deposited alternately in order to stabilize a high-temperature phase of zirconia at room temperature. All these films were characterized by X-ray diffraction (XRD), cross-sectional transmission electron microscopy (XTEM), and atomic force microscopy. The XRD studies of all the multilayer films showed only a tetragonal structure of zirconia and amorphous alumina. The high-temperature XRD studies of a typical 5:5-nm film indicated the formation of tetragonal zirconia at room temperature and high thermal stability. It was found that the critical layer thickness of zirconia is ≤10 nm, below which tetragonal zirconia is formed at room temperature. The XTEM studies on the as-deposited (Al2O3/ZrO2) 5:10-nm multilayer film showed distinct formation of multilayers with sharp interface and consists of mainly tetragonal phase and amorphous alumina, whereas the annealed film (5:10 nm) showed the inter-diffusion of layers at the interface. © 2013 Balakrishnan et al.; licensee Springer. Source

Balakrishnan G.,PERI Institute of Technology | Kuppusami P.,Indira Gandhi Center for Atomic Research | Murugesan S.,Indira Gandhi Center for Atomic Research | Ghosh C.,Indira Gandhi Center for Atomic Research | And 3 more authors.
Materials Chemistry and Physics | Year: 2012

Microstructural characterization of pulsed laser deposited Al 2O 3/ZrO 2 multilayers on Si (1 0 0) substrates at an optimized oxygen partial pressure of 3 × 10 -2 mbar and at room temperature (298 K) has been carried out. A nanolaminate structure consisting of alternate layers of ZrO 2 and Al 2O 3 with 40 bi-layers was fabricated at different zirconia layer thicknesses (20, 15 and 10 nm). The objective of the work is to study the effect of ZrO 2 layer thickness on the stabilization of tetragonal ZrO 2 phase for a constant Al 2O 3 layer thickness of 5 nm. The Al 2O 3/ZrO 2 multilayer films were characterized using high temperature X-ray diffraction (HTXRD) in the temperature range 298-1473 K. The studies showed that the thickness of the zirconia layer has a profound influence on the crystallization temperature for the formation of tetragonal zirconia phase. The tetragonal phase content increased with the decrease of ZrO 2 layer thickness. The cross-sectional transmission electron microscope (XTEM) investigations were carried out on a multilayer thin films deposited at room temperature. The XTEM studies showed the formation of uniform thickness layers with higher fraction of monoclinic and small fraction of tetragonal phases of zirconia and amorphous alumina. © 2012 Elsevier B.V. Source

Balakrishnan G.,PERI Institute of Technology | Sairam T.N.,Indira Gandhi Center for Atomic Research | Kuppusami P.,Indira Gandhi Center for Atomic Research | Thiumurugesan R.,Indira Gandhi Center for Atomic Research | And 3 more authors.
Applied Surface Science | Year: 2011

ZrO2 thin films were deposited at various oxygen partial pressures (2.0 × 10-5-3.5 × 10-1 mbar) at 973 K on (1 0 0) silicon and quartz substrates by pulsed laser deposition. The influence of oxygen partial pressure on structure, surface morphology and optical properties of the films were investigated. X-ray diffraction results indicated that the films are polycrystalline containing both monoclinic and tetragonal phases. The films prepared in the oxygen partial pressures range 2.0 × 10-5-3.5 × 10-1 mbar contain nanocrystals of sizes in the range 54-31 nm for tetragonal phase. The peak intensity of the tetragonal phase decreases with the increase of oxygen partial pressures. Surface morphology of the films examined by AFM shows the formation of nanostructures. The RMS surface roughness of the film prepared at 2.0 × 10-5 mbar is 1.3 nm while it is 3.2 nm at 3.5 × 10-1 mbar. The optical properties of the films were investigated using UV-visible spectroscopy technique in the wavelength range of 200-800 nm. The refractive index is found to decrease from 2.26 to 1.87 as the oxygen partial pressure increases from 2.0 × 10-5 to 3.5 × 10-1 mbar. The optical studies show two different absorption edges corresponding to monoclinic and tetragonal phases. © 2011 Elsevier B.V. All rights reserved. Source

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