Papers by Narendra Dahotre
Materials Science and Engineering: C, 2013
A high intensity continuous wave diode pumped ytterbium laser source was used to deposit CaP coat... more A high intensity continuous wave diode pumped ytterbium laser source was used to deposit CaP coatings on a Ti-6Al-4V biocompatible alloy in order to generate a physically textured surface, enhancing osseointegration. Scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) studies were coupled with X-ray and micro diffraction work to determine the structure, composition, and phases present in various zones of a sample prepared across the coating/substrate interaction zone. Three-dimensional thermal modeling was also carried out to determine the cooling rate and maximum temperature experienced by different regions of the substrate. Combining these results provide us with valuable insights regarding the thermo-physical as well as chemical interactions that take place across the coatingsubstrate interface.
Journal of Materials Science, 1990
Laser surface alloying (LSA) was used to formin situ Fe-Cr-C alloys on AISI 1018 steel substrates... more Laser surface alloying (LSA) was used to formin situ Fe-Cr-C alloys on AISI 1018 steel substrates. Chromium powders of different particle sizes were mixed together to obtain optimum packing density of the powder deposited on the substrate. The surface was then melted using a 2kW CW carbon dioxide laser. The processing conditions were related to solute (chromium) content, microstructural refinement
Journal of Non-Crystalline Solids, 2015
Laser annealing of Fe 77.5 Si 13.5 B 9 and Fe 76.5 Si 13.5 B 9 Cu 1 amorphous melt-spun ribbons w... more Laser annealing of Fe 77.5 Si 13.5 B 9 and Fe 76.5 Si 13.5 B 9 Cu 1 amorphous melt-spun ribbons was carried out. In both alloys, it was found that devitrification occurred, leading to the nucleation of a high density of refined α-Fe(Si) nanocrystals within the amorphous matrix. Interestingly, when laser processed under identical conditions, Fe 74.5 Si 13.5 B 9 Nb 3 , and Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 (FINEMET) amorphous melt-spun ribbons did not exhibit devitrification or copper clustering. Differences in the magnetic properties were observed, with the Fe 77.5 Si 13.5 B 9 and Fe 76.5 Si 13.5 B 9 Cu 1 alloys exhibiting higher saturation magnetization (M S ) and higher coercivity (H C ) values while Fe 74.5 Si 13.5 B 9 Nb 3 , and Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 alloys exhibited lower values of both these properties. These results clearly reveal the enhanced stability of the amorphous phase due to the addition of Nb in Fe-Si-B based melt-spun samples.
Materials Science Forum, 2003
Wear, 2001
In this study, the wear resistance of an A-356 aluminum alloy/WC composite obtained by a laser al... more In this study, the wear resistance of an A-356 aluminum alloy/WC composite obtained by a laser alloying technique has been analyzed. Different laser traversing velocities of 100, 200, 300 and 400cmmin−1 have been used to establish the optimum processing conditions. The interaction time between laser beam and the sample surface, depending on the traversing speed, has a noticeable influence on
Thin Solid Films, 2000
... MH Staia a , Corresponding Author Contact Information , E-mail The Corresponding Author , M. ... more ... MH Staia a , Corresponding Author Contact Information , E-mail The Corresponding Author , M. Cruz a , Narendra B. Dahotre b , E-mail The Corresponding Author. ... [4] GL Goswami, D. Kumar, AK Grover, AL Pappachan and MK Toltlani. Surf. Eng., 15 1 (1999), pp. 324329. ...
physica status solidi (RRL) – Rapid Research Letters, 2007
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Optics and Lasers in Engineering, 2009
Magnesia (MgO) ceramic was machined using a pulsed Nd:YAG laser. A mathematical model was develop... more Magnesia (MgO) ceramic was machined using a pulsed Nd:YAG laser. A mathematical model was developed to predict machined effects. The model took into account the physical phenomena taking place during machining of the ceramic such as multiple reflections influencing the absorbed laser energy, thermal effects in vaporizing the material, dissociation energy losses and effect of vapor pressure in producing a cavity through the ceramic. The laser fluence, machining time and number of pulses required for machining a certain depth of cavity and the efficiency of machining in terms of the specific machining depth were estimated and compared with the experimental data, thus making the model useful for advance energy predictions and enhancement of machining efficiency.
Minerals Engineering, 2006
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Materials Science and Engineering: A, 2005
The temperature range of thermal transitions within the quaternary system (Fe, Ti, Cr, and C) and... more The temperature range of thermal transitions within the quaternary system (Fe, Ti, Cr, and C) and the thermal stability of the evolved phases were studied with the help of differential scanning calorimetry (DSC). DSC studies indicated that the major exothermic reactions (formation of carbides) take place within 850-1150 • C. The evolved phases (TiC, M 7 C 3 , Fe-Cr, and Fe 3 C) were characterized using X-ray diffraction (XRD). This multicomponent powder mixture was used as a precursor for synthesizing a composite coating on the surface of steel via laser surface engineering (LSE). The intended wear applications of the coating made thermal stability investigations vital. Experimental evaluation of thermal stability of the phases formed was done.
Materials and Manufacturing Processes, 1992
Materials and Manufacturing Processes, 1995
JOM, 2009
Materials science and engineering is witnessing an increasing global focus on the materials relat... more Materials science and engineering is witnessing an increasing global focus on the materials related to energy, environment, and medical applications. The Surface Engineering Committee of the Materials Processing & Manufacturing Division (MPMD) of TMS has been active in promoting the novel applications of emerging materials and technology. In 2008, the Surface Engineering Committee had a JOM theme of Materials and Surfaces for Energetics that dealt with subjects ranging from energetics of micro-and nano-scale materials to processing for energetic applications. This year, our committee has focused on Articulation of Surfaces for Bio Applications. The confl uence of materials science with biology has opened up a plethora of opportunities for scientists and engineers to explore this exciting fi eld of research. In this issue of JOM, the Surface Engineering Committee presents fi ve papers that deal with different aspects of surface modifi cations for bio-applications.
Journal of Materials Science: Materials in Medicine, 2008
Laser surface processing was carried out in gaseous nitrogen atmosphere at ambient temperature. T... more Laser surface processing was carried out in gaseous nitrogen atmosphere at ambient temperature. The laser scan speed was varied (50-150 cm/min) at constant power of 1500 watts and resulting changes such as microstructural evolution, hardness, and electrochemical response of modified surface in Ringer's physiological solution at varying pH were studied. Increase in laser scanning speed was found to reduce the thickness of alloyed zone from 258 to 87 microm. The microstructure of laser-modified surface contains dendrites grown perpendicular to the laser traverse direction, beneath which basket weave structure of acicular alpha (martensite) was prevalent. Hardness at the top surface of laser-processed at 50 cm/min was approximately 1137 kg/mm2 that reduced with increase in the laser scan speed (577 kg/mm2 at 150 cm/min). Laser surface processing shifted the corrosion potential of Ti6Al4V towards noble side as compared to untreated alloy; the maximum shift by approximately 494 mV was recorded in pH approximately 9 solution. Passivation after laser surface modification was improved as currents were at least 1/3 of the untreated Ti6Al4V in passive region. While the pitting potential of untreated material was found to increase from 1.84 V for 4.0 pH to >2.5 V for 9.0 pH, the pitting potential after laser treatment was observed to drop from maximum of 74% for 4.0 pH (at 100 cm/min) to maximum of 42% for 9.0 pH (at 150 cm/min).
Journal of Materials Science: Materials in Medicine, 2007
Metals, in addition to ceramics and polymers, are important class of materials considered for rep... more Metals, in addition to ceramics and polymers, are important class of materials considered for replacement of non-functional parts in the body. Stainless steel 316, titanium and titanium alloys, Co-Cr, and nitinol shape memory alloys are the most frequently used metallic materials. These alloys are prone to corrosion in various extents. This review briefly discusses the important biomaterials, their properties, and the physiological environment to which these materials are exposed. Corrosion performance of currently used metallic materials has been assessed and threat to the biocompatibility from corrosion products/metal ions is discussed. The possible preventive measures to improve corrosion resistance by surface modification and to increase the bioactivity of the metallic surfaces have also been discussed. Importance of the formation of oxide layers on the metal surface, another aspect of corrosion process, has been correlated with the host response. The gap areas and future direction of research are also outlined in the paper.
Journal of Materials Research, 2003
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Papers by Narendra Dahotre