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Dey A.,Thermal System Group | Banerjee K.,Bengal Engineering and Science University | Mukhopadhyay K.,Indian Central Glass and Ceramic Research Institute
Materials Technology | Year: 2014

Highly crystalline (∼80%) yet porous (∼20%) hydroxyapatite (HAp) coating was developed on surgical grade SS316L substrate by the microplasma spraying (MIPS) technique. Phase analysis and microstructural characterisations were carried out by X-ray diffraction, scanning electron microscopy and field emission scanning electron microscopy. Nanohardness and Young's modulus were measured by the nanoindentation technique at 100 mN load. Further, the Hap coatings were immersed in simulated body fluid (SBF) environment for 1-14 days to investigate their in vitro properties. Finally, single pass microscratch test was also conducted on the MIPSHAp coatings after immersion in SBF. © 2014 W. S. Maney & Son Ltd. Source


Dey A.,Thermal System Group | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute
International Journal of Applied Ceramic Technology | Year: 2014

Hydroxyapatite coating was developed with high degree of crystallinity on SS316L substrate by the microplasma spraying technique. Systematic in vitro study of the coating was conducted after the immersion into the simulated body fluid for 1-14 days. Inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, and scanning electron microscopy were utilized for physicochemical and microstructural characterizations. Nanoindentation technique employed to evaluate the nanohardness and Young's modulus of the coating at a constant load of 100 mN. Further, the tribological characteristic was also examined by microscratch testing at a ramping normal load of 10-10.6 N. © 2013 The American Ceramic Society. Source


Dey A.,Thermal System Group | Sinha A.,Bengal Engineering and Science University | Banerjee K.,Bengal Engineering and Science University | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute
Materials Technology | Year: 2014

For bioactive prosthetic implant applications, the present work reports the tribolgical behaviour of the recently developed, microplasma (e.g. plasmatron power <1·5 kW) sprayed (MIPS) hydroxyapatite (HAp) coatings on Ti6Al4V substrates at low constant normal load, e.g. 200 mN. Conventionally, the macroplasma (e.g. plasmatron power < 25 kW) sprayed (MAPS) HAp coatings are used for such purpose. The phase analysis and microstructural studies of the HAp coatings were carried out by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Further, the single pass scratch tests were conducted on both the bare substrates and the HAp coatings at an applied normal load of 200 mN. The average coefficient of friction (COF, μ) of the HAp coatings developed by MIPS (e.g. μ∼0·7) was slightly higher than that (e.g. μ∼0·5) of the bare Ti6Al4V substrates. The characteristic, high variability of the m data of the HAp coatings developed by MIPS; was explained in terms of the intrinsic microstructural heterogeneity and the local differences in orientations of the splats. © 2014 W. S. Maney & Son Ltd. Source


Chakraborty R.,Indian Central Glass and Ceramic Research Institute | Dey A.,Indian Central Glass and Ceramic Research Institute | Dey A.,Thermal System Group | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute | And 6 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

To understand how high-strain rate, flyer-plate impact affects the nanohardness of a coarse (∼10 μm) grain, high-density (∼3.978 gm cc -1) alumina, load controlled nanoindentation experiments were conducted with a Berkovich indenter on as-sintered disks and shock-recovered alumina fragments obtained from an earlier flyer-plate shock impact study. The nanohardness of the shock-recovered alumina was much lower than that of the as-sintered alumina. The indentation size effect was severe in the shock-recovered alumina but only mild in the as-sintered alumina. Extensive additional characterization by field emission scanning electron microscopy, transmission electron microscopy, and analysis of the experimental load depth data were used to provide a new explanation for the presence of strong indentation size effect in the shock-recovered alumina. Finally, a qualitative model was proposed to provide a rationale for the whole scenario of nanoindentation responses in the as-sintered and shock-recovered alumina ceramics. © The Minerals, Metals & Materials Society and ASM International 2011. Source


Bandyopadhyay P.,Indian Central Glass and Ceramic Research Institute | Dey A.,Indian Central Glass and Ceramic Research Institute | Roy S.,Indian Central Glass and Ceramic Research Institute | Dey N.,Indian Central Glass and Ceramic Research Institute | And 2 more authors.
Applied Physics A: Materials Science and Processing | Year: 2012

Advanced applications of glass span the range from biomedical technology to special optical lenses to mobile phones and computers. Such advanced applications demand high-precision machining, which is like multiple single scratches occurring simultaneously on the glass surface. However, in spite of the wealth of literature on scratch deformation behavior of glass there is no significant information available on whether the nanomechanical properties are affected inside the scratch grooves. Therefore, nanoindentation experiments were deliberately conducted at a fixed load of 100 mN through the scratch grooves made at various applied normal loads (5-15 N) at a constant speed of 200 μm s -1 on polished soda-lime-silica (SLS) glass slides. The results showed that depending upon the applied normal load used to generate the scratch grooves, the nanohardness and Young's modulus inside the scratch grooves de- creased by about ∼30-60% from the corresponding data of the undamaged SLS glass due to the presence of subsurface shear deformation and microcracking as observed by optical, scanning and field emission scanning electron microscopy. A model for microcracked brittle solids was utilized to explain these results. © 2012 Springer-Verlag. Source

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