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Papers by Nandadulal Dandapat

Freestanding polycrystalline diamond (PCD) coatings are of immense technological importance. PCD ... more Freestanding polycrystalline diamond (PCD) coatings are of immense technological importance. PCD has been grown over silicon substrates by microwave plasma assisted chemical vapor deposition (MWPACVD) process. The coatings are grown by suitable optimisation of the growth parameters of a 915 MHz microwave reactor. Thereafter, 1:1:1 solution of hydrofluoric acid (HF), nitric acid (HNO 3 ) and acetic acid (CH 3 COOH) is used to etch out the silicon wafer from the backside of the coating. Hereby, freshly generated nucleation surface, could be characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and stylus profilometer and could be compared with the growth side. It is found that both the nucleation side and growth side are of very high quality (full width at half maxima, i.e., FWHM < 8 cm -1 ). The growth side is (111) textured, whereas, the nucleation side is very smooth with embedded detonation-nano-diamond (DND) agglomerates. These freestanding coatings are successfully laser cut into different geometrical shapes. They are found to be optically translucent having high refractive index. Cross-sectional microscopy of the laser cut edge reveals novel melting features of the CVD grown diamond columns.

Metals and Materials International, 2012

ABSTRACT An alumina ceramic material (purity-96%) was metallized by the conventional molybdenum-m... more ABSTRACT An alumina ceramic material (purity-96%) was metallized by the conventional molybdenum-manganese (Mo-Mn) process in which an alumina substrate was coated with Mo-Mn paste and subsequently heat treated at 1400 °C for 10 min. During the entire process a moist H2 and N2 gas mixture (dew point-20 °C) with 3:1 ratio was passed continuously through the furnace. X-ray diffraction analysis of the metallized alumina substrate identified only molybdenum phase at the surface of the metallizing layer. The microstructural observations of the metallized alumina substrate were made by scanning electron microscopy. Energy dispersive X-ray analysis showed the elemental compositions along the cross-sectional region of the metallized alumina substrate. The adhesion of the metallic coatings on the alumina substrates was evaluated qualitatively by a scratch testing technique and quantitatively by an adhesion tester. Nanohardness measurements showed gradual change in the nanohardness values across the metallized alumina substrate.

Materials Science and Engineering: B, 2012

... Dandapat a , Someswar Datta a , Corresponding Author Contact Information , E-mail The Corresp... more ... Dandapat a , Someswar Datta a , Corresponding Author Contact Information , E-mail The Corresponding Author , Debabrata Basu a , RS Raju b. a, Bio-Ceramics and Coating Division, CSIR – Central Glass and Ceramic Research Institute, 196, Raja SC Mullick Road, Kolkata ...

Journal of the European Ceramic Society, 2013

ABSTRACT Glaze in the CaO–MgO–Al2O3–SiO2 system was heated at 950–1190 °C for 2 h and characteriz... more ABSTRACT Glaze in the CaO–MgO–Al2O3–SiO2 system was heated at 950–1190 °C for 2 h and characterized. X-ray diffraction showed that only trace amount of mullite was formed in the glass-ceramic glaze heated at 950 °C. Both mullite and α-cordierite were formed in the glass-ceramic glaze heated at 1050 °C as primary and secondary phases. Glass-ceramic glazes heated at 1120 °C and 1190 °C contained α-cordierite and mullite as major and minor phases. Rietveld analysis revealed that the amount of α-cordierite increased and mullite decreased with increasing heating temperature. Field emission scanning electron microscopy showed presence of mullite crystals dispersed within residual glassy phase in the glass-ceramic glazes heated at 950 °C and 1050 °C. In the microstructures of glass-ceramic glazes heated at 1120 °C and 1190 °C α-cordierite crystals were mainly appeared. Energy Dispersive X-ray analysis corroborated X-ray diffraction results. Vickers microhardness measurement demonstrated highest hardness (8.38 ± 0.07 GPa) of the glass-ceramic glaze heated at 1190 °C.

Diamond and Related Materials, 2012

ABSTRACT The tuning (optimization) of the reactor parameters is very important in order to achiev... more ABSTRACT The tuning (optimization) of the reactor parameters is very important in order to achieve spatial temperature uniformity across the large area substrate for growing high quality and uniformly thick diamond coatings. It is also important to minimize the thermal stress, arising from temperature non-uniformity, for producing crack free large area diamond coatings. So by varying different process parameters, such as chamber pressure, microwave power, gas flow rate and cavity lengths (by changing the probe, short and stage positions), the resultant variation of substrate surface temperature can be measured. By tuning these parameters the geometry as well as the density of the plasma discharge which directly influences substrate surface temperature may be controlled. It has been shown that by suitable manipulation of the reactor parameters one could achieve at best 80 °C variation in temperature uniformity over 100 mm diameter, which indeed has resulted in a very uniformly thick (± 12.8%) high quality polycrystalline diamond (PCD) coating.

Ceramics International, 2012

Chronic osteomyelitis is a challenging setback to the orthopedic surgeons in deciding an optimal ... more Chronic osteomyelitis is a challenging setback to the orthopedic surgeons in deciding an optimal therapeutic strategy. Conversely, patients feel frustrated of the therapeutic outcomes and development of adverse drug effects, if any. Present investigation deals with extensive approach incorporating in vivo animal experimentation and human application to treat chronic osteomyelitis, using antibiotic loaded porous hydroxyapatite scaffolds. Micro-to macro-porous hydroxyapatite scaffolds impregnated with antibiotic ceftriaxone-sulbactam sodium (CFS) were fabricated and subsequently evaluated by in vivo animal model after developing osteomyelitis in rabbit tibia. Finally 10 nos. of human osteomyelitis patients involving long bone and mandible were studied for histopathology, radiology, pus culture, 3D CT etc. up to 8-18 months post-operatively. It was established up to animal trial stage that 50N50H samples [with 50-55% porosity, average pore size 110 μm, higher interconnectivity (10-100 μm), and moderately high drug adsorption efficiency (50%)] showed efficient drug release up to 42 days than parenteral group based on infection eradication and new bone formation. In vivo human bone showed gradual evidence of new bone formation and fracture union with organized callus without recurrence of infection even after 8 months. This may be a new, alternative, cost effective and ideal therapeutic strategy for chronic osteomyelitis treatment in human patients.

Transactions of the Indian Ceramic Society, 2013

Polycrystalline diamond (PCD) films have been grown over 100 mm diameter silicon (100) substrate,... more Polycrystalline diamond (PCD) films have been grown over 100 mm diameter silicon (100) substrate, using microwave plasma chemical vapour deposition (MPCVD) technique. The deposition was carried out inside a 15 cm diameter quartz chamber with microwave power of 15 kW at 915 MHz frequency. Uniform substrate surface temperature of 1050 o C with plasma heating was maintained with simultaneous cooling arrangement. The pressure was 110 Torr and the microwave incident power was 8.5 kW. Temperature uniformity and plasma geometry over the substrate are the key parameters for producing uniformly thick MPCVD diamond films of high quality. Thickness uniformity of as-deposited films is ±10% across 100 mm diameters with a growth rate of 1 m.h -1 . The grown PCD was characterized by X-ray diffractometry (XRD), Raman spectrometry, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and bright field imaging technique. Experimental results indicate columnar growth of a very densely crystalline PCD with (111) facets of high quality morphology.

Freestanding polycrystalline diamond (PCD) coatings are of immense technological importance. PCD ... more Freestanding polycrystalline diamond (PCD) coatings are of immense technological importance. PCD has been grown over silicon substrates by microwave plasma assisted chemical vapor deposition (MWPACVD) process. The coatings are grown by suitable optimisation of the growth parameters of a 915 MHz microwave reactor. Thereafter, 1:1:1 solution of hydrofluoric acid (HF), nitric acid (HNO 3 ) and acetic acid (CH 3 COOH) is used to etch out the silicon wafer from the backside of the coating. Hereby, freshly generated nucleation surface, could be characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and stylus profilometer and could be compared with the growth side. It is found that both the nucleation side and growth side are of very high quality (full width at half maxima, i.e., FWHM < 8 cm -1 ). The growth side is (111) textured, whereas, the nucleation side is very smooth with embedded detonation-nano-diamond (DND) agglomerates. These freestanding coatings are successfully laser cut into different geometrical shapes. They are found to be optically translucent having high refractive index. Cross-sectional microscopy of the laser cut edge reveals novel melting features of the CVD grown diamond columns.

Metals and Materials International, 2012

ABSTRACT An alumina ceramic material (purity-96%) was metallized by the conventional molybdenum-m... more ABSTRACT An alumina ceramic material (purity-96%) was metallized by the conventional molybdenum-manganese (Mo-Mn) process in which an alumina substrate was coated with Mo-Mn paste and subsequently heat treated at 1400 °C for 10 min. During the entire process a moist H2 and N2 gas mixture (dew point-20 °C) with 3:1 ratio was passed continuously through the furnace. X-ray diffraction analysis of the metallized alumina substrate identified only molybdenum phase at the surface of the metallizing layer. The microstructural observations of the metallized alumina substrate were made by scanning electron microscopy. Energy dispersive X-ray analysis showed the elemental compositions along the cross-sectional region of the metallized alumina substrate. The adhesion of the metallic coatings on the alumina substrates was evaluated qualitatively by a scratch testing technique and quantitatively by an adhesion tester. Nanohardness measurements showed gradual change in the nanohardness values across the metallized alumina substrate.

Materials Science and Engineering: B, 2012

... Dandapat a , Someswar Datta a , Corresponding Author Contact Information , E-mail The Corresp... more ... Dandapat a , Someswar Datta a , Corresponding Author Contact Information , E-mail The Corresponding Author , Debabrata Basu a , RS Raju b. a, Bio-Ceramics and Coating Division, CSIR – Central Glass and Ceramic Research Institute, 196, Raja SC Mullick Road, Kolkata ...

Journal of the European Ceramic Society, 2013

ABSTRACT Glaze in the CaO–MgO–Al2O3–SiO2 system was heated at 950–1190 °C for 2 h and characteriz... more ABSTRACT Glaze in the CaO–MgO–Al2O3–SiO2 system was heated at 950–1190 °C for 2 h and characterized. X-ray diffraction showed that only trace amount of mullite was formed in the glass-ceramic glaze heated at 950 °C. Both mullite and α-cordierite were formed in the glass-ceramic glaze heated at 1050 °C as primary and secondary phases. Glass-ceramic glazes heated at 1120 °C and 1190 °C contained α-cordierite and mullite as major and minor phases. Rietveld analysis revealed that the amount of α-cordierite increased and mullite decreased with increasing heating temperature. Field emission scanning electron microscopy showed presence of mullite crystals dispersed within residual glassy phase in the glass-ceramic glazes heated at 950 °C and 1050 °C. In the microstructures of glass-ceramic glazes heated at 1120 °C and 1190 °C α-cordierite crystals were mainly appeared. Energy Dispersive X-ray analysis corroborated X-ray diffraction results. Vickers microhardness measurement demonstrated highest hardness (8.38 ± 0.07 GPa) of the glass-ceramic glaze heated at 1190 °C.

Diamond and Related Materials, 2012

ABSTRACT The tuning (optimization) of the reactor parameters is very important in order to achiev... more ABSTRACT The tuning (optimization) of the reactor parameters is very important in order to achieve spatial temperature uniformity across the large area substrate for growing high quality and uniformly thick diamond coatings. It is also important to minimize the thermal stress, arising from temperature non-uniformity, for producing crack free large area diamond coatings. So by varying different process parameters, such as chamber pressure, microwave power, gas flow rate and cavity lengths (by changing the probe, short and stage positions), the resultant variation of substrate surface temperature can be measured. By tuning these parameters the geometry as well as the density of the plasma discharge which directly influences substrate surface temperature may be controlled. It has been shown that by suitable manipulation of the reactor parameters one could achieve at best 80 °C variation in temperature uniformity over 100 mm diameter, which indeed has resulted in a very uniformly thick (± 12.8%) high quality polycrystalline diamond (PCD) coating.

Ceramics International, 2012

Chronic osteomyelitis is a challenging setback to the orthopedic surgeons in deciding an optimal ... more Chronic osteomyelitis is a challenging setback to the orthopedic surgeons in deciding an optimal therapeutic strategy. Conversely, patients feel frustrated of the therapeutic outcomes and development of adverse drug effects, if any. Present investigation deals with extensive approach incorporating in vivo animal experimentation and human application to treat chronic osteomyelitis, using antibiotic loaded porous hydroxyapatite scaffolds. Micro-to macro-porous hydroxyapatite scaffolds impregnated with antibiotic ceftriaxone-sulbactam sodium (CFS) were fabricated and subsequently evaluated by in vivo animal model after developing osteomyelitis in rabbit tibia. Finally 10 nos. of human osteomyelitis patients involving long bone and mandible were studied for histopathology, radiology, pus culture, 3D CT etc. up to 8-18 months post-operatively. It was established up to animal trial stage that 50N50H samples [with 50-55% porosity, average pore size 110 μm, higher interconnectivity (10-100 μm), and moderately high drug adsorption efficiency (50%)] showed efficient drug release up to 42 days than parenteral group based on infection eradication and new bone formation. In vivo human bone showed gradual evidence of new bone formation and fracture union with organized callus without recurrence of infection even after 8 months. This may be a new, alternative, cost effective and ideal therapeutic strategy for chronic osteomyelitis treatment in human patients.

Transactions of the Indian Ceramic Society, 2013

Polycrystalline diamond (PCD) films have been grown over 100 mm diameter silicon (100) substrate,... more Polycrystalline diamond (PCD) films have been grown over 100 mm diameter silicon (100) substrate, using microwave plasma chemical vapour deposition (MPCVD) technique. The deposition was carried out inside a 15 cm diameter quartz chamber with microwave power of 15 kW at 915 MHz frequency. Uniform substrate surface temperature of 1050 o C with plasma heating was maintained with simultaneous cooling arrangement. The pressure was 110 Torr and the microwave incident power was 8.5 kW. Temperature uniformity and plasma geometry over the substrate are the key parameters for producing uniformly thick MPCVD diamond films of high quality. Thickness uniformity of as-deposited films is ±10% across 100 mm diameters with a growth rate of 1 m.h -1 . The grown PCD was characterized by X-ray diffractometry (XRD), Raman spectrometry, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and bright field imaging technique. Experimental results indicate columnar growth of a very densely crystalline PCD with (111) facets of high quality morphology.