Sumana Ghosh

Microwave-assisted brazing of alumina ceramics for electron tube applications

Alumina was joined with alumina using microwave-assisted and conventional brazing methods at 960∘C for 15 min using TiCuSil (68.8Ag–26.7Cu–4.5Ti in wt.%) as the brazing alloy. The brazed joints were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Vickers microhardness evaluation, brazing strength measurement and helium leak test. X-ray diffraction analysis confirmed the formation of Ti-based compounds at the substrate-filler alloy interfaces of the microwave and conventionally brazed joints. The elemental compositions at the joint cross-section were determined by energy dispersive X-ray analysis. Vickers microhardness measurement indicated reliable joint performance for the microwave-assisted brazed joints during actual application in an electron tube. Brazing strength measurement and helium leak test provided the evidence for good alumina-alumina joint formation.

Toxic Metal Removal Using Biosorption Process and Inertization of Generated Hazardous Metal-Laden Biosorbent

The tannery industry waste was used in this study as a low-cost biosorbent. The presence of large number of functional groups in the tannery waste resulting from both live and dead microbial fractions positively favours for higher and faster sequestration rate of metal ions. The batch mode of biosorption process were performed with dried activated tannery sludge for removal of Ni(II), Co(II), Zn(II) and Cd(II) ions in multi-metal system. Zn(II) and Cd(II) ions showed 99% removal efficiency within 10 min of contact time, while Ni(II) and Co(II) attained 98% removal at 20–24 h. The influence of various experimental variables like pH, contact time, biosorbent dosage and initial metal concentrations was studied. The biosorbent was characterized using FESEM-EDX and XPS analysis.

Effect of Thermo-oxidation on the Mechanical Performance of Polymer Based Composites for High Temperature Applications

In the present study the effect of thermo-oxidation on the mechanical properties of polymer based composites has been reported for high temperature applications. The polymer based composites with high thermal stability and future trend towards modification of this type of composites have been discussed here.

Current Trends on Glass and Ceramic Materials

Description: Biomaterials created from innovative glass and bio-ceramic research is emerging as a precursor to several developments useful for solving a wide variety of industry and health related issues. Current Trends on Glass and Ceramic Materials is a review on the latest developments in glass and ceramic materials for technological applications along with biomedical applications in vivo. The volume serves as a useful reference to readers interested in learning about this area of materials science and its multidisciplinary array of applications.

Interfacial properties of metallized alumina ceramics

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.