Sarbasree Dutta

Bio: Sarbasree Dutta is an academic researcher from University of Calcutta. The author has contributed to research in topics: Scanning electron microscope & Graphite. The author has an hindex of 2, co-authored 2 publications receiving 39 citations. Previous affiliations of Sarbasree Dutta include Central Glass and Ceramic Research Institute.

Spinel-Coated Graphite for Carbon Containing Refractory Castables

Abstract: Oxidation resistance and water wettability of graphite flakes have been improved by a thin sol-gel film of magnesium aluminate spinel (MgAl 2 O 4 ) over its surface. The hydrosol has been synthesized by less expensive precursors and the spinel formation has been studied by scanning electron microscopy (SEM), supplemented with energy dispersive spectral analysis. After an easy-to-use mixing procedure, drying (110°C), and subsequent calcination (550°C), coated graphites were sieved to below 75 μm. The coating over the powder contained 1.5 wt% MgAl 2 O 4 , which enormously increased the oxidation resistance (performed at 600°, 900°, and 1200°C) and water wettability, as revealed by hydrophilic functional groups from infrared spectra. Defective, intermediate spinel structure of fine, lamellar Mg-doped γ-Al 2 O 3 has been considered to be significant for this improvement. An approximate (1:2) stoichiometry of (Mg:Al) in the coating composition was confirmed by an X-ray photoelectron spectroscopy test. Castables prepared by this graphite remarkably improved their bulk density and apparent porosity compared with those prepared by the as-received graphite. Casting water was reduced along with the amount of antioxidants. This also enhanced the resistance toward the basic slag by retaining the graphite in the refractory.

Extended studies on surface‐treated graphite vis‐à‐vis its application in high alumina refractory castable

Abstract: This investigation entails our continued research on calcium aluminate coated graphite for application in alumina-carbon monolithic refractories. Surface treatment of graphite flakes by a scalable sol-gel route has been utilized to develop stable bonds between ceramic phases with the functionalized graphite sheets. This study has been primarily conducted to differentiate between the coating evolution pattern at green and calcined conditions. In this regard, C-H-N analysis, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), x-ray diffraction (XRD) with Rietveld analysis, Fourier transformed infrared spectroscopy (FTIR) and zeta potential studies of three kinds of graphites had been compared and critically estimated. These results were supplemented with thermogravimetry (TG), pore size distribution, oxidation resistance and scanning electron microscopy (SEM) of selected samples. A schematic outline of the work has also been proposed. An appreciable improvement of bulk density, apparent porosity and crushing strength of the respective castable has been correlated with the compatibility of the coating to the reactive matrix constituents of the refractory in wide temperature region (110-1500 degrees C).

Molten Salt Synthesis and Characterization of Titanium Carbide-Coated Graphite Flakes for Refractory Castable Applications

Abstract: Titanium carbide (TiC)-coated graphite flakes were prepared using the low-temperature molten salt synthesis technique. Titanium (Ti) particles were mixed with graphite in a mass ratio (Ti/C) between 1/5 and 3/5, and reacted in alkali chloride salts at 650–950°C for 4–8 h. The TiC formation reaction was complete in KCl or the KCl–LiCl eutectic salt after 8 h at 850°C, but not in LiCl or NaCl, indicating that the former were more effective than the latter in accelerating the TiC coating formation. Although various Ti/C ratios were used, the TiC formation reaction was complete in all samples heated for 4 h at 950°C, indicating that the amounts/thickness of TiC coatings could be readily tailored for future castable applications. TiC coatings prepared in KCl or the KCl–LiCl eutectic salt (after 4 h at 950°C or 8 h at 850°C) were of high quality: crack free, homogeneous, and comprising nanosized TiC particles. The coating synthesis process is believed to be dominated by the “template-growth” mechanism.