No abstract

No abstract

No abstract

No abstract

No abstract

Three dicotyledonous woods of local origin (mango (Mangifera indica), jackfruit (Artocarpus integrifolia) and teak (Tectona grandis)) were transformed by pyrolysis into carbonaceous preforms and subsequently converted into microcellular Si/SiC ceramics by liquid Si-infiltration under vacuum. The pyrolyzed mango, jackfruit and teak were characterized in terms of pyrolysis weight loss, shrinkages, bulk density and microstructures. The end ceramics were found to be 91-98% dense with respect to theoretical densities (T.D.) with porosities in the range of 0.1-4.8%. SEM (in back scattered electron (BSE) mode) imaging confirmed the preservation of microcellular tissue anatomy of the precursor wood structure in the morphologies of the final ceramics. The microc~llular Si/SiC ceramics from mango, jackfruit and teak exhibited excellent oxidation resistance during heating to 1350"C In flowing air, showing a marginal weight gain at the highest temperature. Si/SiC-mango was also characterized in terms of flexural strength, Young's modulus and hardness. These biostructural microcellular Si/SiC ceramics possess application potential in various structural ceramic sectors (e.g. mechanical pump seals, wear inserts, kiln support structures, heat exchangers etc).

Results of a gravity survey conducted over Raniganj coalfield, one of the Gondwana basins of Damodar Valley in north‐eastern part of India, are presented. The gravity field was separated into regional and residual components. The residual Bouguer anomaly map shows that the coalfield is characterized by a gravity low of about—32 mGal associated with Gondwana sediments. The deepest part of basin is found to be located near Asansole (23° 40’N, 86° 55’E), where the maximum thickness of sediments is estimated to be about 1.3 miles (2.08 km). The faults along the northern as well as the southern boundaries are found to be normal. The Gondwana sediments appear to continue eastward beneath alluvium and laterite of Bengal basin as far as 87° 25’E.

No abstract