NISCAIR Online Periodicals Repository Collection: IJCT Vol.15(4) [July 2008]

Pressure casting of composite propellant

Sat, 28 Jun 2008 22:58:59 GMT

Title: Pressure casting of composite propellant

Authors: Dombe, Ganesh; Jain, M; Singh, P P; Radhakrishnan, K K; Bhattacharya, B

Abstract: Conventional vacuum casting technique is suitable only to propellant slurry with low viscosity (<16 KP), grains with simple geometry and sufficiently large annular space between mandrel and motor case (web thickness). To overcome these limitations, pressure casting technique is adopted. The present paper gives details of pressure casting technique and its advantages over the other casting techniques. The rheological behaviour of propellant slurry and the methodology for calculation of pressure drop during pressure casting is described. This procedure is illustrated for pressure drop calculation during pressure casting for a typical rocket motor. The pressure drop in the rocket motor is also calculated using CFD software Fluent.

Page(s): 420-423

Some triphosphates as corrosion inhibitors for mild steel in 3% NaCl solution

Sat, 28 Jun 2008 22:58:59 GMT

Title: Some triphosphates as corrosion inhibitors for mild steel in 3% NaCl solution

Authors: Lata, Suman; Chaudhary, R S

Abstract: Inhibition of mild steel corrosion in 3% sodium chloride solution by sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP) and adenosine triphosphate (ATP) in presence of 200 ppm zinc acetate has been investigated using weight loss, electrochemical polarisation and scanning electron microscopy techniques. Various corrosion parameters such as Tafel slopes, corrosion current density, heat of adsorption and activation energy value have been calculated to understand the inhibition mechanism. Inhibition efficiency increased with increase in concentration for STPP and SHMP whereas it decreased for ATP. However, inhibition efficiency decreased for all the three phosphates with increase in temperature. All the three phosphates acted as mixed inhibitors though anodic reactions are suppressed more in comparison to the cathodic reactions. STPP acted through chemisorption whereas SHMP and ATP are physically adsorbed over the surface of mild steel.

Page(s): 364-374

Investigation on pH dependent uptake of Cr(III) and Cr(VI) by Baker’s yeast

Sat, 28 Jun 2008 22:58:59 GMT

Title: Investigation on pH dependent uptake of Cr(III) and Cr(VI) by Baker’s yeast

Authors: Lahiri, Susanta; Roy, Kamalika

Abstract: Yeast cells of Saccharomyces cerevisiae were found to accumulate ⁵¹Cr(III) radioisotope at basic pH in trace level. There was no uptake of Cr(VI) at the same pH (~10.5). An assay of the products of cell lysis reveals that Cr(III) first gets adsorbed at the cell wall and then slowly enters the cytoplasm. On the other hand Cr(VI) has a faster penetration into the cytoplasm which increases with time, attains a maximum value and then release the metal ion from cytoplasm. The behavior and uptake kinetics of ⁵¹Cr(III) or ⁵¹Cr(VI) were studied using -spectrometry.

Page(s): 417-419

Arsenic removal from water using activated carbon obtained from chemical activation of jute stick

Sat, 28 Jun 2008 22:58:59 GMT

Title: Arsenic removal from water using activated carbon obtained from chemical activation of jute stick

Authors: Jahan, M Israt; Motin, M Abdul; Moniuzzaman, M; Asadullah, M

Abstract: Arsenic removal from water in the form of As(III) and As(IV) was investigated using activated carbon obtained from jute stick using H₃PO₄. Arsenic contaminated water was treated in two ways: (1) batch feeding system and (2) continuous flow system through a column filter. Removal of arsenic in continuous system was much better than that of batch feeding system. In the continuous system, where 0.15 ppm arsenic contaminated water was passed through a column packed with activated carbon, the maximum separation of As(III) was as high as 80%. In case of As(V) contaminated solution, almost complete separation of arsenic was achieved with activated carbon column filter. As(III) was converted to As(V) in the solution using very small amount of KMnO₄.

Page(s): 413-416