Construction of master sintering curve of ThO2 pellets using optimization technique

• Published in: Science of sintering 2012, Vol.44 (2), p.147-160
• Main Authors: Ray, A, Banerjee, J, Kutty, T R G, Kumar, A, Banerjee, S
• Format: Article
• Language: English
• Subjects: Activation Energy; Construction; Densification; Density; Fittings; Master Sintering Curve; Mathematical models; Mean Residual Square; Optimization; Sintering; Work of Sintering
• ISSN: 0350-820X; 1820-7413
• DOI: 10.2298/SOS1202147R

Thoria (ThO2) is used instead of urania (UO2) in Indian nuclear power plants to produce fissile 233U due to limited uranium reserves and vast thorium deposits. The sintering kinetics and densification behaviour of pure ThO2 were studied using high-temperature dilatometer experiments at constant heating rate. The activation energy for sintering was determined by the Wang and Raj method. The master sintering curve (MSC) for densification is a functional sintering model that describes densification under an arbitrary time-temperature excursion of a particular material during sintering. The MSC for pure ThO2 was constructed by fitting experimental relative density versus work of sintering data with a modified sigmoid function. Five independent parameters of the fitting function were determined by the Nelder-Mead optimisation technique with the objective of minimising the fitting error in terms of a mean residual square. A FORTRAN program was developed to efficiently construct the best converged master curve. It was shown that the activation energy of pure ThO2 found by the MSC approach is consistent with those obtained by other methods.