Dilatometric analysis of sintering of tungsten and tungsten with ceria and hafnia dispersions
Journal
International Journal of Refractory Metals and Hard Materials
Journal Volume
12
Journal Issue
1
Pages
41-51
Date Issued
1993
Author(s)
Chen L.C.
Abstract
Dilatometric data and analyses are provided for the densification of tungsten powder and tungsten powder with hafnia and ceria additions. The characteristic shrinkage curve was found to depend on the type of oxide added into the W matrix. The activation energies of the densification rate were obtained by analyzing the shift of the iso-density points as a function of the linear-heating rate. A unique density-dependent function in the densification-rate equation is also illustrated. Sintering of both W and ceria-dispersed W was found to be controlled by grain-boundary diffusion, but ceria additions in the W matrix resulted in a higher activation energy. The activation energies for W and ceria-dispersed W were 318±21 and 385±15 KJ/mole, respectively. A possible correlation between activation energy and interfacial energy was discussed. A single predominant mechanism that governs the densification in hafnia-dispersed W could not be determined. A tentative scenario whereby the dispersed hafnia enhances or retards sintering is suggested. © 1994.
SDGs
Other Subjects
Densification;Density (specific gravity);Diffusion;Dilatometers;Dispersions;Interfacial energy;Oxides;Powder metals;Reaction kinetics;Sintering;Activation energy;Ceria;Dilatometric analysis;Hafnia;High temperature mechanical properties;Tungsten
Type
journal article