Some features of the sintering of nickel fibers extruded from viscose-base suspensions. Part I

Conclusions

The sintering of fibers extruded from a viscose-base nickel powder suspension is characterized by volume changes whose intensity varies with temperature: At 200–400°C the fibers undergo densification under the action of capillary forces set up by liquid fractions of the polymer binder being removed during the latter's thermal destruction, the mechanism of the process being analogous to that of high-intensity drying; at 400–800°C the magnitude of shrinkage is independent of temperature because the carbon-metal skeletons of the fibers are stable in hydrogen. Local agglomeration of particles in the temperature range 600–800°C too has no effect on the magnitude of the volume changes of the fibers because of the discreteness of this process; at 800–1200°C the metallic phase sinters by a diffusion-viscous flow mechanism. To the characteristic temperature ranges of densification of fibers extruded froma viscose-base nickel powder suspension there correspond characteristic temperature ranges of polymer binder removal, which points to the existence of a relationship between these two processes.