TiC系サーメットの焼結過程の研究

抄録

An apparatus for measuring the shrinkage of cermet in hydrogen atmosphere was designed, and was used successfully for following up the process of sintering. Also the close examinations under the optical and electron microscopes have added some useful informations. The results may be summarized in the following outline.
1) The velocities of shrinkage under different conditions, and the mode of approaching to an equilibrium value at a certain temperature as well as the subsequent shrinkage by the repeated heating at higher temperatures have revealed that the sintering was governed mainly by temperature but not by holding time. It may, therefore, be concluded that the heating schedule of very short holding time at higher temperature is by far better than the usual one.
2) Sintering started by the thermal diffusion of the materials along the contact surface between the particles which were pressed strongly by the forming process. The increase of the path of diffusion brought about of the decrease of the distance between the particles, and the shrinkage of the mass was observed. When the temperature was too high the perspiration of metal bonding was observed.
3) Sintering by an instantaneous heating, i.e. so called flash sintering method showed no sign of grain growth.
4) Observations under electron microscope have revealed that the rupture of TiC cermets occured in two ways, viz. trans-crystal and inter-crystal, according to tha heating temperature.