Open Pore Generation on Sintered Surface of Ti (C,N) Base Cermet and Its Mechanism (特集硬質材料)

概要

論文の詳細を見る
The open pore generation on the surface of Ti(C, N) base cermets by sintering was investigated as a function of the compositional and processing factors, and then its mechanism was considered. The following were obtained. (1) Phenomena: The generation occurred, when the atmosphere in the temperature-keeping stage during sintering was vacuum (7 Pa), irrespective of the kind of atmospheres (vacuum and nitrogen of 0.13 kPa) in the temperature-raising and cooling stages, and vice versa. The generation became more frequent at higher N/(C+N) atomic ratio of Ti(C, N) powder and/or at higher carbon content of cermet as far as the microstructure was without free carbon phase and (Ti, Mo)<SUB>3</SUB>Ni compound, i.e., θ-phase. The origin of open pore was a dent on the surface of the green compact. (2) Mechanism: The growth of open pores occurs by the net-diffusion, i.e., transport of Ti and Mo atoms mainly from the side and bottom of the dent to the edge. This diffusion is caused by the N content gradient formed due to the denitriding, which occurs more rapidly from the compact surface having lager ratio of surface-area/volume. The method for suppressing the open pore generation was also considered.
社団法人粉体粉末冶金協会の論文
2003-05-15