Page 249 - Book Hosokawa Nanoparticle Technology Handbook

4.5 STRUCTURE CONTROL OF NANOPARTICLE COLLECTIVES BY SINTERING AND BONDING FUNDAMENTALS

Figure 4.5.6
Figure 4.5.4 Relation between initial grain size and calcination
Relation between relative density and the grain size. temperature required for the achievement of densification
in the sintering of the second stage.

nanograins, become narrow as the particle size
decreases. This two-step sintering technique is effective
also for the system with additives. The necessary heat-
ing conditions are shown by the broken line and the dot-
ted line for the systems with grain growth suppresser
and accelerator, respectively.
The applicability of the present technique is noted in
various systems, including alumina [5], ceria [6], and
silicon carbide [7]. In the sintering of silicon carbide in
particular, a drastic reduction of sintering temperature
was possible in the two-step sintering technique com-
pared to the conventional sintering method;
o
1,700–1,750 C for the first stage and 1,550–1,600 C
for the second stage. Achievement of high relative
density over 98% was suggested with this technique.

References
[1] JSPS124 Committee (eds): Production and Application
Figure 4.5.5 of Advanced Ceramics, Nikkan Kogyo Sinbunsha,
Relation between relative density and grain size with Tokyo, Japan (2005).
temperature control in two-stage sintering.
[2] Y. Moriyoshi, T. Sasamoto, K. Uematsu, Y. Ikuma,
H. Monma, T. Ikegami and T. Maruyama: Sintering of
Ceramics, Uchida Rokakuho, Tokyo, Japan (1995).
In the system without additives, high density with [3] R.M. German: Liquid Phase Sintering, Plenum, New
nanograins can be achieved when the sintered bodies York (1985).
with the grain sizes shown by the solid line are heated [4] I.-W. Chen, X.-H. Wang: Nature, 404, 168–171 (2000).
in the respective temperature ranges. High densification [5] A. Rosenflanz, M. Frey, B. Endres, T. Anderson,
is not possible in the sintering of second stage for the
sintered bodies with the density below the line. In con- E. Richards and C. Schardt: Nature, 430, 761–764 (2004).
trast, significant grain growth occurs for the sintered [6] C. Kleinlogel, L.J. Gauckler: Adv. Mater., 13, 1081–1085
bodies above the line, and ceramics with nanoparticles (2001).
is not obtained. The conditions for successful densifica- [7] Y.-I. Lee, Y.-W. Kim and M. Mitomo: J. Mater. Sci., 39,
tion, i.e., simultaneous achievement of high density and 3801–3803 (2004).

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