Abstract
The influence of several sinter-HIP variables on the densification behaviour of silicon nitride-based ceramics has been investigated. The processing conditions were studied for Si3N4 powder mixtures containing controlled amounts of Y2O3+Al2O3 or Y2O3+MgO. The specimens were subjected to sinter-HIP cycles under argon or nitrogen atmospheres at various temperatures and pressures. The final density of the powder compacts exhibited a strong dependence not only on the applied pressure, the composition and the processing temperature, but also on the pressurization rate and the initial pressurization time. The microstructural changes induced by the application of high pressure were followed by transmission electron microscopy. On examination by TEM, large concentrations of dislocations, generated inside someβ-Si3N4 grains, were observed. Characterization of these dislocations showed thatb=〈0001〉 is their most frequently found Burgers vector. Also, two relaxation mechanisms, tending to release the stored energy of deformation in theβ-Si3N4 grains, namely grain penetration (a form of strain-induced boundary migration) and grain fragmentation (the formation of subgrains due to rearrangement of dislocations into low energy configurations), have been identified. The intergranular phases formed were characterized by energy dispersive X-ray spectroscopic analysis, X-ray diffraction and electron diffraction. The influence of different sinter-HIP cycles on theα →β transformation of silicon nitride without additives was also investigated by X-ray diffractometry.
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References
G. Zeigler, J. Heinrich andG. Wötting,J. Mater. Sci. 22 (1987) 3041.
P. Popper, “Problems in sintering silicon nitride”, in Proceedings of the International Symposium on “Factors in densification and sintering of oxide and non-oxide ceramics”, edited by S. Somiya and S. Saito (Tokyo, Japan, 1979) pp. 19–27.
G. R. Terwilliger andF. F. Lange,J. Amer. Ceram. Soc. 57 (1974) 25.
S. Hampshire andK. H. Jack, “The kinetics of densification and phase transformation of nitrogen ceramics”, in “Special Ceramics 7”; Proceedings of the British Ceramic Society, edited by D. Taylor and P. Popper (British Ceramics Society, Stoke on Trent, 1981) pp. 37–49.
L. J. Bowen, T. G. Carruthers andR. J. Brook,J. Amer. Ceram. Soc. 61 (1978) 335.
G. Wötting andG. Ziegler, “Influence of powder properties and processing conditions on microstructure and properties of sintered Si3N4,” in “Ceramic powders”, edited by P. Vincensini (Elsevier, Amsterdam, 1983) pp. 951–62.
F. F. Lange,Int. Met. Rev. 247 (1980) 1.
J. T. Smith andC. L. Quackenbush, “A Study of sintered Si3N4 compositions”, in Proceedings of the International Symposium on “Factors in densification and sintering of oxide and non-oxide ceramics”, edited by S. Somiya and S. Saito (Tokyo, Japan, 1979) pp. 426–42.
H. T. Larker, “Dense ceramic parts hot pressed by hip”, in “Emergent process methods for high-technology ceramics”, Vol. 17, edited by R. F. Davies, H. Palmour and R. L. Porter (Plenum, New York, 1984) pp. 571–82.
Idem, “On hot isostatic pressing of shaped ceramic parts” in Proceedings of the Conference on “Ceramics in Engines”, edited by S. Somiya, E. Kanai and K. I. Ando (Scientific Publications, Tokyo, Japan, 1984) Hakone, Japan, October 1983.
O. Yeheskel, Y. Gefen andM. Talianker,J. Mater. Sci. 19 (1984) 745.
Idem, Mater. Sci. Engng. 78 (1986) 209.
C. Greskovich,J. Amer. Ceram. Soc. 64 (1981) 725.
I. Iturriza, F. Castro andM. Fuentes,J. Mater. Sci. 24 (1989) 2047.
B. D. Cullity, “Elements of X-ray Diffraction”, 2nd edn (Addison-Wesley, Reading, Massachusetts, 1978).
P. Drew andM. H. Lewis,J. Mater. Sci. 9 (1974) 261.
M. Schimada, A. Tanaka, T. Yamada andM. Koizumi, “Densification and phase transformation of Si3N4 by high pressure sintering”, in “Ceramic Powders” edited by P. Vincenzini (Elsevier, Amsterdam, 1983) pp. 871–9.
L. R. L. Falk, G. L. Dunlop andR. Pompe,Mater. Sci. Engng. 71 (1985) 123.
F. F. Lange,Amer. Ceram. Bull. 62 (1983) 1369.
A. G. Evans andJ. V. Sharp, “Transmission electron microscopy of silicon nitride”, in “Electron Microscopy and structure of materials”, edited by G. Thomas, R. M. Fulrath and R. M. Fisher (University of California Press, Berkley, 1972) pp. 1141–54.
R. W. K. Honeycombe, “The plastic deformation of metals” (Arnold, London, 1968) Ch. 10.
J. W. Martin andR. D. Doherty, “Stability of microstructure in metallic systems”, Cambridge solid state science series (Cambridge University Press, 1976) Ch. 3.
J. E. Bailey andP. B. Hirsch,Proc. Roy. Soc. A267 (1962) 11.
A. Cottrell, “An introduction to metallurgy”, 2nd edn. (Arnold, London, 1975) Ch. 19.
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Iturriza, I., Echeberría, J., Gutierrez, I. et al. Densification of silicon nitride ceramics under sinter-HIP conditions. J Mater Sci 25, 2539–2548 (1990). https://doi.org/10.1007/BF00638056
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DOI: https://doi.org/10.1007/BF00638056