Silicon nitride ceramics microstructure

Keywords Silicon nitride ceramics, Phase relations, Processing, Microstructure, Properties... 

Silicon nitride ceramics are not merely only one material but several classes of materials. All of them are multiphased, i.e., they exhibit a heterogeneous microstructure which has formed during sintering (Sect. 6). Therefore in all classes a large variety of properties is predominant and as a consequence also a large variety of potential applications (Sect. 10). Often little variations in the powders and the processing parameters cause remarkable changes in the microstructure which have a pronounced effect on properties (Sects. 6 and 7). 

Woetting G, Feuer H, Gugel E (1993) The Influence of Powders and Processing Methods on Microstructure and Properties of Dense Silicon Nitride. In Chen IW, Becher PF, Mitomo M, Petzow G, Yen TS (eds) Silicon Nitride Ceramics, Mat Res Soc Symp Proc 287. Mat Res Soc, Pittsburgh, p 133... 

Becher PF, Hwang SL, Lin HT, Ticgs TN (1994) Microstructural contributions to the fracture resistance of silicon nitride ceramics. In Hoffmann MJ, Petzow G (eds) Tailoring of Mechanical Properties of Si3N4 Ceramics, NATO ASI Ser E Vol. 276, Kluwer Academic Publishers, Dordrecht, p 87... 

Emoto H, Hirotsuri H (1999) Microstructure Control of Silicon Nitride Ceramics Fabricated from a Powder Containing Fine /(-Nuclei. In Niihara K, Sekino T, Yasuda E, Sasa T (eds) The Science of Engineering Ceramics II Key Eng Mat 161-163. Trans Tech Publications, Switzerland, p 209... 

Shen, Z J., Zhan, Z., Peng, 11, el a ., Formation of tough interlocking microstructures in silicon nitride ceramics by dynamic ripening, Nature, 2002, 417 266. 

Becher, P.F. et al. (1993), The influence of microstructure on the mechanical behaviour of silicon nitride ceramics , in Chen I-W, Silicon Nitride - Scientific and Technological Advances, MRS Symposium Proceedings, 287, MRS, Pittsburgh, PA, p. 147. 

Silicon nitride ceramics should have high flexural strength and fracture toughness at room temperature and good creep resistance at elevated temperatures. Because these properties are determined by the microstructure of these ceramics, further improvement of these ceramics is possible through alloy design. The following sections will be devoted to micro-... 

Fig. 15. Microstructural dependence of flexural strength and fracture toughness of silicon nitride ceramics. The composition of these specimens was 90 wt % Si3N4-10 wt % Y3A15Op (27).

Fig. 17. Microstructure of silicon nitride ceramics sintered at 1900°C for 2 h under 10 atm of nitrogen (27).

Silicon nitride ceramics are one of the most promising materials for structural applications. The properties of the silicon nitride ceramics depend on the phases present and their microstructures. This paper describes how to approach microstructural design of these materials by using the phase equilibrium diagrams of silicon nitride-metal oxide systems. 

F Lofaj, Creep mechanism and microstructure evolution in silicon nitride ceramics, Int. J. Mater. Product Tech., 28, 487-513 (2007). 

The composition of the IGF is important in determining overall creep behavior. For example, using Y2O3 as a sintering aid for silicon nitride ceramics has been found to be superior to using MgO. Other important aspects of the microstructure are the grain size and the volume fraction of liquid present. 

The results of the investigations indicate that tailoring of the microstructure and the grain boundary composition is necessary for the application of silicon nitride ceramics in corrosive environments. 

P. Sajgalik, J. Dusza and M. J. Hoffmann, Relationship between Microstructure, Toughening Mechanism, and Fracture Toughness of Reinforeced Silicon Nitride Ceramics , J. Am. Ceram. Soc., 78, 1995, 2619-24. 

S. lio, A. Okada, A. Akira, A. Tetsuo and Y. Masahiro, Corrosion of silicon nitride ceramics in solutions. Part 3. Corrosion behavior in hot sulfuricacid and microstructure of the corroded layer . Journal of the Ceramic Society of Japan, Int. Edition. 100, 1992, July, 954-956. 

Effective machining of spheroidal irons with mixed microstructures can be performed using coated silicon nitride ceramic and CBN tools. This is due to the fact that these cutting tool materials guarantee acceptable tool life at reasonably high cutting speeds up to 400 m/min. 

PT. Becher, S.L. Hwang, H.T. Lin, T.N. Tiegs, Microstructural contributions to the fracture resistance of silicon nitride ceramics, pp. 87-100 in Tailoring of mechanical properties of Si3N4 ceramics. Edited by M.J. Hoffmann and G. Petzow, Kluwer Academic Publidiers, Dordrecht, 1994... 

The research efforts made to tailor ceramic microstructure so as to improve properties are described in this chapter. Although many material properties are affected by the microstructure, the emphasis here is placed on the mechanical properties, especially strength and fracture toughness. In particular, attention is focused on silicon nitride ceramics, the mechanical properties of vhich have been improved substantially through microstructure tailoring during the past tv o decades. 

Becher, P.F., Hwang, S.L., Lin, H.T., and Tiegs, T.N. (1994) Microstructural Contribution to the Fracture Resistance of Silicon Nitride Ceramics, in Tailoring of Mechanical Properties of Si3N4 Ceramics (eds M.J. HofBnarm and G. Petzow), Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 87-100. 

ROLLING CONTACT FATIGUE PROPERTIES AND FRACTURE RESISTANCE FOR SILICON NITRIDE CERAMICS WITH VARIOUS MICROSTRUCTURES... 

Q. Wei, et al., "Microstructural Changes Due to Heat-Treatment of Annealing and Their Effect on the Creep Behavior of Self-Reinforced Silicon Nitride Ceramics", A/a/. Sci. and Eng., A299,141-151 poi)... 

Q. Wei, et al., "High Temperature Uniaxial Creep Behavior of a Sintered In Situ Reinforced Silicon Nitride Ceramics", Ceramic Engineering Science Proceedings, ed. E. Usttlndag and G. Fischman, 20(3), 1999, The American Ceramic Society Westerville, OH, 463-470 G. Ziegler, "Thermo-Mechanical Properties of Silicon Nitride and Their Dependence on Microstructure", Mat. Sci. Forum, 47, 162-203 (1989)... 

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