Silicon nitride ceramic resistivities

As noted, the oxidation resistance of silicon nitride ceramics depends on the type and concentration of the sintering aids. In materials designed for high temperature appHcations the specific weight gain resulting from oxidation upon a 500-h air exposure at 1200°C and 1350°C is about 1—2 g/m and 2—4 g/m, respectively. The kinetics of the oxidation process have been iavestigated (63,64) as has the corrosion resistance (65). Corrosion resistance is also dependent on material formulation and density. 

As a future alternative to glassed steel there is ceramics-coated steel which is resistant to abrasion, corrosion and high temperatures. The base metal is coated with silicon nitride formed in situ. Silicon nitride has resistance to both acid and alkali and it is durable at temperatures up to 1 000°C, suggesting a promising future coating in aggressive operating environments. 

A c-BN - silicon nitride ceramic composite can be produced directly by sintering a mixture of c-BN powder and Si powder in N2 atmosphere. The composites have high resistance against heat, oxidation, and thermal shock [279]. 

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... 

Li CW, Gasdaska CJ, Goldacker J, Lui SC (1993) Damade Resistance of In Situ Reinforced Silicon Nitride. In Chen IW, Becher PF, Mitomo M, Petzow G, Yen TS (eds) Silicon Nitride Ceramics - Scientific and Technological Advances. Mat Res Soc Symp Proc 287. Materials Research Soc, Pittsburgh, p 473... 

Ohji T (2001) Long Term Tensile at Creep Behaviours of Highly Heat-Resistant Silicon Nitride Ceramics Gas Turbines. In Singh M, Jessen T (eds) 25th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures A (Ceram Eng Sci Proc 22). Am Ceram Soc, Westerville, OH, p 159... 

Komeya K, Meguro T, Atago S, Lin CH, Abe Y, Komatsu M (1999) Corrosion Resistance of Silicon Nitride Ceramics. 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 235... 

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. 19. Creep behavior of silicon nitride ceramics. The composition of this ceramic contains 7 vol % Y3A15Oi2 as a sintering aid. The specimens were hot-pressed at 1750°C under a pressure of 20 Mpa. The holding times are marked on the curve. This curve indicates that crystallization of the grain-boundary phase improves the creep resistance. Garnet crystals were observed at the grain boundaries after annealing [3/]. , Sample A60 , Sample B60 A, Sample B150, x, failure.

Silicon nitride ceramic materials have been intensively studied for many years because of their great potential for use in structural applications at room and high temperatures. This is due to their excellent mechanical properties in combination with good corrosion and thermal shock resistance. 

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... 

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... 

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