Title: Silicon Nitride
CAS Registry Number: 12033-89-5
Additional Names: Trisilicon tetranitride
Molecular Formula: N4Si3
Molecular Weight: 140.28
Percent Composition: N 39.94%, Si 60.06%
Line Formula: Si3N4
Literature References: Non-oxide ceramic material of high thermal stability. Manuf by direct nitridation of pure silicon. Prepn by pyrolysis of silicon diimide (Si(NH2)2): O. Glemser, P. Naumann, Z. Anorg. Allg. Chem. 298, 134 (1954); and characterization: K. S. Mazdiyasni, C. M. Cooke, J. Am. Ceram. Soc. 56, 628 (1973); eidem, US 3959446 (1976 to USA); by pyrolysis of silazanes: D. Seyferth et al., J. Am. Ceram. Soc. 66, C-13 (1983); eidem, US 4397828 (1983 to M.I.T.). Brief review: D. L. Segal, Chem. Ind. (London) 1985, 544.
Properties: Exists in two crystalline forms, a-Si3N4 and b-Si3N4. a-Form occurs when powdered Si3N4 is heated to 1200° >4 hr; increasing the temperature to >1450°C for 2 hr produces the b-form. White when pure but often brown or black powder. mp 2173°K (sublimes). d 3.2 kg/dm3. Coefficient of thermal expansion K-1: 2.5 ´ 10-6.
Melting point: mp 2173°K (sublimes)
Density: d 3.2 kg/dm3
Use: As high temp engineering material for use in gas turbines, diesel engines. |