Nitride-bonded silicon nitride from slip-cast Si + Si3N4 compacts

Rao, Ramachandra R and Kannan, TS (2002) Nitride-bonded silicon nitride from slip-cast Si + Si3N4 compacts. Journal of Materials Research, 17 (2). pp. 386-395. ISSN 0884-2914

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The dispersability of Si and Si3N4 powders in aqueous media was monitored by particle-size distribution, sedimentation behavior, viscosity/rheological studies, and electrokinetic behavior (zeta potential (ZP) analysis] as a function of pH of their slips. The pH values of 4 and 8 for Si and 10 for Si3N4 resulted in optimum dispersion, characterized by minimum in sedimentation height, minimum in viscosity, and maximum in ZP. The optimum slips of Si + Si3N4 mixtures conditioned in the pH range 8 to 10 were slip cast to obtain green compacts having a density in the range of 59-66 percent theoretical value. When nitrided, these compacts yielded nitride-bonded Si3N4 products having a density of 2.06-2.28 g/cu cm, Si3N4 bonding phase of 20-60 percent, and 3-point flexural strength values in the range of 50-150 MPa. The microstructure consisted of very fine particles as well as fibrous or whiskerlike alpha-Si3N4 binding phase enveloping the matrix Si3N4, in total consisting of 90 percent alpha-Si3N4 and the rest being beta-Si3N4 phase.

Item Type: Article
Additional Information: Copyright for this article belongs to Materials Research Society
Uncontrolled Keywords: Silicon nitrides;Slip casting;Nitriding;Densification; Microstructure;Particle size distribution;Mechanical properties
Subjects: CHEMISTRY AND MATERIALS > Nonmetallic Materials
Depositing User: Mr. Ravikumar R
Date Deposited: 07 Sep 2006
Last Modified: 24 May 2010 04:20

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