Kinetics of in-situ {alpha} to {beta} Si{sub 3}N{sub 4} transformation in a barium aluminosilicate matrix

Journal Article · Mon May 01 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00181-T· OSTI ID:64366

Bandyopadhyay, A; Quander, S W; Aswath, P B ^[1]; Freitag, D W; Richardson, K K; Hunn, D L ^[2]

---

1. Univ. of Texas, Arlington, TX (United States)
2. Loral Vought Systems, Dallas, TX (United States)

During sintering of Si{sub 3}N{sub 4}, oxide based additives are added as sintering aids. These oxides form a liquid phase at elevated temperature which aids the {alpha} to {beta} transformation in Si{sub 3}N{sub 4} ultimately resulting in a uniform distribution of randomly oriented {beta}-Si{sub 3}N{sub 4}. It has been reported that the {alpha} to {beta} transformation in Si{sub 3}N{sub 4} is a reconstructive transformation of secondary coordination. This type of transformation requires breaking bonds, so a liquid phase is often needed to enable the transformation to occur. In addition, as this is a solution-diffusion-precipitation type of transformation, the kinetics of the transformation will depend on the sintering time, sintering temperature and amount of liquid phase present in the composites. The intent of this work was to evaluate the role of BAS content and temperature of sintering on the kinetics of the {alpha} to {beta} transformation in Si{sub 3}N{sub 4}.

• OSTI ID: 64366
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 9 Vol. 32; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM SILICATES
BARIUM SILICATES
CHEMICAL COMPOSITION
COMPOSITE MATERIALS
CRYSTAL-PHASE TRANSFORMATIONS
LIQUIDS
NEUTRON ACTIVATION ANALYSIS
POWDERS
SILICON NITRIDES
SINTERING
X-RAY DIFFRACTION