NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Solid State Synthesis and Properties of Monoclinic CelsianMonoclinic celsian of Ba(0.75)Sr(0.25)Al2Si2O8 (BSAS-1) and B(0.85)Sr(O.15)Al2Si2O8 (BSAS-2) compositions have been synthesized from metal carbonates and oxides by solid state reaction. A mixture of BaCO3, SrCO3, Al2O3, and SiO2 powders was precalcined at approx. 900-940 C to decompose the carbonates followed by hot pressing at approx. 1300 C. The hot pressed BSAS-1 material was almost fully dense and contained the monoclinic celsian phase, with complete absence of the undesirable hexacelsian as indicated by x-ray diffraction. In contrast, a small fraction of hexacelsian was still present in hot pressed BSAS-2. However, on further heat treatment at 1200 C for 24 h, the hexacelsian phase was completely eliminated. The average linear thermal expansion coefficients of BSAS-1 and BSAS-2 compositions, having the monoclinic celsian phase, were measured to be 5.28 x 10(exp -6)/deg C and 5.15 x 10(exp -6)/deg C, respectively from room temperature to 1200 C. The hot pressed BSAS-1 celsian showed room temperature flexural strength of 131 MPa, elastic modulus of 96 GPa and was stable in air up to temperatures as high as approx. 1500 C.
Document ID
19970010347
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Bansal, Narottam P. (NASA Lewis Research Center Cleveland, OH United States)
Date Acquired
September 6, 2013
Publication Date
December 1, 1996
Subject Category
Nonmetallic Materials
Report/Patent Number
E-10509
NASA-TM-107355
NAS 1.15:107355
Accession Number
97N15538
Funding Number(s)
PROJECT: RTOP 505-63-12
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available