Development and evaluation of die and container materials. Second quarterly progress report, January 1--March 31, 1978. [For molten silicon]

Technical Report · Sat Apr 15 04:00:00 EST 1978

DOI:https://doi.org/10.2172/6868631· OSTI ID:6868631

Wills, R R; Niesz, D E

Initial samples of four silicon aluminum oxynitride (Sialons) ceramics have been prepared from commercial Si/sub 3/N/sub 4/, Al/sub 2/O/sub 3/, AlN, and SiO/sub 2/ powders by hot pressing at 1750 C. Si/sub 1/./sub 9/Al/sub 0/./sub 1/N/sub 1/./sub 9/O/sub 1/./sub 1/, Si/sub 1/./sub 8/Al/sub 0/./sub 2/N/sub 1/./sub 8/O/sub 1/./sub 2/, and Si/sub 3/./sub 6/Al/sub 2/./sub 4/N/sub 5/./sub 6/O/sub 2/./sub 4/ Sialons were densified to greater than or equal to 90% theoretical density, but Si/sub 5/./sub 4/Al/sub 0/./sub 6/N/sub 7/./sub 4/O/sub 0/./sub 6/ Sialon could be pressed only to 72% theoretical density. None of these materials are single-phase materials; one group of samples contains an unidentified Sialon phase, while the other group contains significant amounts of free elemental silicon. Chlorine in the Si/sub 3/N/sub 4/ powder and free aluminum in the AlN powder are responsible for these effects. Initial evaluation of these materials in contact with molten silicon at 1450 C indicates that chemical reaction is occurring. Thin string-like precipitates found in the silicon after reaction with Si/sub 3/./sub 6/Al/sub 2/./sub 4/N/sub 5/./sub 6/O/sub 2/./sub 4/ Sialon are considered to be due to the presence of a second phase in the material. Electron probe analysis of silicon in contact with a Si/sub 1/./sub 8/Al/sub 0/./sub 2/N/sub 1/./sub 8/O/sub 1/./sub 2/ sample did not detect aluminum in the silicon, but two reaction zones were found at the interface. Solution thermodynamics studies show that beryllium oxide is much more resistant to attack than aluminum oxide. Fifteen weight percent aluminum dissolved in molten silicon compard with 5000 ppM beryllium. The Henry's Law Constants for oxygen, beryllium, and aluminum at concentrations less than or equal to 5000 ppM have been determined.

• Research Organization: Battelle Columbus Labs., Ohio (USA)
• Sponsoring Organization: DOE
• OSTI ID: 6868631
• Report Number(s): DOE/JPL/954876-2; NAS-7-100-954876
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
ALUMINIUM COMPOUNDS
ALUMINIUM NITRIDES
CASTING
CERAMICS
CONTAINERS
CRUCIBLES
DIES
ELEMENTS
FABRICATION
HOT PRESSING
IMPURITIES
MATERIALS
MATERIALS WORKING
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
PRESSING
PRODUCTION
REFRACTORIES
SEMIMETALS
SILICON
SILICON COMPOUNDS
SILICON NITRIDES
THERMODYNAMICS