Thermal expansion in metal/lithia-alumina-silica (LAS) composites

Conference · Tue Mar 01 00:00:00 EST 1988 · Int. J. Thermophys.; (United States)

OSTI ID:5846661

Wolff, E G

Lithia-alumina-silica (LAS) with metallic dispersions offers a new approach toward near-zero, isotopic, thermal expansion composites. The metallic phase contributes a positive coefficient of thermal expansion (CTE) to the negative CTE of the glass/ceramic matrix. In addition, the metal will increase the electrical and thermal conductivities over those of the matrix alone. The LAS systems offers tailorable negative CTEs and light weight compared to other negative CTE ceramics. The most negative CTE phase is crystalline /beta/-eucryptite, whose proportion in an initially glassy matrix can be controlled by heat treatment. Dispersed metal powders were both hot-pressed and cold-pressed and sintered together with LAS matrices prepared by sol gel methods. Super Invar powder was studied for its minimal CTE mismatch, while titanium powders offered a compromise between light weight and low CTE. An ultralow-expansion (ULE) glass- and linear variable differential transducer (LVDT)-based differential dilatometer was developed for rapid screening of compositions, while a double-laser Michelson interferometer was used for precise near-zero CTE measurements. The reinforced /beta/-eucryptite glass/ceramic matrix exhibited both a U-shaped /Delta/L/L curve with temperature and some thermal hysteresis, depending on the fabrication and heat treatment sequences. The temperature of the zero-CTE portion of this curve was found to change with increasing titanium powder content. Results are also given for mixtures of Super Invar powders in ULE glass and /beta/-eucryptite matrices. Negative CTEs in a LAS matrix above ambient temperatures were more difficult to obtain than below, although the use of petalite (high-silica LAS) appears promising.

• Research Organization: Aerospace Corporation, Los Angeles, CA (USA)
• OSTI ID: 5846661
• Report Number(s): CONF-861258-
• Journal Information: Int. J. Thermophys.; (United States), Vol. 9:2; Conference: 9. international thermal expansion symposium, Pittsburgh, PA, USA, 8-10 Dec 1986
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
THERMAL EXPANSION
COMPOSITE MATERIALS
INVAR
LITHIUM OXIDES
SILICA
TITANIUM ALLOYS
DILATOMETRY
FRACTURE PROPERTIES
GLASS
HEAT TREATMENTS
INTERFEROMETRY
METALLURGICAL EFFECTS
POWDERS
PRESSING
QUARTZ
SINTERED MATERIALS
SINTERING
SOL-GEL PROCESS
STRAINS
TEMPERATURE EFFECTS
THERMAL CONDUCTIVITY
THERMAL TESTING
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
ALLOYS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
DIFFRACTION
EXPANSION
FABRICATION
IRON ALLOYS
IRON BASE ALLOYS
LITHIUM COMPOUNDS
MATERIALS
MATERIALS TESTING
MATERIALS WORKING
MECHANICAL PROPERTIES
MINERALS
NICKEL ALLOYS
NONDESTRUCTIVE TESTING
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
SILICON COMPOUNDS
SILICON OXIDES
TESTING
THERMAL ANALYSIS
THERMODYNAMIC PROPERTIES
360204* - Ceramics
Cermets
& Refractories- Physical Properties
360104 - Metals & Alloys- Physical Properties