Effect of time and temperature on transformation-toughened zirconias. Final report

Technical Report · Mon Jun 01 04:00:00 EDT 1987

OSTI ID:6039253

Schioler, L J

The effects of exposure to elevated temperatures (900 to 1300 C) for times ranging from 50 to 500 hours on toughened oxide ceramics intended for use in heat engines were examined. The materials were magnesia-stabilized transformation-toughened zirconia, yttria-stabilized tetragonal zirconia polycrystal, and zirconia-toughened alumina, as well as untoughened zirconias for comparison. The materials were heat treated, and physical and mechanical properties were then measured at room temperature. High-temperature mechanical tests performed were stress rupture and stepped temperature stress rupture. The results of the tests indicate that the mechanical properties of magnesia-stabilized transformation-toughened zirconia degrade substantially after relatively short times at the moderate temperatures expected in low-heat-rejection diesel engines. The yttria-stabilized tetragonal zirconia polycrystal and the untoughened partially stabilized zirconia materials appear to be more stable against the effects of time and temperature.

• Research Organization: Army Materials Research Agency, Watertown, MA (USA). Materials Technology Lab.
• OSTI ID: 6039253
• Report Number(s): AD-A-184356/4/XAB; MTL-TR-87-29
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
CERAMICS
CHALCOGENIDES
CRYSTAL STRUCTURE
DIESEL ENGINES
ELEMENTS
ENGINES
HARDENING
HEAT ENGINES
HIGH TEMPERATURE
INTERNAL COMBUSTION ENGINES
MAGNESIUM
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
STRESSES
TIME DEPENDENCE
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES