Accession Number : ADA184356

Title :   Effect of Time and Temperature on Transformation Toughened Zirconias.

Descriptive Note : Final rept.,

Corporate Author : ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB

Personal Author(s) : Schioler,Liselotte J

PDF Url : ADA184356

Report Date : Jun 1987

Pagination or Media Count : 107

Abstract : 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 at temperature.

Descriptors :   *ZIRCONIUM OXIDES, *MAGNESIUM OXIDES, TRANSFORMATIONS, TIME DEPENDENCE, CERAMIC MATERIALS, MICROSTRUCTURE, STRESSES, MECHANICAL PROPERTIES, RUPTURE, HIGH TEMPERATURE, THERMAL RESISTANCE, HARDENING, ALUMINUM OXIDES, MAGNESIUM, DIESEL ENGINES, MODULUS OF ELASTICITY

Subject Categories : Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE