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Testing of developmental ceramic materials in diesel engine combustion chambers

Conference ·
OSTI ID:6184055

The development of the ''adiabatic'' (i.e., low-heat-rejection) diesel is unique in that it affords opportunities to improve the fuel efficiency of transportation power plants and to utilize lower-quality fuels as well. Achievement of the adiabatic diesel involves the use of high-temperature-resistant, thermally insulating materials in the construction of the combustion chamber. These materials, in the form of coatings or monolithic components, may have to operate at nominal surface temperatures of 1000/sup 0/C. Promising new materials, several under development at ORNL, have not yet been subjected to dynamic engine conditions to aid in determining their feasibility for combustion chamber applications. A testing project at ORNL is seeking to fill in the information gap between materials development in the laboratory and full-fledged component development. An initial set of simply configured ceramic samples were tested in a single-cylinder 0.825-liter diesel engine. The composite ceramic samples were all made from the same material, composed of an alumina (Al/sub 2/O/sub 3/) matrix with silicon carbide (SiC) whiskers. A sample of partially stabilized zirconia (PSZ) was also tested to provide a monolithic material baseline. The samples were mechanically held inside the prechamber of this indirect-injection diesel in a position and configuration resembling the normal glow-plug. They were subjected to individual repetition periods of the same basic hour-long test cycle involving three load changes. Although direct measurement of internal material temperatures was not performed, thermocouple probes indicated peak ceramic bulk temperatures of approx.650/sup 0/C were approached. One of the samples failed catastrophically for uncertain reasons. Microscopic examination of the tested samples generally revealed no significant changes in the composite material's matrix/whisker microstructure.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
AC05-84OR21400
OSTI ID:
6184055
Report Number(s):
CONF-870210-1; ON: DE87004259
Country of Publication:
United States
Language:
English