Tribology of improved transformation-toughened ceramics-heat engine test. Final report: DOE/ORNL Ceramic Technology Project

摘要

A short term study has been carried out to evaluate the suitability as cam roller followers of three ceria zirconia toughened aluminas and two yttria stabilized tetragonal zirconias (YTZPs) previously enhanced in programs supported by ORNL. Norton Si(sub 3)N(sub 4) (NBD-100) was also included in this study as a reference material, because it was known from work at Northwestern University that Si(sub 3)N(sub 4) to experienced little or no wear in this application, and NBD-100 is currently a successful commercial bearing material. The tribological studies were subcontracted to the Torrington Company. They found that in cam roller follower simulated tests that there was essentially no wear after 1 hour and 5 hours of testing detectable by weighing and concluded that all of these ceramics are, therefore, candidate materials. Because of the minute amounts of wear it was not possible to identify the wear mechanism or to make any correlations with the other physical properties which were evaluated such as MOR, K(sub IC) hardness, density and grain size. Phase transformation during rolling has been of interest in the tribology of zirconia contain materials. The least stable of the ceria zirconia toughened aluminas resulted in as much as 33% monoclinic phase after testing whereas the yttria stabilized (TTZ) contained very little of this transformed phase. The results of this study show that oxide materials can now be considered as candidates for cam roller followers in heat engines.