A study of the tribological and surface micromechanical properties of YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/: Final report
The burgeoning interest in high critical temperature (T/sub c/) superconductors has created a need to examine the technological properties of these materials for the purpose of defining potential applications and handling characteristics. While new superconducting compounds continue to be developed, the perovskite-structure oxide ceramics form the basis for these new materials. This report discusses information obtained about the reciprocating sliding friction coefficients (self-mated and on gold), scratch resistance, microindentation hardness, and wear damage mechanisms in YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/ compounds fabricated in several ways. As expected, the materials are quite brittle. Knoop microindentation hardness numbers for single crystals can exceed 4.41 GPa (450 kg/mm/sup 2/). Low-load, precision indentation experiments provided information on the hardness of thin surface regions less than 300 nm deep, as well as on the modulus of elasticity. The modulus of elasticity obtained by indentation experiments was 78 to 81 GPa, which is in relatively good agreement with density-corrected published values obtained by ultrasonic methods. Scratch resistance using a diamond stylus test falls with increasing load because both intergranular and transgranular cracking increase with load. The abrasion rate of YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/ on 180-grit silicon carbide papers is linearly proportional to normal load. Overall results confirm that the YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/ materials are brittle in their monolithic form, and their use in tribological applications should be avoided unless a suitable, more damage-tolerant composite can be developed. 23 refs., 22 figs., 3 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5676811
- Report Number(s):
- ORNL/TM-11053; ON: DE89015680
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ABRASION
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
BRITTLENESS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DOCUMENT TYPES
FRICTION
HARDNESS
MECHANICAL PROPERTIES
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PROGRESS REPORT
SLIDING FRICTION
SUPERCONDUCTORS
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
WEAR
YTTRIUM COMPOUNDS
YTTRIUM OXIDES