The experimental evaluation and application of high-temperature solid lubricants
This dissertation describes a research program meant to develop an understanding of high-tenperature solid lubrication and experimental techniques through the development of a composite lubricant coating system. The knowledge gained through this research was then applied to a specific engineering challenge, the tribology of a sliding seal for hypersonic flight vehicles. The solid lubricant coating is a chromium carbide based composite combined with silver, which acts as a low temperature lubricant, and barium fluoride/calcium fluoride eutectic, which acts as a high temperature lubricant. This composite coating provides good wear resistance and low friction for sliding contacts from room temperature to over 900{degree}C in reducing or oxidative environments. The specific research on this coating included a composition screening using a foil gas bearing test rig and the use of thin silver films to reduce initial wear using a pin-on-disk test rig. The chemical stability of the materials used was also addressed. This research indicated that soft metallic films and materials which become soft at elevated temperatures are potentially good lubricants. The general results from the experiments with the model solid lubricant coating were then applied to a sliding seal design concept. This seal design requires that a braided ceramic fabric slide against a variety of metal counterface materials at temperatures from 25 to 850{degree}C in an oxidative environment. A pin-on-disk tribometer was used to evaluate the tribological properties of these materials and to develop lubrication techniques. The results of this work indicate that these seal materials must be lubricated to prevent wear and reduce fiction. Thin films of silver, gold and calcium fluoride provided lubrication to the sliding materials. 22 refs., 33 figs., 12 tabs.
- Research Organization:
- National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
- Sponsoring Organization:
- DOE/CE
- DOE Contract Number:
- AI01-86CE50162
- OSTI ID:
- 7154223
- Report Number(s):
- DOE/NASA/50162-3; NASA-TM-102476; ON: DE90006338
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
LUBRICANTS
PERFORMANCE TESTING
LUBRICATING PROPERTIES
HIGH TEMPERATURE
BEARINGS
CARBON COMPOUNDS
CERAMICS
CHROMIUM COMPOUNDS
COATINGS
DATA PROCESSING
NASA
RESEARCH PROGRAMS
ROLLING FRICTION
SEALS
SILVER
SLIDING FRICTION
SURFACE PROPERTIES
TECHNOLOGY ASSESSMENT
THIN FILMS
TRIBOLOGY
US DOE
USES
ELEMENTS
FILMS
FRICTION
METALS
NATIONAL ORGANIZATIONS
PHYSICAL PROPERTIES
PROCESSING
TESTING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
US ORGANIZATIONS
320201* - Energy Conservation
Consumption
& Utilization- Transportation- Air & Aerospace
360102 - Metals & Alloys- Structure & Phase Studies
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies