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Detailed information on the selected research project
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| Title |
Development of Tribological Coatings for Cryocoolers |
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Subjects
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Compression & Liquefaction, R&D
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Investigators/
Organizations
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Dhere, N; University of Central Florida/Florida Solar Energy Center
V. Hadagali; University of Central Florida/Florida Solar Energy Center
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Funding
Source(s) |
National Aeronautics and Space Administration; Glenn Research Center; amount:$286,000
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| Dates |
Project start date:01-Oct-2003, Project end date:01-Oct-2005 |
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Abstract
Hydrogen is a clean and sustainable form of carrier of energy that can be used in mobile and stationary applications. Hydrogen can be stored as liquid hydrogen, compressed hydrogen and bonded hydrogen as metal/liquid hydrides or adsorbed carbon compounds. Near term spaceport operations are one of the prominent applications for usage of large quantities of liquid hydrogen as a cryogenic propellant. Efficient storage and transfer of liquid hydrogen is essential for reducing the launch costs. A reliable, compact, lightweight, and highly efficient two-stage Reverse Turbo Brayton Cycle (RTBC) CryoCooler is being developed at University of Central Florida (UCF) for distributed cooling of liquid hydrogen systems for spaceport applications as well as for other applications such as automobiles. All the previous attempts of cryocoolers by NASA for zero boil-off (ZBO) of cryogenic propellants in space have cooling powers of less than 2 W at liquid hydrogen temperature. These versions of flight like cryocoolers would be more appropriate for cooling of sensors and superconducting materials in a spacecraft but would prove unsuitable for ZBO applications. The present cryocooler under development with 50 W of cooling power at liquid hydrogen temperature would be ideal for ZBO of cryogenic propellants in NASA’s future robotic missions to Mars and for other human space missions. One part in development of the cryocooler is to reduce the friction and wear between mating parts thus increasing its efficiency. Tribological coatings having extremely high hardness, ultralow coefficient of friction, and high durability at temperatures lower than 60 K are being developed to reduce friction and wear between the mating parts of the cryocooler thus improving its efficiency. Project Objectives The objective of this project is to develop tribological coatings having extremely high hardness, ultra-low coefficient of friction, and high durability at temperatures lower than 60 K.
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Work Significance
Tribological coatings of titanium nitride (TiN) and molybdenum disulphide (MoS2) by DC magnetron sputtering and RF magnetron sputtering were developed. Morphological and tribological properties of TiN and MoS2 layers and TiN/MoS2 bilayer on glass and aluminum substrates were analyzed. Dense well adherent coatings of TiN/MoS2 were obtained. Scanning electron microscopy images and broad nature of peaks in X-ray diffraction patterns of both TiN and MoS2 coatings show that the grains are nanocrystalline in nature. These composite coatings containing the hard ceramic matrix phase of TiN with microhardness value of 24.90 GPa and average elastic modulus value of 256.60 GPa and a solid lubricating phase of MoS2 provided low friction values. The coefficient of friction values by ball-on-disc method for TiN and TiN/MoS2 coatings on glass and aluminum substrates with various coating pairs (TiN, TiN/MoS2 coated steel ball, average force of 50 g) were in the range of 0.08 – 0.2. |
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Supporting Documents
Dhere - Dev of Trib Coatings for Cryocoolers.pdf
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Document Description
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Project Website
http://www.fsec.ucf.edu/hydrogen/research/funded_nasa.htm
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