MODELING OF CHEMICAL VAPOR DEPOSITED ZIRCONIA FOR THERMAL BARRIER AND ENVIRONMENTAL BARRIER COATINGS

Conference · Tue Apr 22 00:00:00 EDT 2003

OSTI ID:835697

Starr, T L; Xu, W; Qiu, S

Thermal and environmental barrier coatings are important components of current and future energy systems. Such coatings--applied to hot, metallic surfaces in combustors, heat exchanger and turbines--increase the allowable operating temperature and increase the efficiency of the energy system. Because of its low thermal conductivity and high thermal expansion yttria-stabilized zirconia (YSZ) is the material of choice for protection of structural components in many high temperature applications. Current coating application methods have their drawbacks, however. Air plasma spray (APS) is a relatively low-cost process and is suitable for large and relatively complex shapes. It is difficult to produce uniform, relatively thin coatings with this process, however, and the coatings do not exhibit the columnar microstructure that is needed for reliable, long-term performance. The electron-beam physical vapor deposition (EB-PVD) process does produce the desirable microstructure, however, the capital cost of these systems is very high and the line-of-sight nature of the process limits coating uniformity and the ability to coat large and complex shapes. The chemical vapor deposition (CVD) process also produces the desirable columnar microstructure and--under proper conditions--can produce uniform coatings over complex shapes. The overall goal of this project--a joint effort of the University of Louisville and Oak Ridge National Laboratory (ORNL)--is to develop the YSZ CVD process for application of thermal barrier coatings for fossil energy systems. Last year's report described our initial efforts toward developing a model for the process and for ORNL's bench-scale reactor. This model provides an understanding of the transport and kinetics phenomena that control the deposition process and ultimately will provide a tool for fullscale reactor design and optimization. Our overall research approach is: validate the 3-D computer model using experimental results at ORNL, use the model to identify and evaluate potential process improvements and design a reactor for large and complex substrates. This report describes the modeling effort at the University of Louisville which supports the experimental work at ORNL.

• Research Organization: University of Louisville, Louisville, KY (US)
• Sponsoring Organization: US Department of Energy (US)
• OSTI ID: 835697
• Resource Relation: Conference: 17th Annual Conference on Fossil Energy Materials, Baltimore, MD (US), 04/22/2003--04/24/2003; Other Information: PBD: 22 Apr 2003
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CAPITALIZED COST
CHEMICAL VAPOR DEPOSITION
COATINGS
ENERGY SYSTEMS
HEAT EXCHANGERS
MICROSTRUCTURE
OPTIMIZATION
PHYSICAL VAPOR DEPOSITION
SUBSTRATES
THERMAL BARRIERS
THERMAL CONDUCTIVITY
THERMAL EXPANSION