A5075956895- High-Temperature Coating Behaviors
- Advanced ceramic materials synthesis
- Nuclear materials and radiation effects
- Nuclear Materials and Properties
- Intermetallics and Advanced Alloy Properties
- Aluminum Alloys Composites Properties
- Catalytic Processes in Materials Science
- Advanced materials and composites
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Aluminum Alloy Microstructure Properties
- Microwave Dielectric Ceramics Synthesis
- Semiconductor materials and devices
- Ferroelectric and Piezoelectric Materials
- Solidification and crystal growth phenomena
- Glass properties and applications
- Titanium Alloys Microstructure and Properties
- Metallurgical Processes and Thermodynamics
- Electronic and Structural Properties of Oxides
- Magnesium Oxide Properties and Applications
- Metal and Thin Film Mechanics
- Recycling and utilization of industrial and municipal waste in materials production
- nanoparticles nucleation surface interactions
- MXene and MAX Phase Materials
- High Temperature Alloys and Creep
University of California, Santa Barbara
2016-2025
Battelle
2015
University of California System
1995-2009
American Ceramic Society
1997-2008
Stony Brook University
2008
Woods Hole Oceanographic Institution
2003
Max Planck Society
2003
University of Pittsburgh
2001
Fondation Nationale des Sciences Politiques
1988
Laboratoire d'Anthropologie Sociale
1988
▪ Abstract The emphasis in this short review is to describe the materials issues involved development of present thermal barrier coatings and advances necessary for next generation, higher temperature capability coatings.
Thermal barrier coatings (TBCs) are increasingly susceptible to degradation by molten calcium–magnesium alumino silicate (CMAS) deposits in advanced engines that operate at higher temperatures and environments laden with siliceous debris. This paper investigates the thermochemical aspects of phenomena using a model CMAS composition ZrO 2 –7.6%YO 1.5 (7YSZ) grown vapor deposition on alumina substrates. The changes microstructure chemistry characterized after isothermal treatments 4 h...
The thermochemical interaction between a Gd 2 Zr O 7 thermal barrier coating synthesized by electron‐beam physical vapor deposition and model 33CaO–9MgO–13AlO 3/2 –45SiO (CMAS) melt with melting point of ∼1240°C was investigated. A dense, fine‐grained, ∼6‐μm thick reaction layer formed after 4 h isothermal exposure to 1300°C. It consisted primarily an apatite phase based on 8 Ca (SiO ) 6 fluorite ZrO in solid solution. Remarkably, infiltration into the intercolumnar gaps largely suppressed,...
Modern gas turbines rely on ceramic coatings to protect structural components along the hot path. These are susceptible accelerated degradation caused by silicate deposits formed when ingested environmental debris (dust, sand, ash) adheres coatings. This article reviews current understanding of deposit-induced failure mechanisms for zirconia-based thermal barrier and Details melting crystallization behavior, nature chemical reactions occurring between coatings, implications thermocyclic...
Continuous fiber ceramic composites (CFCCs) based on oxides are of interest for high‐temperature applications owing to their inherent oxidative stability. An enabling element is a matrix with an optimum combination toughness and strength, which may be achieved by incorporating controlled amount fine, well‐distributed porosity. Implementation this concept vacuum infiltration aqueous mullite‐alumina slurries into two‐dimensional woven preforms alumina fibers has been investigated. Evaluation...
The temperature capability of yttria‐stabilized zirconia thermal barrier coatings (TBCs) is ultimately tied to the rate evolution “nontransformable” t ′ phase into a depleted tetragonal form predisposed monoclinic transformation on cooling. phase, however, has been shown decompose in small fraction time necessary phase. Instead, modulated microstructure consisting coherent array Y‐rich and Y‐lean lamellar phases develops early process, with mechanistic features suggestive spinodal...
Multilayer ytterbium‐hafnate/silicate coatings deposited by directed vapor deposition and designed to protect SiC ‐based ceramic matrix composites were assessed determine their thermochemical stability resistance attack molten silicate deposits ( CMAS ). The study revealed that reactions occurring at the interface between Yb 2 Si O 7 4 Hf 3 12 layers promote coating delamination following isothermal annealing for 100 h/1500°C while architectures involving SiO 5 in contact with do not...
The relationship between yttria concentration and the unit cell parameters in partially fully stabilized zirconia has been reassessed, motivated by need to improve accuracy of phase analysis upon decomposition t′ ‐based thermal barrier coatings. Compositions ranging from 6 18 mol% YO 1.5 were synthesized examined means high‐resolution X‐ray diffraction. Lattice determined using Rietveld refinement method, a whole‐pattern fitting procedure. revised empirical relationships fall within range...
Thermal barrier coatings (TBCs) made by electron‐beam physical vapor deposition (EB‐PVD) exhibit a thermal conductivity strongly affected hierarchy of pores introduced during the process. These are in form narrow gaps, aligned spheroids, and random spheres at specific sites within coatings. Models for effects on having these shapes spatial arrangements taken from literature combined with new results to provide descriptors overall relationships between relative density pore morphology coating...