Coatings to Protect Materials from Extreme Environments: Environmental and Thermal Barrier Coatings II/Aerosol Deposition
Sponsored by: ACerS Engineering Ceramics Division
Program Organizers: Kang Lee, NASA Glenn Research Center; Yutaka Kagawa, High Performance Materials; Daniel Mumm, University of California, Irvine; Rodney Trice, Purdue University; Emmanuel Boakye, UES Inc.; Valerie Wiesner, NASA Langley Research Center; Edward Gorzkowski, Naval Research Laboratory; Scooter Johnson, Naval Research Laboratory; Richard Chromik, McGill University; Jun Song, McGill University; Christian Moreau, Concordia University; Stephen Yue, Mcgill University

Wednesday 2:00 PM
November 4, 2020
Room: Virtual Meeting Room 31
Location: MS&T Virtual

Session Chair: Daniel Mumm, University of California, Irvine; Bryan Harder, NASA Glenn Research Center; Scooter Johnson, Naval Research Laboratory; Edward Gorzkowski, Naval Research Laboratory

2:00 PM
Integrated Fluid and Materials Modeling of Environmental Barrier Coatings: David Newsome¹; Rae Waxman¹; Andreas Hoffie¹; Ashok Raman¹; Debasis Sengupta¹; Stewart Silling²; ¹CFD Research Corporation; ²Sandia National Laboratory
    Ceramic matrix composites (CMC) are under development as alternative materials to superalloys for engine components. The safe and reliable use of the Si-based materials in the hot sections of gas turbine engines is critically reliant upon the performance and integrity of the environmental barrier coating (EBC). CFD Research is developing a physics-based simulation workflow and multiscale model of an EBC system interacting with the flow environment. The modeling procedure uses computational fluid dynamics (CFD) to establish the conditions at the part surface. The response of the coating materials is modeled in a meshfree continuum mechanics method, peridynamics (PD), at the microscale, where each constituent phase of the coating system is discretely resolved using a digital microstructure of the EBC. We will present our results on microscale delamination mechanism with growth of thermally grown oxide layer under an oxidative environment.

2:20 PM
Aerosol Deposition and Characterization of Sodium Niobate: Eric Patterson¹; Scooter Johnson¹; Edward Gorzkowski¹; ¹U.S. Naval Research Laboratory
    Aerosol deposition was used to produce thick-films with layer thicknesses between 10 to 50 microns. The bonding and densification of the film and film/substrate interface facilitated by high pressure, impact and fracture of the particles, and some form of physical-chemical bonding. The films have microstructures characterized by XRD to have nano-grained crystallites and have been shown to have high residual stresses. This inhibits the formation of ferroelectric domains even in the prototypical ferroelectric system of barium titanate, which correlates to the well-known grain size effect in bulk ceramics. Due to these high residual stresses, materials systems that exhibit either antiferroelectric properties in the bulk (such as NaNbO3) or stress-stabilized ferroelectric materials (such as HfO2), are natural alternatives to be studied via this technique. Deposition was performed onto metal substrates to facilitate the characterization of the electrical properties of the films; including permittivity as a function of temperature.

2:40 PM
Aerosol Deposition Method: Influence of Particle Agglomeration on SiC Film Density: Derek Davies¹; Michael Gammage²; Michael Becker¹; John Keto¹; Desiderio Kovar¹; ¹University of Texas at Austin; ²CCDC DEVCOM Army Research Laboratory
    The aerosol deposition method (ADM) process produces thick films by accelerating aerosolized nanoparticles through a nozzle from near atmospheric pressure (300-760 Torr) to medium vacuum (1-3 Torr). By impacting these particles on a substrate translated orthogonal to the aerosol jet, patterned films are deposited. Compared to other particle deposition processes using high velocity impaction such as cold spray, ADM has demonstrated the unique capability of depositing high quality ceramic films at room temperature. Particle agglomeration occurs ubiquitously for the sub-micron particles used in ADM and is believed to significantly affect the density and microstructure of the deposited film. We perform molecular dynamics simulations of multi-particle agglomerate impact, varying the size and shape of the agglomerate, to determine the effect of agglomeration on film density. These simulation results are compared to experimental results from SiC films with the aim of understanding how agglomerate size and morphology influences deformation and bonding mechanisms.

3:00 PM
Dry Aerosol Deposition of SiO_x Coatings for Protection of Polymers in Low Earth Orbit: Robert Calvo¹; Paul Fuierer¹; ¹Department of Materials Engineering, New Mexico Institute of Mining and Technology
    The explosion of satellite activity in low earth orbit (LEO) has renewed interest in protective ceramic coatings for vulnerable space materials and structures. LEO constitutes an extreme environment due to conditions such as high velocity micrometeoroids/debris, vacuum-ultraviolet radiation, and atomic oxygen (AO). The effect of AO is especially detrimental to lightweight, ubiquitous polymers, used for example as satellite solar array substrates, solar reflector blankets, and multi-layer insulation. Dry aerosol deposition (DAD) is an ideal process to produce ceramic oxide coatings to protect these polymeric systems from AO erosion. In particular, SiO_x (x≤2) may act as a cost effective and robust protective coating compared with current sputter deposited thin films. Experimental results for DAD SiOx on Kapton® will be presented. The effects of process parameters on stoichiometry, thickness, adhesion, roughness, hardness and residual stress will be shown. The essential criteria for selection of coatings for AO erosion mitigation will be discussed.