Coatings to Protect Materials from Extreme Environments: On-Demand Coatings for Extreme Environments
Sponsored by: ACerS Engineering Ceramics Division
Program Organizers: Kang Lee, NASA Glenn Research Center; Yutaka Kagawa, The University of Tokyo; 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
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 9
Location: MS&T On Demand
Session Chair: Emmanuel Boakye, UES Inc.
Invited
Modelling Oxygen Permeability through Top Coat and Thermally Grown Oxide in Dense Yb2Si2O7 Environmental Barrier Coatings: Kuiying Chen1; 1NRC
Oxidant diffusion through EBC system was studied using physics-based and numerical modelling. Oxygen permeability of dense YbDS top coat and TGO are systematically evaluated in terms of thermodynamics using defect reactions and parabolic rate constant (kp). Dry oxygen and wet oxygen conditions as well as different temperatures, partial pressures and top coat modifiers are investigated. Results offer evidence that oxygen permeability for YbDS top coat is an order of magnitude higher than for TGO, hindering oxidant diffusion stronger, proving to be the diffusion rate controlling layer. Moreover, water vapor strongly increases the oxidant permeation with defect reactions playing a key role. Mass transfer through top coat is primarily by outward ytterbium ion diffusion and inward oxygen ion movement, with the latter being dominant, particularly in wet environments. The effect of top coat modifiers on oxidant permeation is composition sensitive and related to their interaction with oxygen ions and mobility.
Obtaining Surface Titanium Coatings for Enhance the Material Performance in SHS Conditions: Borys Sereda1; Dmytro Sereda1; 1Dneprovsky State Technical University
Offered promising methods of applying protective wear-resistant coatings - technology for producing powder coatings by in a high-temperature synthesis (SHS). This kind of protection is the most promising and less costly, since it does not require changes in the technology of materials. For parts operating under conditions of wear, alternating loads, high temperatures, speeds and pressures, as well as aggressive corrosive environments, the properties of the surface layer are of great importance. In work with the use of mathematical modeling, optimal compositions of SHS blends have been developed to produce titanium-chromium coatings that positively affect the properties of the resulting coatings operating in extreme conditions. A thermodynamic analysis was performed to calculate the equilibrium state of the reaction products in multicomponent powder systems. The research results are due to an increase in the microhardness of the layer surface by 1.8-2.1 times.
Obtaining Surface Coatings Providing Protection Against High Temperatures in the Production of Coke: Borys Sereda1; Dmytro Sereda1; 1Dneprovsky State Technical University
For machines and assemblies, in aggressive environments and in the production of coke, high corrosion resistance is required. Surface coatings obtained in SHS conditions improve the characteristics of the material, providing protection from extreme conditions, such as high temperature.This method of protection is the most promising and less expensive. The composition of the saturating medium is selected based on the requirements for the use of protective coatings on the studied materials. The production environment of a coke-chemical enterprise is characterized by an uneven distribution of aggressive substances in the working area. A comparative analysis of the corrosion resistance of protective coatings obtained under SHS conditions showed an increase of 1.7-2.0 times in comparison with the results processed under isothermal conditions when the equipment was operated at high temperatures in the conditions of coke production.
Coatings for Improving the High Temperature Oxidation Resistance of Mo-based Systems
: Katharina Beck1; Frauke Hinrichs2; Martin Heilmaier2; Anke Ulrich1; Mathias Galetz1; 1DECHEMA-Forschungsinstitut; 2Karlsruher Institut für Technologie
The range of operation temperature of conventionally used Ni-base alloys ends at around 1100 °C. New materials are required to further increase the operation temperatures in order to improve the performance and efficiency of combustion engines. The high melting point and good mechanical properties of Mo-based refractory systems designate them as promising substitutes. To counteract their oxidation issues, foremost pesting, two strategies are followed: i) smart alloying with Si and Ti and ii) coating application (e.g., Al or Cr-based).Cr- and Al-coatings with layer thicknesses between 10 and 120 μm were successfully applied on pure Mo and Mo-Si-Ti alloys (eutectic and eutectoid) using pack-cementation processes. Oxidation kinetics were investigated using thermogravimetric analysis for 100 h in synthetic air at three different temperatures (700°C, 900°C, 1300°C). The obtained kinetics were correlated to Cr₂O₃ and Al₂O₃ oxide scale formation investigated using XRD, EPMA, and SEM.
In-Situ Ceramic Oxide Coating on Stainless Steels for Molten Salt Corrosion Prevention for Concentrated Solar Power Applications: Animesh Kundu1; Sreya Dutta2; Chase Clapp1; Hannah Clarkson1; 1Lehigh University; 2Dynalene, Inc
The excessive corrosion of stainless steels in molten chloride salt blends prevents the alloys to be considered for concentrated solar power applications that would utilize the chloride salt blends and operate at a high temperature of 750°C. In this research, additives are developed that reacts with the stainless-steel alloys in a molten chloride environment at elevated temperatures and form a protective ceramic oxide coating minimizing further corrosion. The efficacy of this corrosion mitigation strategy has been systematically investigated for a series of binary, ternary and quaternary molten chloride salt blends with the aid of electron microscopy. The ceramic oxide coating has been observed to form in all the salt blends studied. The thermo-kinetics of the formation of the coating has been studied. The oxide can form within two hours of reaction at 750°C and its initial nucleation on the stainless steel surfaces has been observed to be ubiquitous.