Innovators at NASA’s Glenn Research Center have created exciting new developments in thermal barrier coatings, both in the chemical compositions of the coatings and in the process by which they are applied. NASA’s researchers have developed a revolutionary bond coat system that improves the performance of silicon-carbide/silicon- carbide ceramic matrix composites (SiC/SiC CMCs). This groundbreaking system enables higher-temperature operating conditions, protects against erosion and corrosion, and reduces mechanical loading. NASA’s scientists have also designed a means of creating multilayer thermal and environmental barriers with a remarkable new deposition technique to improve the coverage and quality of the coatings.
In devices such as gas turbine jet engines, the increased efficiency of a higher-temperature system comes with a price — higher stresses, increased materials phase instability, and thermal oxidation. All of these factors can lead to premature failure of components. To address this problem, researchers at NASA’s Glenn Research Center have developed cutting-edge ways to enhance the effectiveness of thermal and environmental barrier coatings.
Glenn’s innovators have succeeded in bolstering SiC/SiC CMCs by applying a zirconia-based thermal bond coat, which helps make the silicon in the CMCs more durable and better able to withstand extremely high temperatures. These bond coat systems can include an advanced silicon/silicide component, an oxide-silicate component, or a combination. In addition to the advances made by altering the mix of materials used for thermal barrier coatings, Glenn’s scientists have also created a newly patented technology for combining plasma spray and physical vapor deposition, so that layers may be deposited from a liquid phase, a vapor phase, or both phases simultaneously. This technology allows layers to be generated with a multi-system architecture, forming both planar and columnar structures in a faster, onestep coating process. This approach creates an environmental barrier coating layer, an intermediary layer, and a topcoat layer that together help optimize the performance of components in extreme environments.
Potential applications include aerospace (gas turbine engine components), energy (gas turbine engine and generator components), batteries and fuel cells, nuclear fission and fusion reactors, heat exchangers, and furnace components.