A unique organic electrodeposition technique has been developed which allows rapid, smooth, and consistent coating application at low temperatures, low voltages, and with no pollutants. Precursor coatings of Aluminum, Al-Si, and Al-Mullite have been applied to Mo-Si-B turbine materials through immersion deposition and organic electrolytic cathodic deposition in an ionic liquid. These coatings were applied in protective atmosphere boxes and followed by low-temperature annealing to create a graded precursor layer. A graded precursor layer is desirable to minimize thermal shock, improve adhesion and achieve oxidation protection. The reactions across the interface region were characterized to assist in creation of the proper graded precursor layers for mullite formation. The optimal coating deposition method and composition has been assessed. High-temperature oxidation is being performed to form graded corrosion-resistant mullite thermal barrier coatings. The optimum deposition, annealing, and oxidation parameters will be characterized to achieve the proper thickness and compositional gradient of the thermal barrier coating. Coatings with various compositions and compositional gradients in the Mo-Si-B substrate and mullite layer are being assessed in a high-temperature simulated burner environment. Additional protective layers, such as barium-strontium-alumino-silicate (BSAS) are being developed to extend service life.
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