REU/RET Project

Ronn Philip Walvick
University: New Jersey Institute of Technology (NJIT)
Mentor: Dr. Y.-H. Sohn – AMPAC and Mechanical, Materials and Aerospace Engineering

Development of Direct Laser Deposited Thermal Barrier Coatings from Micro and Nano Sized Powders

The performance and efficiency of advanced turbine engines has significant environmental and technological implications. In general, performance and efficiency of the turbines is directly related to its operating temperature. This has been the driving force behind many engineering disciplines including engine design and material innovations such as air-cooling systems and direction or single crystal solidification of supperalloys. High laser power produced the most uniform coating, because the heated molten powders promote the formation of a thin oxide scale on the surface of the stainless steel. This oxide scale seems to improve the wetting behavior of molten YSZ particles and a uniform deposition of TBCs.The DLD process and related pre-heat treatment parameters can be further optimized to deposit a uniformly deposited YSZ-based coatings including TBCs. It has been shown by the secondary electron micrographs that the DLD process can make nanostructured TBCs from nano-sized YSZ particles. The nano particles retain their nano-structure throughout DLD. Once on the surface, the nano-particles consolidate into coatings consisting of spherical particles that range from 90nm to 220nm in diameter. During isothermal heating, the 1.5kW samples held up the best. There are virtually no metal portions that can be seen through the coating.