QUANTATIVE MICROSTRUCTURAL ANALYSIS OF THERMAL BARRIER COATINGS PRODUCED BY ELECTRON BEAM PHYSICAL VAPOR DEPOSITION

摘要

Thermal Barrier Coatings (TBC) produced by Electron Beam Physical Vapor Deposition (EB-PVD) are used primarily for system critical components of power turbines. The performance of coatings is highly dependant on micro and nano structural features. This paper proposes and demonstrates quantitative microstructural analysis of TBC produced by the EB-PVD. Metallographic techniques were applied to surfaces parallel and perpendicular to the columnar growth direction. Multiple levels perpendicular to the columnar growth direction were prepared to identify descriptive statistical values for coating microstructure throughout coating thickness. Metallographic surfaces were imaged with Scanning Electron Microscopy (SEM) and evaluated with commercial image analysis software. Samples produced with different vapor incidence angles were evaluated by the proposed method and show distinct quantitative differences of column grain size, inter-columnar porosity, and levels of re-nucleation. Microstructural results will be presented as a function of coating thickness and vapor incidence angle.