A Conventional Metallographic Method for Ytterbium Disilicate and Yttrium Ytterbium Disilicate Air Plasma Spray Coatings

Author(s):

Arturo Villegas, Nickolas Sotiropoulos, Joshua Taggart-Scarff, and Clara Mock

Abstract:

Ytterbium-based environmental barrier coatings for silicon carbide (SiC)-based ceramic matrix composites (CMCs) are of great interest to enable gas turbine engines to operate at higher temperatures. Metallographic evaluation of the coatings is challenging due to the hard, brittle nature of the coatings and substrate, causing artifacts such as coating pull-out and uneven polishing. A technique for the metallographic preparation of ytterbium disilicate coatings on monolithic SiC was developed. This enables key features to be measured through optical microscopy, highlighting the effectiveness of the proposed methodology in minimizing artifacts and leading to high-quality microscopy images and robust evaluations. This approach enables enhanced assessment of CMCs for high-temperature aerospace applications.