Microstructure Observation and Nanoindentation Size Effect Characterization for Micron-/Nano-Grain TBCs

Abstract

Microstructure observation and mechanical properties characterization for micron-/nano-grain thermal barrier coatings were investigated in this article. Scanning electron microscope images demonstrated that both micron-grain coating and nano-grain coating had micrometer-sized columnar grain structures; while the nano-grain coating had the initial nanostructures of the agglomerated powders reserved by the unmelted particles. The mechanical properties (hardness and modulus) of micron-/nano-grain coatings were characterized by using nanoindentation tests. The measurements indicated that the nano-grain coating possessed larger hardness and modulus than the micron-grain coating; which was related to the microstructure of coatings. Nanoindentation tests showed that the measured hardness increased strongly with the indent depth decreasing; which was frequently referred to as the size effect. The nanoindentation size effect of hardness for micron-/nano-grain coatings was effectively described by using the trans-scale mechanics theory. The modeling predictions were consistent with experimental measurements; keeping a reasonable selection of the material parameters.

Software (GUI/APP) for Developing AI-Based Models Capable of Predicting Load-Displacement Curve and AFM Image during Nanoindentation

“…Nanoindentation is widely used for determining mechanical properties of materials by analyzing the load-displacement curve [1,2], while atomic force microscopy (AFM) is an essential tool for analyzing the deformation of material during indentation [3,4]. In order to perform experiments on a new material, an experimentalist relies on their experience or refers to the literature on tests performed on similar systems, and accordingly designs their approach regarding applied load and holding time for similar systems [5][6][7].…”

Functional Ceramic Coatings

“…In-depth studies of the release of Ni and Cr ions into aqueous solutions have shown very good barrier properties of these coatings, therefore they can significantly contribute to reducing potential cytotoxicity and improving the biocompatibility of prosthetic alloys. The last work on the barrier ceramic coatings was that of Liu et al [7], about the microstructure and mechanical properties of 8% yttria-stabilized zirconia (8YSZ) thermal barrier coatings deposited on Ni-based superalloy (GH3128) by plasma spraying. The authors analyzed the effect of the parameterdependent plasma spraying deposition process on the microstructure of the coatings and their micromechanical properties.…”