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Characterization on Fracture Toughness of Cermet Coating Coupling Instrumented Indentation and X-Ray Computed Tomography

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1 Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing, 100081, China

* Corresponding Author: Zhaoliang Qu. Email:

The International Conference on Computational & Experimental Engineering and Sciences 2024, 30(1), 1-1. https://doi.org/10.32604/icces.2024.011440

Abstract

The surface brittle fracture of cermet coating seriously restricts its application. Accurate evaluation of the fracture toughness of cermet coating is a prerequisite for improving its life. This paper aims to propose an accurate characterization method for fracture toughness of cermet coating. By coupling instrumented indentation and X‑ ray computed tomography, the indentation-induced fracture behaviors under various loads within WC-12%Co coatings were studied. The indentation response was correlated with the damage evolution directly observed within the coating. The impact of substrate effects on indentation-induced fracture behaviors was further studied using finite element analysis (FEA). The three-dimensional subsurface crack morphologies under different loads were nondestructively observed. The first pop-in event in the load-displacement (P-h) curve was determined to be triggered by bottom cracking, marking the onset of the multiple fracture mode. With the absence of pop-in events in the indentation response, Laugier's equation offered a consistently stable and reliable estimation of fracture toughness for the coating. The critical indentation depth for the first pop-in was suggested as the threshold for reliably extracting intrinsic fracture toughness of coatings. Numerical results revealed a constant linear relationship between the critical depth and coating thickness, and a high sensitivity of the critical depth to yield stress of the substrate.

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Keywords

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