Application of Acoustic Emission Technology for Quantitative Characterization of Plasma-Sprayed Coatings Subjected to Be
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Application of Acoustic Emission Technology for Quantitative Characterization of Plasma-Sprayed Coatings Subjected to Bending Fatigue Tests Jian-nong Jing1,2 • Li-hong Dong2 • Hai-dou Wang2 • Guo Jin1
Submitted: 2 May 2018 / in revised form: 16 August 2018 Ó ASM International 2018
Abstract Plasma-sprayed coatings are widely used in industry, e.g., in applications subject to high wear and corrosion damage, or requiring thermal insulation. However, the failure behavior of such coatings has a great influence on the service safety of mechanical parts. Acoustic emission (AE) has attracted much attention due to its proven usefulness for real-time monitoring of damage evolution and high sensitivity to fracture sources. In this study, the damage evolution behavior of a plasma-sprayed coating subjected to three-point bending fatigue tests was monitored using the AE method. A method combining parameterized, Fourier, and wavelet analysis was used to distinguish the damage modes in the coating. The analysis results revealed two crack modes (surface vertical crack and interface crack) with two different peak frequencies. A finite element method was used to quantify the fracture stress and propagation behavior of cracks, revealing that the thickness of the coating had a strong influence on its spalling. Keywords acoustic emission bending fatigue tests finite element method plasma-sprayed coating quantitative assessment Suo–Hutchinson model
& Li-hong Dong [email protected] & Hai-dou Wang [email protected] 1
College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
2
National Key Laboratory for Remanufacturing, Army Academy of Armored Forces, Beijing 100072, China
Introduction Coating technology has drawn attention from many researchers because of its ability to improve the performance and extend the lifetime of parts greatly (Ref 1-3). As one of the most versatile processes, thermal spray technology can effectively improve the wear resistance, corrosion resistance, and heat insulation properties of parts. This process also does not suffer from any limitations regarding the sprayed material or the thickness of the deposited coating in the range from tens of micrometers to several millimeters. Moreover, it can satisfy complex spraying requirements on substrates of various shapes and sizes, offering the advantage of keeping the thermal deformation of the substrate relatively low. As a typical plasma-sprayed coating material, NiCrBSi is often used as a protective coating for metallic substrates because of its excellent wear resistance, corrosion resistance, and mass production at relatively low cost. However, presence of microdefects in the as-sprayed coating and weak mechanical combination between the as-sprayed coating and substrate can significantly influence the performance and service life of as-sprayed coatings (Ref 4-6). The physical state of the coating, e.g., residual stress, surface integrity, etc., which can affect the overall performanc
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