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5414 |
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Thursday, June 08, 2017, Hall 26 11:00 AM Characterization & Testing Methods I |
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Interplay among adhesion, residual stress, and tensile properties of thermal spray coated laminates |
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Gregory Smith* / Stony Brook University, USA Dr. Xiaotao Luo / Stony Brook University, USA Dr. Andrew Vackel/ Stony Brook University, USA Prof. Sanjay Sampath/ Stony Brook University, USA |
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Adhesion is a critical mechanical parameter that governs the integrity of thermal spray (TS) coatings. For a majority of TS coatings, the primary mode of bonding between the sprayed layer and the substrate is attributed to mechanical interlocking between the coating and the deliberately roughened substrate surface. This mechanism appears to primarily dependent on the substrate roughness and process type, and to a lesser extent on materials. ASTM C633 has long been the default standard for measuring coating bond strengths, however it as many shortcomings. With repair and additive manufacturing applications becoming more common place within TS, and more dedication to application and service functional coatings, there is an emerging need to develop enhanced methods to measure and assess adhesion. Recent work by Vackel et al examined the efficacy of additive restoration and remanufacturing using high velocity oxy-fuel (HVOF) coatings. In this work, the authors seek a successive study to further examine the capability of the simple tensile test of a substrate-coating system with variances to the interfacial roughness achieved via grit blasting, while simultaneously studying the adhesion strength using the C633 method for equivalent process-substrate situations. The study is further enhanced through the measurement of process induced stresses through in-situ beam curvature methods which provides a framework for robust comparison and interpretation of the various test methods. It is envisioned that the results presented in this study will enable a new approach to quantify adhesion in situations which are limited by the ASTM C633 technique, as well as evaluate in-depth, the interfacial load transfer behavior occurring between the spray coating and substrate. |