Performance analysis and modeling of thermally sprayed resistive heaters

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Journal titleJournal of Thermal Spray Technology
Pages947953; # of pages: 7
Subjectalumina; electrically conductive coatings; finite-element modeling; thermal properties; thermal stress
AbstractMany processes and systems require hot surfaces. These are usually heated using electrical elements located in their vicinity. However, this solution is subject to intrinsic limitations associated with heating element geometry and physical location. Thermally spraying electrical elements directly on surfaces can overcome these limitations by tailoring the geometry of the heating element to the application. Moreover, the element heat transfer is maximized by minimizing the distance between the heater and the surface to be heated. This article is aimed at modeling and characterizing resistive heaters sprayed on metallic substrates. Heaters were fabricated by using a plasma-sprayed alumina dielectric insulator and a wire flame-sprayed iron-based alloy resistive element. Samples were energized and kept at a constant temperature of 425 °C for up to 4 months. SEM cross-sectional observations revealed the formation of cracks at very specific locations in the alumina layer after thermal use. Finite-element modeling shows that these cracks originate from high local thermal stresses and can be predicted according to the considered geometry. The simulation model was refined using experimental parameters obtained by several techniques such as emissivity and time-dependent temperature profile (infra-red camera), resistivity (four-probe technique), thermal diffusivity (laser flash method), and mechanical properties (micro and nanoindentation). The influence of the alumina thickness and the substrate material on crack formation was evaluated.
Publication date
AffiliationAutomotive and Surface Transportation; National Research Council Canada
Peer reviewedYes
NRC number141472
NPARC number21268365
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Record identifierdc34fd2e-6e32-4364-9ead-0c712d82c6fa
Record created2013-07-04
Record modified2016-05-09
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