Analytical computation of transient heat transfer and macro-constriction resistance applied to thermal spraying processes

摘要

An analytical solution of the thermal macro-constriction resistance is derived by using the Hankel finite transform and the Duhamel theorem leading to a simple expression of the solution as a serial expansion with fast convergence. The application concerns the thermal macro-constriction resistance estimate during the spreading and coated formation involved in thermal spraying process.In such a process, the heat flux reaches a few hundreds of W/mm ~2 while the spreading duration is extremely short (about μs). The phenomena of thermal macro-constriction deposit/substrate interface play are of primary importance because they control the coating cooling and the thermo-mechanical behavior of the deposited layer, as well.The effect of the spreading velocity on the thermal macro-constriction resistance has been studied. Results show the existence of a critical threshold of spreading velocity for which the transient problem has to be considered. On the other side (below the threshold) the study state regime should be sufficient for the macro-constriction estimate.