Removal of spent coatings by pulsed intense electron beams
V. Engelko 1 ,G. Mueller2, G. Vjasmenova 1, V. Shulov 3
1- Efremov Institute of Electrophysical Apparatus, 196641, St. Petersburg, Russia
2- Forschungszentrum Karlsruhe, IHM, Postfach 3640, D-76021 Karlsruhe, Germany
3- Moscow Aviation Institute, 125 993 Moscow, Russia
Using pulsed intense electron beams for removal of spent protective coatings of turbine blades allows to decrease essentially the cost of refurbishment in comparison with conventional mechanical and chemical methods.
In the paper results of numerical simulation and experimental investigations of electron beam treatment of coatings of MCrAlY type are presented. The calculations were performed to optimize beam parameters and treatment modes at the electron accelerators GESA-I and GESA-II.
It was found that maximum erosion depth for one pulse - 7.10-3 g/cm2 ╗ 10Ám is achieved with pulse duration of 20-25Ás, electron kinetic energy of 120-160 keV and beam current density of 30-70 A/cm2 . Comparison of experimental results and calculations allows to conclude that coatings removal occurs not only through material evaporation from the treated surface but also in form of droplets of the melt.