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 » 10µm
is achieved with pulse duration of 20-25µs, 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.