PULSED ELECTRON BEAMS AND THEIR USE FOR MATERIAL MODIFICATION

A. Weisenburger1, V. Engelko2, W. An1, Annette Heinzel1, Adrian Jianu1, Fabian Lang1, G. Müller1 and Frank Zimmerman1

1 Forschungszentrum Karlsruhe, Institut für Hochleistungsimpuls- und Mikrowellentechnik,

Hermann-von Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen, Germany

2 Efremov Institute of Electrophysical Apparatus, 189631, Saint Petersburg, Russia

 

ABSTRACT

 

Intense pulsed electron beams are applied for surface modification of materials since several years in our laboratories. The intense pulsed electron beams are generated by the GESA (Gepulste Elektronen Strahl Anlage) facilities[1]. One peculiarity of these facilities are the multi point explosive emission cathodes allowing the generation of large area intense electron beams. These beams have following parameters: accelerating voltage between 80–400kV, power-density at the target from 2 to 6MW/cm2, beam-diameter 4 to 10cm and pulse-duration of 4 to 250µs. Electron beams deposit their energy volumetric in the target and therefore an almost adiabatic melting of a definite surface layers is achieved. The underlaying bulk remains relatively cool during the pulse and therefore rapid cooling < 107K/s by heat conduction into the bulk will take place. This results in a change in microstructure and in the case of surface alloying also to a change in chemical composition [2]. An improvement of properties like wear, corrosion and oxidation resistance was found.

Changes in microstructure of 16MnCr5 steel after the GESA treatment increases the hardness by 60 to 80%. GESA treated gears of this material showed an increase in wear resistance by a factor of 6 to 8. The thermal cycle stability of thermal barrier coatings deposited on HVOF sprayed MCrAlY coatings of stationary gas turbines blades could be increased by a factor of two compared to none treated HVOF sprayed coatings [3]. GESA treatment of Ti - blades lead to increased fatigue strength of about 40% compared to untreated blades [4]. Surface alloying of Al into steels increases their oxidation resistance in liquid lead alloys by the selective formation of alumina scales. More than 10000h of exposure without significant oxidation and corrosion are performed. Surface-fusing of FeCrAlY coatings is investigated as a corrosion protection layer in liquid lead alloys too. Such layers show the same positive oxidation behaviour like the Al- surface alloyed materials without deteriorating the mechanical properties of the materials as shown in low-cycle-fatigue tests [6] and with pressurized tube tests [7].

 

Oral

References

 

[1] V. ENGELKO, B. YATSENKO, G. MÜLLER, H. BLUHM, Vacuum, 62(2001) S.211-16

[2] G. Müller, V. Engelko, A. Heinzel, Vacuum, 77(2005) S.469-74

[3] N. NOCHOVNAYA, V. SHULOV, A. PAYKIN, V. ENGELKO, G. MÜLLER, A. WEISENBURGER, edited by G. Lütjering, Proceedings of the 10th World Conf. on Titanium,

(Hamburg, July 13-18, 2003), Vol.V S.2777-84

[5] R.G. WELLMANN, A. SCRIVANI, G. RIZZI, A. WEISENBURGER, F.H. TENAILLEAU, J.R. NICHOLLS, Surface and Coatings Technology, 202(2007) S.709-13

[6] A. WEISENBURGER, A. HEINZEL, C. FAZIO, G. MÜLLER, V.G. MARKOV and A.D. Kastanov,  J. Nucl. Mater. 377 1 (2008) 261-267

[7] A. WEISENBURGER, A. HEINZEL, G. MÜLLER, H. MUSCHER and A. ROUSSANOV, J. Nucl. Mater. 376 3 (2008) 274-281