Electrospark deposition

Electrospark deposition (ESD) is a pulsed micro-welding process that is being used increasingly for small scale and precision coating and repair of high value components. Based on short duration, high current pulses, ESD imparts a low heat input to the substrate material, resulting in little or no modification of the substrate microstructure.

ESD offers a particular advantage when coating or repairing materials that are considered difficult-to-weld because of poor HAZ properties. Many materials can be processed without pre- or post-weld heat treatment. Components can be restored to original dimensions as the substrate material remains near to ambient temperature and thermal distortion, shrinkage and high residual stresses can be avoided.



Etched cross section of a nickel coating

Etched cross section of a nickel coating
ESD power supply and applicators

ESD power supply and applicators


Application Substrate material Coating material Other comments
Hot section blades/vanes e.g. repair of blade tips, knife edge seals Ni or Co superalloys:
EA
DS
SX		 Matching or alternative alloy Post coating heat treatment, e.g. HIPping for consolidation of coating and/or propagation of DS structures into coating
Hot section blades/vanes e.g. localised repair of coatings Ni or Co superalloys:
EA
DS
SX		 MCrAlY
Pt		 Post coating heat treatment, e.g. HIPping for consolidation of coating
Stator blades - coating and repair of z-notches Ni or Co superalloys Hardfacing alloys e.g. Tribaloy 800
Stellite alloys		  

EA - Equi-axed, DS - Directionally solidified, SX - Single crystal, HIPping - Hot Isostatic Pressing


For further information, please contact: power@twi.co.uk

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