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Tuesday, May 16, 2006 - 2:30 PM
EAP15.3

Vacuum Plasma Spraying of Thick W Coatings onto Surface Sculptures for Fusion Armour Applications

G. Thomas, Oxford University, Oxford, United Kingdom; P. S. Grant, University of Oxford, Oxford, United Kingdom; R. G. Castro, Los Alamos National Laboratory, Los Alamos, NM; P. Coad, G. Matthews, UKAEA, Abingdon, United Kingdom

Thick (>2mm) vacuum plasma sprayed (VPS) W coatings hold great promise for plasma facing components in future fusion devices. However, the large coefficient of thermal expansion (CTE) mismatch between W and underlying structural steels poses a significant problem for manufacturing and service life because of the evolution of large thermally induced stresses leading to failure. In this paper the concept of using steel surfaces with regular surface sculptures of millimetre scale created by e-beam surface manipulation, termed surfi-sculpt and developed by TWI (UK), is investigated both to enhance coating adhesion and as a method to engineer macroscopic variations in the effective CTE through the thickness of the subsequently VPS deposited W coating. A series of stainless steels substrates with surface sculpture features have been coated with thick VPS W. The effects of surface geometry on coating adhesion, microstructure, roughness and quality have been investigated by a variety of microscopy and other techniques, and the key surface sculpture geometrical features required for high adhesion, high quality W coatings identified.

Summary: Description of the use of a new e-beam 3D surface sculpturing technique to dramatically enhance the performance of ultra thick VPS W coatings - we believe this is novel work with considerable broad potential