Session Details

Session 12: Advances in Surface Finishing

Abstract Number:

86

‎• Brief introduction to scintillators and their importance in x-ray ‎computing tomography
‎• Why pixelated scintillator screens provide improved imaging over ‎monolithic screens
‎•Why Nickel-Copper alloys are attractive for this application
‎•How bath composition and plating parameters plays a key role in ‎surface finish optimization

Topics:

Advances in Surface Finishing Technology

This study explored copper electroplating onto pure pixelated nickel ‎screens; this study explored ‎screen morphology as a function of ‎deposition time. In order to determine optimal process ‎parameters, ‎this study focused on bath chemistry composition, electroplating ‎parameters, optical ‎imaging and small-scale diffusion bonding ‎experiments.‎

Monolithic scintillator screens for x-ray computing tomography (CT) ‎applications are widely used in ‎the aerospace industry to certify ‎dense parts and ensure quality. These screens are able to convert ‎‎ionizing radiation (i.e. gamma rays, x-rays) into visible light to ‎generate an image with a camera. The ‎ability for these screens to ‎interact with x-rays depend on the density of the screen ‎composition; ‎here, metallic materials possess high densities within ‎the range of 7 – 10 grams/cm3. Pixelated ‎metallic screens can enable ‎more interactions at pixelated sites resulting in less time to acquire ‎an ‎image and reduce x-ray exposure to the part. Over the past few ‎years, we have worked with several ‎types of electroplated coatings ‎to improve the performance of pixelated aperture arrays. Nickel-‎‎Copper alloys are applicable to this application space due to its ‎bondable intermetallic diffusion and ‎formation of a solid solution. By ‎electroplating nickel screens with copper and stacking them, we are ‎‎able to diffusion bond these screens together under high vacuum ‎conditions, allowing us to improve ‎our CT capability.‎

PIXELATED NICKEL-COPPER SCINTILLATOR SCREENS WITH ‎IMPROVED EFFICIENCY FOR X-RAY ‎COMPUTED TOMOGRAPHY (CT)‎

Donald Johnson

R&D Engineer

Los Alamos National Laboratory