Session 12: Advances in Surface Finishing
• 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
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.