A NOVEL OXYGEN-PLASMA SPRAY SYSTEM FOR THE PROCESSING OF HIGH TEMPERATURE SUPERCONDUCTORS

PLASMA SPRAY DEPOSITION TECHNOLOGY CAN BE USED TO PROCESS COATINGS AND FREE-STANDING FORMS OF HIGH TEMPERATURE SUPERCONDUCTING OXIDES. WHILE THIS VERSATILE TECHNIQUE HOLDS HIGH POTENTIAL, IT NONETHELESS HAS DEFICIENCIES, SINCETHE COATING AS SPRAYED DOES NOT DISPLAY A SUPERCONDUCTING TRANSITION BUT, RATHER, MUST BE SUBJECTED TO A RELATIVELY HIGH TEMPERATURE ANNEAL TO REPLACE THE OXYGEN THAT WAS LOST DURING THE PLASMA SPRAY PROCESS. THIS POST-SPRAY ANNEAL COMPLICATES THE FABRICATION PROCESS AND SEVERELY LIMITS THE SUBSTRATE MATERIAL THAT CAN BE EMPLOYED TO FABRICATE A DEVICE. IN THIS PROJECT A PLASMA SPRAY DEVICE WILL BE DEVELOPED THAT CAN OPERATE WITH AN OXYGEN PLASMA. WITH CONVENTIONAL PLASMA GUNS THIS IS NOT POSSIBLE BECAUSE AN OXYGEN-BEARING PLASMA WOULD DESTROY THE ELECTRODES. USING ASPECIALLY CONFIGURED PLASMA GUN, CAPABLE OF ESTABLISHING AN OXYGEN-RICH PLASMA ENVIRONMENT, THIS PROJECT WILL FORM AS-SPRAYED DEPOSITS HAVING THE PROPER OXYGEN CONTENT TO ENABLE HIGH CRITICAL TEMPERATURE (T(C)) BEHAVIOR. NO POST-SPRAY ANNEAL WOULD BE REQUIRED, WHICH WILL PERMIT THE COATING OF A WIDE RANGE OF SUBSTRATE MATERIALS.