PULSE MODULATED ELECTROPLATING OF MOLYBDENUM FROM ALKALI CHLORIDE MELTS

REFRACTORY METALS, WITH THE EXCEPTION OF CHROMIUM, CANNOT BE PLATED FROM AQUEOUS SOLUTIONS IN COHERENT FORM. ELECTROPLATING CAN BE ACHIEVED FROM MOLTEN ELECTROLYTES OPERATING AT THE TEMPERATURE RANGE FROM 500-1000 DEGREES C. BECAUSE OF THE HIGH TEMPERATURES AND ASSOCIATED MATERIALS PROBLEMS, THESE SYSTEMS HAVE REACHED A COMMERCIAL STAGE ONLYIN THE CASE OF TANTALUM. THE IMPETUS TO DEVELOP ELECTROLYTIC PROCESSES OPERATING AT LOWER TEMPERATURES IS CONSIDERABLE, AND PROBLEMS ASSOCIATED WITH GUN BARREL EROSION AND PROPULSION SYSTEM'S CORROSION HAVE REINFORCED THIS NEED. THIS PROPOSAL ADDRESSES THE QUESTION OF REFRACTORY METAL DEPOSITION, PARTICULARLY THAT INVOLVING MOLYBDENUM, FROM CHLORIDE MELTS IN THE TEMPERATURE RANGE 350-500 DEGREES C. PREVIOUSLY IDENTIFIED PROBLEMS WITH THESE MELTS RELATING TO THE FORMATION OF POWDERS AND/OR DENDRITES MAY BE OVERCOME BY THE APPLICATION OF GALVANOSTATIC PULSE MODULATED ELECTROLYSIS. CONSEQUENTLY, THE THRUST OF THE PHASE I WORK WILL BE TO IDENTIFY THE CHARACTERISTICS OF THE DEPOSITION PROCESS IN THE CANDIDATE MELT AT 350 AND 450 DEGREES C ENABLING THE PARAMETERS NECESSARY FOR COHERENT METAL DEPOSITION TO BE SELECTED. THESE OBJECTIVES WILL BE ACHIEVED THROUGH THE USE OF GALVANOSTATIC AND POTENTIOSTATIC TECHNIQUES. THE PLATE QUALITY DETERMINED MICROSCOPICALLY AND PHYSICALLY WILL BE A MEASURE OF THE SUITABILITY OF THE PULSE MODULATING TECHNIQUE. THESE STUDIES WILL FORM THE BASIS OF A PROGRAM TO DEVELOP A MOLYBDENUM PLATING PROCESS.