AUTOMATED HULL POTENTIAL MEASUREMENT SYSTEM USING A AG/AGCL REFERENCE ELECTRODE AND A MICROCOMPUTER

NAVY IS SEEKING DEVELOPMENT OF A PORTABLE, SELF-CONTAINED HULL POTENTIAL MEASUREMENT SYSTEM THAT CAN BE MOUNTED BY A DIVER WHILE THE SHIP IS IN PORT AND THAT MEASURES ELECTROLYSIS ACTIVITY WHILE THE SHIP IS UNDERWAY. MONITORING THE CORROSION POTENTIAL OF A CORRODING METAL/SOLUTION INTERFACE CAN GIVE INFORMATION ON THE RATE AND MECHANISM OF THE LOSS OF METAL AT THAT INTERFACE. BUT TRANSIENT GALVANIC ACTIVITY ASSOCIATED WITH THE PROCESSING OF CLEANING TO BARE METAL, MAKES CORROSION POTENTIAL MEASUREMENTS ON MARINE STRUCTURES DIFFICULT. IN ADDITION, POTENTIAL FIELDS ARE KNOWN TO RESPOND TO FLUID VELOCITIES, THEREFORE, MEASUREMENTS TAKEN IN PORT WILL NOT REFLECT THE SHIPS CONDITION WHILE IT IS UNDERWAY. WE PROPOSE TO MONITOR THE CORROSION POTENTIAL OF CARBON STEEL USED AS THE HULL IN 3.5 WT% NACL USING A AG/AGCL INTERNAL REFERENCE ELECTRODE USING A MICROCOMPUTER. WE WILL ALSO DETERMINE THE CORROSION POTENTIAL AS A FUNCTION OF SPEED (0-20 FT/S), SALINITY (0-04 WT% NACL) AND TEMPERATURE (0-100 DEG C). WE WILL USE THIS DATA, ALONG WITH EXISTING DATA-BASE ON THE CARBON STEEL-SEAWATER SYSTEM AND THEORETICAL EQUATIONS TO WRITE AN INTERACTIVE COMPUTER PROGRAM TO RUN IN THE MICROCOMPUTER. THIS PROGRAM WILL DETERMINE WHETHER ELECTROLYSIS ACTIVITY ARE WITHIN ACCEPTABLE LIMITS BASED ON THE MEASURED CORROSION POTENTIAL, AND KNOWN SPEED, SALINITY AND SEAWATER TEMPERATURE. THE PROPOSED WORK WILL BE PERFORMED IN COLLABORATION WITH DR. DIGBY MACDONALD OF SRI INTERNATIONAL.