EVALUATION OF HIGH SENSITIVITY MAGNETIC IMAGING FOR DETECTION OF HIDDEN CORROSION

EXPERIMENTS AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY (MIT), THE NAVAL RESEARCH LABORATORY, AND QUANTUM MAGNETICS HAVE DEMONSTRATED A NEW POWERFUL NONINVASIVE TECHNIQUE FOR MONITORING ELECTROCHEMICAL CORROSION PROCESSES VIA THEIR ASSOCIATED MAGNETIC FIELDS. IN ADDITION TO REMOTELY DETECTION CORROSION ACTIVITY, SIMPLE ANALYSIS OF THE TIME EVOLUTION OF THESE MAGNETIC FIELDS CAN HIGHLIGHT SPECIFIC MAGNETIC SIGNATURES ASSOCIATED WITH SPECIFIC CORROSION PHENOMENA SUCH AS PITTING. IN COLLABORATION WITH MIT, QUANTUM MAGNETICS DEVELOPED A FULLY AUTOMATED ULTRA SENSITIVE DETECTION SYSTEM SPECIFICALLY FOR THE STUDY OF CORROSION. THIS INSTRUMENT HAS ALREADY PROVIDEDVERY IMPORTANT AND PERHAPS VERY SIGNIFICANT DATA CONCERNING FUNDAMENTAL CORROSION PROCESSES AND IS CURRENTLY IN USE AT MIT. IN PHASE I WE PROPOSE TAKE ADVANTAGE OF THESE UNIQUE MEASUREMENT CAPABILITIES, WHICH ARE AVAILABLE FOR THE FIRST TIME, TO INVESTIGATE CORROSION IN MECHANICALLY FASTENED OR BONDED AIRCRAFT JOINTS AND UNDER PAINTED SURFACES IN ORDER TO DEVELOP NEW PRACTICAL TECHNIQUES FOR DETECTING IT. BASED ON OUR PHASE I EXPERIMENTS, WE PROPOSE IN PHASE II TO DESIGN AND BUILD A SMALL HANDHELD VERSION OF THIS DETECTOR FOR USE ON AIRCRAFT. THE HANDHELD VERSION WILL BE EXTENSIVELY TESTED TO ESTABLISH POD CURVES, FALSE ALARM RATES AND ESTIMATES OF THE MINIMUM DETECTABLE FLAW SIZE.