000			02529nab a2200193 4500
005			20260608201727.0
008			260224s2011 xxu
100	1		_aKing, A.D. _949898
100	1		_aScully, J.R. _927367
245	0	0	_aSacrificial anode-based galvanic and barrier corrosion protection of 2024-T351 by a Mg-rich primer and development of test methods for remaining life assessment
260			_a _b _cmayo 2011
270			_a19/05/2011 ; 19/05/2011
300			_a22 p. ; 055004
520			_aTranscripción del resumen del autor. The sacrificial and barrier mechanisms of protection afforded to the aluminum alloy (AA)2024-T351 (UNS A92024) substrate by a Mg-rich primer (MgRP) were investigated. Test methods were developed to estimate the total residual stored Mg anode capacity and electrically "well-connected" Mg in the primer, as sensed electrochemically, after various environmental exposures. The residual barrier properties after depletion of the Mg primer were also assessed. To determine the quantity of Mg that was electrically and ionically well connected to the AA2024-T351 substrate, as sensed electrochemically, and to monitor coating barrier characteristics after partial MgRP utilization, a full-immersion testing protocol was designed. The testing regimen included an open-circuit hold to assess galvanic coupled potentials between the MgRP and 2024-T351, electrochemical impedance spectroscopy to assess coating barrier properties, potentiostatic holds to asses Mg anodic dissolution charge, and x-ray diffraction to assess the total elemental Mg remaining in the MgRP. Changes in these parameters are reported after full immersion in 50 mM sodium chloride (NaCl) solution as a function of MgRP pigment volume fraction (PVC) with or without a topcoat. X-ray diffraction was used to estimate the total amount of Mg in the MgRP before and after full immersion. Preliminary findings suggest two possible modes of protection: long range protection of remote defects and local or short range Mg pigment-based protection of local and buried defects. Both modes of protection are mediated by the high ionic and electrical resistance of the coating system as a function of MgRP PVC, primer polymer, and topcoat properties. A method for estimating the remaining capacity of the coating for each mode of protection is developed. Future testing will extend these methods to both field and accelerated test environments.
581			_a5
773			_g
942			_cARTICULO
999			_c181828 _d181828