Abstract：The corrosion behavior of primid-curing solidified polyester powder coating defects in marine environment was investigated by CASS test, immersion test, electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe (SKP). The results show that the primid-curing polyester powder coating has a small amount of blisters along the scratch edge, the maximu single side corrosion width is less than 0.5mm, and the surface adhesion is 0 after 240 hours' CASS test. The EIS map in 0.6mol/L NaCl solution exhibits that the corrosion rate of aluminu alloy is decreased with increasing immersion time and gradually stable. The scanning Kelvin spectrum reveals that the corrosion of the metal under the coating of the polyester powder is extended from scratch to the coating, the anode and the cathode are alternately changed, which leads to the expansion of the corrosion area.
 LEENA K P, JAMES W M, ROBERT O W. Electrostatic powder coating: principles and pharmaceutical applications [J]. International Journal of Pharmaceutics, 2016, 505(1-2): 289-302.
 GRUNDMEIER G, SCHMIDT W, STRATMANN M. Corrosion protection by organic coatings: electrochemical mechanism and novel methods of investigation[J]. Electrochimica Acta, 2000, 45(15-16): 2515-2533.
 POSNER R, WAPNER K, STRATMANN M, et al. Transport processes of hydrated ions at polymer/oxide/metal interfaces Part 1. Transport at interfaces of polymer coated oxide covered iron and zinc substrates[J]. Electrochimica Acta, 2009, 54: 891-899.
 POSNER R, TITZ T, WAPNER K, et al. Transport processes of hydrated ions at polymer/oxide/metal interfaces Part 2. Transport on oxide covered iron and zinc surfaces[J]. Electrochimica Acta, 2009, 54: 900-908.
 MORCILLO M, RODRIGUEZ F J, BASTIDAS J M. The influence of chlorides, sulphates and nitrates at the coating-steel interface on underfilm corrosion[J]. Progress in Organic Coatings, 1997, 31(3): 245-353.
 WAPNER K, STRATMANN M, GRUNDMEIER G. Structure and stability of adhesion promoting aminopropyl phosphonate layers at polymer/aluminium oxide interfaces[J]. International Journal of Adhesion & Adhesives, 2007, 28(1):59-70.
 DOHERTY M, SYKES J M. Micro-cells beneath organic lacquers: a study using scanning kelvin probe and scanning acoustic microscopy [J]. Corrosion Science, 2004, 46(5):1265-1289.
 胡吉明,张鉴清,谢德明.水在有机涂层中的传输Ⅰ:Fick扩散过程[J].中国腐蚀与防护学报, 2002,22 (5):311-316. HU J M, ZHANG J Q, XIE D M. Water transport in organic coatingⅠ: Fickian diffusion[J]. Journal of Chinese Society for Corrosion and Protection, 2002, 22 (5):311-316.
 BASTIDAS J M, MORCILLO M, RODRIGUEZ F J. Mild steel corrosion in saline solutions: comparison between bulk solutions and steel-coating interfacial solutions[J]. Journal of Coatings Techno1ogy, 1998, 70(882): 61-66.
 LI J, ECCO L, FEDEL M, et al. In-situ AFM and EIS study of a solventborne alkyd coating with nanoclay for corrosion protection of carbon steel[J]. Progress in Organic Coatings, 2015, 87: 179-188.
 FURBETH W, STRATMANN M. The delamination of polymeric coatings from electrogalvanised steel—a mechanistic approach [J]. Corrosion Science, 2001,43:207-243.
 SCHMIDT W, STRATMANN M. Scanning Kelvin probe investigations of filiform corrosion on aluminum alloy 2024-t3[J]. Corrosion Science,1998,40(8):1441-1447.
 DEFLORIAN F, ROSSI S, FEDEL M, et al. Study of the effect of corrosion inhibitors on powder coatings applied on steel[J]. Progress in Organic Coatings, 2014, 77(12): 2133-2139.
 DONG C F, FU A Q, LI X G, et al. Localized EIS characterization of corrosion of steel at coating defect under cathodic protection [J]. Electrochimica Acta, 2008,54(2):628-633.
 FEDRIZZI L, RODRIGUEZ F J, ROSSI S, et al. The use of electrochemical techniques to study the corrosion behavior of organic coatings on steel pretreated with sol-gel zirconia films [J]. Electrochimica Acta, 2001, 46(24): 3715-3724.
 GRAEDEL T E. Corrosion mechanisms for aluminum exposed to the heat atmosphere [J]. Journal of the Electrochemical Society, 1989, 136(4): 204-212.
 OH S J, COOK D C, TOWNSEND H E. Atmospheric corrosion of different steels in marine, rural and industrial environments [J]. Corrosion Science, 1999, 41(9): 1687-1702.
 WAPNER K, STRATMANN M, GRUNDMEIER G.In situ infrared spectroscopic and scanning kelvin probe measurements of water and ion transport at polymer/metal interfaces [J]. Electrochimica Acta, 2006, 51(16):3303-3315.
 LIU S, GU L, ZHAO H C, et al. Corrosion resistance of graphene-reinforced waterborne epoxy coatings [J]. Journal of Materials Science & Technology, 2016, 32(5): 425-431.
 WANG Z Y, MA T, HAN W,et al. Corrosion behavior on aluminum alloy LY 12 in simulated atmospheric corrosion process science [J]. Transactions of Nonferrous Metals Society of China, 2007, l7(2): 326-334.
 HUTTUNEN-SAARIVIRTA E, YUDIN V E, MYAGKOVA L A. Corrosion protection of galvanized steel by polyimide coatings: EIS and SEM investigations[J]. Progress in Organic Coatings, 2011, 72(3): 269-278.
 MORCILLO M. Soluble salts: their effects on premature degradation of anticorrosive paints [J]. Progress in Organic Coatings, 1999, 36(3):137-147.
 LENG A, STRECKELA H, STRATMANN M. The delamination of polymeric coatings from steel, PartⅠ:calibration of the Kelvin probe and basic delamination mechanism[J]. Corrosion Science, 1998, 41(3): 547-578.
 LENG A, STRECKELA H, STRATMANN M. The delamination of polymeric coatings from steel Part Ⅱ: first stage of delamination, effect of type and concentration of canons on delamination, chemical analysis of the interface [J]. Corrosion Science, 1998, 41(3): 579-597.
 REDDY B, DOHERTY M J, SYKES J M. Breakdown of organic coatings in corrosive environments examined by scanning kelvin probe and scanning acoustic microscopy[J]. Electrochimica Acta, 2004, 49(17-18): 2965-2972.
 LENG A, STRECKELA H, HOFMANN K, et al. The delamination of polymeric coatings from steel Part 3: effect of the oxygen partial pressure on the delamination reaction and current distribution at the metal/polymer interface[J]. Corrosion Science, 1998, 41(3): 599-620.