ELECTROCHEMICAL STUDY OF PRETECTIVE PAINTS FOR STEEL /IN FRENCH/

THIS THREE-PART ARTICLE STUDIES (1) THE BEHAVIOR OF PAINT FILMS AWAY FROM THEIR SUPPORT, (2) THE ELECTROCHEMICAL BEHAVIOR OF PAINTED STEEL, AND (3) LABORATORY TEST RESULTS COMPARED TO RESULTS OF NATURAL AGING AND CORROSION TESTS CARRIED OUT ON THE SAME PRODUCTS. THE FOLLOWING CONCLUSIONS ARE REACHED: BY STUDYING PAINT FILMS AWAY FROM THEIR SUPPORT, IT IS POSSIBLE TO DEFINE THE ABSORPTION MECHANISM BUT RESULTS ARE NOT SUFFICIENTLY DIFFERENTIATED TO ENABLE THE QUALITY OF THE PRODUCTS TO BE COMPARED. ELECTROCHEMICAL TESTS SHOW THAT, IN A NON-AGGRESSIVE MEDIUM, THE PROTECTION AFFORDED BY PAINTING RESULTS FROM THE STRONG POLARIZATION OF ELECTROCHEMICAL REACTIONS AT THE STEEL-PAINT INTERFACE, PARTICULARLY THE ANODIC OXIDATION REACTION OF IRON. THE POLARIZATION EFFECT TENDS TO DIMINISH WHEN THE WATER ABSORPTION RATE INCREASES. INCREASE IN THE THICKNESS OF THE PAINT FILM ABOVE A GIVEN LIMIT DOES NOT NECESSARILY INFLUENCE ITS PROTECTIVE EFFECT. THE PRESENCE OF A CORROSIVE SUBSTANCE SUCH AS SODIUM CHLORIDE CAUSES A RAPID AND IRREVERSIBLE DECREASE IN RESISTANCE TO POLARIZATION. THE POLARIZATION EFFECT OF ELECTROCHEMICAL REACTIONS BECOMES THEN NEGLIGIBLE AND THE CORROSION RATE DEPENDS SOLELY ON THE RATE OF EXCHANGES BETWEEN THE STEEL AND ITS ENVIRONMENT. ACCORDING TO THE LAW OF DIFFUSION, CORROSION RATE SHOULD BE INVERSELY PROPORTIONAL TO THE THICKNESS OF THE FILM. LCPC(A)/RRL/

• Supplemental Notes:
  • No 18 pp 149-164, 3 FIG, 5 TAB, 4 PHOT
• Corporate Authors:

  Bull Centre Rech & Essais De Chatou /Fr

  ,    
• Authors:
  • Bureau, M
• Publication Date: 1968

Subject/Index Terms

• TRT Terms: Absorption; Aging (Materials); Behavior; Coatings; Corrosion tests; Diffusion (Optics); Electrochemistry; Film; Laboratory tests; Metal coating; Metal coatings; Metals; Paint; Polarization; Protective coating; Protective coatings; Steel; Water
• Old TRIS Terms: Anodizing; Test results
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00216584
• Record Type: Publication
• Source Agency: Road Research Laboratory /UK
• Files: TRIS
• Created Date: Apr 10 1971 12:00AM