THE ELECTROCHEMICAL MEASUREMENT OF GALVANIC INTERACTIONS FOR THE STUDY OF CORROSION BEHAVIOR OF COATED AND UNCOATED COUPLES

WHEN CURRENT FLOWS BETWEEN TWO METALS IN CONTACT, AN ELECTRIC FIELD FORMS IN THE ELECTROLYTE SURROUNDING THE METALS. THE MEASUREMENT OF POTENTIALS IN THE FIELD BY THE USE OF TWO CALOMEL REFERENCE ELECTRODES PROVIDES A SUITABLE MEANS FOR STUDYING CURRENT DISTRIBUTION AND FOR FOLLOWING CHANGES IN CORROSION CURRENT THAT RESULT FROM REACTIONS AT METAL SURFACES. THIS APPROACH WAS USED TO STUDY GALVANIC INTERACTIONS BETWEEN COUPLES OF DIFFERENT METALS AND BETWEEN COATED AND UNCOATED SURFACES OF METALS. THE METHOD HAS BEEN USED TO SHOW DIFFERENCES IN PHOSPHATE AND ANODIZED COATINGS. GALVANIC EFFECTS BETWEEN CAST IRON AND ALUMINUM WERE FOUND TO VARY WITH THE COMPOSITION OF THE ALUMINUM ALLOY. THOSE BETWEEN COUPLES OF STAINLESS STEEL AND MILD STEEL WERE REDUCED WHEN THE STAINLESS STEEL WAS PLATED WITH CHROMIUM. INHIBITORS WERE STUDIED BY OBSERVING THE CHANGE IN POTENTIAL AT A SELECTED POINT IN THE SOLUTION AFTER THE ADDITION OF AN INHIBITOR. THE EFFECT OF POTASSIUM DICHROMATE ON A COPPER-STEEL COUPLE WAS DETERMINED IN ACID SOLUTIONS AND THAT OF SODIUM NITRITE IN A SODIUM SULFATE SOLUTION. ALTHOUGH THE METHOD HAS CERTAIN ADVANTAGES FOR STUDYING GALVANIC COUPLES, ITS LIMITATIONS ARE THAT THE SOLUTION RESISTANCE MUST BE FAIRLY HIGH AND THAT IT IS DIFFICULT TO DETERMINE WHICH CORROSION REACTION IS BEING AFFECTED. /AUTHOR/

• Supplemental Notes:
  • Vol 5, No 2, PP 323-338, 11 FIG, 2 TAB, 8 REF
• Corporate Authors:

  American Society for Testing and Materials (ASTM)

  100 Barr Harbor Drive, P.O. Box C700
  West Conshohocken, PA  United States  19428-2957
• Authors:
  • Rowe, L C
• Publication Date: 1970-6

Media Info

• Serial:
  • Journal of Materials
  • Publisher: American Society for Testing and Materials (ASTM)

Subject/Index Terms

• TRT Terms: Aluminum; Anodic protection; Anticorrosion coatings; Cast iron; Chromium; Corrosion protection; Couplers; Electric fields; Electrochemistry; Electrodes; Electrolytes; Galvanic corrosion; Measurement; Metal coatings; Metals; Protective coatings; Shell plating; Stainless steel
• Old TRIS Terms: Anodic coatings; Plating
• Subject Areas: Geotechnology; Highways; Marine Transportation; Materials;

Filing Info

• Accession Number: 00216999
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 26 1970 12:00AM