Measurement of adhesion properties between topcoat paint and metallized/galvanized steel with surface energy measurement equipment.

Details

• Creators:
  Yang, Sze C. ; Lee, Kang-Won Wayne ; Mirville, Maureen ; Lu, Chen ; Pahram, Anthony
• Corporate Creators:
  University of Rhode Island. Dept. of Civil and Environmental Engineering ; University of Rhode Island. Dept. of Chemistry
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Paint
  • Galvanized metals
  • Adhesive strength
  • Metal coating
  • Structural steel
  • Zinc
  • Corrosion protection
  • Corrosion resistance
  • Research projects
• Publication/ Report Number:
  NETCR93
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Corporate Publisher:
  New England Transportation Consortium
• Abstract:
  The objectives of this research project are: (1) Compare the adhesion properties of NEPCOAT-approved topcoat paint over ; metallized or galvanized steel. Use “surface-energy” measuring technique to characterize the wetting properties of the liquid paint ; on the profiled zinc surfaces. Explore correlation between the adhesive strength and the liquid paint wetting properties. As control ; the adhesion properties of topcoat paint over zinc primer painted steel substrates will also be measured. (2) Investigate various ; factors affecting the adhesion of topcoat paint over galvanizing. (3) Report and recommend practices that produce the best adhesion ; of NEPCOAT-approved topcoat paints over metallized and particularly galvanized steel surfaces. We prepared four different types ; of test panels coated with five different commercial paint systems. The paint systems include four systems adapted from the ; NEPCOAT list of intermediate and top paints qualified for bare steel, and one system of epoxy sealer for metallized surface. Four ; types of substrates were used for fabricating the test panels: (1) galvanized steel with mechanical grinding to produce rough ; surface, (2) galvanized steel with blast profiling to produce rough surface, (3) galvanized steel stored indoors for two weeks before ; blast profiling and painting, and (4) metallized steel with inherent roughness due to the thermal spray process. We recorded, as a ; function of time, the contact angle of droplets of freshly prepared liquid paints on the replicas of the substrate used for spray ; painting. The cured test panels were subject to pull-off strength tests according to the ASTM D4541 standard, and the X-cut tape ; tests according to Method A of ASTM D3359 standard. Images of the pull-off test break surfaces were photographed and ; examined. We analyzed the correlation between the pull-off strengths and the contact angles. The correlation provided insight on ; the relative adhesive strengths of the different paint-substrate pairs. We concluded that (1) the NEPCOAT paints could be used for ; galvanized and metallized steel to obtain comparable adhesion performance as that of the zinc-rich organic primer coated steel, (2) ; although the NEPCOAT intermediate paint on the metallized surface has adequate pull-off strength to pass the inspection, it is ; highly recommended that the state DOT specification of the use of sealant is strictly followed, (3) although the exposure to ; atmosphere after galvanizing is commonly recognized as a problem for paint adhesion, we found that a time delay of two weeks ; between galvanizing and profiling/painting is permissible if the galvanized steel is stored in the normal indoor dry atmosphere, (4) ; we think a refined quantitative correlation between pull-off strength and contact angle could be useful for optimizing the paint-tosubstrate ; match.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27857/dot_27857_DS1.pdf
• File Type:
  [PDF - 135.63 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:9c94797df754d3da1a3760a4ca3192e86defff6b42dceb09acac3b47a59b93d7