Details:

Creators:
Yang, Sze C. ; Lee, Kang-Won Wayne ; Mirville, Maureen ; Lu, Chen ; Pahram, Anthony
Yang, Sze C. ; Lee, Kang-Won Wayne ; Mirville, Maureen ; Lu, Chen ; Pahram, Anthony Less -
Corporate Creators:
University of Rhode Island. Dept. of Civil and Environmental Engineering ; University of Rhode Island. Dept. of Chemistry
University of Rhode Island. Dept. of Civil and Environmental Engineering ; University of Rhode Island. Dept. of Chemistry Less -
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Adhesive Strength Corrosion Protection Corrosion Resistance Galvanized Metals Metal Coating Paint Research Projects Structural Steel Zinc
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.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:9c94797df754d3da1a3760a4ca3192e86defff6b42dceb09acac3b47a59b93d7
Download URL:
https://rosap.ntl.bts.gov/view/dot/27857/dot_27857_DS1.pdf
File Type:

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