Final Report - Strategic Environmental Research and Development ...

Pressure x Radius (kN/m)
were created to study a number of parameters: adhesion after immersion in hot DI water (60 o C)
using the constant infusion BT; adhesion using standard techniques such as ASTM D 4541 (pulloff
test) and ASTM D3359 (tape test); corrosion resistance through ASTM B117, filiform
corrosion, and EIS measurements at different times of exposure to 5 wt% NaCl; and surface
characteristics of the treated surface prior to primer application using XPS, optical profilometer,
and contact angle measurements using DI water. However, the samples were contaminated
during the processing at NAVAIR. Figure 4.35 shows the results from the BT. Delaminated area
was observed under an optical microscope for all the samples and no primer residue was found.
The samples exhibited adhesive failure without fracture. As described above, previous
experiments performed using acetoacetate, the same primer used for this batch of samples,
showed that cleaning/deoxidizing step improved adhesion for samples non-treated with CC and
samples treated with NCP and TCP. However, this was not observed in this batch of samples.
The maximum Pxr value decreased for NCP and TCP when the cleaning/deoxidizing step was
included in the coating process. In addition, the adhesion strength values were very different
from those calculated from the first batch of samples. The maximum Pxr value was measured
and used for adhesion strength calculations taking into account the primer thickness and Young’s
modulus. Table 4.7 displays the adhesion strength values obtained from the old and the new
samples. The values for the same coating system were very different. The only two coating
system that had similar adhesion strength were those that were neither cleaned nor deoxidized
but treated with NCP and the cleaned/deoxidized and treated with TCP. The values of adhesion
strength between batches differed by at least 8.79 J/m 2 for the rest of the coating systems.
Therefore, the new coating systems obtained must be different from the old ones, even though
the same commercial solutions were used in their preparation.
0.3
0.25
0.2
March 30 2012 NCNP 1
Dotted lines --> Non-cleaned
Solid lines --> Cleaned
Non-pretreated
PR (KN/m) NCNP 1
PR (KN/m) NCNP 2
PR (KN/m) 5200 o 1
PR (KN/m) 5200 o 2
PR (KN/m) SO 1
PR (KN/m) SO 2
PR (KN/m) 1200 o 1
PR (KN/m) 1200 o 2
PR (KN/m) CO 1
PR (KN/m) CO 2
PR (KN/m) cl 5200 1
PR (KN/m) cl 5200 2
PR (KN/m) cl surtec 1
PR (KN/m) cl surtec 2
0.15
TCP
0.1
0.05
NCP
CCC
0
1 2 3 4 5 6 7 8
Radius (mm)
Figure 4.35. Pressure x radius trend for samples (a) non-cleaned/deoxidized and (b)
cleaned/deoxidized and coated with AVIOX CF 37619.
200