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(a) Si Si O O O Al Cu Cu Al Cu (b) Thin film Thin film Figure 7.10. SEM and EDS results of aged Al-Cu thin films. 352
Pit 1 and pit 2 as shown in Figure 7.8 were calculated according to Equation 7.3 as shown in Figure 7.11c and d. The analysis shows that the anodic current density itself decays with time. By fitting the anodic current density of pit 1 as a function of time, the equation is shown as follows, 0.98 i a t (eq. 7.4). In the same way, the anodic current density of “pit 2” in Figure 7.8 is given by, 0.74 i a t (eq. 7.5) Figure 7.11 d shows the aged thin film single pit growth current density. The fitting curve is, 6 i .9 1.17 t 1 (eq. 7.6) The current densities estimated from these expressions yield values that range from 2.6 down to 0.2mA/cm 2 . However, at the same time as shown in the blue line in Figure 7.11 c and d, the current density of aged thin films is higher than that of as-deposited condition. This is attributed to the inhibiting effect of Cu dissolved in the solid solution of the as-deposited thin film. Nonetheless, multiple pits nucleated at the random sits in as-deposited thin films compared with only single pit nucleated in aged thin films, suggesting that the θ phase particles did not have an effect on the pit initiation. 5.7.3.3 Al-Cu thin films under Deft primers exposed to 0.5M NaCl. Both the as-deposited and aged Al-Cu thin films were coated with a Deft primer (02GN084) and exposed to aerated 0.5M NaCl solutions. The undercoating pit morphologies are shown in Figure 7.12. For the asdeposited thin films, round and irregular pits were observed suggesting that the growth rates were changing at different locations around the pit perimeter with time. However, in the aged thin film, the corrosion propagated primarily and preferentially in one direction. Both for the asdeposited and aged thin films, large numbers of discrete pits nucleated across the whole exposure surface. This suggested that the availability of dissolved oxygen to the substrate was greater than with neat epoxy primer. This is consistent with high pigment loading levels in the Deft primer. In both cases, the pit growth ended with the pit extending under the mask placed on top of the primer. For the case of as-deposited thin films, multiple pits nucleated at random sites in both the neat epoxy coated samples and Deft primer. At early times the pit morphology was smooth. At later times it became irregular suggesting a decrease in pit growth rate. Both the round pits passivated after a burst of growth leaving an irregular pit active, which grew steadily. However, results show that in as-deposited thin films, the pit initiated after 5 days of immersion in NaCl solution. This was delayed for 7 days for the neat epoxy coated sample immersed to the same solution. This indicates that the Deft primer did not delay the initiation of the pitting corrosion. 353
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FINAL REPORT Scientific Understandi
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This report was prepared under cont
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List of Acronyms AES Atomic Emissio
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List of Figures Figure 1.1. Figure
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Figure 1.21. Figure 1.22. Figure 1.
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Figure 3.11. Cathodic polarization
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Figure 4.12. Average Roughness of R
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Figure 5.4. Figures 5.5. Apparatus
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Figure 5.36. Figure 5.37. R paramet
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Figure 6.23. Two commercial samples
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Figure 7.1. a) instrumental configu
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List of Tables Table 1.1. Table 1.2
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Table 6.4. Processing parameters fo
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Keywords 1. Al alloys 2. Non-chroma
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1. Executive Summary This report su
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the role of electrophoresis in inhi
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occurring at low pHs and release at
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were obtained by a post treatment w
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4. G.O. Ilevbare, J.R. Scully, J. Y
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3. Objective The primary objective
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5. Results and Accomplishments In t
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powder, slurried with ultrapure wat
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TCP-coated AA2024-T3. A Kratos AXIS
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X-ray Photoelectron Spectroscopy (X
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Potential (V vs. Ag/AgCl) -0.2 -0.3
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Signal Intensity (counts/s) assessi
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Al (including both Al 0 and Al 3+ c
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TEM or during sample preparation, s
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Potential (V vs. Ag/AgCl) and uncoa
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5.1.4.8 Effects of Aging on the Fil
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Intensity (counts/s) Concentration
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|Z| 0.01Hz (ohm cm 2 ) |Z| 0.01Hz (
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The artificial scratch cell was als
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Raman intensity, a.u. 4000 880 3500
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Figure 1.24. Raman spectra for the
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peak at 520 cm -1 and an intense Cr
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Figure 1.28. Plots of the intensity
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Figure 1.30. (A) Video micrograph o
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The Zr and O signals arise from the
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Figure 1.35. (A) Corrosion potentia
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Table 1.1. Corrosion current (i cor
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additional pitting. The TCP coating
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Figure 1.41. Cr(VI) peak intensity
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Work is ongoing to understand how t
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9. L. Li, D-Y. Kim and G. M. Swain,
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carefully rinsed with DI water, air
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decrease to a net anodic current in
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Potential (mV vs. SCE) Potential (m
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i (A/cm 2 ) Immediately after silic
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Potential (mV vs. SCE) Rp (ohm.cm 2
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2.4.4 In situ AFM Scratching Result
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Figure 2.31. In situ AFM scratching
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(2.3) Figure 2.35. Specie diagram f
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concentration and the silicon to ca
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analysis coupled with XPS revealed
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5.2.4.4 In Situ AFM Scratching Befo
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esults in the formation of silicate
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26. P. Schmutz and G.S. Frankel, J.
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Pr 3+ , Y 3+ showed [12] an order o
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0.1M NaCl solution with varying con
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8.7 through pH 12.6 due to the lowe
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(b) (c) 99
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immersed in Ce 3+ remained bright w
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S phase and dissolution of Al matri
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Corrosion rate, i corr (A/cm 2 ) 6x
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I L (microA) 600 500 400 300 NC (-8
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than that of chromate[35]. Historic
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coupon was immersed with the polish
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5.3.2.4 Results 5.3.2.4.1 Speciatio
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(c) Figure 3.8. Speciation diagram
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E vs. SCE (V) -0.70 -0.75 -0.80 -0.
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E vs. SCE (V) 1000 rpm E vs. SCE (V
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Chemical quantification showed a me
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(a) (b) Figure 3.15. (a) (top) SEM
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E vs. SCE (V) E vs. SCE (V) E vs. S
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-Z" (ohm) -Z" (ohm) -Z" (ohm) -Z" (
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(Figure 3.8b). However, no effect o
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CPS CPS CPS x 2 14 10 12 10 8 6 4 2
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CPS CPS 100 95 90 85 80 75 70 x 10
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I k L 0. 2 1 2 AnFC B D 2 3 O 1
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i -800 (A/cm 2 ) 10 -4 NaCl NaCl+5
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Corrosion rate ( 1/R p ) ohm -1 cm
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particles compared to zinc-free sol
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and Zn bentonite compounds have red
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2) Deoxidizing for 3 minutes in an
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Scintag (now ThermoARL) Pad-V TM an
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Table 3.5. Characterization of bent
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Zn 2+ cation release (meq/100g) Pr
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(a) (b) (c) Figure 3.33. (a) An exp
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|Z| (ohm) Phase angle (degrees) 5.3
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|Z| at 0.01 Hz (ohm.cm 2 ) Pore Res
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|Z| at 0.01 Hz (ohm.cm 2 ) |Z| at 0
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pigmented coatings exhibited partia
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5.3.3.6 Conclusions 1. Exchange ben
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39. M. Mahdavian and M. M. Attar, P
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100. F.Liebau, Structural Chemistry
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of the coated sample, which is tigh
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Lubricant Blue (Struers) was used f
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good grip on the dolly, the equipme
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Pressure (kPa) r (mm) Pressure x Ra
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Pressure x Radius (kN/m) plateau bu
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Pressure x Radius (kN/m) Pxr (KN/m)
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Average Roughness (m) In contrast,
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Adhesion Strength (J/m 2 ) PVB PVB
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Pressure (kPa) Constant Infusion up
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(a) (b) (c) (d) Figure 4.19. Coatin
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Min. Potential (V vs SHE) Min. Pote
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Pressure (kPa) exposure in hot wate
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Engineering Stress (MPa) slope of t
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Adhesion Strength (J/m 2 ) ASTM D33
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Pressure (kPa) Pressure (kPa) Radiu
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Adhesion Strength (J/m 2 ) Pressure
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Table 4.7. Adhesion Strength values
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Non-Cl./Deox. No CC Cleaned/Deox. N
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5.4.5 Conclusions and Implications
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5.5 Task 5: Inhibitor Activation an
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solution for equilibration at contr
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Table 5.2. Techniques applied to sp
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The capacitance was determined by E
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combination with zinc molybdate, a
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Concentration, mmol / L Final pH te
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Alkaline affects praseodymium solub
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MoO 4 2- ) inhibition to the system
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Zinc molybdate is reported to be si
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The presence of a salt that has no
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This approach yields two figures of
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Inhibitor mapping of the Hentzen 16
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The molybdate loss in the strontium
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The capacitance dC is given by 0 (
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2 C( r, t) C( r )[1 r 2 exp( D nt
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-thea (degree) logIZI (Ohm-Cm 2 ) P
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Capacitance (F) respectively. The c
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Capacitance (F) Weight gain (g) For
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Normalized Capacitance Change Norma
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Potential V (Ag/AgCl) Corrosion rat
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5.5.4.7 Nanopore structure characte
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Normaalized Transport Rate (g/m^2_d
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S-Parameter S-Parameter Penetration
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S-Parameter S-Parameter Penetration
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R-parameter R-parameter Penetration
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5. T. M. Letcher, “Thermodynamics
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pigment of CaSiO 3 with initial pH
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allowed a comparison of the differe
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The solution resistance (R sol ) va
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Theta [degrees] theta |Z| [ohm] 10
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C [F/cm2] Rcorr [ohm*cm2] 7075-AHN
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C [F/cm 2 ] Rcorr [ohm*cm 2 ] Rcorr
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Visual TTF [hours] Table 6.2. Param
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of Metallast pre-treatment, which h
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Prediction of the TTF obtained by A
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5.6.2 Electrochemical Impedance Spe
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5.6.2.2.1 Coating system descriptio
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Table 6.4. Processing parameters fo
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population of total TTF vectors th
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components of the impedance and the
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Figure 6.17. EIS spectra for sample
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Figure 6.18. Kaplan-Meier survival
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Maximum c i range Maximum ci range
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The type and number of input neuron
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Predicted TTF The BFM method, intro
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The most significant variables to i
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5.6.3 Characterization of Pigment D
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Page 337 and 338: Figure 6.26. Cross-sectional view o
Page 339 and 340: Figure 6.28. EDX maps of primer cro
Page 341 and 342: Figure 6.31. EDX maps of primer cro
Page 343 and 344: In Figure 6.34, Ca and Si existed a
Page 345 and 346: Table 6.8. Average percentage resid
Page 347 and 348: strictly limited due to the barrier
Page 349 and 350: Figure 6.37. Coating systems in det
Page 351 and 352: Each corrosion volume of scribed ar
Page 353 and 354: Corrosion Area (mm 2 ) 1200 1000 80
Page 355 and 356: Corrosion Area (mm 2 ) Corrosion Ra
Page 357 and 358: Corrosion Rate (mm/yr) Corrosion Vo
Page 359 and 360: Corrosion Area (mm 2 ) corrosion ra
Page 361 and 362: corrosion rate (mm/yr) Corrosion Vo
Page 363 and 364: Corrosion Volume (mm/yr) Corrosion
Page 365 and 366: ate, PPG CA7233 coated samples had
Page 367 and 368: Appendix 6B Table 6B.1. Corrosion v
Page 369 and 370: Table 6B.3. Corrosion rate of sampl
Page 371 and 372: Table 6B.5. Corrosion area of sampl
Page 373 and 374: 5.7. Task 7: Characterization of Lo
Page 375 and 376: at 65C. After using DI water to rin
Page 377 and 378: Transmission Mode Conduct EIS measu
Page 379 and 380: Cdl(F/cm 2 ) Rp(.cm 2 ) relatively
Page 381 and 382: pit bottom area (cm 2 ) pit bottom
Page 383 and 384: 2days 2days 1mm 1mm 7days 7days Pit
Page 385: (a) (b) Si Si O Al Na Ca K Si Al-Cu
Page 389 and 390: In these experiments, Deft primers
Page 391 and 392: For the case of as-deposited thin f
Page 393 and 394: 3. L. Balazs, Physica E, 54, 1183-1
Page 395 and 396: and subsequently re-oxidized in two
Page 397 and 398: not represent true adhesion strengt
Page 399 and 400: • The pit morphology in 0.5 M NaC
Page 401 and 402: Appendix 2. List of Scientific/Tech
Page 403 and 404: “The Secret Life of Chromate Free
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