Evaluation of Coating Resins for Corrosion Protection of Steel

7 Evaluation of Coating Resins for Corrosion Protection of Steel Exposed to Dilute Sulfuric Acid 1

Downloaded by NANYANG TECH UNIV LIB on November 2, 2014 | http://pubs.acs.org Publication Date: October 14, 1986 | doi: 10.1021/bk-1986-0322.ch007

Malcolm L. White and Henry Leidheiser, Jr.

2

1

Center for Surface and Coatings Research, Lehigh University, Bethlehem, PA 18015 Department of Chemistry and Center for Surface and Coatings Research, Lehigh University, Bethlehem, PA 18015

2

Three types of coatings--a vinyl ester, a polyester and four epoxies--were coated on steel and exposed to 0.1M H S O at 60°C. Measurements of corrosion potent i a l , AC conductance, tensile adhesion and weight gain were made on the coated substrates after 1000 hours of exposure, and the values were compared with the observed corrosion of the steel substrate. The best correlation of parameter values with corrosion was found with conductance. Corrosion potential did not show a consistent relationship, and weight gain and tensile adhesion showed no correlation with corrosion. It was concluded that the most important properties for coatings to be used in acid media are low permeability and resistance to degradation by acid. The vinyl ester, a bisphenol A epoxy cured with an aliphatic amine, and a novolac epoxy cured with a mixed aromatic/cycloaliphatic amine provided the best corrosion protection. The saturated polyester and a bisphenol A epoxy cured with a polyamide amine showed significant deterioration in acid and corrosion of the underlying steel. Two novolac epoxies cured with aromatic amines showed i n termediate performance. 2

4

The m e c h a n i s m f o r t h e i n i t i a l c o r r o s i o n o f s t e e l i n n e u t r a l o r a l k a l i n e s o l u t i o n s i s g e n e r a l l y a c c e p t e d as t h e o x i d a t i o n o f iron from the m e t a l l i c s t a t e to the f e r r o u s i o n : Fe -

Fe""

+

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0097-6156/86/0322-0077S06.00/0 © 1986 American Chemical Society

In Polymeric Materials for Corrosion Control; Dickie, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

of

hy-

(2)

POLYMERIC MATERIALS FOR CORROSION CONTROL

78


A v a r i e t y o f t e c h n i q u e s has been d e v e l o p e d t o m e a s u r e t h e c o n d i t i o n o f a c o a t i n g s o t h a t some e v a l u a t i o n o f i t s p r o t e c t i v e a b i l i t y c a n be made. M a n y o f t h e s e a r e b a s e d on e l e c t r o c h e m i c a l m e a s u r e m e n t s [2]. The f o u r t e c h n i q u e s u s e d i n t h i s s t u d y a r e (1) corrosion p o t e n t i a l , ( 2 ) AC c o n d u c t a n c e , ( 3 ) t e n s i l e a d h e s i o n , and ( 4 ) w e i g h t gain. The c o r r o s i o n p o t e n t i a l i s d e t e r m i n e d by t h e p o t e n t i a l a t w h i c h t h e a n o d i c and c a t h o d i c r e a c t i o n s o c c u r a t t h e same r a t e [ 3 ] . T h e AC conductance i s a measure of the ease w i t h which charge i s t r a n s m i t ted through the coating [4]. The a d h e s i v e s t r e n g t h o f t h e c o a t i n g t o t h e s t e e l s u r f a c e i s a f f e c t e d by r e a c t i o n s o c c u r r i n g a t t h e interface. The w e i g h t g a i n o f c o a t i n g s h a s b e e n s t u d i e d by F u n k e and H a a g e n [ 5 ] who h a v e s h o w n t h a t a w e i g h t g a i n e x c e e d i n g t h a t o f a f r e e f i l m i n d i c a t e s an a c c u m u l a t i o n o f w a t e r a t t h e i n t e r f a c e

[5]. These t e c h n i q u e s are f r e q u e n t l y used to study c o r r o s i o n under c o a t i n g s i n n e u t r a l s o l u t i o n s and e n j o y s p o r a d i c s u c c e s s , d e p e n d i n g p r i m a r i l y on t h e t y p e and t h i c k n e s s o f c o a t i n g b e i n g s t u d i e d . The m e c h a n i s m o f s t e e l c o r r o s i o n i n a c i d s o l u t i o n s , h o w e v e r , is d i f f e r e n t from that in neutral s o l u t i o n s in that the reduction r e a c t i o n i s the f o r m a t i o n of hydrogen from hydrogen i o n : 2H

+

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2

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P r e v i o u s w o r k i n t h i s l a b o r a t o r y has e s t a b l i s h e d t h a t f o r e p o x y and f 1 uoropolymer c o a t i n g s exposed to d i l u t e s u l f u r i c acid, there i s movement o f a c i d t h r o u g h t h e c o a t i n g t o t h e s t e e l s u r f a c e so t h a t Equation 3 i s the predominant reduction r e a c t i o n [6]. Because of t h i s d i f f e r e n c e i n c o r r o s i o n mechanism i n a c i d s o l u t i o n , t h e u s e f u l n e s s o f t h e f o u r e v a l u a t i o n t e c h n i q u e s d i s c u s s e d above may be d i f f e r e n t t h a n i n n e u t r a l s o l u t i o n s . The p u r p o s e o f t h i s w o r k was t o e v a l u a t e t h e s e f o u r t e c h n i q u e s f o r p r e d i c t i n g t h e behavior of c o a t i n g r e s i n s in a c i d s o l u t i o n s . In a d d i t i o n , t h e a b i l i t y of several d i f f e r e n t types of c o a t i n g r e s i n s to p r o t e c t s t e e l a g a i n s t c o r r o s i o n i n a c i d s o l u t i o n was e v a l u a t e d . Experimental The f o l l o w i n g c o a t i n g r e s i n s w e r e u s e d : (1) a v i n y l e s t e r ( D e r a k a n e 4 7 0 f r o m Dow C h e m i c a l ) ; ( 2 ) a p o l y e s t e r ( A t l a c 3 8 2 - 0 5 AC f r o m ICI); and (3) f o u r e p o x y r e s i n / h a r d e n e r c o m b i n a t i o n s . The d e t a i l s o f t h e r e s i n s and h a r d e n e r s u s e d a r e s h o w n i n T a b l e I. One o f t h e e p o x y / h a r d e n e r c o m b i n a t i o n s was r e p r e s e n t e d by m a t e r i a l s f r o m t w o sources. The c o a t i n g s w e r e a p p l i e d t o o n e s i d e o f a s t e e l s u b s t r a t e by means o f a s p r a y gun f o r t h e l o w e r v i s c o s i t y c o a t i n g s , o r by d o c t o r b l a d i n g w i t h an a d j u s t a b l e G a r d n e r k n i f e f o r t h e h i g h e r viscosity materials. A c a s t i n g t e c h n i q u e was a l s o used i n w h i c h a known v o l u m e o f t h e c o a t i n g m a t e r i a l was p o u r e d i n t o a known a r e a d e f i n e d b y h e a v y t a p e a n d w a s a l l o w e d t o s p r e a d w h i l e on a l e v e l s u r f a c e .



Cobalt

Martek

Naphthanate

Ciba/Geigy

Epoxies CON/CHEM

(6%).

NOV/AR/AL

BPA/PA

NOV/AR 2

NOV/AR 1

BPA/AL

PE

Polyester ICI Americas (Atlac 382-05

AC)

VE

Designation

Vinyl Ester Dow C h e m i c a l (Derakane 470)

Supplier Resin

I.

A

Novolac

Bisphenol

A

Multifunctional Novolac

Multifunctional

Bisphenol

Bisphenol A-Fumarate P o l y e s t e r + 1% C o N a p * + DMA; 50% S t y r e n e

Cycloaliphatic/ A r o m a t i c Amine

Polyamideamine

Aromatic Amine

Aromatic Amine

Aliphatic Amine

MEKP

Cumene Hydroperoxide

Hardener

Coating Materials

Bisphenol A Vinyl E s t e r + . 1 5 % CoNap ; 36% S t y r e n e

Table

1.82:1

2.77:1

100:46

100:50

100:20

100:2

100:2

Resin: Hardener Ratio


Cured

8-9

8 - 12

10-11

10-12

9-10

6-12

7- 9

(mils)

203-229

203-305

254-279

254-305

229-254

152-305

178-229

(my)

Thickness

80



The c o a t i n g s w e r e c u r e d i n t w o s t e p s : f i r s t , a room t e m p e r a t u r e e x p o s u r e f o r a t l e a s t f i v e h o u r s t o a l l o w any s o l v e n t p r e s e n t t o e v a p o r a t e a n d / o r t h e r e s i n t o g e l a n d , s e c o n d , an e l e v a t e d t e m p e r a t u r e c u r e . The v i n y l e s t e r , p o l y e s t e r and e p o x i e s w e r e b a k e d a t 60°C f o r 4-16 hours. The c o a t i n g t h i c k n e s s a f t e r c u r i n g was m e a sured w i t h a micrometer, s u b t r a c t i n g the substrate thickness. The t h i c k n e s s o f t h e c o a t i n g s r a n g e d f r o m 6 t o 12 m i l s ( 1 5 0 - 3 0 0 urn) and i s shown f o r each t y p e i n T a b l e I. The s u b s t r a t e s w e r e c o l d r o l l e d , l o w - c a r b o n SAE 1 0 1 0 s t e e l , 32 m i l s ( 0 . 8 mm) t h i c k (Q P a n e l s ) . T h e y w e r e s a n d b l a s t e d on b o t h s i d e s t o a 6 pm p r o f i l e w i t h s i l i c a s a n d . No f u r t h e r c l e a n i n g was d o n e . A c i r c u l a r d i s k 3 . 3 3 cm i n d i a m e t e r was p r e p a r e d f r o m a l a r g e r c o a t e d p a n e l w i t h a punch and d i e s e t . The d i s k was p l a c e d on a 1 2 5 ml widemouth screw-cap polypropylene b o t t l e , using a rubber gasket to make a t i g h t s e a l , w i t h t h e c o a t e d s i d e f a c i n g t h e i n s i d e o f t h e bottle. The d i s k and g a s k e t w e r e h e l d on t h e b o t t l e w i t h t h e c a p , f r o m w h i c h t h e c e n t r a l p o r t i o n had been r e m o v e d , so t h e back ( u n c o a t e d ) s i d e o f t h e s t e e l s u b s t r a t e was e x p o s e d . The b o t t l e was i n v e r t e d and h a l f f i l l e d w i t h 0.1 M H 0 S O 4 t h r o u g h a h o l e d r i l l e d i n the bottom of the b o t t l e in order to contact the a c i d w i t h the coating. The i n v e r t e d b o t t l e was p l a c e d i n an o v e n a t 6 0 ° C . The c o r r o s i o n p o t e n t i a l was m e a s u r e d b y p u t t i n g a s a t u r a t e d c a l o m e l e l e c t r o d e / s a l t bridge i n t o the s o l u t i o n through the hole in the b o t t o m o f t h e p l a s t i c b o t t l e and c o n t a c t i n g t h e b a c k s i d e o f t h e s u b s t r a t e t o c o m p l e t e t h e c i r c u i t as s h o w n i n F i g u r e 1. A K e i t h l e y 600A e l e c t r o m e t e r w a s u s e d f o r t h e m e a s u r e m e n t . T h e AC c o n d u c t a n c e was d e t e r m i n e d by i n s e r t i n g a c a r b o n r o d i n t o t h e s o l u t i o n and m e a s u r i n g t h e c o n d u c t a n c e a t 2 kHz f r e q u e n c y and 2 0 0 mv p o t e n t i a l w i t h an E x t e c h M o d e l 4 4 0 D i g i t a l C o n d u c t i v i t y M e t e r . The c o n d u c t a n c e v a l u e s w e r e c o n v e r t e d t o s p e c i f i c c o n d u c t i v i t y by m u l t i p l y i n g by t h e t h i c k n e s s a n d d i v i d i n g by t h e a r e a ( 5 c m ) . 2

The a d h e s i o n w a s m e a s u r e d b y f a s t e n i n g a l e a d a n c h o r o f known a r e a (2.84 cm ) t o the c o a t i n g w i t h a c y a n o a c r y l a t e adhesive (Loctite 4 1 4 ) and a f t e r c u r i n g , p u l l i n g i t o f f n o r m a l t o t h e s u r f a c e w i t h a Dillon tensile tester. The f o r c e t o r e m o v e t h e c o a t i n g was d i v i d e d by t h e a r e a o f a t t a c h m e n t t o c o n v e r t i t t o a n o r m a l i z e d t e n s i l e adhesion value. 2

The w e i g h t g a i n was m e a s u r e d by w e i g h i n g t h e c o a t e d d i s k a f t e r it was removed f r o m t h e p l a s t i c b o t t l e , f o l l o w i n g a w a t e r r i n s e and removal of surface water. The c o a t i n g and s u b s t r a t e w e r e o b s e r v e d t h r o u g h t h e h o l e i n t h e b o t t l e during the exposure to the acid. Since the coatings were transparent, i t was p o s s i b l e t o o b s e r v e any v i s i b l e corrosion o c c u r r i n g on t h e s t e e l s u b s t r a t e . The c o r r o s i o n p r o d u c t s on t h e s t e e l w e r e g r a y o r b l a c k , e x c e p t when t h e c o a t i n g b l i s t e r e d and some r u s t i n g was s e e n . As c o r r o s i o n p r o g r e s s e d d u r i n g t h e a c i d exposure, the steel surface gradually darkened from the i n i t i a l l i g h t g r a y o f t h e o r i g i n a l s a n d b l a s t e d s u r f a c e t o an a l m o s t black surface. The e x t e n t o f c o r r o s i o n was e s t i m a t e d f r o m t h e a m o u n t o f d a r k e n i n g o b s e r v e d on t h e s t e e l s u r f a c e .


Evaluation of Coating Resins


WHITE A N D LEIDHEISER

F i g u r e 1. Technique f o r e l e c t r o c h e m i c a l measurements. Reproduced w i t h p e r m i s s i o n from R e f e r e n c e 12. Copyright 1985, National A s s o c i a t i o n of Corrosion Engineers.


82


Results


F i g u r e 2 summarizes the values o b t a i n e d f o r the f o u r measurements on t h e s e v e n c o a t i n g s a f t e r e x p o s u r e t o 0.1 M H 0 S O 4 a t 6 0 ° C f o r 1 0 0 0 hours. The o r d i n a t e s h o w s t h e v a l u e s m e a s u r e c f f o r e a c h o f t h e f o u r t e c h n i q u e s , and t h e a b c i s s a r e p r e s e n t s t h e amount o f c o r r o s i o n o b s e r v e d on t h e s t e e l u n d e r e a c h o f t h e c o a t i n g s a f t e r t h e a c i d exposure, w i t h the amount of observed c o r r o s i o n d e c r e a s i n g from l e f t to right. The c o r r o s i o n p o t e n t i a l s s h o w a g e n e r a l t r e n d o f i n c r e a s i n g v a l u e s with d e c r e a s i n g s u b s t r a t e c o r r o s i o n , with the exception of the p o l y e s t e r a n d t h e n o v o l a c e p o x y c u r e d w i t h an a r o m a t i c / c y c l o a l i p h a t i c amine. T h e s p e c i f i c AC c o n d u c t i v i t y v a l u e s s h o w a g e n e r a l l y d e c r e a s i n g v a l u e w i t h d e c r e a s i n g s u b s t r a t e c o r r o s i o n , w i t h one e x c e p t i o n : the n o v o l a c e p o x y c u r e d w i t h an a r o m a t i c / c y c l o a l i p h a t i c a m i n e . This is one o f t h e c o a t i n g s t h a t a l s o d i d not f i t i n t o t h e t r e n d f o r t h e corrosion potential values. The t e n s i l e a d h e s i o n v a l u e s show no c o r r e l a t i o n w i t h t h e e x t e n t o f c o r r o s i o n ; the b i s p h e n o l A epoxy cured w i t h a p o l y a m i d e amine showed b l i s t e r i n g , w h i c h r e p r e s e n t s a complete l o s s of adhesion. The p o l y e s t e r s h o w e d c o h e s i v e f a i l u r e a t l e s s t h a n 1000 h o u r s o f e x p o s u r e , so a t r u e a d h e s i o n v a l u e c o u l d n o t be d e t e r m i n e d . The o t h e r e p o x i e s a n d t h e v i n y l e s t e r a l l had v a l u e s i n t h e 1 5 0 - 2 0 0 p s i r a n g e , w i t h no a p p a r e n t r e l a t i o n s h i p t o t h e a m o u n t o f c o r r o s i o n . Weight change d a t a were o b t a i n e d f o r o n l y f o u r o f t h e seven c o a t i n g s , a n d t h o s e d a t a s h o w e d no c o r r e l a t i o n w i t h t h e e x t e n t o f s t e e l substrate corrosion. The p o l y e s t e r s h o w e d a w e i g h t l o s s , rather t h a n a w e i g h t g a i n , p r o b a b l y d u e t o an a t t a c k and d i s s o l u t i o n o f t h e e p o x y by t h e a c i d . I t s h o u l d be n o t e d t h a t t h e e l e c t r o c h e m i c a l m e a s u r e m e n t s ( c o r r o s i o n p o t e n t i a l and c o n d u c t i v i t y ) f o r t h e t w o n o v o l a c e p o x i e s c u r e d w i t h an a r o m a t i c a m i n e f r o m d i f f e r e n t s o u r c e s s h o w e d g o o d a g r e e m e n t , a l t h o u g h t h e t e n s i l e a d h e s i o n and w e i g h t g a i n v a l u e s w e r e n o t as reproducible. Discussion The b e s t p e r f o r m i n g c o a t i n g s w e r e t h e v i n y l e s t e r , t h e b i s p h e n o l A e p o x y c u r e d w i t h an a l i p h a t i c a m i n e , and a n o v o l a c e p o x y c u r e d w i t h a mixed a r o m a t i c / c y c l o a l i p h a t i c amine. The s a t u r a t e d p o l y e s t e r , and a b i s p h e n o l A e p o x y c u r e d w i t h a p o l y a m i d e a m i n e s h o w e d s i g n i f i c a n t d e t e r i o r a t i o n o f t h e c o a t i n g m a t e r i a l i n t h e a c i d , and c o r r o s i o n o f t h e u n d e r l y i n g s t e e l . Two t y p e s o f n o v o l a c e p o x i e s c u r e d w i t h a r o m a t i c a m i n e s showed i n t e r m e d i a t e p e r f o r m a n c e . O n l y one relation l a t i o n of the f a c t

o f t h e f o u r t e c h n i q u e s — t h e c o n d u c t i v i t y — s h o w e d any c o r w i t h t h e o b s e r v e d e x t e n t o f c o r r o s i o n . The l a c k o f c o r r e the t e n s i l e adhesion values w i t h c o r r o s i o n i s a r e s u l t of t h a t t h e method i n t e g r a t e s a d h e s i o n l o s s a t t h e s u b s t r a t e


In Polymeric Materials for Corrosion Control; Dickie, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1986. ΒΡΑ AL NOV AR/ AL

POTENTIAL

P

A

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ΡΕ I NOV AR/ AL

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4

Figure H S0 .

. Γ

Γ

h

WEIGHT

NOV AR 2

GAIN

BPA AL

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CORROSION

MINIMAL

BPA AL

VE

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to

DECREASING ·

0.1 M

EXTENSIVE MODERATE MINIMAL AMOUNT OF CORROSION

I

BLIS. WT ITER.LOSS!

I

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| B P A | PE PA

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NOV AR 2

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NOV AR 1

NOV AR/ AL

CONDUCTIVITY

AMOUNT

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BPA PA

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ITERJHES.) .FAIL.,

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BPA AL

ADHESION

NOV AR 1 NOV AR 2

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ΒΡΑ ΡΑ

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3


84


i n t e r f a c e and t h e c o h e s i o n l o s s d u e t o d e t e r i o r a t i o n o f t h e p o l y m e r by a c i d . A l s o , t h e c o r r o s i o n o f t e n i s l o c a l i z e d and t h e a r e a a t t a c k e d i s a s m a l l f r a c t i o n of the t o t a l i n t e r f a c i a l area. The weight gain i s not a r e l i a b l e measure of c o r r o s i o n protection b e c a u s e t h e r e may be an a t t a c k a n d s o l u b i l i z a t i o n o f t h e c o a t i n g m a t e r i a l i t s e l f (as o c c u r r e d w i t h the p o l y e s t e r ) , so t h a t the o b s e r v e d c h a n g e i n w e i g h t w i l l be t h e n e t r e s u l t o f a w e i g h t l o s s f r o m s o l u b i l i z a t i o n and a w e i g h t g a i n f r o m w a t e r and a c i d e n t r y into the c o a t i n g . The o n l y way t o s e p a r a t e t h e t w o e f f e c t s i s t o measure the w e i g h t change o c c u r r i n g w i t h a f r e e f i l m o f t h e c o a t i n g and a s s u m e i t w i l l be t h e s a m e as a c o a t i n g on a s u b s t r a t e ; this was t h e t e c h n i q u e u s e d by F u n k e [ 5 ] . T h e r e i s much m o r e l i k e l i h o o d of attack of c o a t i n g m a t e r i a l s in a c i d s o l u t i o n s because of i n c r e a s e d r a t e s o f h y d r o l y s i s r e a c t i o n s a t l o w pH*s. T h e i n t e r p r e t a t i o n o f c o r r o s i o n p o t e n t i a l has a l w a y s b e e n d i f f i c u l t . W o l s t e n h o l m e [ 3 ] c o n c l u d e d t h a t t h e c o r r o s i o n p o t e n t i a l was n o t an u n a m b i g u o u s i n d i c a t o r o f t h e a m o u u n t o f c o r r o s i o n , and C e r i s o l a a n d B o n o r a [ 7 ] d e s c r i b e d t h e m e a s u r e m e n t a s o n e w i t h no q u a n t i t a t i v e r e l a t i o n s h i p to amount of c o r r o s i o n . The r e s u l t s shown i n F i g u r e 2 c o n f i r m the q u e s t i o n a b l e v a l u e of p o t e n t i a l m e a s u r e m e n t s i n c o r r e l a t i o n s w i t h t h e c o r r o s i o n o f an u n d e r l y i n g substrate. The c o a t i n g c o n d u c t a n c e , on t h e o t h e r h a n d , h a s b e e n r e p o r t e d by n u m b e r o f p e o p l e t o be r e l a t e d t o t h e e x t e n t o f c o r r o s i o n u n d e r coating [8-11]. The c o n d u c t a n c e , e i t h e r AC o r DC, i s a f u n c t i o n t h e amount o f c h a r g e t h a t can p a s s t h r o u g h t h e c o a t i n g and t h amount of charge i s a f u n c t i o n of the amount of aqueous phase the c o a t i n g t h a t p e r m i t s charge motion.

a a of is in

T h u s , i n a c i d s o l u t i o n i t a p p e a r s t h a t an i m p o r t a n t p r o p e r t y o f a coating for corrosion protection i s i t s permeability to acid. This v a r i a t i o n i n p e r m e a b i l i t y i s t h o u g h t t o be t h e r e a s o n f o r the d i f f e r e n c e in behavior of coatings observed during exposure to a c i d environments [12J. The p e r m e a b i l i t y i s a l s o a f f e c t e d by t h e d e g r a d a t i o n o f t h e c o a t i n g as c a u s e d b y r e a c t i o n w i t h t h e a c i d . Conclusions O f t h e f o u r t e c h n i q u e s s t u d i e d f o r e v a l u a t i n g c o a t i n g s on s t e e l f o r c o r r o s i o n c o n t r o l ( c o r r o s i o n p o t e n t i a l , c o n d u c t a n c e , a d h e s i o n and w e i g h t g a i n ) , t h e m o s t u s e f u l was c o n d u c t a n c e . Corrosion potential d i d n o t show a c o n s i s t e n t r e l a t i o n s h i p , and w e i g h t g a i n a n d t e n s i l e a d h e s i o n s h o w e d no c o r r e l a t i o n w i t h c o r r o s i o n . The b e s t p e r f o r m i n g c o a t i n g s s t u d i e d w e r e a v i n y l e s t e r , a b i s p h e n o l A e p o x y c u r e d w i t h an a l i p h a t i c a m i n e , a n d a n o v o l a c e p o x y cured w i t h a mixed a r o m a t i c / c y c l o a l i p h a t i c amine. A s a t u r a t e d p o l y e s t e r , and a b i s p h e n o l A e p o x y c u r e d w i t h a p o l y a m i d e a m i n e s n o w e d s i g n i f i c a n t d e t e r i o r a t i o n i n t h e a c i d and c o r r o s i o n o f t h e underlying steel. Two t y p e s o f n o v o l a c e p o x i e s c u r e d w i t h a r o m a t i c amines showed i n t e r m e d i a t e p e r f o r m a n c e .


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Acknowledgments The a u t h o r s a r e i n d e b t e d t o t h e E l e c t r i c P o w e r R e s e a r c h I n s t i t u t e , P a l o A l t o , C a l i f o r n i a , f o r s u p p o r t i n g t h i s w o r k and t o B. C. S y r e t t of t h a t o r g a n i z a t i o n f o r h e l p f u l d i s c u s s i o n s during the study.


Literature Cited 1. Fontana, M. G.; Greene, N. D. "Corrosion Engineering"; McGraw-Hill: New York, 1978; 2nd ed. 2. Leidheiser, H. Jr. Prog. Org. Coatings 1979, 7, 79-104. 3. Wolstenholme, J . Corr. Sci. 1973, 13, 521-30. 4. Mansfeld, F.; Kendig, M. W.; Tsai, S. Corrosion 1982, 38, 478-85. 5. Funke, W.; Haagen, H. Ind. Eng. Chem. Prod. Res. Dev. 1978, 17, 50-53. 6. White, M. L.; Paper given at ACS Meeting, Philadelphia, PA, August 1984. Submitted to Ind. Eng. Prod. Res. Dev. for publication in 1986. 7. Cerisola, G.; Bonora, P. L. Mater. Chem. 1982, 7, 241-48. 8. D. J. Mills. In Coatings and Surface Treatment for Corrosion and Wear Resistance; Strafford, K. N., Ed.; Horwood: Chichester, England, 1984; pp. 315-30. 9. Rajagopalan, K. S.; Guruviah, S.; Rajagopalan, C. S. J. Oil Col. Chem. Assoc. 1980, 63, 144-48. 10. Touhsaent, R. E.; Leidheiser, H. Jr. Corrosion 1972, 28, 43540. 11. Vertere, V.; Rozados, E.; Carbonari, R. J. Oil Col. Chem. Assoc. 1978, 61, 419-26. 12. White, M. L.; Leidheiser, H. Jr., Materials Performance 1985, 24, 9-16. RECEIVED January 27, 1986


Evaluation of Coating Resins for Corrosion Protection of Steel

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