الفهرس 
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Abstract
SUMMARY
The thesis comprises three main chapters; the first one deals with
the following fields of interest:
Corrosion theory, corrosion protection types of corrosion and corrosion
behavior of aluminum in aqueous environments. Finally, literature survey
of corrosion behavior of aluminium and aim of the present work.
The second chapter deals with the experimental techniques, which include
preparation of the sodium hydroxide solution, the investigated of ( N -
thiazolyl- 2 - cyanoacetamide derivatives and N- thiazolyl- 2 - cyano-
2-propeneamide derivatives) solutions and the procedures used for the
corrosion measurements such as weight loss and polarization techniques.
Chapter three deals with the results and discussion, the results obtained
and their interpretations are shown under three separated sections, (A) ,
(B) and (C).
Section (A) :
Contains the results of weight loss measurements for aluminum in
0.0IM sodium hydroxide solution containing different concentrations of
(N-thiazolyl-2-eyanoacetamide derivatives and N-thiazolyl-2-eyano-2-
propeneamide derivatives) solutions.
These results revealed that these compounds behave similarly and the
weight loss is generally decreases with increasing the concentration of
these compounds and also depends upon the nature and type of
investigated inhibitors.
The inhibition efficiency of these compounds decreases 10 the
following order:
~1S6-
i) For first series compounds:
(c»(b»(a)
ii) For second series compounds:
( f) > ( e ) > ( d )
The synergistic effect of barium chloride , strontium chloride ,
calcium chloride and magnesium chloride was examined by addition of
BaCh.6H20, SrCh.6H20 , CaCh.6H20 and MgCI2.6H20 to enhance the
inhibited effect of these (N-thiazolyl-2- cyanoacetamide derivatives and
N-thiazolyl-2-cyano-2-propeneamide derivatives) compounds . This
conducted by studying the effect of addition constant concentration of the
selected salts with different concentrations of investigated inhibitors.
A number of mathematical relationships for the adsorption isotherms
have been suggested to fit the experiment data of the present work.
The simplest equation that fits our results is that due to Frumkin’s
adsorption isotherm and is given by the general equation :
KC = e/ 1- eexp ( -2a e)
The effect of temperatures on the corrosion rates of aluminium in
a.OIM sodium hydroxide solutions containing different concentrations of (
N-thiazolyl-2-cyanoacetamide derivatives and N-thiazolyl-2-eyano-2-
propeneamide derivatives) compounds was studied. Arrhenius plots of
logarithm corrosion rate ( log k) against reciprocal of absolute temperature
(1If) were found to be linear and obeyed the following equation :
Log k = 10gA- (E a*/2.303RT)
from the transition state equation , plots of logarithm corrosion rate
divided by absolute temperature ( log kIT ) against reciprocal of absolute
temperature ( Iff ) were found to be linear and obeyed the following
equation:
Rate =RTINh exp (LlS*/R) exp (-AH*IRT)
.... :
-IS7 -
Thermodynamic parameters (AlI* ads and as *ads ) are also computed .
and discussed. The percentage inhibition efficiency decreases with
increasing temperature.This indicated that, these compounds are physically
adsorbed on aluminium surface.
The values of activation energy and heat of adsorption (aH* ads) are
increased with increasing inhibitor concentration while entropy of
adsorption (as* ads) is decreased at the same time, also the adsorption of
the inhibitors on the aluminium surface is physically.
Section (B) :
Contains the results of galvanostatic polarization measurements for
aluminium in 0.01M NaOH in absence and presence of different
I
(N-thiazolyl-2-cyanoacetamlde derivatives and N-thiazolyl-2-cyano-2-
propeneamide derivatives) compounds. The polarization curves indicated
that these compounds influence both cathodic and anodic processes(mixed
type inhibitors), but the data suggested that the anode is more polarized
when an external current was applied. The order of decreased inhibition
efficiency for the additives:
i) For first series compounds:
(c»(b»(a)
ii) For second series compounds;
(f»(e»(d)
This is in a good agreement with the observed order of corrosion inhibition
determined by the weight loss method. This indicates the validity of the
results obtained by two different methods.
Section (e) :
The influence of the chemical structure of the used inhibitors on
their inhibition efficiencies was discussed on the basis of the substituent
groups in the p-position and the molecular size of these compounds.