Corrosion and corrosion inhibition study of galvanized steel in salty acidic and basic media

العناوين الأخرى

دراسة تآكل و تثبيط تآكل حديد الصلب المغلون في المحيطات الملحية الحامضية و القاعدية

مقدم أطروحة جامعية

Abbas, Hayfa Abd al-Amir

مشرف أطروحة جامعية

al-Sadi, Khulud Abd Salih

أعضاء اللجنة

Afif, Rana
al-Samurai, Abd al-Karim M. A.
al-Abaji, Muayyad Qasim Yasin

الجامعة

جامعة بغداد

الكلية

كلية العلوم

القسم الأكاديمي

قسم الكيمياء

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2012

الملخص الإنجليزي

This thesis includes the electrochemical study for the galvanized steel corrosion in the presenceof 0.05-1 mol.dm-3NaCl over a pH range of 2,4,10,12 in the temperature range ( 298 -328) K, by using the computerized {been obtained by the extrapolation of linear logarithmic sections of cathodic and anodic Tafel lines of the point intersection .Acidic solution (PH=2-4) have been prepared from a stock 0.1 mol/dm-3 HCl solution, while the basic solution have been prepared from the a stock 0.1 mol/dm-3 NaOH solution .

The experimental study results revealed that : 1.

The current density increase with increasing the temperature and acidity, it have a miximum value 704.12×10-6 A.dm-2 in pH =2 and temperature =328K.

2.

The current density increase with increasing NaCl concentration in acidic medium, it was found to be 1298×10-6 A.dm-2 in 1M NaCl , and varied with increasing NaCl in basic solution .

3.

The variation of corrosion potential reflect the heterogeneous nature for the corrosion process on the G.S.

surface.

4.

The thermodynamic parameters ΔH,ΔG and ΔS were calculated at different NaCl concentration and temperature , the value of ΔH,ΔG and ΔS was (-50.23 ‒ -871.66)kJmol-1, (-87.81 ‒ -206.08)kJ.K-1.mol-1 and (+0.004 ‒ -0.845)kJ.mol-1}respectively.

Last data indicates the spontaneous and exothermic corrosion process.

5.

The general behavior for the kinetic studied depend on Arrhenius equation.

A linear relationship was found between log A and Ea suggesting the operation of a compensation effect in the kinetic behavior of galvanized steel corrosion .Negative activation energy have been obtained for some samples which mean that ,increasing the temperature leads to decreases the rate of the corrosion.

6.

The values of weight losses increase with increasing temperature with some exception in basic solution.

IX 7.

The volume of hysteresis loop increase with increasing NaCl concentration, signs pitting corrosion.

This thesis also involves the polentiostats studies for the inhibition effect of hexamine on galvanized steel corrosion in the presence of hydrochloric acid 0.01mol.dm-3 over the temperature range of 298-328 K.

The study indicated that: 1.

The current density increase slightly with increasing the temperature and hexamine concentration.

2.

The corrosion potential vibrated between the Nobel direction (less negative) and active directions (more negative) which mean the inhibitor act as a mixed type for anodic and cathodic regions.

3.

The values of inhibition efficiency of hexamine increase with increasing the temperature it was found to be 66.6%−86.6% with respect to 298−328K.

, and decreases with increasing concentration.

4.

The values of thermodynamic function obtained from Langmuir isotherm , negative values of ΔG= -28.8− -21.6 kJ.K-1.mol-1 indicated the spontaneous nature of adsorption process ,negative values of ΔH=36.5−39.

9 kJ.K-1.mol-1 indicated the chemisorptions nature for the hexamine adsorption on the metal surface.

5.

The general behavior for kinetic adsorption process confirm with Arrhenius equation .The value of Ea was found to be =8.5−20.7kJ/mol.

6.

A very narrow hysteresis loop, signs no pitting corrosion.

التخصصات الرئيسية

الكيمياء

عدد الصفحات

93

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-599650