تحضير وتشخيص المركبات الحلقية غير المتجانسة الجديدة والمشتقة من الجالكونات == Synthesis And Characterization of New Heterocyclic Compounds Derived From Chalcones
Author name:
نبراس مظفر جميل
Supervisor name:
جمبد هرمز توما | ضحى فاروق حسين
General topic:
Chemistry
Specific topic:
Physical Chemistry
Degree:
Master
University:
University of Baghdad - College Of Science - Chemistry Department
Language:
English
University location:
Baghdad
First pages:
25T1470 - p.pdf
Abstract:
يتقصى البحث امكانية الحصول على طبقة طلاء رقيقة ومتجانسة لبوليمر البايرول على بعض السبائك مثل الفولاذ المقاوم للصدا 316 والفولاذ الكربوني بواسطة البلمرة الكهروكيميائية لمونمر البايرول ودراسة امكانية تحسين مقاومة التاكل في مختلف الاوساط البيئية مثل المياه ا | This research focuses on getting thin and homogeneous polypyrrole (PPy) layer on carbon steel (45) and stainless steel (316) alloys by electropolymeriztion procedure of pyrrole monomer, and study the possibility of improving the corrosion resistance in different medias; saline water (3.5% NaCl), acidic media (1M H2SO4) and basic media (1M NaOH) at different temperature of 293, 303, 313 and 323 K. The deposited PPy layer on samples under investigation were examined by Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), Visible and Ultraviolet Spectroscopy (UV - Vis), Fourier Transform Infrared Spectroscopy (FT - IR), Thermogravimetric Analysis (TGA) and X - Ray Diffraction (XRD).The corrosion parameters are including corrosion potential (Ecorr), corrosion current (icorr), protection efficiency (%PE), polarization resistance (Rp) and the effect of temperature on the inhibition efficiency in the absence and in the presence of PPy coating at temperature ranging from 293 to 323K were obtained and expressed as; Ea, ?H*, ?S*, and ?G* of all samples were estimated from Tafel plots using potentiostatic technique.The SEM and AFM images of PPy films revealed a nanofiber like structure; diameter from 20 to 120 nm, the thicknesses were measured by gravimetric and special AFM scans, they showed values between 1300 to 1450 nm. UV - Vis studies showed that the PPy films exhibit weaker absorption peak at 477 nm and stronger absorption peak at 906 nm and the XRD patterns of the deposited PPy show two peaks around 2? of (43o) and (50o).The shift in Ecorr of the uncoated and of the PPy coated samples are between ( - 600 to - 200 mV) and ( - 200 to 100mV) for CS and SS316 respectively.The protection effectiveness of all PPy coated specimens showed remarkable degree of enhancement, and the %PE ranged between (30 to 80%) for CS and (78 to 96%) for SS316 in all medias.The values of Ea and ?H* of the coated PPy metals are always higher than the uncoated ones which indicate more energy barrier. The negative entropy ?S* for the uncoated and coated samples indicates that the activated complex in the rate determining step represents an association rather than a dissociation step, the measured ?G* values takes positive values and showed almost small change with increasing temperature, indicating that the activated complex was not stable and the probability of its formation decreased somehow with rise in temperature and the ?G* values for coated samples reveal that in the activated corrosion complex becomes less stable as compared to the uncoated specimens.Single cyclic potentiodynamic tests conducted at 293 K to follow up the pitting probabilities of each alloy in all medias before and after coating, the I - V plots indicated that only SS316 in salty media specimens suffer from pitting corrosion and the PPy coating reduces the pitting area of the hysterias loop with pushing the pitting potentials for more positive values
