تطبيقات الطرق العددية في التاكل الكلفاني للمعادن المزدوجة == Applications of Numerical Methods In Galvanic Corrosion of Coupled Metals
Author name:
بسمة محمد كاظم الشاهر
Supervisor name:
جمال مانع علي الربيعي
General topic:
Chemical Engineering
Specific topic:
Industrial Processes
Degree:
Master
University:
University of Technology - Department Of Chemical Engineering - Chemical Process Engineering Branch
Language:
English
University location:
Baghdad
First pages:
38T273 - p.pdf
Abstract:
تم دراسة سلوك تاكل معادن النحاس والكربون الصلب والزنك في تراكيز مختلفة من حامض الهيدروكلوريكHCl) ) (0.025، 0.05 و0.075 مولاري ) عند درجات حرارة مختلفة (30، 40 و50 درجة مئوية) باستخدام القياسات الكهروكيميائية (Electrochemical Measurements) في حالة المعا | The corrosion behaviors of metals Copper, Carbon Steel and Zinc in a different concentrations of HCl acid (0.025, 0.05 and 0.075M) at different temperatures (30, 40 and 50°C) were investigated using electrochemical measurements in couple and single state.The galvanic behaviors of coupled metals (Cu - Fe),( Cu - Zn) and (Fe - Zn)were studied using Zero Resistance Ammeter (ZRA) technique, it has been used to measure the galvanic current (Ig) and galvanic potential (Eg) with time. The galvanic corrosion cells for all couples have equal areas of anode and cathode (2×2cm).The galvanic current density (ig) is increased with increasing solution concentration and temperature. The galvanic potential (Eg) is shifted to less negative with increasing solution concentration and temperature and it is close to the corrosion potential of the anode in the couple conditions.The potentiostatic polarization behavior of single three metals (Copper, Carbon Steel and Zinc) in different concentrations of dilute HCl acid (0.025, 0.05 and 0.075M) at temperature (40°C) is found under activation control. The corrosion current density is increases with increasing solution concentration and gives the following arrangement of metals : Cu> Fe > Zn A numerical analysis of galvanic corrosion was presented. The analysis was based on three numerical methods as the boundary element method (BEM), the finite element method (FEM) and the finite difference method (FDM).The potential and current density distributions on the galvanic elements are described by the Laplace equation. The Laplace equation was solved numerically, to determine the potential, current density, and corrosion caused by the galvanic cell using designed computer programs in MATLAB R2014a. The experimentally determined polarization curves have been used in order to define the nonlinear boundary conditions. This boundary value problem has been solved using Newton - Raphson iterative numerical procedure. For the three couple systems (Cu - Fe, Fe - Zn and Cu - Zn), the results obtained for galvanic potential and current density, using the numerical methods (BEM, FEM and FDM) with the overall deviations are 6.689, 10.818 and 18.846 respectively for galvanic current density and 0.631, 1.210 and 1.787 respectively for galvanic potential. From these results it can conclude that the galvanic current density and galvanic potential distribution calculated from the BEM model was in good agreement with the experimental measurements. These are because the main advantages of the BEM over the Finite Element Method (FEM) and the finite difference method (FDM) are high accuracy, discretization on the boundary only which results in a very small number of unknowns, easy dealing with non - regular boundaries and openings that only the domain boundary of interest is required to be discrete, also BEM needs fewer equations and a smaller matrix size than FEM and can solve both finite and infinite domain problems.
