اسم المؤلف:
حيدر ياسر ثامر الياسري
اسم المشرف:
محمد جاسم كاظم | عدنان شمخي جبر
المستخلص:
عملية الترسيب او التحليل الكھربائي تعتبر من الطرق التصنيعية الرئيسية التي تستخدم لانتاج مختلف الاشكال والاحجام (ضمن المدى الميكروي) من حبيبات مسحوق معدن النحاس والتي تستخدم لاحقا بواسطة تكنولوجيا المساحيق لانتاج اجزاء محددة. ايضا استخدمت ھذه الطريقة بمد | Electrolytic or electrodeposition process is considered a main way to produce many shapes and sizes (micro range) of copper powder to be used in powder metallurgy process. It is used broadly to deposit copper coatings with nanosized grains, but it is rarely used to produce nanosized particles of copper. Reaching this goal is highly dependent on the optimum design of the parameters of electrodeposition process.This work aims to study the important variables that most affect the electrodeposition process outputs. These variables are : copper sulphate pentahydrate salt concentration CuSO4.5H2O (1, 5.5, and 10) g/l, cathodic current density (12.5, 25 , and 37.5) mA/cm2, ultrasonic (20 KHz frequency) vibration amplitude (5%, 20%, and 35%) from the maximum amplitude (1 ?m), and amount of sulphuric acid H2SO4 (H2SO4 concentration > 97%) in electrodeposition cell (0.05, 0.10, and 0.15) ml/l. The study of effects of these variables is concerned with size of resultant powder particles, also their effect on the purity, morphology, and shapes of particles is studied, and the crystallinity of particles is also covered.The design of experiment (DOE) approach is applied here through Taguchi design of experiments, to manage and analyze the results and study the specific effects of each. The arrangement of variables’ levels is done using the setup of (Taguchi L9).The analysis of experiment tests of the study of electrodeposition process to get copper nanoparticles showed that all variables have effect on the size of resultant copper particles, but in different ways and degrees. The mean particle size of all samples is about 86 nm. It was found that the increasing of concentration of copper sulphate salt (1, 5.5, and 10) g/l had a negative on the increasing the size of copper particles in the range (71, 69, and 117) nm.While the increasing of cathodic current density (12.5, 25 , and 37.5) mA/cm2 had an effect of decreasing the particle size of copper in the range (114, 75, and 68) nm. The case was the same for increasing of amplitude of ultrasonic vibration, where increasing it (5%, 20%, and 35%) caused decreasing in the particle size in the range (97, 92, and 68) nm. And the effect of acid amount (0.05, 0.10, and 0.15) ml/l was multiple because it decreased the particle size first and increased it later in the range (90, 65, and 102) nm. The amount of effect of each variable on the process was calculated using specific equations of Taguchi design. It was found that the current density has the bigger effect (35%) on the resultant particle size (it minimized the size). The salt copper concentration has the second effect (34%) (it maximized the size), and thirdly the acid concentration effect is 19% (it had multiple effect on the size).Finally the ultrasonic vibration has 12% effect (it minimized the size). The optimum values of process parameters that lead to minimum size of the particles were : CuSO4.5H2O concentration = 5.5 g/l, Current density = 37.5 mA/cm2, Ultrasonic amplitude = 35%, H2SO4 concentration = 0.1 ml/l.The SEM photographs were used to examine the morphology of particles. The results show that the shape and morphology widely vary between many modes : from treelike through irregular, angular, or rounded shapes to a wellfaceted truncated octahedron. The forming of well - faceted truncated octahedron copper particles is related strongly to the presence of ultrasonic vibration which plays the role of inhibitor.Energy dispersive spectroscopy (EDS) elemental analysis of copper nanoparticles indicates the high purity of most of samples except the cases where there are traces of oxygen from very thin layer of oxides and/or carbon from residual alcohol.The x - ray diffraction studies reveal that the resulting particles are a crystalline copper element with a face center cubic (FCC) crystal structure.
