Alüminyuma belli oranlarda magnezyum ilavesiyle elde edilen alaşımların elektrod potansiyellerinin incelenmesi

Abstract

SUMMARY INVESTIGATION OF ELECTRODE POTANTIALS OF ALLOYS OBTAINED FROM THE ADDITION OF CERTAIN AMOUNTS OF MAGNESIUM TO ALUMINUM Alloys containing 1, 5, 10, 20, 40 and 50 percent of magnesium respecti-vely are obtained by the addition of magnesium to aluminum in the nitrogen gas medium. Electrochemical cells consisting of saturated calomel elerktrode as cathode? and Fe, Mg, Al and alloy electrodes as anode are constructed. 1 M eacth of AİCİ, and MgCl, solutions, and sea water are used as electrolytes in these cells and the potentials of the cells and the potentials of the cells are measured. Finally, using iron electrode as cathode, aluminum and alloy electrodes as anode and natural sea water as electrolyte, a series of electrochemical cells is constructed again. Results are presented in Tables 2, 3, 4 and Figures 19, 20, 21. According to these results, the potential of the alloy electrodes obtained from the addition of magnesium to aluminum becemes more negative as the percentageof magnesium in the alloy increases. An aluminum electrode, three alloy electrodes containing 1, 5 and 10 percent of magnesium respectively, and five iron electrodes are weighed and thei r photographes are taken from the middle point of their surfaces by using a metal microscope. Iron electrode alone, and iron-aİTjminuro, iron-alloy electrode pairs are constructed and these elektrodes are dipped into the beakers conta iningone liter of sea water. The electrodes are allowed to stand one week in the beakers. After one week, the electrodes are lifted from the beakers, and then they are rinsed, weighed and their surface photographes are taken. The results shown in Tabl 5. and Figure 22,23,24,25,26 are obtained. It is shown that the corrosion rate of iron, dipped into the sea water without any ?8oMprotection is too fast and aluminum in the sea water can not protect the iron from corrosion sufficiently. It is also shown that as the percentage of magnesium iî? the alloy electrodes increases, a better preventation of iron from corrosion occurs. Alloy electrode containing 10 percent magnesium provides an excellent protection of iron from corrosion. To determine pitting, critical pitting potentials of electrodes, and corrosion currents, polarization curves are plotted. Iron, ahluminum, and alloy electrodes containing 1, 5, 10 and 20 percent of magnesium are insulated with -an.Insulator so as to give a surface area of 1 cm'. Plotting current versus potential graph in the anodic region, pitting and critical, pitting potentials are determined. Results shown in Table 6 indicates that, as the percentage of magnesium in the alley electrodes increases, pitting potentials become more negative. Potential versus log I graph is plotted using cathodic polarization curves of the same electrodes mentioned above. Corrosion current is found by extrapolating this graph (Tafel extrapolating methods). Again using the same electrodes, an external current which is approximately equal to the corrosion potential, is applied and graps showing over tension versus current in anodic and cathodic regions are plotted. Using the slope of the linear portion of these graphs, corrosion currents are calculated (Linear polarization method). As shown in Table. 13., different corrosion currents are obtained for the different amounts of magnesium alloy. In this study, investigating the electrode, pitting, and critical pitting potentials of electrodes, and corrosion currents, the behavior of alloy electrodes in the corrosive sea water medium, and their effects in the cathodic protection of iron are determined. a»QY *

SUMMARY INVESTIGATION OF ELECTRODE POTANTIALS OF ALLOYS OBTAINED FROM THE ADDITION OF CERTAIN AMOUNTS OF MAGNESIUM TO ALUMINUM Alloys containing 1, 5, 10, 20, 40 and 50 percent of magnesium respecti-vely are obtained by the addition of magnesium to aluminum in the nitrogen gas medium. Electrochemical cells consisting of saturated calomel elerktrode as cathode? and Fe, Mg, Al and alloy electrodes as anode are constructed. 1 M eacth of AİCİ, and MgCl, solutions, and sea water are used as electrolytes in these cells and the potentials of the cells and the potentials of the cells are measured. Finally, using iron electrode as cathode, aluminum and alloy electrodes as anode and natural sea water as electrolyte, a series of electrochemical cells is constructed again. Results are presented in Tables 2, 3, 4 and Figures 19, 20, 21. According to these results, the potential of the alloy electrodes obtained from the addition of magnesium to aluminum becemes more negative as the percentageof magnesium in the alloy increases. An aluminum electrode, three alloy electrodes containing 1, 5 and 10 percent of magnesium respectively, and five iron electrodes are weighed and thei r photographes are taken from the middle point of their surfaces by using a metal microscope. Iron electrode alone, and iron-aİTjminuro, iron-alloy electrode pairs are constructed and these elektrodes are dipped into the beakers conta iningone liter of sea water. The electrodes are allowed to stand one week in the beakers. After one week, the electrodes are lifted from the beakers, and then they are rinsed, weighed and their surface photographes are taken. The results shown in Tabl 5. and Figure 22,23,24,25,26 are obtained. It is shown that the corrosion rate of iron, dipped into the sea water without any ?8oMprotection is too fast and aluminum in the sea water can not protect the iron from corrosion sufficiently. It is also shown that as the percentage of magnesium iî? the alloy electrodes increases, a better preventation of iron from corrosion occurs. Alloy electrode containing 10 percent magnesium provides an excellent protection of iron from corrosion. To determine pitting, critical pitting potentials of electrodes, and corrosion currents, polarization curves are plotted. Iron, ahluminum, and alloy electrodes containing 1, 5, 10 and 20 percent of magnesium are insulated with -an.Insulator so as to give a surface area of 1 cm'. Plotting current versus potential graph in the anodic region, pitting and critical, pitting potentials are determined. Results shown in Table 6 indicates that, as the percentage of magnesium in the alley electrodes increases, pitting potentials become more negative. Potential versus log I graph is plotted using cathodic polarization curves of the same electrodes mentioned above. Corrosion current is found by extrapolating this graph (Tafel extrapolating methods). Again using the same electrodes, an external current which is approximately equal to the corrosion potential, is applied and graps showing over tension versus current in anodic and cathodic regions are plotted. Using the slope of the linear portion of these graphs, corrosion currents are calculated (Linear polarization method). As shown in Table. 13., different corrosion currents are obtained for the different amounts of magnesium alloy. In this study, investigating the electrode, pitting, and critical pitting potentials of electrodes, and corrosion currents, the behavior of alloy electrodes in the corrosive sea water medium, and their effects in the cathodic protection of iron are determined. a»QY *