1. EFFECT OF STRONTIUM (Sr) AS ALLOYING ELEMENTS ON MAGNESIUM (Mg) SACRIFICIAL ANODE PERFORMANCE
Sacrificial anode is one of the two general types of cathodic protection systems in underground corrosion prevention. Research on sacrificial anode materials has been studied in all over the world and it was found that the most practical anode material used to protect buried steel component is pure magnesium (Mg). Open circuit potential for pure Mg is occasionally less than -1.70VSCE which not much enough is to produce a sufficient protective current to prevent a corrosion attack in highly resistance electrolyte such as soil. To overcome these weaknesses, Mg alloy anode is designed by addition of higly electronegative elements such as strontium (Sr).
In its pure form Sr is extremely reactive with air and spontaneously combusts. During alloy fabrication, Sr shows high loses when added in pure form into molten Mg because of evaporation. Some of them will not dissolve at Mg melting temperature. Thus Mg-Sr alloys fabrication will carry out by using master alloy. In this study the amount of Sr are varied from 0.05 ~ 1.5 wt.%.
To study the effect of Sr in Mg alloy on corrosion behaviour, electrochemical testing such as open circuit potential, Tafel plot, potentiodynamic anodic polarization will be studied by potentiostat/ galvanostat. Anode effieciency is determined by columeter/ amphere hour meter based on ASTM G97. Effect of alloying elements on Mg alloys microstructure will be observed by optical microscope.
2. EFFECT OF BARIUM (Ba) CONTENT ON MAGNESIUM (Mg) SACRIFICIAL ANODE PERFORMANCE
Sacrificial anode is one of the two general types of cathodic protection systems in underground corrosion prevention. Research on sacrificial anode materials has been studied in all over the world and it was found that the most practical anode material used to protect buried steel component is pure magnesium (Mg). Open circuit potential for pure Mg is occasionally less than -1.70VSCE which not much enough is to produce a sufficient protective current to prevent a corrosion attack in highly resistance electrolyte such as soil. To overcome these weaknesses, Mg alloy anode is designed by addition of higly electronegative elements such as barium (Ba).
In its pure form, barium (Ba) is a metallic element that is chemically reactive. This metal oxidizes very easily when exposed to air and is highly reactive with water or alcohol, producing hydrogen gas. Burning in air or oxygen produces not just barium oxide (BaO) but also the peroxide. During alloy fabrication, Ba shows high loses when added in pure form into molten Mg because of evaporation. Some of them will not dissolve at Mg melting temperature. Thus Mg-Ba alloys fabrication will carry out by using master alloy.
In this study the amount of Ba are varied from 0.05 ~ 1.5 wt.%. To study the effect of Ba in Mg alloy on corrosion behaviour, electrochemical testing such as open circuit potential, Tafel plot, potentiodynamic anodic polarization will be studied by potentiostat/ galvanostat. Anode effieciency is determined by columeter/ amphere hour meter based on ASTM G97. Effect of alloying elements on Mg alloys microstructure will be observed by optical microscope.
3. EFFECT OF CALCIUM (Ca) CONTENT ON MAGNESIUM (Mg) SACRIFICIAL ANODE PERFORMANCE
Sacrificial anode is one of the two general types of cathodic protection systems in underground corrosion prevention. Research on sacrificial anode materials has been studied in all over the world and it was found that the most practical anode material used to protect buried steel component is pure magnesium (Mg). Open circuit potential for pure Mg is occasionally less than -1.70VSCE which not much enough is to produce a sufficient protective current to prevent a corrosion attack in highly resistance electrolyte such as soil. To overcome these weaknesses, Mg alloy anode is designed by addition of higly electronegative elements such as Calcium (Ca).
In its pure form, calcium is chemically reactive. During alloy fabrication, Ca shows high loses when added in pure form into molten Mg because of evaporation. Some of them will not dissolve at Mg melting temperature. Thus alloys fabrication will carry out by using master alloy.
In this study the amount of Ca are varied from 0.05 ~ 1.5 wt.%. To study the effect of Ba in Mg alloy on corrosion behaviour, electrochemical testing such as open circuit potential, Tafel plot, potentiodynamic anodic polarization will be studied by potentiostat/ galvanostat. Anode effieciency is determined by columeter/ amphere hour meter based on ASTM G97. Effect of alloying elements on Mg alloys microstructure will be observed by optical microscope.
4. EFFECT OF SOLUTION TREATMENT PERIOD ON Mg-Sr SACRIFICIAL ANODE
Magnesium alloys usually are heat treated either to improve mechanical properties or as means of conditioning for specific fabricating operations. However, in this study heat treatment is applied to increase the protective current of Mg sacrificial anodes in order to increase its protective current to reduce the corrosion problem on underground iron based materials. Previous study on Mg-Mn alloys, microstructure result shows that the needle like particles which believed consists of a-Mn give an idea about a cathodic characteristic that results the reduction of corrosion potential. Nevertheless, by prolongs the solution treatment, the needle like particles was found reduces and results the significant increasing of anode potential. By using the same idea, the highly negative element such as Sr is used as alloying element in Mg alloy. Solution treatment will carry out at 300 and 400oC for 3, 6 & 9 hrs respectively. After solution treatment, all of samples were cooled by using annealing method. Electrochemical corrosion behaviour such as open circuit potential, Tafel plot, potentiodynamic anodic polarization will be studied by potentiostat/ galvanostat. Anode effieciency will be determined by columeter/ amphere hour meter based on ASTM G97. Effect of solution treatment on Mg alloys microstructure and its relation to electrochemical properties will be examined by optical microscope.
5. EFFECT OF SOLUTION TREATMENT PERIOD ON Mg-Ba SACRIFICIAL ANODE
Magnesium alloys usually are heat treated either to improve mechanical properties or as means of conditioning for specific fabricating operations. However, in this study heat treatment is applied to increase the protective current of Mg sacrificial anodes in order to increase its protective current to reduce the corrosion problem on underground iron based materials. Previous study on Mg-Mn alloys, microstructure result shows that the needle like particles which believed consists of a-Mn give an idea about a cathodic characteristic that results the reduction of corrosion potential. Nevertheless, by prolong the solution treatment, the needle like particles was found reduces and results the significant increasing of anode potential. By using the same idea, the highly negative element such as Ba is used as alloying element in Mg alloy. Solution treatment will carry out at 300 and 400oC for 3, 6 & 9 hrs respectively. After solution treatment, all of samples were cooled by using annealing method. Electrochemical corrosion behaviour such as open circuit potential, Tafel plot, potentiodynamic anodic polarization will be studied by potentiostat/ galvanostat. Anode effieciency will be determined by columeter/ amphere hour meter based on ASTM G97. Effect of solution treatment on Mg alloys microstructure and its relation to electrochemical properties will be examined by optical microscope.
6. EFFECT OF SOLUTION TREATMENT PERIOD ON Mg-Ca SACRIFICIAL ANODE
Magnesium alloys usually are heat treated either to improve mechanical properties or as means of conditioning for specific fabricating operations. However, in this study heat treatment is applied to increase the protective current of Mg sacrificial anodes in order to increase its protective current to reduce the corrosion problem on underground iron based materials. Previous study on Mg-Mn alloys, microstructure result shows that the needle like particles which believed consists of a-Mn give an idea about a cathodic characteristic that results the reduction of corrosion potential. Nevertheless, by prolong the solution treatment, the needle like particles was found reduces and results the significant increasing of anode potential. By using the same idea, the highly negative element such as Ca is used as alloying element in Mg alloy. Solution treatment will carry out at 300 and 400oC for 3, 6 & 9 hrs respectively. After solution treatment, all of samples were cooled by using annealing method. Electrochemical corrosion behaviour such as open circuit potential, Tafel plot, potentiodynamic anodic polarization will be studied by potentiostat/ galvanostat. Anode effieciency will be determined by columeter/ amphere hour meter based on ASTM G97. Effect of solution treatment on Mg alloys microstructure and its relation to electrochemical properties will be examined by optical microscope.
