Development of Material for the Overhead Contact Line of the Addis Ababa Light Rail Transit (AA-LRT)

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Addis Ababa University


The purpose of this research is to develop a better material for the AA-LRT overhead contact line production. So with this in mind, the mechanical wear and corrosion resistance as well as the conductivity and hardness test of Cu-Ag and three other age-hardened copper alloys (Cu-Sn, Cu-Sn-Cr, and Cu-Ag-Sn) were studied using a pin-on-disk tribometer, a Rockwell Hardness Test machine and a Corrosion resistance test apparatus. For a tribological test, the samples were forced to slide against a rotating disk made of a stainless steel at a room temperature under un-lubricated condition with a constant velocity of 80km/h and a vertical load up to 7N (The actual pressing force of the pantograph against the conduct line in real situation is far greater than 7N, however, due to the limitation of laboratory equipments the maximum load used was seven Newton. The worn surfaces of the samples were examined under an optical microscope. Upon examination of the surfaces it was observed that the mechanisms of wear were both abrasive and adhesive. The corrosion resistance test was done by immersion of samples in three different solutions, Na-Cl, PH5 acidic rain, and distilled water. Continuous fresh air was pumped through the fluids and a 30volt DC current was applied for an electrolytic condition. In both the tribological and corrosion resistance test weight difference of the sample alloys before and after the respective test was taken as a measure of their wear and corrosion resistance property. With its high wear and corrosion resistance as well as good conductivity, the Cu-Sn-Cr alloy is an appropriate material for future production of an alternate overhead contact line of the Addis-Ababa Light Rail Transit system.



Addis Ababa Light Rail Transit (AA-LRT), Overhead Contact Line, Material