Ductile and Gray Cast Irons Deterioration with Time in Various NaCl Salt Concentrations

Abstract

Gray cast iron is used in wide engineering applications especially pipes and these pipes are exposed to failure in most cases so that ductile cast iron is used instead of it later. This project deals with the study of microstructure characteristics and chemical analysis for both materials in order to use them in the analysis of the microstructure after the corrosion tests involving immersion, polarization in different sodium chloride concentrations (0.01%, 0.58% and 3.5% NaCl). Immersion results indicate that the corrosion resistance of both types of cast irons is excellent and ductile iron is better than gray cast iron and the reduction in corrosion rates for both materials is related to barrier layer deposited on the surface which is more uniform on ductile iron surface. The electrochemical tests involve measurement of corrosion potential in open circuit using the same solutions for both materials and potentiostatic test is used to measure cathodic and anodic polarization in the above solutions. The test started from cathodic region to the anodic region with sweep rate of 10 m V/min to obtain the general behavior and measure the polarization parameters for both materials. The measured corrosion potentials of the open circuit in all solutions are more noble values for gray iron than that for ductile iron. Corrosion potentials on polarization measurements point out to the same indication but the ability to start and form barrier layer in ductile is better than in gray iron. Microstructure observations after the electrochemical tests indicate the presence of uniform layer on ductile surface and graphitization process is obtained on gray iron. ‫ﺍﻟﺨﻼﺼﺔ‬ ‫ﺮﺮض‬ ‫ﻟﺘﻌﺮ‬ ‫ﺔﺔ‬ ‫وﻧﺘﻴﺠﺔ‬ ‫ﺐﺐ‬ ‫اﻷﻧﺎﺑﻴﺐ‬ ‫ﺎﺎ‬ ‫أهﻤﻬﺎ‬ ‫ﻌﻌﺔ‬ ‫واﺳﻌ‬ ‫ﻴﻴﺔ‬ ‫هﻨﺪﺳﻴ‬ ‫ﺎﺎت‬ ‫ﺗﻄﺒﻴﻘﺎ‬ ‫ﻲﻲ‬ ‫ﻓﻲ‬ ‫ﺎﺎدي‬ ‫اﻟﺮﻣﺎ‬ ‫ﺮﺮ‬ ‫اﻟﺰهﺮ‬ ‫ﺪﺪ‬ ‫ﺣﺪﻳﺪ‬ ‫ﺘﺘﺨﺪم‬ ‫ﻳﺴﺘ‬ ‫أﻟﻤﻄﻴﻠﻲ‬ ‫اﻟﺰهﺮ‬ ‫ﺑﺤﺪﻳﺪ‬ ‫اﺳﺘﺒﺪل‬ ‫ﻟﺬﻟﻚ‬ ‫ﻟﻠﻔﺸﻞ‬ ‫اﻷﺣﻴﺎن‬ ‫ﻣﻌﻈﻢ‬ ‫ﻓﻲ‬ ‫اﻷﻧﺎﺑﻴﺐ‬. ‫ﺮﺮض‬ ‫ﻟﻐﺮ‬ ‫ﻮﻮﻋﻴﻦ‬ ‫اﻟﻨﻮ‬ ‫ﻼﻼ‬ ‫ﻟﻜﻼ‬ ‫ﺎﺎوي‬ ‫اﻟﻜﻴﻤﻴﺎ‬ ‫ﻞﻞ‬ ‫واﻟﺘﺤﻠﻴﻞ‬ ‫ﻪﻪ‬ ‫أﻟﻤﺠﻬﺮﻳﻪ‬ ‫ﺔﺔ‬ ‫اﻟﺒﻨﻴﺔ‬ ‫ﺎﺎﺋﺺ‬ ‫ﺧﺼﺎ‬ ‫ﺔﺔ‬ ‫دراﺳﺔ‬ ‫ﺚﺚ‬ ‫اﻟﺒﺤﺚ‬ ‫ﻤﻤﻦ‬ ‫ﺗﻀﻤ‬ ‫ﺗ‬ ‫ﻓﻲ‬ ‫اﺳﺘﺨﺪاﻣﻬﺎ‬ ‫اﻟﻤﻌﺪﺪﻧﻴﻦ‬ ‫ﻟﻜﻼﻼ‬ ‫واﻻﺳﺘﺘﻘﻄﺎب‬ ‫ﺑﺎﺎﻟﻐﻤﺮ‬ ‫اﻟﺘﺂآﻞﻞ‬ ‫اﺧﺘﺒﺎﺎرات‬ ‫ﺑﻌﺪﺪ‬ ‫أﻟﻤﺠﻬﺮﻳﻪﻪ‬ ‫اﻟﺒﻨﻴﺔ‬ ‫ﻧﺘﺎﺋﺞ‬ ‫ﺤﻠﻴﻞ‬ ‫ﺗﺮ‬ ‫ﻓﻲ‬ ‫ا‬ ‫اﻟﺼﻮدﻳﻮم‬ ‫آﻠﻮرﻳﺪ‬ ‫ﻣﻦ‬ ‫ﻣﺨﺘﻠﻔﺔ‬ ‫آﻴﺰ‬) 0.01 % ، 0.58 % ‫و‬ 3.5. (% ‫ﻟﺤﺪﻳﺪ‬ ‫اﻟﺘﺂآﻞ‬ ‫وﻣﻘﺎوﻣﺔ‬ ‫ﻣﻤﺘﺎزة‬ ‫اﻟﻤﻌﺪﻧﻴﻦ‬ ‫ﻟﻜﻼ‬ ‫اﻟﺘﺂآﻞ‬ ‫ﻣﻘﺎوﻣﺔ‬ ‫ﺑﺎن‬ ‫اﻟﻐﻤﺮ‬ ‫ﻧﺘﺎﺋﺞ‬ ‫ﺗﺸﻴﺮ‬ ‫أﻟﻤﻄﻴﻠﻲﻲ‬ ‫اﻟﺰهﺮﺮ‬ ‫ﺪﺪ‬ ‫اﻟﺤﺪﻳﺪ‬ ‫ﻦﻦ‬ ‫ﻣﻦ‬ ‫ﻞﻞ‬ ‫أﻓﻀﻞ‬ ‫ﺎﺎﺟﺰة‬ ‫اﻟﺤﺎ‬ ‫ﺔﺔ‬ ‫ﺑﺎﻟﻄﺒﻘﺔ‬ ‫ﺮﺮﺗﺒﻂ‬ ‫ﻣﺮ‬ ‫ﺪﺪﻧﻴﻦ‬ ‫اﻟﻤﻌﺪ‬ ‫ﻼﻼ‬ ‫آﻼ‬ ‫ﻲﻲ‬ ‫ﻓﻲ‬ ‫ﻞﻞ‬ ‫اﻟﺘﺂآﻞ‬ ‫ﺪﺪل‬ ‫ﻣﻌﺪ‬ ‫ﻲﻲ‬ ‫ﻓﻲ‬ ‫ﺎﺎﻗﺺ‬ ‫واﻟﺘﻨﺎ‬ ‫ﺎﺎدي‬ ‫اﻟﺮﻣﺎ‬ ‫أﻟﻤﻄﻴﻠﻲ‬ ‫اﻟﺤﺪﻳﺪ‬ ‫ﻓﻲ‬ ‫ﺗﺠﺎﻧﺴﺎ‬ ‫أآﺜﺮ‬ ‫ﺗﻜﻮن‬ ‫واﻟﺘﻲ‬ ‫اﻟﻤﺘﺮﺳﺒﺔ‬. Eng.&Tech.Vol.26,No.1,2008 Ductile and Gray Cast Irons Deterioration with Time in Various NaCl Salt Concentrations. ‫ﻟﻜﻼﻼ‬ ‫اﻟﻤﺤﺎﻟﻴﻞﻞ‬ ‫وﺑﻨﻨﻔﺲ‬ ‫اﻟﻤﻔﺘﻮﺣﺔﺔ‬ ‫اﻟﺪاﺋﺮة‬ ‫ﻓﻲ‬ ‫اﻟﺘﺂآﻞ‬ ‫ﺟﻬﺪ‬ ‫ﻗﻴﺎس‬ ‫ﺗﻀﻤﻨﺖ‬ ‫اﻟﻜﻬﺮوآﻴﻤﻴﺎوﻳﺔ‬ ‫اﻻﺧﺘﺒﺎرات‬ ‫ﻟﻘ‬ ‫ﺎﺎآﻦ‬ ‫اﻟﺴﺎ‬ ‫ﺎﺎد‬ ‫اﻟﻤﺠﻬﺎ‬ ‫ﺎﺎز‬ ‫ﺟﻬﺎ‬ ‫ﺘﺘﺨﺪام‬ ‫واﺳﺘ‬ ‫ﺪﺪﻧﻴﻦ‬ ‫اﻟﻤﻌﺪ‬ ‫ﻞﻞ‬ ‫اﻟﻤﺤﺎﻟﻴﻞ‬ ‫ﻨﻨﻔﺲ‬ ‫وﺑﻨ‬ ‫ﻮﻮدي‬ ‫واﻻﻧﻮ‬ ‫ﺎﺎﺛﻮدي‬ ‫اﻟﻜﺎ‬ ‫ﺘﺘﻘﻄﺎب‬ ‫اﻻﺳﺘ‬ ‫ﺎﺎس‬ ‫ﻴﺎ‬ ‫ﺪﺪل‬ ‫ﺑﻤﻌﺪ‬ ‫ﺔﺔ‬ ‫اﻻﻧﻮدﻳﺔ‬ ‫ﺔﺔ‬ ‫اﻟﻤﻨﻄﻘﺔ‬ ‫ﻰﻰ‬ ‫إﻟﻰ‬ ‫ﻞﻞ‬ ‫اﻟﺘﺂآﻞ‬ ‫ﺪﺪ‬ ‫ﺑﺠﻬﺪ‬ ‫ﺮﺮورا‬ ‫ﻣﺮ‬ ‫ﺔﺔ‬ ‫اﻟﻜﺎﺛﻮدﻳﺔ‬ ‫ﺔﺔ‬ ‫اﻟﻤﻨﻄﻘﺔ‬ ‫ﻦﻦ‬ ‫ﻣﻦ‬ ‫ﺎﺎر‬ ‫اﻻﺧﺘﺒﺎ‬ ‫ﺘﺘﻢ‬ ‫ﻳﺘ‬ ‫ﺚﺚ‬ ‫ﺣﻴﺚ‬ ‫ﻼﻼﻩ‬ ‫أﻋﻼ‬ ‫ﺘﺘﻘﻄﺎب‬ ‫اﺳﺘ‬) m V/min 10 (‫ﻼﻼ‬ ‫ﻟﻜﻼ‬ ‫ﺘﺘﻘﻄﺎب‬ ‫اﻻﺳﺘ‬ ‫ﺎﺎﻣﻼت‬ ‫ﻣﻌﺎ‬ ‫ﺎﺎس‬ ‫وﻗﻴﺎ‬ ‫ﺎﺎم‬ ‫اﻟﻌﺎ‬ ‫ﻠﻠﻮك‬ ‫اﻟﺴﻠ‬ ‫ﻰﻰ‬ ‫ﻋﻠﻰ‬ ‫ﻮﻮل‬ ‫ﻟﻠﺤﺼﻮ‬ ‫اﻟﻤﻌﺪﻧﻴﻦ‬. ‫ﺑﺎﺳﺘﺨ‬ ‫اﻟﻤﻘﺎﺳﺔ‬ ‫اﻟﺘﺂآﻞ‬ ‫ﺟﻬﻮد‬ ‫آﺎﻧﺖﺖ‬ ‫اﻟﺮﻣﺎﺎدي‬ ‫اﻟﺰهﺮ‬ ‫ﻟﺤﺪﻳﺪ‬ ‫اﻟﻤﺤﺎﻟﻴﻞ‬ ‫ﺟﻤﻴﻊ‬ ‫ﻓﻲ‬ ‫اﻟﻤﻔﺘﻮﺣﺔ‬ ‫ﺑﺎﻟﺪاﺋﺮة‬ ‫ﺪام‬ ‫أﻟﻤﻄﻴﻠﻲﻲ‬ ‫اﻟﺰهﺮﺮ‬ ‫ﻟﺤﺪﻳﺪﺪ‬ ‫اﻟﻤﻘﺎﺳﺔﺔ‬ ‫ﺗﻠﻚﻚ‬ ‫ﻣﻦﻦ‬ ‫ﻧﺒﺒﻼ‬ ‫أآﺜﺮ‬ ‫ﻗﻴﻤﻬﺎ‬. ‫اﻟﻨﺘﻴﺠﺔﺔ‬ ‫ﻧﻔﺲﺲ‬ ‫إﻟﻰﻰ‬ ‫اﻻﺳﺘﺘﻘﻄﺎب‬ ‫ﻧﺘﺎﺎﺋﺞ‬ ‫وﺗﺸﻴﻴﺮ‬ ‫أﻟﻤﻄﻴﻠﻲ‬ ‫اﻟﺰهﺮ‬ ‫ﺣﺪﻳﺪ‬ ‫ﻓﻲ‬ ‫أﻓﻀﻞ‬ ‫وﺑﺪﺋﻬﺎ‬ ‫اﻟﺤﺎﺟﺰة‬ ‫اﻟﻄﺒﻘﺔ‬ ‫ﺗﻜﻮن‬ ‫ﻗﺎﺑﻠﻴﺔ‬ ‫وﻟﻜﻦ‬. ‫ا‬ ‫ﻼﻼل‬ ‫ﺧﻼ‬ ‫ﻪﻪ‬ ‫أﻟﻤﺠﻬﺮﻳﻪ‬ ‫ﺔﺔ‬ ‫اﻟﺒﻨﻴﺔ‬ ‫ﺎﺎﺋﺞ‬ ‫ﻧﺘﺎ‬ ‫ﻄﻄﺢ‬ ‫ﺳﻄ‬ ‫ﻰﻰ‬ ‫ﻋﻠﻰ‬ ‫ﺔﺔ‬ ‫ﻣﺘﺠﺎﻧﺴﺔ‬ ‫ﺎﺎﺟﺰة‬ ‫ﺣﺎ‬ ‫ﻪﻪ‬ ‫ﻃﺒﻘﻪ‬ ‫ﻮﻮل‬ ‫ﺣﺼﻮ‬ ‫ﺖﺖ‬ ‫اﺛﺒﺘﺖ‬ ‫ﻞﻞ‬ ‫ﻟﺘﺂآﻞ‬ ‫ﺪﺪ‬ ‫اﻟﺤﺪﻳﺪ‬ ‫اﻟﺮﻣﺎدي‬ ‫اﻟﺰهﺮ‬ ‫ﺑﺤﺪﻳﺪ‬ ‫ﻓﺘﺔ‬ ‫اﻟﻜﺮ‬ ‫ﻋﻤﻠﻴﺔ‬ ‫وﺣﺼﻮل‬ ‫أﻟﻤﻄﻴﻠﻲ‬ .