Effect Of Dissolved Oxygen Concentration On The Corrosion Behavior Of CuCrZr Alloy

At the forefront of the energy challenge is the necessity of operating power plants for as long as possible in a safe and cost-effective manner.Corrosion is one of the main factors that determine the operational lifetime of any type of thermal power station.The ITER(International Thermonuclear Experimental Reactor)in its design,includes coolant water interface with the copper alloy CuCrZr exposed to high water velocities.For reasons of structural integrity,the formation of activated corrosion products,and the need for water purification,it is important to assess the erosion corrosion susceptibility of CuCrZr.Literature shows that various factors like pH,dissolved oxygen,resistivity,corrosion potential and temperature contribute in corrosion rate of copper and its alloys in water.A fair amount of work has already been performed on the corrosion of copper but the work on the effect of dissolved oxygen on the corrosion of copper alloys is very limited hence effect of dissolved oxygen on the corrosion of copper alloys should be explored.In this thesis,corrosion experiments on CuCrZr alloy were performed in continuous high temperature and high pressure corrosion test bench.The experiment was performed at three different dissolved oxygen concentrations of 10 ppb(parts per billion),250 ppb and 1500 ppb.During the experiment the cooling water temperature was 150? and flow rate was maintained at 1 ml/min.Mass loss methodology was used to find the corrosion rate.The microstructure and chemical composition of the corrosion products were observed by SEM,EDS,XPS and other instruments.Based on Corrosion process of CuCrZr alloy in cooling water,the influence of dissolved oxygen concentration on the corrosion of CuCrZr alloy has been discussed.The results show that at the mass loss follows the laws m=0.048t0.366,m=0.085t0 386 and m=0.041t0.458 for the dissolved oxygen concentrations of 10ppb,250ppb and 1500ppb respectively.The oxide scales gradually formed on the specimens consisted of CuO and Cu2O and became more and more compact with time.At 1500 h,the thickness of the corrosion product layer under the three dissolved oxygen concentrations of 10ppb,250ppb,and 1500ppb was 0.75?m,2.1?m and 2.3?m respectively and it increased with the corrosion time.This research thesis discusses the importance of corrosion and its effects on industries.Then it explains historical background of ITER and explains the need of fusion reactor.This paper also explains the current problems and future scope of ITER as well.It also sheds some light on the need to investigate the effect of dissolved oxygen concentration on the corrosion behavior of CuCrZr alloy because corrosion is highly dependent on oxygen concentration.It also highlights the work that has already been performed on the related topics by other researchers.