Corrosion has become an increasingly significant design consideration when components and equipments are exposed to marine environments. The predominant factors affecting corrosion are pH value, NaCl concentration of sea water and exposed time of the equipment. High Carbon steel and its alloy are widely used in services such as oil rigs and marine industries due to their high strength. But when these are exposed to sea environments their strength gets reduced due to corrosion. For Tensile strength Improvement of High carbon steel, tin bronze coating is applied. The corrosion behavior of Tin Bronze alloy (C903) is evaluated by conducting test in NaCl solution at different chloride ion concentrations, pH value, and solution flow rate and exposure time. An attempt is also made to develop an empirical relationship to predict the corrosion rate of Tin Bronze alloy and tensile strength of C903 coating on High carbon steel. Experiments are carried out when solution is at steady state and dynamic state, for estimating corrosion rate and tensile strength. Three factors, five level, central composite rotatable design matrix is used to minimize the number of experimental conditions for optimizing the values. The empirical relation is developed by using Response Surface method. The developed relationship can be effectively used to predict the pitting corrosion rate of Tin Bronze alloy and tensile strength of tin bronze coating on High carbon steel at 95% Confidence level. The significance of each regressor (factor) in this model has been estimated and surface response is drawn using 3D mapping in MINITAB Software. This research work proves a better corrosion resistance of Tin Bronze alloy at the alkaline solution than the acidic and the neutral solutions, moreover, low corrosion rate is found at low concentrated .
Keywords : Tin Bronze, Chloride ion concentration, Corrosion rate, Optimization, Response surface Method