Hot Water Efficiently Aluminum Alloy Sacrificial Developed

With the development of society and the increase of its population, the absence of fresh water has aroused the whole world attention. China belongs to the countries of deficiency of water, especially its cities along the sea. According to data, water for industry, 80% of which is water for cooling, covers 80% of water for the city. To save fresh water, people want to replace freshwater with seawater for cooling in industry. However, in seawater cooling system, the corrosion of the outlet of heat-exchanger and its following steel implements, whose temperatures are about 50C or even up to 55 C, is very serious. Thus it is important to solve the problem. Application of sacrificial anode is one effective method to prevent steel equipment in seawater from corrosion, but at 50C, the current efficiency of the types of sacrificial anodes in common use is much lower. So it is significant to study and make one new type of sacrificial anode, which can apply at 50C. Twenty-eight types of sacrificial anodes were made and according to the standard of GB 4950-85, their potentials were tested, their current efficiencies were calculated and their corrosion products?falling off and corrosion uniformity were observed. It was shown that the corrosion uniformity was the most important factor of affecting the performance of sacrificial anodes at high temperature. Three samples?anodic polarization curves were drawn. It showed that the polarization degree of sacrificial anodes was great when anodic polarization current density was 0.2 or 0.4 mA/cm2, that the potential would keep stable in spite of increasing polarization current density, and that with the temperature rising, the degree is higher and higher so that the anodes are unfavorable to offer enough protect potential. Mathematical grey interrelation analysis method was used to study the correlation between Al anode elements and working potential, current efficiency, corrosion uniformity. It showed that Mg was the good element to increase corrosion uniformity of sacrificial anodes at 20C and 40C, and Ga good at 60(2. According to the conclusion of grey interrelation analysis, it was proposed that Al-Zn-In-Ga-Mg is good at 20 C and 40 C, and Al-Zn-In-Ga good at 60 C.