Study Of Electrochemical Corrosion Behaviors Of Copper, Zinc And Their Alloy

Copper has been applied in the field of intrauterine device(IUD) for nearly 50 years. Znic and znic alloys also have potential applications in the field of IUD. They all make use of metal ions which are released by corrosion of metals in body fluid to enhance the contraceptive effect or achieve other effects. Therefore, their corrosion is very important for the development of novel IUDs. In this paper, the corrosion behavior of three types of copper particles in different sizes, and three bulk metals of pure copper, pure zinc and brass in distilled water, normal saline and simulated uterine solution, was separately studied by electrochemical methods including testing their polarization curves, cyclic voltommograms and electrochemical impedance spectra.For three copper particles with different sizes including copper microparticles, copper sub-microparticles and copper nanoparticles, the results show that their corrosion behaviors in three solutions are different. In distilled water, copper microparticles are the most prone to corrode and copper nanoparticles are the most difficult to corrode; In normal saline, copper nanoparticles are the most prone to corrode and copper sub-microparticles are the most difficult to corrode; In simulated uterine solution, copper nanoparticles are the most prone to corrode and copper microparticles are the most difficult to corrode. Besides, in any solution, the corrosion processes of copper microparticles and copper sub-microparticles are controlled by both electrochemical step and diffusion step, while the corrosion process of copper nanoparticles is mainly controlled by electrochemical step. Therefore, under the combined influence of diffusion of ions and absorption of products, the corrosion rate of copper nanoparticles is the largest in distilled water and normal saline, while the corrosion rate of copper sub-microparticles is the largest in simulated uterine solution.For the bulk metals including pure copper, pure zinc and brass, the results show that all of three bulk metals are the most prone to corrode in normal saline and the most difficult to corrode in distilled water. In distilled water, pure copper and pure znic appear passivation in a certain degree because of the formation of oxide film on the surface, but it is not very obvious for brass. In normal saline, phenomena of the pitting corrosion can be observed for three metals, while dezincification can be observed for brass. In simulated uterine solution, the corrosion rate of each metal is slower than in normal saline, which can be attributed to the adsorption of complexes and protein. In addition, the sensitivity of dezincification for brass successively increases in distilled water, normal saline and simulated uterine solution.The above results will be beneficial in the future for using different copper particles, or zinc and zinc alloys into IUD materials system. It will also provide a good reference and basis for developing new IUDs with less side effects and high efficiency.