Measurement of low corrosion rate of coronary stents-made of 316L and 317L stainless steel / 生物医学工程学杂志

Electrochemical constant current linear polarization and atomic absorption spectroscopy were used to measure the corrosion rate of coronary stents made of 316L and 317L stainless steel in 30 degrees C Tyrode's solution. The results indicated that the corrosion rate of 316L and 317L stainless steel was 21 X 10(-3) microm/a, 9.8 X 10(-3) microm/a and 0.8 X 10(-3) m/a, 0.6 X 10(-3) microm/a, respectively. All corrosion rates were lower than the medical materials corrosion rate criteria, i.e. 0.25 microm/a. Moreover the corrosion resistance of 317L stainless steel was much higher than that of 316L stainless steel. The results from atomic absorption spectroscopy may correctly reflect the quantity of releasing metal ions in the solution.

Study on electrochemical mechanism of coronary stent used austenitic stainless steel in flowing artificial body fluid / 生物医学工程学杂志

The electrochemical mechanism of austenitic stainless steel (SUS316L and SUS317L) coronary stents in flowing artificial body fluid has been investigated with electrochemical technologies. The results indicated that the flowing medium coursed the samples' pitting potential Eb shift negatively, increased the pitting corrosion sensitivity, accelerated its anodic dissolution, but had little effects on repassivated potential. The flowing environment had great effects on cathodic process. The oxygen reaction on the samples' surface became faster as the cathodic process was not controlled by oxygen diffusion but by mixed diffusion and electrochemical process. With the increase of velocity of solution, the pitting corrosion becomes liable to occur under this circumstance.

Corrosion rate measurements of biomedical TiNi shape memory alloy and cobalt alloys / 生物医学工程学杂志

The corrosion rates of TiNi, CoCrNiW and CoCrNiMo were measured in Tyrode's solution with potentiodynamic linear polarization, fore-point weak polarization, Cao Chunan weak polarization, transient linear polarization and atomic absorption spectroscopy. Results indicated that corrosion rates of these three alloys were very low due to their excellent corrosion resistance and the corrosion resistance of CoCrNiMo was the best. Corrosion rates of TiNi, CoCrNiW and CoCrNiMo were 0.691, 0.0595, 0.0490 micron/a and 0.0528, 0.0383, 0.0387 micron/a, respectively. The results measured by the first three methods were about ten times of those by the latter two methods, this was related to the applicability of each method and the alloy surface state. Transient linear polarization technique can determine low corrosion rate conveniently and quickly. Atomic absorption spectroscopy method, determining directly the concentration of ion in solution, and thus provide reference for material biocompatibility. And these two methods are properly used in measuring corrosion rates for biomedical materials.