Papers by Author: Stanislav Lasek

Abstract: The contribution is aimed at corrosion propertied and wettability of basic graded of stainless steel commonly used in medicine as a standard for construction of instruments and other applications. Samples of AISI 304 (1.4301) steel were chemical passivated by nitric acid and tested for corrosion resistance in environment of sodium hypochlorite (NaClO), which is commonly used for basic disinfection of surfaces or devices in hospital facilities. It was found that chemical passivation of stainless steel surface increases its corrosion resistance and lower corrosion rate. Passivation layer also shows more polarization resistance. The wettability of passivated surface was measured by sessile drop method. Wettability itself determinates effectivity of disinfection process as the surfaces with lower contact angle may be cleaned and disinfected with more efficiency. It was proofed that chemical passivation increases wettability by lowering contact angle of treated surface.

Abstract: This paper is focused on prediction of nitinol stents lifetime. Stents have been tested before and after mechanical loading. Corrosion tests of mechanically loaded specimens indicated impairment of corrosion resistance and SEM observation confirmed presence of micro cracks in surface oxide layer created during heat treatment. Electrochemical impedance spectroscopy and potentiodynamic polarization in physiological solution was used for these particular experiments. Corrosion rate and other parameters have been used for calculation of released nickel ions weight and prediction of application lifetime.

Abstract: Three types of corrosion attack frequently suffered by type Cr18Ni10 stainless steel in the heat-affected zone of welds were studied – knife-line, fusion-line, and fissure corrosion. Possible mechanisms and selected preventative measures were discussed in the light of microstructural findings.