W osadach rzeki Raby na południu Polski odkryto pnie czarnych dębów wraz z dobrze zachowanymi chrząszczami o nazwie kozioróg dębosz. Ślady życia tych owadów w kopalnym lub częściowo kopalnym drewnie dostarczają cennych informacji o środowisku i klimacie.
An important discovery has been made at Targowisko in southern Poland, where ancient bog-oak trunks with well-preserved remains of great capricorn beetle galleries were found in old sediments of the Raba River. Traces of these insects in fossilized or partially fossilized wood provide valuable information, helping us interpret the ancient environment and climate.
In the present work, different Cu-alloyed model ductile irons with ferritic (0%Cu-0.09%Mn), mixed ferritic-pearlitic (0.38%Cu-0.40%Mn) and pearlitic (0.69%Cu-0.63%Mn) microstructure were produced and analyzed in terms of their electrochemical corrosion behavior in a 3.5wt.%NaCl aqueous solution containing naturally dissolved oxygen at room temperature (25°C). The remaining elements such as Si and Mg were kept at balanced levels in an attempt to minimize variations in graphite size and distribution among different samples. The corrosion resistance was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization. Microstructure analysis of the cast alloys confirmed similarity in the graphite morphology among the different cast samples and the expected variations in the metallic matrix. In the absence of passivation, it was found that the addition of copper led to an increase in corrosion resistance, which could be attested by higher values polarization resistance and corrosion potential.