EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS

In this paper there is presented the corrosion behavior of the cast magnesium alloys as cast state, after heat and laser treatment. Pitting corrosion resistance of the analyzed alloys was carried out using the potentiodynamic electrochemical method (direct current), based on a anodic polarization curve. On the basis of the achieved anodic polarization curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electrochemical corrosion process of the investigated alloys: value of the corrosion potential Ecorr (mV), polarization resistance RP (kohm.cm2), corrosion current density icorr (10-6A/cm2), corrosion rate Vcorr (mm/year) as well the mass loss Vc (g/m2<)

Assessment of water quality in the Wiśniówka River considering circulation of organic matter

Variation of hydrochemical conditions, with special reference to adequacy of waters as fish habitats, was traced based on selected hydrochemical parameters obtained during the studies conducted from February 2013 till February 2014 year. The results were compared with earlier studies. The sources of organic pollution were identified, and the effects of biogenic substances on the biomass, as well as the self-purification capability of the river, were assessed. The total suspension exceeded the requirements for waters which are habitats of both salmonid and cyprinid fishes. Compared to the previous years, the load of organic and inorganic matter in the waters of Wiśniówka River increased; this may have resulted from external inflow, neighbourhood of the hatchery but also, to a small extent, from internal supply. The high availability of nitrogen-(NNH_4+; N-NO_2-, N-NO_3-) and phosphorus-(total phosphorus; P-PO_4 ^3-) based biogenic (substances favoured the biomass production, thus contributing to the increase in organic matter load in the river

The effect of long-term impact of elevated temperature on changes in the microstructure of inconel 740H alloy

This paper presents the results of investigations on microstructure changes after the long-term impact of temperature. The microstructure investigations were carried out by light microscopy and scanning electron microscopy. The qualitative and quantitative identification of the existing precipitates was carried out using X-ray phase composition analysis. The effect of elevated temperature on precipitation processes of test material were described. The obtained results of investigations form part of the material characteristics of new-generation alloys, which can be indirectly associated with the stability of functional properties under the simultaneous effect of high temperature and stress

Investigations of resistance to abrasive wear of selected engineering polymers

W artykule przedstawiono wyniki tribologicznych badań porównawczych odporności na zużywanie ścierne wybranych polimerów inżynieryjnych: PA6, PEEK, PEI, PET, PSU. Do badań wykorzystano stanowisko badawcze Tester T-07. Badania prowadzono w obecności luźnego ścierniwa, którym był elektrokorund F90, przy zachowaniu jednakowych warunków tarcia dla wszystkich badanych materiałów. W celu wyjaśnienia przyczyn różnej odporności na zużycie ścierne badanych polimerów przeprowadzono badania mikrotwardości ich powierzchni trących przed i po procesie ścierania oraz dokonano próby powiązania odporności na zużywanie ścierne poszczególnych polimerów z ich podstawowymi własnościami wytrzymałościowymi.The paper presents the results of comparative studies of abrasive wear resistance of selected engineering polymers: PA6, PEEK, PEI, PET, PSU. The study used a research position Tester T-07. The research testing stand Tester T-07 was used for a study. The study was conducted in the presence of loose abrasive, which was the F90 corundum, while maintaining the same friction conditions for all tested materials. In order to clarify the causes of various abrasive wear resistance of investigated polymers, the testing of microhardness of friction surfaces before and after abrasion was conducted, and the attempt to link abrasive wear resistance of various polymers with their fundamental strength properties was also done

Zooplankton structure in midfield ponds in north-west part of Poland

Midfield ponds are characterised by a rich biodiversity. A significant role in the function of these specific water ecosystems is played by resident zooplankton, which is a valuable component of numerous trophic networks. The aim of the present work was to study the taxonomic composition, concentration and biomass of zooplankton in two midfield ponds situated in the area of one commune, but geomorphologically different from each other. Experiments were conducted in the summer seasons (June-August) in the years 2011-2013 in two ponds. The presence of 55 zooplankton taxa, commonly present in such water reservoirs in Poland, was observed. Most species were determined. The largest group comprised rotifers (Rotifera) - 35 taxa. The crustacean zooplankton was less diverse: 11 taxa of copepods (Copepoda) and 9 taxa of water fleas (Cladocera) were found. The reservoir in Stare Czarnowo exhibited a greater number of taxa, where as many as 40 taxa were observed. However, 35 taxa belonging to various zooplankton groups were found in the pond in Żelisławiec. The relatively low Jaccard index confirmed small qualitative similarity between the studied ponds. Both reservoirs contained representatives of species defined as characteristic for oligosaprobic and mesosaprobic waters, which may indicate small contamination of the two ponds and the occurrence of a large amount of organic matter undergoing decomposition