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Prędkość opadania ziaren piasków rzecznych

100%

Popek Z.

tom 13

nr 1[28]

Investigation of Some Moulding Properties of a Nigerian Clay-Bonded Sand

63%

Oke A. O. , Omidiji B. V.

2016

tom Vol. 16, iss. 3

71--76

Moulding properties of Isasa River Sand bonded with Ipetumodu clay (Ife-North Local Government Area, Osun State, Nigeria) were investigated. American Foundry men Society (AFS) standard cylindrical specimens 50mm diameter and 50mm in height were prepared from various sand and clay ratios (between 18% and 32%) with 15% water content. The stress-strain curves were generated from a universal strength testing machine. A flow factor was calculated from the inclination of the falling slope beyond the maximum compressive strength. The result shows that the flowability of the samples increases from 18% to 26% clay content, its maximum value was attained at 26% and then it decreases from 30% to 32% clay content. The green compressive strength, dry compressive strength and air permeability values obtained from the mould samples were in accordance with standard values used in foundry practice. The x-ray diffraction test shows that the sand contains silicon oxide (SiO2), Aluminium oxide (Al2O3), and Aluminium silicate (Al6Si2O13). The mould samples were heated to a temperature of 1200 oC to determine the sintering temperature; fussion did not take place at this temperature. The results showed that the sand and clay mixture can be used to cast ferrous and non-ferrous alloys.

Charakterystyka ruchu wleczonego rumowiska piaszczystego w małym cieku nizinnym

51%

Popek Z.

Acta Scientiarum Polonorum. Formatio Circumiectus

2010

tom 09

nr 3

W pracy przedstawiono wyniki badań laboratoryjnych i terenowych dotyczących charakterystyki ruchu piaszczystego rumowiska wleczonego w warunkach przepływu ustalonego i nieustalonego. Badania laboratoryjne naprężeń granicznych wykonano w korycie hydraulicznym z płaskim dnem ruchomym, uformowanym z piasków o zróżnicowanej charakterystyce uziarnienia. Charakterystykę zmienności natężenia wleczenia oparto na wynikach badań terenowych, wykonanych w korycie nizinnej rzeki Zagożdżonki. W badaniach tych wykorzystano łapacz rumowiska wyposażony w aparaturę do ciągłego pomiaru intensywności wleczenia.

In the paper are presented the most important results of laboratory and field investigations concerning of sandy bedload characteristics in aspects of initiation of motion and variability of bedload discharge in small lowland river, i.e. in steady and unsteady flow conditions. Investigations of critical shear stress have been carried out in laboratory flume with flat movable bottom formed by sands with different grain-size distributions. The characteristics of bedload discharge variability are presented on the basis of field investigation results conducted in the Zagożdżonka riverbed. The bedload trap provided with devices for continuous measuring and data recording was used in field investigations.