This paper deals with the issue of using moulding sands with a new two-component binder: furfuryl-resole resin – PCL polycaprolactone for the production of ductile iron heavy castings. The previous laboratory studies showed the possibility of using biodegradable materials as binders or parts of binders’ compositions for foundry moulding and core sands. The research proved that addition of new biodegradable PCL in the amount of 5% to the furfuryl-resole resin does not cause significant changes in moulding sand’s properties. The article presents research related to the production of ductile iron castings with the use of moulds with a modified composition, i.e. sands with furfuryl resole resin with and without PCL. Mechanical properties and microstructure of the casting surface layer at the metal/ mould interface are presented. The obtained test results indicate that the use of a biodegradable additive for making foundry moulds from moulding sand with a two-component binder does not deteriorate the properties of ductile iron castings.

Two different complexing agents, namely citric acid and gelatin, were used for gel-combustion synthesis of yttria stabilized zirconia. The influence of synthesis conditions on properties of powders and sintered bodies was studied by X-ray Diffraction Analysis (XRD), Scanning Electron Microscope (SEM) and helium pycnometer measurements.

The behavioural model of a graphene field-effect transistor (GFET) is proposed. In this approach the GFET element is treated as a “black box” with only external terminals available and without considering the physical phenomena directly. The presented circuit model was constructed to reflect steady-state characteristics taking also into account GFET capacitances. The authors’ model is defined by a relatively small number of equations which are not nested and all the parameters can be easily extracted. It was demonstrated that the proposed model allows to simulate the steady-state characteristics with the accuracy approximately as high as in the case of the physical model. The presented compact GFET model can be used for circuit or system-level simulations in the future.