The paper discusses the reasons for the current trend of substituting ductile iron castings by aluminum alloys castings. However, it has been shown that ductile iron is superior to aluminum alloys in many applications. In particular it has been demonstrated that is possible to produce thin wall wheel rim made of ductile iron without the development of chills, cold laps or misruns. In addition it has been shown that thin wall wheel rim made of ductile iron can have the same weight, and better mechanical properties, than their substitutes made of aluminum alloys.

The paper presents results of metallographic examination of faults occurring in the course of founding thin-walled cast-iron castings in

furan resin sand molds. A non-conformance of the scab type was Observed on surface of the casting as well as sand buckles and cold

shots. Studied the chemical composition by means of a scanning electron microscope in a region of casting defects: microanalysis point

and microanalysis surface. Around the observed defects discloses high concentration of oxides of iron, manganese and silicon.

A computer simulation of the casting process has been carried out with the objective to establish the cause of occurrence of cold shots on

casting surface. The simulation was carried out with the use of NovaFlow & Solid program. We analyzed the flowing metal in the mold

cavity. The main reason for the occurrence of casting defects on the surface of the casting was gating system, which caused turbulent flow

of metal with a distinctive splash stream of liquid alloy.

The paper is a presentation of a study on issues concerning degradation of protective paint coat having an adverse impact on aesthetic

qualities of thin-walled cast-iron castings fabricated in furan resin sand. Microscopic examination and microanalyses of chemistry

indicated that under the coat of paint covering the surface of a thin-walled casting, layers of oxides could be found presence of which can

be most probably attributed to careless cleaning of the casting surface before the paint application process, as well as corrosion pits

evidencing existence of damp residues under the paint layers contributing to creation of corrosion micro-cells

The excellent property combination of thin wall ductile iron castings (TWDI), including thin wall alloyed cast iron (e.g. austenitic TWDI) has opened new horizons for cast iron to replace steel castings and forgings in many engineering applications with considerable cost benefits. TWDI is considered as a potential material for the preparation of light castings with good mechanical and utility properties, the cost of which is relatively low. In this study, unalloyed and high Ni-alloyed (25% Ni) spheroidal graphite cast iron, with an austenitic metallic matrix were investigated. The research was conducted for thin-walled iron castings with 2, 3 and 5mm wall thickness, using different mould temperature (20°C, and 160°C) to achieve various cooling rates. The metallographic examinations i.e. characteristic of graphite nodules, metallic matrix, and primary grains of austenite dendrites (in high-nickel NTWDI) and mechanical properties were investigated. The study shows that homogeneity of the casting structure of thin-walled castings varies when changing the wall thickness and mould temperature. Finally, mechanical properties of thin-walled ductile iron castings with ferritic-pearlitic and austenitic metallic matrix have been shown.

The flow of the investigated fluid in a measuring system of a rheometer – a capillary or a slit between rotating parts – may be disturbed by anisotropic behavior of the fluid near the wall. This phenomenon, so-called wall slip, often takes place in concentrated suspensions and solutions of linear polymers and introduces experimental errors to measurement results. There are methods of correction of these errors in the case of capillary and coaxial cylinders measuring systems. In the cone and plate system the correction seems to be more difficult because the width of the gap between cone and plate changes along the radius and thus the influence of the wall slip on the shear stress varies along the radius in an unpredictable and complicated manner. This dependency of the shear stress on the distance from the axis underlies the presented method of correction of experimental results obtained in the cone and plate system. The method requires several series of measurements of shear stress vs. shear rate performed using one measuring set, at various degrees of filling the gap.

The authors present a numerical study of a start-up of a boiler with a thick-walled element subjected to thermomechanical loading. The significance of calculations of real heat transfer coefficients has been demonstrated. Fluid dynamics, mechanical transient thermal and static structural calculations have been conducted in both separate and coupled modes. Strain-stress analyses prove that the effect of the heat transfer coefficient changing in time and place in comparison with a constant one as recommended by standards is the key factor of fatigue calculations.

The aim of this study was to determine the hardness and reduced modulus of elasticity of juvenile wood of Scots pine (Pinus sylvestris L.) using the nanoindentation method, and then to compare the results obtained with those of mature wood. The hardness of juvenile pine wood determined by means of the nanoindentation method was 0.444 GPa while for mature wood it was 0.474 GPa. Statistically significant differences between the values were found. The reduced modulus of elasticity in juvenile wood was 14.0 GPa and 16.4 GPa in mature wood. Thus, the hardness values obtained were about 7% higher, while the modulus of elasticity was 17% higher in mature wood. All determinations were made in the S2-layer of the secondary cell wall.

In the article, the authors presented the results of microbiological air quality studies in selected buildings with additional thermal insulation applied from the inside using a silicate and lime system, as well as the results of a survey study concerning the comfort of use of said buildings. The microbiological air quality studies, conducted in buildings immediately prior to and after the application of additional thermal insulation using silicate and lime sheets, demonstrated a significant decrease in the number of mould spores in interior spaces. This was also reflected in the results of a survey study. The survey study was conducted with users of public and commercial buildings and municipal housing buildings in Krakow. Thanks to the additional insulation applied from inside using the silicate and lime system, all of the utilitarian parameters of internal spaces had improved. The most significant changes concerned parameters like comfort of use, the aesthetic of the spaces and breathing comfort. According to experts, the silicate and lime system was also rated highly in terms of the analysed parameters.