The paper presents the results of preliminary research on the use of silica sands with hydrated sodium silicate 1.5% wt. of binder for the performance of eco-friendly casting cores in hot-box technology. To evaluate the feasibility of high quality casting cores performed by the use of this method, the tests were made with the use of a semiautomatic core shooter using the following operating parameters: initial shooting pressure of 6 bar, shot time 4 s and 2 s, core-box temperature 200, 250 and 300 °C and core heating time 30, 60, 90 and 150 s. Matrixes of the moulding sands were two types of high-silica sand: fine and medium. Moulding sand binder was a commercial, unmodified hydrated sodium silicate having a molar module SiO2/Na2O of 2.5. In one shot of a core-shooter were made three longitudinal samples (cores) with a total volume of about 2.8 dm3. The samples thus obtained were subjected to an assessment of the effect of shooting parameters, i.e. shooting time, temperature and heating time, using the criteria: core-box fill rate, bending strength (RgU), apparent density and surface quality after hardening. The results of the trials on the use of sodium silicate moluding sands made it possible to further refine the conditions of next research into the improvement of inorganic warm-box/hot-box technology aimed at: reduction of heating temperature and shot time. It was found that the performance of the cores depends on the efficiency of the venting system, shooting time, filling level of a shooting chamber and grains of the silica matrix used.

The paper presents results of bend tests at elevated temperatures of aluminium alloy EN AC-44200 (AlSi12) based composite materials

reinforced with aluminium oxide particles. The examined materials were manufactured by squeeze casting. Preforms made of Al2O3

particles, with volumetric fraction 10, 20, 30 and 40 vol.% of particles joined with sodium silicate bridges were used as reinforcement. The

preforms were characterised by open porosity ensuring proper infiltration with the EN AC-44200 (AlSi12) liquid alloy. The largest

bending strength was found for the materials containing 40 vol.% of reinforcing ceramic particles, tested at ambient temperature. At

increased test temperature, bending strength Rg of composites decreased in average by 30 to 50 MPa per 100°C of temperature increase.

Temperature increase did not significantly affect cracking of the materials. Cracks propagated mainly along the interfaces particle/matrix,

with no effect of the particles falling-out from fracture surfaces. Direction of cracking can be affected by a small number of

agglomerations of particles or of non-reacted binder. In the composites, the particles strongly restrict plastic deformation of the alloy,

which leads to creation of brittle fractures. At elevated temperatures, however mainly at 200 and 300°C, larger numbers of broken,

fragmented particles was observed in the vicinity of cracks. Fragmentation of particles occurred mainly at tensioned side of the bended

specimens, in the materials with smaller fraction of Al2O3 reinforcement, i.e. 10 and 20 vol.%.

The paper presents results of Ti-addition to High Chromium Cast Iron (HCCI) on the structure and selected mechanical properties. For this

study casted two sets of cylinders with dimensions ø20 mm, ø15 mm x 250 mm, for the High Chromium Cast Iron (HCCI) and with the

4% by mass Ti-addition. Melts were performed in the induction furnace crucible capacity of 15 kg. During the heats the cup with installed

S type thermocouple was poured to record the cooling curves. The cylinders were subjected to the static bending strength test. Samples for

the test microstructure and Rockwell hardness were cut from the cylinders. The study shows that the addition of titanium had an impact on

the structure and thus the properties of High Chromium Cast Iron (HCCI). In subsequent studies, through an appropriate choice of

chemical composition and proper process control, it is planned to obtain in the structure the titanium carbides TiC and chromium carbides

with type (Cr, Fe)7C3.

The results of investigations of the influence of the matrix grain sizes on properties of cores made by the blowing method are presented in

the hereby paper. Five kinds of matrices, differing in grain size compositions, determined by the laser diffraction method in the Analysette

22NanoTec device, were applied in investigations. Individual kinds of matrices were used for making core sands in the Cordis technology.

From these sands the shaped elements, for determining the apparent density of compacted sands and their bending strength, were made by

the blowing method. The shaped elements (cores) were made at shooting pressures being 3, 4 and 5 atn. The bending strength of samples

were determined directly after their preparation and after the storing time of 1 hour.

The development of the construction industry and the growing ecological awareness of society encourages us search for new solutions to improve building materials. Therefore, an attempt was made to improve building gypsum by modifying it with the addition of polyoxymethylene (POM). Polymer grains, with a particle size below and above 2 mm, were added to the samples in the amount of 1% and 2% relative to gypsum. The work contains the results of bending and compressive strength tests of prepared gypsum beams. It was shown that the compressive strength increased by 7% and the bending strength increased by 31% when compared to the reference test without the addition of polymer. All the obtained gypsum composites were characterized by a growth of strength. The best results were obtained for the sample containing gypsum composite modified with polymer in the amount of 1% and with a diameter of grains below 2 mm.

The aim of the paper was to assess the bending strength of steel plate - concrete composite members, based on an experimental study performed by the authors together with theoretical and numerical analyses. The values of the mechanical parameters of the materials the beams were made from were adopted on the basis of the tests results. The proposed solutions have been verified by experiment. For this purpose the results of tests performed by the authors and other researchers have been used. The former ones are original, and the way of their presentation makes them applicable by other researchers. Following the results it can be stated that with respect to bending strengths from the experimental study the results obtained from the theoretical analysis are underestimated 6,6 % on average. The results based on the numerical analysis, on the other hand, are overestimated by - 7,5 % on average. The results of the theoretical and numerical analyses indicate that the interface slip between the steel plate and concrete part affect the bending strength of steel plate-concrete composite beams only slightly (about 2% on average).