In this paper, the influence of bentonite (BNT) on rheological properties, linear shrinkage, hardness, and structure of polyethylene wax (PE-wax) used in the lost-wax casting process are studied. Experiments were conducted with PE-wax with different contents of bentonite (from 0.1 to 5 wt.%). The structural changes of modified polyethylene wax were evaluated using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The addition of bentonite in a concentration range between 0 and 0.8 wt.% into PE-wax caused a decrease of the linear shrinkage and the hardness of PE-wax/BNT blends. Modified polyethylene wax containing greater than 1 wt.% of the filler showed an increase in viscosity. The DSC-based investigations confirmed good miscibility and a uniform structure of PE-wax with BNT. Moreover, an increase in melting temperature onset and its enthalpy observed for filler PE-wax material showed an influence of bentonite on the crystalline structure of the polymeric matrix. SEM observations of the fractured surfaces confirmed the homogeneous structure of blends with contents up to 0.8 wt.% BNT. In the case of higher filler concentrations, the presence of more numerous and large clusters of filler in the polymer matrix was observed due to the increase in the viscosity of the PE-wax/BNT melt composition during mixing. The PE-wax blend with 0.4 wt.% BNT gives better results of reduced linear shrinkage and lower hardness than unmodified material. Lastly, a new developed material (PE-wax/0.4 BNT) was subjected to technological tests, consisting of the preparation of the mold and manufacture of a high-quality aluminum cast, using the lost-wax method.

The paper presents the results of the microstructure investigation, phase and chemical composition, microhardness as well as corrosion and wear resistance tests of B-Si coatings produced on C45 steel. In this study, boron and silicon were added to the surface of steel using the laser alloying process. The main purpose of the study was to check whether the use of silicon, boron or a mixture of these chemical elements would improve the mechanical properties of the surface. Boron and silicon, as well as its mixture, were prepared in various proportions and subsequently were applied on steel substrate in the form of pre-coat (paste) of 80 µm thick. All pre-coats were processed by a laser beam and the obtained microstructures were analyzed and compared. Laser alloying processes were carried out using device equipped with a CO₂ laser. After laser alloying, the microstructure consisted of a melted zone, heat affected zone and unchanged steel substrate. The newly created B-Si coatings were characterized by properties better than the case of boron and silicon coatings, with particularly high microhardness in the range from 1430 HV to 1870 HV, as well as high corrosion and wear resistance.

The paper presents study results of laser alloying of CT90 tool steel with an applied pre-coat of boron, molybdenum or a mixture of these elements. Pre-coats were applied on steel substrates in the form of a paste. The aim of the study was to investigate the microstructure, chemical and phase composition, microhardness and corrosion resistance of these newly-formed coatings. The laser alloying process was carried out using a diode laser with a nominal power of 3 kW. In this study a laser beam power of 900 W and a scanning speed of 48 mm/s were used. As a result of the laser beam action, the presence of three areas was observed in cross-sections of specimens: a remelted zone, a heat affected zone and the substrate. The properties of coatings enriched with both molybdenum and boron were better than those of the steel substrate, but only the use of a Mo-B mixture resulted in a significant improvement in microhardness and corrosion resistance.

This study investigated the upgrading process of polymer fractions obtained from automotive waste by a three-stage flotation–sedimentation separation process. The separated automotive recycled blend (ARB) fraction was modified with a compatibiliser at contents of 5, 10 and 15 wt%, and the resulting blends were processed by extrusion and injection moulding. Multipoint FTIR analysis confirmed the multicomponent character of the ARB fraction and indicated the presence of, among others, polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), high-density polyethylene (HDPE) and polystyrene (PS). The influence of compatibiliser addition on density, Shore D hardness, tensile properties, thermal behaviour and fracture-surface morphology was evaluated using gas pycnometry, static tensile testing, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that increasing compatibiliser content gradually reduced the density of the blends, while hardness remained at a level comparable to that of the reference material. Tensile testing indicated that the addition of the compatibiliser reduced Young’s modulus, whereas ultimate tensile strength and tensile stress at break were maintained close to the unmodified blend. Among the modified blends, the most favourable balance of the evaluated properties was observed for the ARB/10C sample containing 10 wt% compatibiliser. This blend exhibited the highest tensile stress at break among the investigated blends and a comparatively compact fracture-surface morphology. DSC analysis showed similar principal thermal transition ranges for all blends. The results indicate that 10 wt% compatibiliser is an optimal addition for upgrading recycled automotive polymer fractions.