The study involved measurements of surface tension of liquid binary copper-bismuth alloys with respect to their chemical composition and temperature as well as investigations of the liquid alloy -refractory material -gaseous phase system wettability using usual refractory materials, i.e. aluminium oxide, magnesium oxide and graphite. The experiments were performed with the use of sessile drop method and a high-temperature microscope coupled with a camera and a computer was utilised.Keywords: surface tension, contact angle, wettability, sessile drop method, high-temperature microscope, liquid Cu-Bi alloys W ramach pracy przeprowadzone zostały pomiary napięcia powierzchniowego ciekłych dwuskładnikowych stopów miedzi z bizmutem, w funkcji składu chemicznego i temperatury oraz badania zwilżalności w układzie: ciekły stop-materiał ogniotrwały-faza gazowa z wykorzystaniem typowych materiałów ogniotrwałych, to jest tlenku glinu, tlenku magnezu oraz grafitu. Badania wykonano metodą kropli leżącej, przy użyciu mikroskopu wysokotemperaturowego sprzężonego z kamerą i komputerem.

In the paper, results of surface tension measurements with regard to liquid copper-silver alloys with the maximum silver content of 40 % mass Ag are presented. The measurements were performed at 1373-1573 K with the use of the sessile drop method. In the study, a high-temperature microscope, coupled with a camera and a computer equipped with the software designed for experiment recording and picture analysing, was applied. In order to determine surface tension values, the least square estimation of the parameters of the system of differential equations, describing the shape of a liquid sessile drop, was used.Keywords: surface tension, sessile drop method, high-temperature microscope, liquid Cu-Ag alloys W prezentowanej pracy przedstawiono wyniki pomiarów napięcia powierzchniowego ciekłych stopów miedzi ze srebrem o maksymalnej zawartości 40 % mas. Ag. Badania przeprowadzono w zakresie temperatur 1373-1573 K. Wykorzystano metodę kropli leżącej. Zastosowano aparaturę pomiarową składającą się z mikroskopu wysokotemperaturowego sprzężonego z kamerą i komputerem wyposażonym w oprogramowanie pozwalające na rejestrację przebiegu eksperymentu oraz analizę obrazu. Do wyznaczania napięcia powierzchniowego zastosowano procedurę obliczeniową polegającą na estymacji metodą najmniejszej sumy kwadratów parametrów układu równań różniczkowych opisujących kształt leżącej kropli cieczy.

Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO2, Al2O3 and Cs) were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting) technology, followed by plastic work (the KOBO method). The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

A big interest in application of cold crucible furnace (CCF) for industrial, particularly metallurgical, processes has been observed in recent years. They are mainly utilised for melting of metal, glass and other materials. Analyses of processes that occur in such devices are performed; however, computer modelling is rarely applied. As a precise determination of the electromagnetic field distribution is essential for a proper analysis of processes in furnaces with cold crucibles, a complex 3D model development is necessary. In the paper, effects of a crucible design and current frequency on the efficiency of the induction furnace with cold crucible are presented. Numerical calculations were performed with the use of the Flux 3D professional software.

In the paper, results of experimental smelting of the Ti-6Al-7Nb alloy in a vacuum induction furnace are presented. The experiments were performed at 5-1000 Pa and 1973-2023 K. For the analysed alloy, a significant impact of pressure on aluminium loss was observed. Pressure reduction in the device from 1000 Pa to 5 Pa was accompanied by Aluminium content decrease from the initial value of 5.5 % mass to a value even below 3.2 % mass. Moreover, aluminium elimination was enhanced when the smelting temperature increased. Additionally, values of a so-called evaporation coefficient (Ω) were determined. In terms of titanium and niobium, Ω Al/Ti and Ω Al/Nb values suggest that, thermodynamically, aluminium loss may result from its intense evaporation from the investigated alloy.