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.
When designing the composition and structure of a composite material intended for tribological cooperation, many external and structural factors must be considered. The aim of this research was to compare the tribological properties (wear resistance and friction coefficient) of AlSi7Mg1Sr0.03/SiCp and AlSi7Mg1Sr0.03/GCsf single-reinforced composite layers with AlSi7Mg1Sr0.03/SiCp + GCsf hybrid composite layer formed in sleeves via vertical centrifugal casting. Profilometry enabled quantitative and qualitative analyses to be performed on the wear traces formed on investigated surfaces. The results show that a hybrid composite layer containing spherical glassy carbon particles had a significantly lower and more stable coefficient of friction (μ) and a higher wear resistance compared with single composite layers. The obtained effect was related to the mechanism of vitreous carbon consumption, which was crushed during operation, and then introduced between the cooperating friction surfaces. In this way, it acted as a solid lubricant, which stabilized the coefficient of friction and reduced the wear process.
Aluminium based metal matrix composites are well known for their good wear resistance, high specific strength, stiffness and hardness. They have been applied in the aerospace, military and, especially, in the automotive industries. This paper presents the results of tests with regard to the application of a mixture of particles in aluminium matrix (AlCu2SiMn) composites where a mixture of SiC ceramic particles was used. The aim of the research was to determine the tribological properties as well as the phenomena and mechanisms which accompany the tribological wear of composites under dry friction conditions. The tribological investigations were conducted on a pin-on-block tester. The results of the tests show the composite obtained can be applied for sliding elements. Based on microscopic examinations and profilometry of the composites AlCu2SiMn+SiC surfaces at interaction the relationship between the size of reinforcing particles and the geometry of the surface layer of the composite was described. The study made it possible to develop a model of tribological wear of composites depending on the size of reinforcing particles.Keywords: tribology, metal matrix composites, wearKompozyty z osnową stopów aluminium, są dobrze znane z ich dobrej odporności na zużycie, wysokiej wytrzymałości, sztywności i twardości. Znalazły one zastosowanie w przemyśle lotniczym, wojskowym, ale zwłaszcza w przemyśle motoryzacyjnym. W artykule przedstawiono wyniki badań tribologicznych kompozytów o osnowie stopu AlCu2SiMn wzmacnianego cząstkami węglika krzemu (SiC) o rozmiarze ziaren od 25 do 50 µm. Celem badań było określenie właściwości tribologicznych oraz zjawisk i mechanizmów, które towarzyszą zużycie tribologicznemu kompozytów w warunkach tarcia suchego. Badania tribologiczne przeprowadzono na testerze pin-on-blok. Wyniki predysponują badane kompozyty do zastosowania na elementy ślizgowe. Na podstawie przeprowadzonych badań mikroskopowych i profilografometrycznych, powierzchni kompozytów po współpracy, opisano zależność pomiędzy wielkością cząstek zbrojących a geometrią warstwy wierzchniej kompozytu. Przeprowadzone badania pozwoliły na opracowanie modelu zużycia trybologicznego kompozytu w zależności od rozmiaru cząstek zbrojących.
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