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Odkształcalność metalicznych stopów metali wytwarzanych niekonwencjonalnymi metodami spiekania

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Praktyczne zastosowanie wyrobów wytwarzanych niekonwencjonalnymi metodami, takimi jak SLM (Selective Laser Melting), SLS (Selectve Laser Sintering) oraz metali o strukturze mikro- i nanokrystalicznej jest uwarunkowane znajomością charakterystyk ich właściwości. W pracy przedstawiono wyniki badań uzyskane w próbie ściskania próbek stali, wykonanych niekonwencjonalnymi i innowacyjnymi technologiami, oraz porównano z próbkami wykonanymi klasycznymi metodami kucia i wyciskania na gorąco. Do badań plastyczności próbek o średnicy 2 i 3 mm zaprojektowano i wykonano specjalny przyrząd badawczy. Na podstawie analizy wykresów umocnienia wyznaczono moduł Younga oraz określono mechanizm odkształcenia plastycznego podczas ściskania. Practical application of products made by unconventional methods such as SLM (Selective Laser Melting), SLS (Selective Laser Sintering) as well as metals with micro- and nanocrystallic structure requires knowledge of broad characteristics of their properties. The paper present investigation results obtained in a compressive test of samples) manufactured by modern methods; the results were compared to those made by conventional method of forging, casting and hot extrusion. For compressing the samples of 2 and 3 mm diameter, it was necessary to make a special test device to determine plasticity. Basing on the consolidation curves, the Young’s modulus has been determined and the mechanism of plastic strain during compression have been defined. Słowa kluczowe: próba ściskania, struktura nanometryczna, PLC Key word: compression test, nanometric structure, PLC Wpr[...]

Manufacturing powder bearings modified with solid lubricant nanoparticles for high temperature applications

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With the rapid development of industries and advanced technologies, more and more mechanical devices are required to work in high temperature, for example, the various devices used in aviation and electrical industries, the engine sliding components, and the mechanical devices in the nuclear industry. The conventional grease lubricating systems used in the high temperature do not meet the present requirements, so it is urgent to develop materials with excellent self-lubricating property from the room temperature to about 1000°C. Sliney and co-workers prepared several high temperature self-lubricating sintered materials [1÷4], three typical materials among which are PS101 (30% Ni-Cr, 30% Ag, 25% CaF, 15% glass), PS200 (80% Ni-Co-Cr3C2, 10% Ag, 10% BaF2/CaF2), and PS300(80% Ni-Cr-Cr2O3, 10% Ag, 10% BaF2/CaF2). These materials show good self-lubricating properties (friction coefficient about 0.1÷0.3) in a wide temperature range. New advanced materials are generally considered as essential for the development of novel solid lubricants giving access to high temperature applications [5]. The nanoparticle solid lubricant materials have been identified as being of potentially outmost importance for many industrial high temperature applications, as a consequence of their original two-dimensional lamellar structure and superior friction properties. These materials have been identified as strong candidates for high temperature tribology applications because of their atomic-scale structure involving strong covalent bonds and non-compact space filling. Detailed analysis of nanoparticles mechanical behaviour during sliding is essential to gain understanding of the complex physical nature of these nanostructures during friction process. The shape, strength, fracture and interparticle friction properties of such nanostructures are of great importance. The nanoparticle ensemble behavior is believed to be identified by continuum mechanics metho[...]

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