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Historie neželezných kovů v leteckém průmyslu
Dušek, Přemysl ; Gejdoš, Pavel (oponent) ; Němec, Karel (vedoucí práce)
Bakalářská práce se zabývá lehkými neželeznými kovy, konkrétně podává obecný přehled hořčíkových slitin, shrnuje jejich výhody i nevýhody a popisuje jednotlivé skupiny hořčíkových slitin dle legujících prvků. Zmiňuje také tepelné zpracování a technologické vlastnosti hořčíkových slitin. Částečně je uvedeno i srovnání se slitinami hliníku. Druhá část práce je věnována aplikaci hořčíkových slitin v konstrukci letadel, a to jak z pohledu historie (období 2. světové války), tak i u novodobých letadel.
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Effect of grit blasting surface treatment on high temperature low cycle fatigue life of Inconel 713LC
Šulák, Ivo ; Obrtlík, Karel ; Čelko, L. ; Gejdoš, P.
This paper presents the results of high temperature low cycle fatigue tests carried out on Inconel 713LC. This polycrystalline nickel based superalloys is mainly used for high temperature applications such as disks, blades and vanes of gas turbine engines. These machine components are manufactured by investment casting and undergo a series of postcast processes to remove remnants of shells, oxides and other contaminants. Grit blasting is one of the most widely used and cheapest technology ensuring adequate cleaning of the surface and at the same time is used to treat the substrate surface prior to application of metalic bond coat and various protective coatings (like diffusion, overlay or thermall barier coatings). Low cycle fatigue tests were conducted on as-received and grit blasted material in fully reversed pull-push cycle in strain control mode with constant total strain amplitude and strain rate at 900 °C in air. Experimental data on fatigue life were evaluated and parameters of Baquin and Coffin-Manson curves were obtained for both tested materials. Specimen surface and cross sections of both treated and untreated materials were analysed prior to fatigue tests and also after testing by means of optical microscopy (OM), as well as scaning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and Vickers microhardness was measured. Fatigue degradation mechanisms was documented in both materials and negligible effect of grit blasting on low cycle parameters was discussed.
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