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Aluminij je zaradi svoje nizke gostote in dobrih mehanskih lastnosti vse bolj uporabljan v industriji. Med obdelavo se pridela veliko odpadnega aluminija, ki ga je smiselno reciklirati. V tem delu smo poskusili optimizirati način reciklaže aluminija, s čim nižjo porabo energije. Obravnavali smo hladno reciklažo aluminijevih odrezkov s postopkom kompaktiranja in kasnejše toplotne obdelave s sintranjem. Vrednotili smo dva načina kompaktiranja (enostransko enkrat kompaktirano in kompaktirano z gnetenjem oziroma večkratnim obračanjem) ter pet različnih temperatur sintranja (550°C, 570°C, 590°C, 610°C in 630°C), pri vsaki smo sintrali pri treh različnih časih, razen pri 610°C in 630°C, kjer smo sintrali le pri 60 min. Na vzorcih smo analizirali mikrostrukturo, poroznosti vzorca in mikrotrdoto po Vickersu. Izvedli smo tlačne preizkuse za izris krivulje plastičnosti. Enkrat kompaktirani vzorci so se izkazali za nekompaktne in drobljive, zato smo sintranje izvedli le na z gnetenjem kompaktiranih vzorcih. Pri pregledu mikrostrukture in poroznosti so najboljše rezultate izkazali vzorci sintrani na temperaturi 570°C, 60 minut. Vzorec, obdelan pri tej temperaturi in času, je po drugi strani izkazal najnižjo trdoto, kar se je potrdilo tudi na tlačnih preizkusih, saj je bil najbolj plastičen. Obdelava na temperaturah 610°C ali več se ni izkazala za učinkovito, predvsem zaradi višanja poroznosti. Aluminum is increasingly used in industry due to its low density and good mechanical properties. During processing a lot of scrap aluminum is produced, which is suitable to be recycled. In this research we tried to optimize the way aluminum is recycled with the lowest possible energy consumption. Cold recycling of aluminum chips by the cold compression and subsequent heat treatment by sintering was analysed. We evaluated two compression methods (unilaterally compressed once and compressed by kneading or repeated turning) and five different sintering temperatures (550°C, 570°C, 590°C, 610°C and 630°C). In each case we sintered for three different time durations, except at 610°C and 630°C, where we sintered only for 60 minutes. The microstructure, sample porosity, and Vickers microhardness were analyzed on the samples. We performed pressure tests to plot the plasticity curve. Once compressed samples proved to be non-compact and brittle, so sintering was performed only on samples, compressed by kneading. Examination of the microstructure and porosity showed the best results in samples sintered at 570 ° C for 60 minutes. The sample processed at this temperature and time, on the other hand, showed the lowest hardness, which was also confirmed by pressure tests, as it was the most plastic. Treatment at temperatures of 610 ° C or higher has not been shown to be effective, mainly due to the increase in porosity. |
