Spremljanje homogenizacije aluminijevih zlitin z meritvijo električne upornosti

Vončina, Miha (author), Medved, Jože (mentor), Petrič, Mitja (comentor)

Aluminij je ena izmed najpomembnejših kovin. Njegove zlitine se uporabljajo na mnogih področjih od letalske, živilske, farmacevtske, avtomobilske, elektro in do gradbene industrije. Tako razširjeno uporabo omogočajo njegove dobre lastnosti, ki zajemajo odlično razmerje med trdnostjo in gostoto, visoko duktilnost, dobro temperaturno in električno prevodnost in korozijsko odpornost. Aluminijeve gnetne zlitine skupine 1xxx zajemajo tehnično čist aluminij, med njih spada tudi zlitina 1070, zlitine skupine 3xxx pa so aluminijeve gnetne zlitine z glavnim zlitijskim elementom manganom. V to skupino zlitin pa spada zlitina 3003. V diplomskem delu smo želeli vzpostaviti merilni sistem merjenja specifične električne upornosti z namenom spremljanja homogenizacije aluminijevih zlitin. Za ta namen smo nadgradili dilatometer DIL801, da bi na njem poleg meritev sprememb dimenzije vzorca izvedli še meritev specifične električne upornosti v odvisnosti od temperature. Ker meritve niso bile uspešne, smo vzpostavili merilni sistem v horizontalni cevni uporovni peči. Izvedli smo meritve električne upornosti aluminijevih gnetnih zlitin 1070 in 3003 pri 12 urni homogenizaciji na temperaturi 580 °C. Za potrditev poteka homogenizacije, smo izvedli tudi diferenčno vrstično kalorimetrijo (DSC). Po opravljenih meritvah specifične električne upornosti in izdelanih grafih smo potrdili delovanje merilnega sistema v horizontalni peči. Saj pri aluminijevi zlitini 1070 pričakovano, na temperaturi 580 °C, ni prišlo do spremembe specifične električne upornosti. Pri zlitini 3003, pa se je pojavil padec upornosti s časom na temperaturi 580 °C. Na pravilnost poteka homogenizacije je pokazala tudi DSC analiza, saj je DSC krivulja v prvih 7 urah na temperaturi 580 °C padala podobno kot krivulja električne upornosti. V naslednjih 5 urah pa sta obe krivulji (DSC in električna upornost) padali z nižjim naklonom. Tako lahko zaključimo, da se večji del homogenizacije aluminijeve gnetne zlitine 3003 na temperaturi 580 °C zaključuje po 7 urah.

• Language: Slovenian
• Keywords: specifična električna upornost, homogenizacija, zlitina 1070, zlitina 3003
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-110355
• COBISS.SI-ID: 1834847
• Publication date in RUL: 14.09.2019

Secondary language

• Language: English
• Title: Monitoring of homogenization of aluminium alloys by measuring electrical resistance

Abstract

Aluminum is one of the most important metals. Its alloys are used in many fields, from aerospace, food, pharmaceutical, automotive, electrical and construction industries. Such a widespread use is possible because of its good properties, which include the excellent ratio between strength and density, high ductility, good temperature and electrical conductivity, and corrosion resistance. Aluminum alloys in group 1xxx are wrought alloys which comprise technically pure aluminum, including 1070 alloys, and the 3xxx group alloys are aluminum wrought alloys with the main alloy element of manganese. Aluminum alloy 3003 belongs to this group. In this diploma work titled Monitoring of Homogenization of Aluminum Alloys by Measuring Electrical Resistance, we wanted to establish a measuring system to measure specific electrical resistivity in order to monitor the homogenization of aluminum alloys. For this purpose, we supplemented the dilatometer DIL801 to measure specific electrical resistivity as a function of temperature, in addition to dilatation measurements. Since the measurements were not successful, we inserted a measuring system in a horizontal tube resistance furnace. The electrical resistivity measurements of aluminum alloys 1070 and 3003 were carried out at a 12 hours period of homogenization at 580 °C. The differential scanning calorimetry (DSC) was also performed to confirm the homogenization process. After the measurements of the specific electrical resistivity and the produced graphs, we confirmed the operation of the measuring system in the horizontal furnace. However, with the aluminum alloy 1070 as expected at a temperature of 580 °C, there was no change in its specific electrical resistivity. With the 3003 alloy, there was a decrease in resistivity in a period of time at the temperature of 580 °C. The DSC analysis also showed the correctness of the homogenization process, as the DSC curve decreased in the first 7 hours at a temperature of 580 °C, as well as the electrical resistivity curve. In the next 5 hours, both curves (DSC and electrical resistivity) decreased with a lower slope. Therefore, it can be concluded that the main part of the homogenization of aluminum alloy 3003 at 580 ° C is finished after 7 hours.

• Keywords: specific electrical resistivity, homogenization, alloy 1070, alloy 3003