Toplotni izolativni kompozit na osnovi zlitine NiTi

Reberčnik, Domen (author), Fajfar, Peter (mentor), Šalej Lah, Alenka (comentor)

Diplomska naloga predstavlja izdelavo kompozita, pametne tekstilije, pri kateri se glede na zunanjo temperaturo spreminja njena toplotna prevodnost. Spremembo toplotne prevodnosti dosežemo s spreminjanjem debeline zračne plasti, ki med postopkom segrevanja nastane v večplastnem kompozitu. Spremembo debeline zračne plasti pa dosežemo z vstavitvijo pletiva iz zlitine NiTi, ki ima lastnost dvosmernega spomina. Pletivo se odzove na spremembo temperature s spremembo oblike, pri čemer nastane zračna plast oziroma se le ta poveča. Zračna plast deluje kot toplotni izolator med sosednjimi plastmi tekstilij iz visokozmogljivih ognjevarnih vlaken. Naredil sem primerjavo med različnimi debelinami zračne reže, kar so omogočili za ta namen izdelani leseni okvirji iz različnega števila lepljenih plošč. Kompozit sem skupaj z izolativnim ognjevarnim ohišjem iz kamene volne namestil na komoro peči, tako da je bilo prehajanje toplote zagotovljeno preko odprtine v izolativnem ohišju. Izveden je bil tudi test izpostavitve toplotno izolativnega kompozita direktnemu ognju gorilnika, saj se s tem preizkus približa dejanskemu stanju, če bi tekstilni kompozit služil kot ognjevarna obleka gasilcev. Za merjenje toplotne izolativnosti kompozita sem uporabljal termoelemente, katerih namen je merjenje temperature površin posameznih plasti kompozita. Z dobljenimi rezultati meritve toplotno izolativnega kompozita sem ugotovil, da se z večanjem zračnega žepa spreminja tudi prehod toplote, saj sem pri večjem zračnem žepu dosegel nižje temperature. Kot preiskovalno metodo premen zlitine NiTi sem uporabil metodo za detekcijo strukturnih sprememb z merjenjem električne upornosti, s katero sem ugotovil temperaturo, pri kateri poteka premena zlitine pri ohlajanju oziroma segrevanju.

• Language: Slovenian
• Keywords: Nitinol, zlitina NiTi, toplotno izolativni kompozit, oblikovni spomin, strukturne spremembe
• Work type: High school thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-120228
• COBISS.SI-ID: 31494915
• Publication date in RUL: 17.09.2020

REBERČNIK, Domen, 2020, Toplotni izolativni kompozit na osnovi zlitine NiTi [online]. Bachelor’s thesis. [Accessed 23 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=120228

Secondary language

• Language: English
• Title: Thermal insulation composite based on NiTi alloy

Abstract

The thesis introduces the production of a composite, a smart textile, in which its thermal conductivity changes according to the external temperature. The change in thermal conductivity is achieved by changing the thickness of the air layer, which is formed in the multilayer composite during the heating process. The change in the thickness of the air layer is achieved by inserting a knit from NiTi alloy, which has the property of two-way memory. The knit responds to the change in temperature by changing the shape, either creating the air layer or increasing it. The air layer acts as a thermal insulator among adjacent textile layers of high-performance refractory fibres. A comparison among different air gap thicknesses has been made by using wooden frames from different numbers of glued panels made solely for this purpose. During this process the composite and the insulating fireproof housing made of stone wool were placed on the furnace chamber together so that heat transfer was ensured through the opening in the insulating housing. A test of the exposure of the heat-insulating composite to the direct fire of the burner has also been performed, as this test resembles the actual condition as much as possible, providing a textile composite serves as a fireproof clothing for firefighters. In order to measure the thermal insulation of the composite, thermocouples have been used, the purpose of which has been to measure the surface temperature of the individual layers of the composite. With the obtained results of the heat-insulating composite measurement, I have determined that when increasing the air pocket, the heat transfer changes as well, since I have achieved lower temperatures with a larger air pocket. For the research in the changes of the NiTi alloy the method of structural change detection with measuring of the electrical resistance has been used. This is how the temperature at which the change in the alloy during cooling or heating takes place has been determined.

• Keywords: Nitinol, NiTi alloy, thermal insulation composit, shape memory, structural changes