Razvoj monolitne aluminijeve oksidne keramike uz dodatak otpadnoga keramičkoga praha

doctoral thesis

• Title (english): Development of monolithic alumina ceramics with the addition of waste ceramic powder
• Author: Milan Vukšić
• Mentor: Irena Žmak (mentor)
• Committee member: Lidija Ćurković (predsjednik povjerenstva)
• Committee member: Danko Ćorić (član povjerenstva)
• Committee member: Biserka Runje (član povjerenstva)
• Committee member: Slaven Dobrović (član povjerenstva)
• Committee member: Stanislav Kurajica (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2022-04-04, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering
• Universal decimal classification (UDC): 502.1 - The environment and society; 666 - Glass industry. Ceramics. Cement and concrete

Abstract

Trenutni obrasci industrijskog razvoja ukazuju na prekomjerno vađenje i potrošnju prirodnih sirovina. Posljedice ovakvog ljudskog djelovanja odražavaju se štetnim učinkom na okoliš. Stoga je razvoj ekološki prihvatljivih tehnologija, koje podrazumijevaju oporabu i recikliranje materijala, neophodan za postizanje ekološke održivosti i gospodarskog rasta. Kao reprezentativni primjer, u doktorskom radu istražena je mogućnost recikliranja otpadnoga aluminijeva oksida, prikupljenog nakon strojne obrade keramičkih sirovaca tijekom industrijske proizvodnje aluminijeve oksidne tehničke keramike, u obliku praškastih strugotina. Korištenje otpadnoga aluminijeva oksida u obliku sekundarne proizvodne sirovine doprinosi očuvanju prirodnih resursa i smanjenju količine otpada za zbrinjavanje.
Uzorci monolitne aluminijeve oksidne keramike bez dodatka i s dodatkom otpadnoga keramičkog praha pripremljeni su postupkom lijevanja, osim uzoraka sinteriranih u električnom luku koji su pripremljeni postupkom prešanja. Nadalje, provedena je detaljna karakterizacija polaznih sirovina, pripravljenih suspenzija, keramičkih sirovaca i sinteriranih uzoraka aluminijeve oksidne keramike. Keramički sirovci sinterirani su konvencionalnim postupkom sinteriranja poznatijim kao jednostupanjsko sinteriranje te nekonvencionalnim postupcima sinteriranja poput dvostupanjskog sinteriranja, hibridnog mikrovalnog sinteriranja i sinteriranja u električnom luku. Određeni su optimalni režimi sinteriranja za konvencionalne i nekonvencionalne postupke. Na sinteriranim uzorcima monolitne aluminijeve oksidne keramike, bez dodatka i s dodatkom otpadnoga keramičkoga praha, analizirana je i uspoređena mikrostruktura, tvrdoća i indentacijska lomna žilavost u cilju vrednovanja utjecaja dodanog otpadnoga praha na svojstva sinteriranih uzoraka i opravdanosti njegove primjene.

Abstract (english)

Current patterns of industrial development showing enormous extraction and depletion of natural resources, which reflected negatively on the environment. Thus, the development of environment-friendly technologies, which include the reuse, remanufacturing, or recycling of materials, to achieve both environmental sustainability and economic growth is nowadays important. As a representative example, the present study shows the possibility of recycling waste alumina obtained after the green machining step during the manufacturing process of alumina ceramics as a broken ware. The use of waste ceramic powder as secondary raw materials saves natural resources and consequently reduces the amount of disposed waste.
The samples of monolithic aluminum oxide ceramics with and without the addition of waste ceramic powder were prepared by slip casting method except for spark plasma sintering. Furthermore, a detailed characterization of the starting materials, prepared suspensions and green bodies were performed. Alumina green bodies were sintered by the conventional sintering process, which is referred to as one-step sintering and by the non-conventional methods including two-step sintering, hybrid microwave sintering, and spark plasma sintering. The optimal sintering regimes for each sintering process were determined. Microstructure, hardness, and indentation toughness of sintered samples of monolithic alumina ceramics with and without the addition of waste ceramic powder were analyzed and compared in order to evaluate the influence of the waste ceramic powder onto the properties of sintered samples and the viability of its application.

• Keywords: kružno gospodarstvo; recikliranje; aluminijeva oksidna keramika; nekonvencionalno sinteriranje; mehanička svojstva
• Keywords (english): circular economy; recycling; alumina ceramics; non-conventional sintering; mechanical properties
• Language: croatian
• URN:NBN: urn:nbn:hr:235:869847
• Study programme: Title: Mechanical Engineering and Naval Architecture; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje tehničkih znanosti (doktor/doktorica znanosti, područje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Repository: Repository of Faculty of Mechanical Engineering and Naval Architecture University of Zagreb
• Created on: 2022-04-28 13:42:28