Reološka svojstva Al2O3 suspenzija koje sadrže biootpad

master's thesis

• Title (english): Rheological properties of Al2O3 suspensions which contain biowaste
• Author: Domagoj Udovičić
• Mentor: Lidija Ćurković (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; (Department of Materials); (Chair of Materials and Tribology); Zagreb
• Defense date and country: 2021-12-16, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

U ovom radu ispitana je mogućnost uporabe dodatka otpadnog taloga kave za pripravu porozne Al2O3 keramike lijevanjem suspenzije (engl. slip casting) u gipsani kalup. Otpadni talog kave je pogodan materijal u metodi sa žrtvenom fazom jer se sastoji većinski od organskih materijala, jeftin je i ekološki prihvatljiv. U tu svrhu pripravljeno je pet 60 %–tnih Al2O3 suspenzija s masenim udjelom 0, 1, 5, 10 i 15 % otpadnog taloga kave, uz dodatke disperzanta Dolapixa (0,2 %) i veziva PVA (0,5 %). Suspenzije su pripravljene homogenizacijom u planetarnom kugličnom mlinu, nakon čega su im određena reološka svojstva na rotacijskom viskozimetru. Reološka svojstva keramičkih suspenzija određena su snimanjem krivulja tečenja (reoloških dijagrama): dijagram ovisnosti prividne viskoznosti (η) o brzini smicanja (γ), te dijagram ovisnosti smičnog naprezanja (τ) o brzini smicanja (γ). Lijevanjem pripravljenih suspenzija u gipsani kalup oblikovani su sirovci Al2O3 keramike s masenim udjelom 0, 1, 5, 10 i 15 % otpadnog taloga kave. Sirovci su sinterirani u laboratorijskoj električnoj peći uz odgovarajući režim sinteriranja pri 1600 °C. Sinteriranim uzorcima analizirana je mikrostruktura pretražnim elektronskim mikroskom (SEM) te je određena gustoća, poroznost i skupljanje.

Abstract (english)

In this thesis, the use of spent coffee grounds for preparation of porous Al2O3 ceramics by slip casting into gypsum mold is investigated. Spent coffee grounds can be used in sacrificial template method because they consist mostly of organic materials, they are cheap and environmentally friendly. For this purpose, five 60 wt. % Al2O3 suspensions of with a mass fraction of 0, 1, 5, 10 and 15 wt. % of spent coffee grounds were prepared, with the addition of the dispersant Dolapix (0.2 wt. %) and PVA binder (0.5 wt. %). The suspensions were homogenized in a planetary ball mill, after which their rheological properties were determined on a rotational viscometer. The rheological properties of ceramic suspensions were determined by recording flow curves (rheological diagrams): the dependence of the apparent viscosity (η) on the shear rate (γ), and the dependence of the shear stress (τ) on the shear rate (γ). By slip casting of prepared suspensions in gypsum mold, green bodies of Al2O3 ceramic materials with a mass fraction of 0, 1, 5, 10 and 15 wt. % of spent coffee grounds were formed. The green bodies were sintered in laboratory electric kiln with an appropriate sintering regime at 1600 °C. The microstructure of sintered samples was analyzed by scanning electron microscopy (SEM), as well as density, porosity and shrinkage were determined.

• Keywords: aluminijev oksid; porozna keramika; otpadni talog kave; reološka svojstva; lijevanje suspenzija
• Keywords (english): aluminium oxide; porous ceramics; spent coffee grounds; rheological properties; slip casting
• Language: croatian
• URN:NBN: urn:nbn:hr:235:896483
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-12-07 11:16:51