engleski

The effect of waste coffee ground on the porosity and structure of slip cast alumina ceramics

Porous ceramics have been used in various industrial applications such as high temperature filtration, orthopaedic implants, thermal insulation, catalyst supports, lightweight structural components, etc. [1]. Porous ceramics can be obtained by the following methods: (i) replica template [1], (ii) sacrificial fugitives [2], (iii) direct foaming [3] and (iv) partial sintering [4]. In this work, porous alumina ceramics was obtained by the sacrificial fugitive method. This method is based on mixing appropriate amounts of sacrificial fugitives as pore-forming agents with raw ceramic powder and evaporating or burning them out before or during sintering to create pores. This work presents the preparation of porous alumina ceramics by the addition of waste coffee grounds as an eco-friendly pore-forming agent. Green bodies of alumina ceramics were prepared by slip casting of 60 wt. % alumina suspensions containing different amounts of waste coffee grounds (0 wt. %, 1 wt. %, 5 wt., 10 wt. and 15 wt. %). The influence of waste coffee grounds amount in green alumina bodies on density, porosity and microstructure of sintered ceramics was evaluated. The viscosity of all suspensions was determined using a rotational viscometer. The sintering regime was determined according to the simultaneous differential thermal and thermogravimetric (DTA/TGA) analysis where thermal decomposition of waste coffee grounds was observed. The density and porosity of the obtained sintered samples were investigated and calculated. Microstructure and pore morphology were characterized by Scanning Electron Microscopy (SEM). It was found that the density of sintered ceramics decreased from 3.743 to 2.172 g/cm3 as the amount of waste coffee grounds increased from 0 wt. % to 15 wt. %. Therewith, the porosity increased from 6.12 % to 45.52 % as the amount of waste coffee grounds increased from 0 wt. % to 15 wt. %.

prous ceramics, slip cast alumina ceramics, waste coffee ground

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