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Influence of deflocculant addition on rheological properties of the slurries based on bauxite

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Koralnik M. , Małek M. , Wiśniewski P. , Szymańska J. , Zarzycka D. , Mizera J. , Kurzydłowski K. J.

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2015

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tom Vol. 73, nr 2

106--109

EN

Purpose: The objective of the paper is to present the properties of ceramic slurries based on bauxite with different deflocculants. Design/methodology/approach: The slurries were performed in air conditioned laboratory by a mechanical mixer. The rotation speed of the mixer was 300 RPM and the mixing time was 3 hours. To characterize the bauxite structure, SEM Hitachi SU-70 was used. Furthermore, chemical composition by XRF method was executed. Grain size of bauxite was measured by Horiba laser diffractometer. The rheological properties were studied at Rheometer MCR 102 (Anton Paar) by coaxialcylinders method. Findings: Investigated ceramic slurries based on bauxite show stable rheological properties in time. It could be concluded that ceramic slurries with obtained properties might be used in ceramic proppant manufacturing in the future. Research limitations/implications: The main restriction in rheological properties of ceramic slurries modification is to use aqueous binders and deflocculant solutions. In Polish manufacturing water as a main binder (max. 5 wt. %) and of deflocculant (0.25 wt. % with respect to the powder) additives are required. This kind of limitation has an influence on the part of the solid phase concentration of ceramic slurries. For that reason ceramic slurries with 45 wt. % solid content are investigated. Practical implications: Presented ceramic slurries could be used in ceramic proppant fabrication by spray drying process in the future. Originality/value: This is one of the first application of bauxite to produce ceramic proppants using spray dryer in Poland. Ceramic proppants could be used as additives to fracturing liquid in shale gas extraction process.

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Rheological Properties of Typical Ceramic Slurries Used in the Lost Wax Technology

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Kolczyk J. , Jamrozowicz Ł. , Kaźnica N.

Archives of Foundry Engineering

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2017

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tom Vol. 17, iss. 1

197--201

EN

The results of investigations of the rheological properties of typical ceramic slurries used in the investment casting technology – the lost wax technology are presented in the paper. Flow curves in the wide range of shear velocity were made. Moreover, viscosity of ceramic slurries depending on shearing stresses was specified. Tests were performed under conditions of three different temperatures 25, 30 and 35oC, which are typical and important in the viewpoint of making ceramic slurries in the investment casting technology. In the light of the performed investigations can be said that the belonging in group of Newtonian or Non – Newtonian fluid is dependent on content of solid phase (addition of aluminum oxide) in the whole composition of liquid ceramic slurries.

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Reologiczne właściwości mas ceramicznych z ZRSIO4 z przeznaczeniem na ceramiczne formy odlewnicze

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Szymańska J. , Wiśniewski P. , Małek M. , Mizera J.

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2015

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tom T. 67, nr 4

443--447

PL

W pracy przedstawiono wyniki badań właściwości reologicznych mas lejnych z ZrSiO4, przeznaczonych do wytwarzania ceramicznych form odlewniczych, mających zastosowanie w procesie odlewania precyzyjnego elementów silników lotniczych z nadstopów niklu. Stężenie fazy stałej w ceramicznych masach lejnych wynosiło 75% wag. W celu zmodyfikowania właściwości reologicznych mas lejnych, zastosowano cztery komercyjnie dostępne środki upłynniające: DISPEX N-40, DURAMAX, POLIKOL oraz THS, jako wodne roztwory 10%, których ilość wynosiła 0,25% wagowych w stosunku do proszku. Masy lejne przygotowano w mieszadłach mechanicznych przy szybkości 300 obr./min przez 3 h. Proszek ZrSiO4 scharakteryzowano pod względem wielkości cząstek (metodą dyfrakcji laserowej), morfologii powierzchni (SEM), a także składu chemicznego (XRF). Właściwości reologiczne mas lejnych określono w odniesieniu do lepkości dynamicznej w warunkach laboratoryjnych w temperaturze 21 ºC. Otrzymane wyniki dowodzą, że masa lejna na bazie krzemianu cyrkonu charakteryzuje się zróżnicowaną zdolnością do upłynniania. Mieszanki poddane działaniu środków upłynniających znacząco kontrastują pod względem wielkości lepkości dynamicznej z masą lejną, do której nie dodano upłynniacza. Krzemian cyrkonu wykazuje obiecujące właściwości, stanowiące podstawę do udoskonalania technologii otrzymywania form przeznaczonych do otrzymania części silników lotniczych.

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This research concerns properties of ceramic slurries prepared from ZrSiO4 applied for the “prime coat” fabrication in ceramic shell moulds in the investment casting process. The solid phase content was 75% by weight. Modification of the slurry rheological properties was based on addition of four deflocculants such as DISPEX N-40, DURAMAX, POLIKOL and THS as a 10 wt% water solution in an amount of 0.25 wt% with respect to the powder. The ceramic slurries were prepared in a mechanical mixer with a speed equal to 300 RPM within 3 hours. The morphology and chemical properties of ZrSiO4 powder were characterized by SEM and XRF. The powder grain size distribution was determined by laser diffraction. The rheological properties like dynamic viscosity were studied in an air-conditioned lab at 21 °C. The obtained results for the ZrSiO4 based ceramic slurries indicate that the application of deflocculants can decrease or increase dynamic viscosity significantly, when compared to the slurry containing only water).The addition of deflocculants to ZrSiO4 based ceramic slurries is very useful to modify viscosity of them in industrial conditions.

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The Influence of Silica Sand Granulometry and Sorting Level on Thermal Expansion

67%

Bašistová M. , Lichý P.

Archives of Foundry Engineering

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2023

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tom Vol. 23, iss. 3

12--15

EN

The quality of the castings depends, among other influences, on the quality of the moulding mixture used. The silica sands used are characterized by high thermal expansion compared to other sands. The tendency to dilatation of the moulding mixture can be influenced by the choice of the granulometric composition of the basic sand and the grain size. The aim of this work is to present the influence of grain distribution of foundry silica sand BG 21 from Biala Góra (Poland) and the degree of sorting (unsorted, monofraction, polyfraction) on the degree of thermal dilatation of the sand and thus on the resulting quality of the casting and susceptibility to foundry defects. For the purpose of measuring thermal dilatation, clay wash analysis was performed, sieve analysis of the sand was carried out, and individual sand fractions were carefully sorted. The measurements confirmed a higher thermal expansion in the case of monofractional sand grading, up to 51.8 %. Therefore, a higher risk of foundry stress-strain defects, such as veining, can be assumed.