Bezecný, Ján

Faturíková, Katarína

Lukáč, Anton

Marčeková, Lýdie

Mikulová, Emília

Pagáčová, Jana

Plško, Alfonz

Staňová, Iveta

English

DSpace at VSB Technical University of Ostrava

IT I i· . :.._ � B �.\b: � uSk,.,r.,;k v!det:kýtb· p;ací Vysoké školy báňské- Technické univerzity Ostrava číslo l, rok 2008, ročník LI, řada hutnická článek č. 1410 INFLUENCE OF THE RELATIVE HUMIDITY ON THE "SELF - ASSEMBL Y" GROW OF THE SiO2 FIBRES A. PLŠKO 1 •, A. LUKÁČ 1 , E. MIKULOVÁ\ J. PAGÁČOVÁ 1, I. STAŇOVÁ\ L. MARČEKOVÁ 1, K. FATURÍKOVÁ1 ; J.BEZECNÝ 1 1 *Department of Chemistry and Technology of lnorganic Materials, Faculty of lndustrial Technologies,2TnU AD, I.Krasku 1809/34, 020 OJ Púchov, Slovakia, e-mail: plsko@fpt.tnuni.skDepartment of Physica/ Engineering of Materials, Facu/ty of lndustria/ Technologies, TnU AD, I. Krasku 1809134, 020 01 Púchov, SlovakiaABSTRACT: The interesting phenomenon of sol - gel transition in silicic ·acid :_ NH3 _:. HCI - H2O system is „spontaneous"origin of fibres on gels'surfaces. ln the mentioned system we studied the influence ofrelative huminity (RH) on the „spontaneous·• fibres' growth. At the RH - !?oint of 52, 9 % the growth of fibres reaches its maximum, in the case of high values of RH is the grl>wth practicaly stopped. KEY WORDS: sol-gel methods, fibres, silicic acid, spontaneous growth 1. INTRODUCTIONSol-gel methods based cm the use and control of solution-sol-gel-product trans1t10n allow preparation, of various materials often with unanticipated . characteristics [I, 2, 3]. lnteresting phenomenon of sol - gel - product transition is „spontaneous·' occurrence of various and often fibrous formations. These „spontaneouslý" occurred fibrous formations are measured in dimensions from nanometers to centimeters (4). Best-known systems, in which „spontanéous" growth of fibres and fibrous structures occiirs, are called chemical gardens but also silicate gardens, colloidal gardens and crystal gardens, mostly because ofthe similarity to the growth ofplants [5]. They occur after addition of grain of soluble salt of metal into solutions containing anions such as silicates, aluminates, borates, carbonates, phosphates, ferricyanides and many others (6). Nascent crystalline material is in few cases decisive for final shape. This · is how inorganic materials are „spontaneously" created with morphogenesis similar. to biological systems in water solution of silicates in the· presence of water­soluble baric salts (7). Driving force of „spontaneous" growth in this case is crystallization of respective salt that is affected and controlled by present colloid. 2. EXPERIMENT AL2.1 Preparatioli of silicic acid sol We have used freshly prepared solution of sodium silicates in water for preparation of silicic acid. Solution of sodium silicates has been prepared by dissolving of porous SiO2 (Silica from DEGUSSA company) in calculated quantity ofNaOH solution. Solution of sodium silicates had concentration of SiO2 - 1.5 mot.dm·3 and molar rate of Na2O : SiO2 was I : 3. Silicic acid sol has been prepared by ionic exchange ofNa+ for l1 using Amberlite IR cation exchanger- 120H+ form 0.3 - 1.2. Created sol had concentration of SiO2 - 1.25 mol.dm"3 and pH - 2.4. 278 

Influence of the relative humidity on the "self - assembly" grow of the SiO2 fibres

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Influence of the relative humidity on the "self - assembly" grow of the SiO2 fibres

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