SVIBOR - Project code: 2-15-023

MINISTRY OF SCIENCE AND TECHNOLOGY

Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69
E-mail: ured@znanost.hr

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Project code: 2-15-023


TRANSPARENT AND SINTERED GLASS-CERAMICS


Main researcher: TKALČEC-ČIŽMEK, EMILIJA (49605)


Assistants
Type of research: applied
Duration from: 01/01/91. to 12/31/94.
Papers on project (total): 33
Papers on project quoted in Current Contents: 4
Institution name: Fakultet kemijskog inženjerstva i tehnologije, Zagreb (125)
Department/Institute: Department of inorganic chemical technology and non-metals
Address: Marulićev trg 20
City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 4552-477
Fax: 385 (0)1 4550-725
Summary: Processes of nucleation and crystallization in the course of accquiring transparent glass-ceramics with mullite, Zn-spinel and high-quartz solid solution have been studied. Mechanism of crystallization of high-quartz solid solution, mullite, Zn-spinel, and influence of dopants (Co, Mn, Fe ) on kinetic parameters in non-isothermal conditions were investigated. With the mathematical modeling and computer simulation new methods were established, for studying the processes of nucleation and crystallization of two or more phases, that occur in the same temperature range. A special mathematical model was derived to separate the processes of nucleation and crystal growth of each phase, and thus to influence the microstructure and properties of glass-ceramics.The sol-gel method has been used to prepare single-phase and diphasic aluminosilicate gels. The influence of preparation routes on the phase development and sintering behaviour of mullite powders (with nanometer particles size) needed for the production of high density mullite ceramics has been studied.

Keywords: glass-ceramics, mullite, Zn-spinel, high-quartz solid solution, nucleation, crystallization, non-isothermal kinetics, microstructure, sol-gel process, mathematical modeling, computer simulation.

Research goals: To obtain ceramic materials by controlled crystallization of glasses or by synthering of amorphous powders (obtained by sol-gel technics) it is particularly important to control theprocesses of nucleation and crystallization and to establish the influence of various factors as: nucleating agents,dopants,thermal treatment and the composition of glasses on the phase composition and microstructure of ceramic products.The aim of this research is to find out how each of the mentioned factors influences the process of nucleation and crystallization, in order to prepare materials with strictly defined properties.Results of the investigation will increase the theoretical and practical knowledge in the field of controled crystallization of glases and sintering of aluminosilicate gels,that are neceseary to produce glass-ceramics and ceramicsmaterials at lower temperatures than nowdays.Because of an increasing need for the materials with fully new combination of properties in electronic, telecomunications, rocket technics and machine building,the correlation of structure and properties becomes of an extreamly fundamental and practical significance.

COOPERATION - INSTITUTIONS


  1. Name of institution: Institut fuer Neue Materialien, Universitat des Saarlandes ( suradnja uspostavljena 1993. godine)
    Type of institution: Economical/Production
    Type of cooperation: Joint publishing of scientific papers
    City: D-66123 - Saarbruecken, SR Njemačka
Other information about the project.
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Last update: 10/10/95
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