MINISTRY OF SCIENCE AND TECHNOLOGY
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E-mail: ured@znanost.hr
Title: Silicon, Silicates
Title: Phase Composition, Microstructure and Nucleation
Temperature Range of Zinc-Aluminosilicate Glass-Ceramics
Title: Ultrafine Ceramic Powders and Glass Coatings Obtained by
Sol-gel Technique
Title: Nucleation and crystallization in mullite gels
Title: the influence of chromium on crystallization of mullite
from gels
Title: Nucleation and crystallization in mullite gels
Title: Glass-ceramics as a host for luminescent ions
Title: Crystallization kinetics of lithium-aluminosilicate
glasses
Title: Influence of TiO2/ZrO2 ratio on the crystallization of
Zn-aluminosilicate glass
Title: Mullite synthesis by sol-gel method
Title: Crystallization of Mullite from Single-phase and Two-phase
xerogels
Title: High Temperature XRD Examination of Mullite Formation from
Amorphous Al2O3/SiO2 Gels
Title: The influence of various dopants on the kinetic parameters
of nucleation and crystal growth of high-quartz solid solution in
lithium-aluminosilicate glass
Title: Sinterability of various prepared hydroxylapatite powders
Title: The Crystallization of Mullite, Gahnite and High-Quartz
Solid Solution in Multicomponent Zn-Aluminosilicate Glasses
Title: Nucleation and crystallization processes in multicomponent
zinc-alumosilicate glasses
Title: Non-isothermal kinetics of 3Al2O3*2SiO2 monophasic and
diphasic gels
Title: Crystallization kinetics of lithium-aluminosilicate glass
determined by DTA
Title: Preparation of mullite by sol-gel process
Title: Mullite formation kinetics
Title: High Temperature X-ray Diffraction Study of Mullite
Formation from Al2O3/SiO2 Gels
Title: Determination of kinetic parameters for crystallization of
multicomponent system from DTA or DSC curves
Title: The preparation of mullite in Al2O3-SiO2 system
Faculty: Fakultet kemijskog inženjerstva i tehnologije Sveučilište u Zagrebu
Date of defense: 12/23/91
Language: hrvatski
Number of pages: 122
Summary:
Mullite, 3Al2O3*2SiO2 was synthesized by reaction sintering amixture of
kaolinite and Al2O3. The influence of mineralizers(NaF, TiO2, MnO and
Cr2O3) has been investigated. Among theexamined mineralizers, TiO2 shows
efficient influence on themullitization process. Efficiency of TiO2 depends
upon itsquantity and the reaction temperature. Maximum of mullitizationhas
been determined by quantitative XRD analysis as well as bysuccessive
dissolution of phases with an HF solution in thesamples treated at 1600 C
with < 1 wt% TiO2 added. At theseconditions the maximum of densification as
well as the minimumsize of mullite crystals have been determined. The
microstructureand microanalyses of the samples were defined by using SEM
andAEM analyses. Two morphologically and compositionally differentmullites
have been found out (the large prismatic mullites andthe small
needle-shaped ones, embedded into the glassy matrix)but also rutile in the
form of needle-shaped crystals embedded inthe glassy matrix. On the surface
of prismatic mullites, theexolution of a phase enriched in titanium and
iron has beendetected. However, the formation of tialite, Al2TiO5, has
beenproved neither by XRD nor by AEM analyses. A greater Al/Si ratiohas
been determined in needle-shaped mullites than on theprismatic ones using
EDX analyses. Prismatic mullites haveconstant Al2O3 values, not dependent
on the sintering temperatureand on TiO2 added. The solubility of TiO2 in
mullites decreaseswith increasing temperature. Incorporation TiO2 and Al2O3
inmullite crystals increases lattice parameters. This influence ismore
significant in mullite crystals obtained at 1750 C, becauseat this
temperature a higer content of needle-shaped metastablemullites was formed.
The calculated lattice parameters of mullitepresents an average of lattice
parameters of the prismaticmullites and the needle-shaped ones.
Keywords: Mineralizers, mullite, reaction sintering
Title: Mechanism of crystallization in Li2O-Al2O3-SiO2 system
Faculty: Fakultet kemijskog inženjerstva i tehnologije Sveučilište u Zagrebu
Author: ŠENIJA DAVOR
Date of defense: 06/17/93
Language: hrvatski
Number of pages: 123
Summary: The LiO2-Al2O3-SiO2 system as well as the effect of
colouringdopes on kinetic parametars and phase composition of
resultingglass ceramics were studied.
Differential Thermal Analysis (DTA), method for studying thenonisothermal
kinetics, X-ray Diffraction (XRD), technique forphase composition
determination, were used. Separation intomicrophases and qualitative
composition of formed phases werecharacterised by means of Scanning
Electron Microscopy (SEM) andEnergy Dispersive X-ray Analysis (EDAX).
Thermal characteristicsof resulting glass-ceramics were checked up by using
dilatometricmeasurements.
The investigated samples are glasses with different particlesizes, i,e.,
from glass powder, with particle size < 63micrometers, to monolithic
glasses.
The obtained results showed that the colouring cations has ansignificant
effect on the kinetic parameters, with an emphasis onthe temperature range
of maximum nucleation rate.
Fourthermore, great effects on colouring cations is reflected onthe phase
composition of glass ceramic which has a directinfluence on thermal
characteristics of resulting glass ceramicsas well as on its application.
The lattice parameters of high quarts solid solution indicate that
colouring cations areincorporated into the structure of high quartz.
Keywords: Colouring dopes, Li2O-Al2O3-SiO2 system, nonisothermal kinetics, phase composition (beta-quartz, beta-spodumene), parameter of unit cell of high-quartz solid solution.
Title: Crystallization kinetics of polycomponent glasses
Faculty: Fakultet kemijskog inženjerstva i tehnologije Sveučilište u Zagrebu
Author: KURAJICA STANISLAV
Date of defense: 10/10/94
Language: hrvatski
Number of pages: 145
Summary: The processes of nucleation and crystallization of
polycomponent ZnO-(Li2O)-Al2O3-(B2O3)-SiO2 glasses with TiO2 and ZrO2 as
nucleating agents were studied. The methods used were isothermal and
nonisothermal differential thermal analysis (DTA) and differential scanning
calorimetry (DSC) as well as X-ray diffraction (XRD). For each studied
glass the temperature of the maximum nucleation rate was determined, it was
established which phases in an individual system made the crystallization
and the temperature range of the crystallization of each crystal phase was
defined. Since in the studied glasses trough a termic process a
crystallization of several crystal phases occur in a very narrow
temperature interval, the DTA and DSC curves of the studied glasses are
characterized by the superposition of the exothermic effects of
crystallization. Therefore a procedure was developed and a computer program
made for separating individual exothermic effects and establishing kinetic
parameters of crystallization for each individual phase by an analysis of
the shape of the experimental DTA i. e. DSC curves. This program is, in
distinction from the commercial profile fitting program packages,
specialized for solving the problem of superposition of DTA, i. e. DSC
curves and enables refinement as many as 16 parameters at the same time.
The program is founded on adjusting the shape of the curves obtained
through theoretical functions to an experimentally achieved curve,
initialisation of the parameters is brought about by a direct definition of
the shape of the theoretical curves and refinement through least squares
method. By using the program the kinetic parameters of crystallization of
individual phases in glasses are established.
Keywords: Glassceramics, gahnite, high-quartz solid solution, mullite, differential thermal analysis (DTA), differential scanning calorimetry (DSC), crystallization kinetics, activation energy, proffile fitting.
Title: Mechanism of crystallization in Li2O-Al2O3-SiO2 system
Faculty: Fakultet kemijskog inženjerstva i tehnologije Sveučilište u Zagrebu
Date of defense: 06/17/93
Number of pages: 123
Author: Šenija Davor
Degree level: M.A.
Title: The preparation of mullite in Al2O3-SiO2 system
Faculty: Fakultet kemijskog inženjerstva i tehnologije Sveučilište u Zagrebu
Date of defense: 12/23/91
Number of pages: 122
Author: Navala Dr. Dragica
Degree level: Ph.D.
Title: Crystallization kinetics of polycomponent glasses
Faculty: Fakultet kemijskog inženjerstva i tehnologije Sveučilište u Zagrebu
Mentor: TKALČEC-ČIŽMEK EMILIJA
Date of defense: 10/10/94
Number of pages: 145
Author: Kurajica dipl. inž. Stanislav
Degree level: M.A.
Title: Noizokin
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