TITLE: DTA and X-ray Analysis Study of Nucleation and Crystallization of MgO-Al₂O₃ - SiO₂ Glasses Containing ZrO₂, TiO₂ and CeO₂

J. Amer. Ceram. Soc. 58 [5-6] 163-169, 1975.

By W.A. Zdaniewski

Crystallization sequences of glasses with compositions in the tridymite primary phase field of the MgO- Al₂O₃ - SiO₂ system were studied by DTA, X-ray diffraction, and other techniques. Crystallization was catalyzed by the addition of 7wt% of either ZrO₂ or TiO₂. Up to 10 w% CeO₂ was added to some glasses. Metastable solid solutions with the high-quartz structure exhibiting varying lattice parameters commonly occurred at low temperatures, transforming into a high cordierite at higher T. Depending on the composition and heat tretment, other phases also appeared. The rate of crystallization was markedly dependent on the catalyst. Colloidal precipitation of the catalyst accompanied by bulk crystallization of the glass was observed with ZrO₂, but no crystalline TiO₂ was onbserved. In the presence of CeO₂, TiO₂ was a more effective catalyst than ZrO₂. Although CeO₂ lowered the melting T of the glass-ceramic, it increased the stability of the glasses and inhibited volume nucleation.

TITLE: Microstructure and Kinetics of Crystallization of MgO-Al₂O₃-SiO₂ Glass Ceramics

J. Amer.Ceram. Soc. 61 [5-6] 199-204, 1978.

By W.A. Zdaniewski

Quantitative X-ray diffraction and microscopy were used to study the morphology development and overall crystallization rate between 900º and 990º C of MgO- Al₂O₃ - SiO₂ glasses with added ZrO₂, TiO₂, CaF₂, or CeO₂. Three basic stages of microstructural delopment were distinguishable: I - an induction period, II - a spherulitic crystallization stage, and III - a final crystallization stage. The duration of the induction period, the crystallization rate of the high- quartz solid solution, and the microstructures varied markedly with prior nucleation treatment and the type of modifier present in the glass of nearly equal silica content. The roles of major (high-quatrz ss, high-cordierite) and of minor crystalline and liquid phases in textural development are discussed and it is postulated that nucleants (ZrO₂, TiO₂) act also as growth-modifying “impurities.”

TITLE: Nucleation and Crystallization of MgO-Al₂O₃-SiO₂ Glass Ceramics

Chalmers University of Technology, No. 1349, Gothenburg, 1975.

By W.A. Zdaniewski

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TITLE: Crystallization and Structure of MgO-Al₂O₃-SiO₂-TiO₂ Glasses

J. Mater. Sci. 8, 192-202, 1973.

By W.A. Zdaniewski

The structure and changes occurrinng during the volume crystallization of a MgO-Al₂O₃-SiO₂-TiO₂ glass induced by heat treatment at temperatures in the range 740º to 1300º C were investigated by means of DTA, SEM, X-ray diffraction EMX analysis, density and other measurements. Crystallization proceeds by liquid phase separation and coalescence of small particles forming larger microcrystalline regions dispersed in the glassy phase. The scanning electron microscope revealed two crystalline phases in the initial stage (850-890º C) of crystallization while X-ray diffraction identified only u-cordierite type structure (i.e. high-quartz ss), which at T above 1100º C is transformed into the alpha-form.

TITLE: Review: The Internal Friction of Glasses

J. Mater. Sci. [14] 763-775, 1979.

By W.A. Zdaniewski, G.E. Rindone and D.E. Day.

Basic fundamentals of the elastic behaviour of astandard linear solid and the internal friction technique based on this model are briefly described. Th internal friction (Q^-1) caused by various thermally activated processes in vitreous solids are reviewed for several glass compositions in relation to ionic mobility and other relevant properties. Similar relaxation mechanisms characterize many vitreous solids. The relaxation of alkali ions is essentially independent of the glass network former and has an activation energy of 15 to 25 kcal mol^-1. Other processes like the interaction of oxygen ions and protons, alkali ions and protons, mixed-alkali ion interaction and the motion of single bonded oxygen ions have an activation energy of 30 to 40 kcal mol^-1. The activation energy for relaxation of the glass network is 100 to 120 kcal mol^-1.

TITLE: Effect of Water Vapor on the Internal Friction of Binary Silicate Glasses

J. Amer. Ceram. Soc. 64 [12] C183-84, 1981.

By W.A. Zdaniewski and G.E. Rindone

Internal friction and shear modulus of Na, K, and Li disilicate glasses were measured by a torsional pendulum as a function of water vapor treatment at T=300º C. H₂0 produced changes in the acoustic spectra similar to the mixed-alkali effect wchich appears upon introduction of a second alkali to a single-alkali glass. An Na₂0.2Si₂0 glass free from the common nonbridging oxygen relaxation was produced.

TITLE: Determination of Crystallization Kinetics of Industrial Waste Slags and Glasses by Viscosity Measurements.

Inst. Mat. Budowl., Pub. No. 29737-A, Krak—w, 1970.