The influence of TiO2 content on the properties of glass ceramics: Crystallization, microstructure and hardness
TL;DR: In this article, the effects of compositional variation, crystallization behavior, crystalline phases and microstructure formed in the SiO23Al2O33CaO (SAC) glass system using various amounts of TiO2 as nucleating agent were investigated by Differential Thermal Analysis (DTA), X-ray powder diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive Xray spectroscopy (EDAX) and Fourier transform infrared spectrography (FTIR) techniques.
About: This article is published in Ceramics International.The article was published on 2014-04-01. It has received 68 citations till now. The article focuses on the topics: Glass-ceramic & Crystallization.
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TL;DR: In this paper, the melting-quench technique was used to obtain the glass-ceramics and the de-polymerization of phosphate groups was observed in all the samples.
70 citations
TL;DR: In this paper, a short overview of the production of unique high performance glass-ceramics using coal fly ash as a raw material is presented, and a detailed description of the methodologies for the synthesis of glass-cameramics from coal fly-ash and the principal crystal phases, corresponding property and possible usage of those materials are introduced.
58 citations
TL;DR: In this paper, the effect of MgO addition on the sinterability and crystallization of sintered glass-ceramics prepared from powder mixtures of waste glass and fly ash was investigated.
53 citations
TL;DR: In this article, spodumene was used as the main raw material, and TiO2 and ZrO2 were added as crystal nucleating agents to prepare transparent glass-ceramics with low expansion coefficient.
Abstract: The price of lithium-containing minerals and other chemical materials continues to increase, resulting in an increase in the production cost of Li2O-Al2O3-SiO2 (LAS) system glass-ceramics. In the LAS glass-ceramics component, the reduction in the amount of Li2O used can reduce the cost of the product. It is worthwhile to study whether it is possible to prepare glass-ceramics with low expansion properties under low Li2O content. The effect of Li2O content on the glass-ceramics of LAS system was studied. In this paper, spodumene was used as the main raw material, and TiO2 and ZrO2 were added as crystal nucleating agents to prepare transparent glass-ceramics with low expansion coefficient. The effects of the change of Li2O content on the crystal phase and microstructure of glass-ceramics were investigated by XRD, DSC, FTIR and SEM. The results show that the main crystalline phase of the low expansion transparent glass-ceramics is β-quartz solid solution. When Li2O content is in the range of 2.99 wt% to 4.13 wt%, low expansion glass ceramics can be prepared by an appropriate method. With the increase of Li2O content, the average coefficient of thermal expansion (CTE) in the temperature range of 30 °C–300 °C shows a decreasing trend. When Li2O content is in the range of 3.51 wt% to 4.13 wt%, the thermal expansion coefficient of the glass ceramics is extremely small, and even a negative expansion coefficient occurs.
42 citations
TL;DR: In this paper, the effects of SiO2/(CaO+MgO) ratio on the crystallization behavior, microstructure and properties of glass-ceramics were investigated.
Abstract: Granite wastes were used as the raw materials for the preparation of CaO-MgO-Al2O3-SiO2 glass-ceramics. The waste loading was about 50.24–68.34 wt% in the batch depending on the chemical compositions of glasses. Effects of SiO2/(CaO + MgO) ratio on the crystallization behavior, microstructure and properties of glass-ceramics were investigated. The results showed that the crystallization activation energy Ec increased from 322.68 to 477.10 kJ/mol, and Avrami parameter n decreased from 3.78 to 2.89 as the SiO2/(CaO + MgO) ratio increase from 1.72 to 4.99, while, the crystallinity of diopside decreased gradually, and the main crystalline phase changed into armalcolite with SiO2/(CaO + MgO) ratio increase to 4.99. The increase in SiO2/(CaO + MgO) ratio lead to the decreasing in Vicker's hardness, bending strength and alkali resistance of the glass-ceramics, but improved the acid resistance.
42 citations
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TL;DR: In this article, an extension of the Kissinger method was proposed for the analysis of the transformation kinetics of the metastable equiatomic tin-nickel alloy with differential thermal analysis (DTA).
Abstract: Several isothermal experiments are generally needed to determine the parameters of the Avrami equation which describe most of the heterogeneous solid state reactions. Differential scanning calorimeters are suitable for such experiments. While most differential thermal analysis (DTA) apparatus cover a wider temperature range than DSC apparatus they cannot be used to perform isothermal determinations. However, Kissinger has already shown how activation energy and frequency factor can be calculated from DTA experiments for the case of homogeneous reactions following first order kinetics. We derive in this paper an extension of the Kissinger method and show its applicability to heterogeneous reactions described by an Avrami expression. The new method will allow the study of the kinetics of metallic reactions at the higher temperature range obtainable with DTA. The transformation kinetics of the metastable equiatomic tin-nickel alloy are given as an example.
1,067 citations
TL;DR: In this paper, the authors proposed an index of brittleness based on the ratio H/Kc, where H is hardness (resistance to deformation) and Kc is toughness.
Abstract: The ratio H/Kc, wjere His hardness (resistance to deformation) and Kc. is toughness (resistance to fracture), is proposed as an index of brittleness. Indentation mechanics provides the scientific basis for this proposal. The analysis, developed in terms of a model contact system, indicates that all materials are more susceptible to deformation in small-scale loading events and to fracture in large-scale events. By normalizing the characteristic dimensions of the two competing processes and the contact load in terms of appropriate functions of H and Kc a universal deformation/fracture diagram can be constructed. From this diagram the mechanical response of any material of known hardness and toughness may be predicted for any prospective in-service contact loading conditions. The concept offers a simple approach to materials classification for design purposes.
703 citations
TL;DR: In this article, the modified Kissinger-type equation was derived on the basis of the nucleation and growth equations, and the validity of the equation was ascertained by applying to the crystallization of Li 2 O·2SiO 2 glass whose kinetic data regarding crystallization are already well-known.
Abstract: For the purpose of analyzing the crystallization process of glass by DTA, the modified Kissinger-type equation was derived on the basis of the nucleation and growth equations, and the validity of the equation was ascertained by applying to the crystallization of Li 2 O·2SiO 2 glass whose kinetic data regarding crystallization are already well-known. The modified Kissinger-type equation is identical with the so-called Kissinger equation only when the crystallization starts at the surface and grows towards the inside of the glass one-dimensionally. The conditions required for applying the Kissinger plot or modified Kissinger-type plot to the crystallization of glass were discussed, and it was concluded that the crystallization mechanism should be known in order to obtain the meaningful activation energy.
451 citations
TL;DR: In this paper, five glasses in the CaO−SiO2 binary system with different silica content (50−90% in mol) have been prepared by the sol−gel method.
Abstract: Five glasses in the CaO−SiO2 binary system with different silica content (50−90% in mol) have been prepared by the sol−gel method. The referred glasses have been characterized by thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) showing clear differences in composition and specific surface and porosity between those glasses with low SiO2 content (50−70% in mol) and those with high SiO2 content (80−90% in mol). The in vitro bioactivity study of all glasses prepared were carried out by soaking in a simulated body fluid (SBF) at 37 °C. The FTIR, XRD, SEM, and EDS analysis of the surface of these glasses after the in vitro assays reveal the formation of a hydroxycarbonate apatite (HCA) layer. The formation process of this layer on the glass is a function of the glass composition. The rate of formation increases in those glasses with lower SiO2 (50−70...
216 citations