Effect of Different Concentrations of Titanium Oxide (TiO2) Addition on the Crystallization Behaviour and Some Properties of Alkaline Earth Aluminosilicate Glass-Ceramics

Glass-ceramics in the CaO-MgO-Al2O3-SiO2 quaternary base glass system was produced via melting technique using feldspar, limestone and magnesite as sources of starting materials. Glass-ceramics production involves making a base glass, annealing and cooling to room temperature and then reheating the base glass to nucleation and crystal growth temperatures. Characterization of the produced glass-ceramics was carried out using a scanning electron microscope (SEM). The effects of the crystallization process on some properties such as hardness, chemical durability in acid and alkali media of samples were determined. The results portrayed that glass-ceramic samples to which various amounts of TiO2 (2,4,6,8 and 10 wt.%) were incorporated showed the formation of crystalline phases dispersed in the matrix of their respective residual glassy phases. Significant improvement in hardness, as well as minimum weight loss, were recorded for all the glass-ceramic samples. On the contrary, the glass samples did not crystallize despite subjecting them to heat treatment, their hardness values were low and they were not resistant to acid (1M HCl) and alkali (1M NaOH) attacks. The inability of TiO2 addition to fully transform them into glass-ceramics remains a shortcoming. However, the glass-ceramic samples obtained from this study can be used for tiling works.

Patterns of coloring with ionic dyes of the base glass matrix and enamel coatings in the system R2O–ВаО–ZnO–Al2O3–В2О3–TiO2–SiO2

The paper presents the study on the identification of patterns of coloring of a basic glass matrix and enamel coatings based on it in the system R2O–ВаО–ZnO–Al2O3–В2О3–TiO2–SiO2 by a number of ionic dyes. Regardless of the dye content, ionic dyes give the same color tone to both glasses and coatings based on these glasses as follows: CuO (1.0–3.0 wt.%) =489–494 nm (blue-green), Fe2O3 (0.5–2.0 wt.%) =575–585 nm (yellow), K2Cr2O7 (0.5–2.0 wt.%) =570–576 nm (yellow-green), CoO (0.5–1.0 wt.%) =441–463 nm (blue-violet), and NiO (0.5–1.0 wt.%) glass=559'–571' nm, coatings=598–629 nm (brown). It is shown that according to the degree of color intensity of glasses and coatings based on them, the dyes are arranged in the following sequence: CoO>NiO>CuO>K2Cr2O7>Fe2O3.. The research was conducted using a special computer program COLOR GLASS. The established patterns are used in the development of lead-free glass enamels for jewelry and decorative products.

ADDITION OF FLY ASH TO THE FIBER COMPOSITE GLASS ON COMPOSITE FUEL RESISTANCE PROPERTIES

The process of making composites into several main stages, namely preparation of tools, cutting of specimens. Then the base (glass) is cleaned and coated with molding wax and PVA. Mix the resin with the addition of variations of fly ash 0%, 10%, 20% and 30%. Next, apply resin and glass fiber to the base (glass) for up to 3 layers then press it. After 12 hours remove the specimen and cut it to size

Study on the Preparation and Properties of Fe-tailings Based Foamed Glass-ceramics

Traditional building materials have disadvantages such as high pollution and high energy consumption, so it is particularly important to develop new environmentally friendly materials. In this paper, foamed glass-ceramics are prepared by high-temperature melting method with iron tailings, blast furnace slag, and desulfurization slag as the main raw materials, and CaCO3 as foaming agent. The effects of three kinds of basic glass scheme, the content of the foaming agent and heat treatment system on the degree of crystallization, micro-morphology, and crystal phase composition of foamed glass-ceramics are studied. The nucleation temperature and crystallization temperature of the basic glass are determined by differential thermal analysis curve to be 730 ℃ and 1000 ℃, respectively. Orthogonal experiments show that the optimal composition ratio of the prepared base glass is CaO: 22.25 wt.%, MgO: 4.57 wt.%, Al2O3: 6.19 wt.%, SiO2: 41.8 wt.%. The optimized scheme is based on a base glass prepared with 45 wt.% iron tailings, 25 wt.% blast furnace slag, and 30 wt.% desulfurization slag, added with 10% CaCO3 and sintered to 1000 °C for 3 h. The bending strength, fracture toughness, and elastic modulus are 95.73 Mpa, 53.09 Mpa·m1/2, 28023.55 Mpa, respectively.

O efeito do tratamento térmico sobre a microdureza e cristalinidade de uma vitrocerâmica obtida da reciclagem de resíduos vítreos

<p>The growth in the consumption of industrialized products has implied a considerable increase in the generation of urban solid waste, among which stand out the glass waste. The great technological advantage of glass is its high recycling potential, as well as the possibility of being molded into the desired shape, which contributes to various applications. In this sense, this work aims to analyze the efficiency of the heat treatments applied to green-soda-glass vitreous samples from the recycling of filling bottles, and compare with the hardness of the base glass. Initially the bottles were benefited and manually crushed for later sieving. Then, the vitreous residues were accommodated in an autoclaved cellular concrete (CCA) mold and subjected to heat treatments, which resulted in the melting and annealing of the pieces. Four distinct heat treatments were tested, with melting temperatures of 800ºC (20 min), 820ºC (20 min), 840ºC (15 min) and 840ºC (30 min). The obtained samples were analyzed by X-ray diffraction (XRD) and Vickers microhardness test. The results indicated that the fourth heat treatment (840ºC - 30min.) Gave higher hardness than the base glass and higher degree of crystallinity.</p>

The Crystallization and Characterization of Calcium-Magnesium- Aluminosilicate Glass-Ceramics

Calcium-magnesium-aluminosilicate (CaO.MgO.Al3O3.SiO2) glass-ceramics was developed from the base glass system of the composition 52.00 wt% SiO2, 16.00 wt% Al2O3, 12.00 wt% CaO, 8.00 wt% MgO, 2.00 wt% K2O, 6.00 wt% TiO2, 0.30 wt% NaCl and 3.70 wt% in this study. The study focused attention on the crystallization of CaO.MgO.Al3O3.SiO2 base glass system using 363℃ & 663℃ as nucleation and crystal growth temperatures respectively, and 1 – 4 hours as soaking time. The composition was melted at 1600℃ for 3 hours in a muffle furnace and the molten glass was cast into rods, annealed at 600℃ for 1 hour and finally cooled to room temperature. Due to the presence of impurities in the starting materials, the glasses produced have a brownish physical appearance. Base glasses were crystallized into glass-ceramics using double-stage heat treatment schedule, and XRD and SEM were used to characterize the produced samples. The XRD identified the crystalline phases precipitated in the residual glass matrix of the sample soaked for 4 hours as albite, quartz, wollastonite and witherite. The SEM result revealed that the microstructure of the sample is characterized by dense, circular-like and needle-like clusters alongside micro-sized voids dispersed in the residual glassy phase matrix. The density and hardness values were found to increase while weight loss decreased with increase in soaking time across the samples. The sample soaked for 4 hours has the lowest weight loss but with the highest density and hardness values making it suitable for use for abrasion due to its excellent properties.

Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.