Characterization Of Glass-ceramics Research Articles

Immobilize Nd2O3 as simulated nuclear waste in silicate-apatite glass-ceramics

The solidification of nuclear waste has far-reaching developmental implications. Nuclear waste management is not only essential for the earth’s ecological balance but also can address the increasing depletion of human exploitable resources in the future. Scientists are dedicated to finding a better solidification matrix and ensuring the sustainable development of the nuclear industry in search of alternative energy sources. The present work has fabricated a simulated nuclear waste form using a sintering process of diopside. The results have shown that the Fe element in diopside granite porphyry shows an impact on the amorphization process and mechanical properties of the final waste form. Moreover, the study finds a natural analog in the glassy bulk, i.e. (Ca2Nd8(SiO4)6O2 or (K, Na)Nd9(SiO4)6O2), which can solidify the simulated trivalent actinide of Nd3+. The FT-IR results suggested that the polymerization degree of glass components in waste form decreased initially and then increased with Nd2O3 doping. Q3 unit is considered to be a key component in the waste forms. Finally, the loading capacity of Nd2O3 in waste form reached 19 wt.%. The waste form has the characteristics of glass-ceramics containing a silicate-apatite structure that is evenly distributed and has a quite considerable prospect for mechanical properties.

Preparation and characterization of glass-ceramics with granite tailings and titanium-bearing blast furnace slags

The resource utilization of granite tailings and titanium-bearing blast furnace slags is an emphasis of current research and is widely considered. In this work, by adopting these two slags as raw materials, diopside-based glass-ceramics were synthesized by melting-cooling-monolithic crystallization. The influence of the content of granite tailings, namely, the ratio of (SiO2+Al2O3/CaO+TiO2) on the structure and properties of glass-ceramics was characterized with differential scanning calorimetry, X-ray diffraction, scanning electron microscope, volume density and microhardness. The results suggest that the introduction of granite tailings makes the melting quality of glass deteriorate and the crystallization tendency decrease, the number of microcrystalline in glass-ceramics decreases and the glass phase increases. Moreover, the increase of Si/O ratio is advantageous to the precipitation of wollastonite but not diopside, and the volume density and microhardness of glass-ceramics decrease with the increase of granite tailings. When the content of granite tailings is 40 wt%, the crystal structure of glass-ceramics is moderate, the volume density and microhardness are 3.0207 g/cm3 and 8.6 GPa, respectively, which are excellent for architectural decoration.

Preparation and characterization of glass-ceramics from oil shale ash: Effect of basicity and sintering temperature on crystallization behavior, properties, and environmental risk

Oil shale ash is an inorganic by-product generated from the combustion and refinement of oil shale. In this study, it was used as main raw material to produce glass-ceramics. The crystalline phases, crystallization mechanism, bulk density, compressive strength and microstructure of glass-ceramics were studied. Specifically, the leaching characteristics and ecological risk assessment of heavy metals in glass-ceramics were emphasized. The results showed that the increase of basicity reduced the crystallization activation energy, but the surface crystallization mechanism of different samples has not changed. Anorthite and diopside were identified as the main crystalline phases in glass-ceramics despite varying basicity and sintering temperatures. The compressive strength and bulk density increased with the increase of sintering temperature. The compressive strength of VS2 (basicity = 0.3) was higher than that of VS1 (basicity = 0.2) for the same sintering temperature due to more crystals and denser microstructure. Independent of the basicity, a higher sintering temperature promoted the sintering and densification of products. The highest compressive strengths of VS1 and VS2 were 219.14 ± 12.8 and 255.57 ± 15.6 MPa, respectively. In addition, the reliable stability and low potential ecological risk index of heavy metals in the final products make it to be a competitive eco-friendly construction material.

Preparation and characterization of glass-ceramics via co-sintering of coal fly ash and oil shale ash-derived amorphous slag

Abstract A novel preparation method of glass-ceramics from coal fly ash (CFA) and oil shale ash-derived amorphous slag (OSAS) was developed in this study. Effects of important factors such as OSAS/CFA ratio and sintering temperature on the crystalline phase compositions, microstructure, mechanical-chemical properties, heavy metals leaching characteristics, and potential ecological risk assessment of glass-ceramics were investigated. The results showed that the properties of glass-ceramics increased with increasing OSAS/CFA ratio and sintering temperature, and S4 glass-ceramics (100% OSAS) showed the most superior product performances, followed by the S3 (80%OSAS-20%CFA), S2 (60%OSAS-40%CFA), and S1 (100% CFA). As for the products from the mixed sources, the best product properties of S2 glass-ceramics (density, 2.00 ± 0.04 g/cm 3 ; water absorption, 3.11 ± 0.22%; and compressive strength, 106.67 ± 28.42 MPa) were achieved at 1085 °C. S3 glass-ceramics showed the highest density of 2.16 ± 0.04 g/cm 3 , and lowest water absorption of 0.22 ± 0.01%, and highest compressive strength of 195.99 ± 23.85 MPa at 1085 °C. Specially, the overall energy consumption for preparing S2 and S3 glass-ceramics was estimated to be reduced 23.66–27.00% and 11.67–13.50%, respectively, compared to that of S4 glass-ceramics. In addition, the good chemical stability, low heavy metals leaching concentrations and low potential ecological risk of OSAS-CFA-derived glass-ceramics further confirmed its potential and feasibility as building material in engineering application.

Development and Characterization of Glass-Ceramics from Combinations of Slag, Fly Ash, and Glass Cullet without Adding Nucleating Agents.

Developments in the field of materials science are contributing to providing solutions for the recycling of industrial residues to develop new materials. Such approaches generate new products and provide optimal alternatives to the final disposal of different types of industrial wastes. This research focused on identifying and characterizing slag, fly ash, and glass cullet from the Boyacá region in Colombia as raw materials for producing glass-ceramics, with the innovative aspect of the use of these three residues without the addition of nucleating agents to produce the glass-ceramics. To characterize the starting materials, X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM) techniques were used. The results were used to evaluate the best conditions to produce mixtures of the three waste components and to determine the specific compositions of glass-ceramics to achieve products with attractive technical properties for potential industrial applications. The proposed mixtures were based on three compositions: Mixture 1, 2, and 3. The materials were obtained through thermal treatment at 1200 °C in a tubular furnace in accordance with the results of a comprehensive characterization using thermal analysis. The microstructure, thermal stability, and structural characteristics of the samples were examined through SEM, differential thermal analysis (DTA), and XRD analyses, which showed that the main crystalline phases were diopside and anorthite, with a small amount of enstatite and gehlenite. The obtained glass-ceramics showed properties of technical significance for structural applications.

Characterization of Glass Ceramics Produced from Natural and Waste Raw Materials

Glass ceramics were prepared from fly ash, waste window glass and fluorite rawmaterials. Mixtures of raw materials were melted at 1300, 1400 and 1500 °C for 4 h and quenchedin cold water. The crystallization behavior of glass ceramics was investigated by differentialthermal analysis-thermogravimetry (DTA-TG). Crystallization at various temperatures (700, 800,900 and 1000 °C) for 30 min was used to obtain the glass ceramics. The obtained glass ceramicswere characterized by X-ray diffraction (XRD), light microscopy and hardness test. XRD studyrevealed that the crystallized phases were plagioclase-type minerals (diopside and albite). TheVickers hardness of the glass ceramics increased from 0.80±0.19 GPa to 6.35±0.35GPa and densityranged from 1.44 g/cm3 to 2.42 g/cm3 depending on the treatment temperature. Glass ceramicsprepared from fused glass melted at 1500 °C temperature showed the highest hardness comparedwith those melted at lower temperatures.

Characterization of Glass-Ceramics by TEM

The characterization technique of glass-ceramics by TEM was discussed by comparing the effects of single layer carbon film technique and double layers carbon film technique on the microstructure of Li-Al-Si glass-ceramics. The results show that double layers carbon film technique can improve glass-ceramics sample’s conductivity, reduce the induction of elctron beam on glass-ceramics, and avoid the temperature increasing of glass-ceramics particles caused by the charges aggregation on the particles’ surface when TEM electron beam hit down, prevent glass-ceramics from crystallization and the transformation of microstructurec. So, compared with single layer carbon film technique, double layers carbon film technique is more suitable for the research of microsture of glass-ceramics by TEM.

A Comparative Overview of Glass-Ceramic Characterization by MAS-NMR and XRD

Glass-ceramics are polycrystalline materials formed by controlled crystallization of parent glasses, which can be studied complementarily by XRD and NMR. XRD probes long-range order, while NMR is more element specific and probes the immediate environment around the atoms. These techniques allow considerable insights into the crystalline and amorphous constituents of glass-ceramics. In this article, we highlight some key issues in the characterization of glass-ceramics: phase identification and quantification, and structural characterization of the residual glass. The application of both NMR and XRD techniques are considered in these areas and their advantages and limitations discussed using our recent work and examples from the literature.

Preparation of Glass-Ceramics Using Molybdenum Tailings

In order to utilization the molybdenum tailings which be deposited in large quantities. Test used it to prepare glass-ceramics as main raw material, TiO2 as nucleation agents and CaO-Al2O3-SiO2 system and wollastonite as the principal crystalline phase. Heat treatment system of glass-ceramics was based on the differential thermal analysis. The crystalline phase, microstructure and characteristics of glass-ceramics were analysis by XRD, SEM and physical, chemical properties test. The result shows that the performance of glass-ceramics was superior to the other types of building decoration stone.

Production and Characterization of Glass-Ceramics From Waste Materials

The fly ash, produced by power plant in Republic of Macedonia have been milled and sintered with addition of waste glass to obtain glass-ceramics. The physical, chemical and mechanical properties of fly ash and waste glass were determined. Through adequate sintering time and temperature, the glass-ceramic materials were manufactured. Chemical, physical and mechanical properties of the obtained composites were defined. The optimal composition of the composite was fly ash with the addition of 40% waste glass. Optimal sintering condition was 1000oC with 1h isothermal time at final temperature and heating rate of 10o/min. The addition of 40%wt of waste glass in the fly ashes increased the E-modulus from 4.24±1 to 30.55±2 GPa and increased the bending strength from 9.93±1 to 63.18±4 MPa Porosity of the compacts decreased from 44.34±3 to 14.32±2%. Investigation of durability of the produced systems did not show presence of any harmful elements in the obtained solution. Owning to combination of the macroscopic appearance, microstructure, mechanical and thermal properties developed, dense materials could be used in the civil engineering.

Characterization of Glass-Ceramics Produced from Waste Materials

Characterization of Glass-Ceramics Produced from Waste Materials

Production and characterization of glass ceramics from steelwork slag

Glass and glass ceramics were obtained using steelwork slag as a raw material. Glass was melted at 1500°C and heat treatments were performed at 720°C for nucleation and at 883°C for crystallization. Differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM), with energy dispersive X-ray spectrometer (EDX) were used to investigate glass and glass ceramics. The crystalline phases developed were diopside and augite. The final microstructure was made up of crystals uniformly distributed, with a size of 1 to 3.5 μm.