Papers by Keyword: Glas Ceramics

Abstract: By utilizing chrysotile asbestos tailing from Shannan ore in Sichuan as the main raw material, diopside-based glass-ceramics were successfully synthesized in the laboratory by adding some limestone, quartz sand, Al₂O₃, H₃BO₃, Na₂CO₃ and CaF₂. The optimum procedure for glass-ceramics was as follows: melting at 1400 for 60 min, sintering at 1100 for 120 min. Through the tests of physical and mechanical properties, the glass-ceramics materials with more crystalline phase had high density, fine performance of resisting compression (366MPa) and negligible water absorption. Through chemical resistance tests, the glass-ceramics samples showed strong corrosion resistance. Overall result indicated that it was a feasible attempt to produce glass-ceramics materials for building and decorative materials from chrysotile asbestos tailing.

Abstract: Sm³⁺ doped transparent glass-ceramics of CaO-B₂O₃-SiO₂ (CBS) system were prepared and characterized.The precursor glass was prepared by melting method and annealed at 450°C for 2h and cooled to room temperature at a speed of 5°C/min.The appropriate heat treatment schedule to precursor glass was determined to be 2h at 600°C for nucleation and 3h at 810°C for crystallizition.The transmittion of glass-ceramics at the range of visable light is 68% in average. Five main emission bands of Sm³⁺ are centered around 564nm,605nm,646nm,679nm and 789nm,which correspond to the ⁴G _5/2→⁶H _5/2,⁴G _5/2→⁶H _7/2,⁴G _5/2→⁶H _9/2,⁴G _5/2→⁶H _11/2 and ⁴G _5/2→⁶H _13/2 transitions.Very strong luminescence at around 599nm is observed in glass-ceramics,This indicates glass-ceramics to be a better host for Sm3+ than precursor glass and a hopeful laser material.

Abstract: The Li-ion fast conductor, Li_1-XAl_xTi_2-X(PO₄)₃ (LATP) compound were synthesized by a sol-gel method. Effects due to the addition of Al³⁺ into Li_1-XAl_xTi_2-X(PO₄)₃ (x=0.0-0.5) glass-ceramics system have been investigated using electrochemical impedance spectroscopy (EIS), X-ray differential analysis (XRD) and permittivity studies. The crystalline phase of the samples obtained confirming that they had a characteristic of glass-ceramics structure.

Abstract: Lithium carbonate, zinc oxide and silica as the main raw materials, potassium oxide and sodium as flux, phosphorus pentoxide as nucleating agent, the glass in Li₂O-ZnO-SiO₂ was synthesized by conventional melt cooling method and then converted to glass-ceramics. The crystallization behavior, microstructure and thermal expansion coefficient of the resulting glass-ceramics were investigated by XRD, SEM and thermal performance test. The results show that the Tg of the matrix glass is about 508°C, initial crystallization temperature is about 620°C. When the crystallization temperature ranges from 650°C to 750°C, the main crystal phase is Li₂ZnSiO₄. Increasing crystallization temperature to 850°C, much cristobalite crystals is formed. Owing to the high TEC of the cristobalite, the glass-ceramics with TEC of 12.27×10^-6°C^-1 were obtained, which is matched with the TEC of stainless steel SAE 1010.

Abstract: The glass-ceramics were made of arc-melting slag from incinerator fly ash mixed with glass cullet additive by sintering method. The effects of ball milling time and powder compaction pressure on the microstructure, physical and mechanical properties of the glass–ceramics were respectively investigated. Results showed that with milling time delaying, granularity of the parent glass evidently reduces, the major phases of glass–ceramics have no change but the diffraction peaks present intensive trend, the crystal sizes of glass–ceramics decrease, the properties such as volumetric densities, compressive strength, bending strength and toughness are improved, the appropriate milling time is 6h with fifty percent of the volume (d50 value) of 10.62μm. The physical and mechanical properties first increase and then decrease with compaction pressure increasing, and the optimal compaction pressure is 60MPa.

Abstract: Ag₂O-CaO-Fe₂O₃-SiO₂ glass-ceramic was prepared by the sol-gel method. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used to investigate crystallization process of Ag₂O-CaO-Fe₂O₃-SiO₂ glass. The kinetic results show that the values of the activation energy and frequency factor of the glass are 441.991 KJ/ mol and 1.58×10²⁰, respectively. And the dimensionality of crystal growth, n, decreases as the heating rate increases. The crystalline phases of the glass-ceramic are magnetite, wollastonite and minor hematite. The saturation magnetization and coercive force of the heat-treated glass are 0.08 Wb/m² and 14 KA/m at room temperature. The glass-ceramic has some capacity of anti-microbial.

Abstract: Lime phosphosilicate and soda lime phosphosilicate glasses prepared by sol-gel method were precursors of bioactive glass-ceramics. The structure of the samples and the distribution of the [SiO₄] units was investigated by X-ray diffraction and infrared spectroscopy. Human osteosarcoma cell line (MG63) was used for the in vitro cellular response. DNA staining (Hoechst 33258) assay was performed for assessing samples colonization.

Abstract: The aim of this work was to improve a newly developed family of glass-ceramic composite materials by incorporating silver ions in the ceramic structure, thus developing new Ag-doped materials with the ability of showing antibacterial activity for dental applications. Two different sol-gel methodologies were applied for the fabrication of colorless, homogenous and chemically durable materials which can slowly release silver ion for relatively long periods. Both methods led to the successful development of Ag-doped glass-ceramics with silver ions incorporated in the structure that can slowly release in buffer solution, during a period of 45 days. The potential, application of these materials involve the development of bioactive surfaces on dental substrates which can seal the marginal gap creating a bacterial free environment finally supporting the success of dental restorations.

Abstract: Modification of surface morphology and composition of niobophosphate glass and glass-ceramic in the system P₂O₅-CaO-Nb₂O₅-Na₂O was investigated. Amorphous, partly crystalline and crystalline samples were prepared in shape of pellet with diameter 10 mm. Samples were treated in 1 and 5 days in citric acid at 37°C and 3h in boiling HCl. Surface morphology before and after treatment was investigated by scanning electron microscopy (SEM), phase composition by X-ray powder diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Glass sample was smooth, after treatment in citric acid it had cracks and pit-holes on the surface. Partly crystalline sample was smooth and contained inclusions of crystalline Ca₃(PO₄)₂ and Ca₂P₂O₇. Platy crystals of Ca₃(PO₄)₂ dissolved first, than bulky Ca₂P₂O₇. Crystalline samples contained Na₄Nb₈P₄O₃₂ and calcium phosphate phases; surface was rough before and after treatment. EDX showed that amount of phosphorous is proportional to amount of calcium and inversely proportional to amount of sodium and niobium in glass-ceramic samples.

Abstract: Beta-spodumene glass-ceramic powder was prepared by Sol–gel route. Tetraethyl orthosilicate (TOES), aluminum nitrate, lithium carbonate were used as starting materials. X-ray powder diffraction (XRD), thermal expansion coefficient (TEC), scanning electron microscope (SEM) and transmission electron microscope (TEM) were utilized to characterize the dried LAS gels and glass-ceramic blocks. The results suggest beta-spodumene is the only crystals phase in the prepared LAS glass-ceramics powder when sintering temperature is 950 °C. The average particle size of the beta-spodumene crystal is about 30 nm with a narrow size distribution both in prepared LAS glass-ceramics powder and block. The thermal expansion coefficient of moulding pressed blocky LAS glass-ceramics is lower than 0.6×10^{-6 o}C^-1.