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Bishiou Chiou - One of the best experts on this subject based on the ideXlab platform.

  • low temperature sintering and crystallisation behaviour of low loss Anorthite based glass ceramics
    Journal of Materials Science, 2003
    Co-Authors: Jenqgong Duh, Bishiou Chiou
    Abstract:

    Anorthite-based glass-ceramics including TiO2 as nucleating agent were melted and quenched in this study. The effect of particle size on the sintering behaviour of glass powders was investigated in order to obtain low-temperature sintered glass-ceramics. Anorthite glass-ceramic starts to densify at the transition temperature of glass (T g = 770°C) and is fully sintered before the crystallisation occurrence (880°C). Therefore, a dense and low-loss glass-ceramic with predominant crystal phase of Anorthite is achieved by using fine glass powders (D 50 = 0.45 μm) fired at 900°C. The as-sintered density approaches 99% theoretical density and the apparent porosity is as low as 0.05 Vol%. The dense and crystallized Anorthite-based glass-ceramic exhibits a fairly low dielectric loss of 4 × 10−4 at 1 MHz and a thermal expansion coefficient of 4.5 × 10−6°C−1. Furthermore, the microwave characteristics were measured at 10 GHz with the results of K = 9.8, Q f = 2250, and temperature coefficient of resonant frequency τf = −30 ppm/°C.

  • microstructure characteristics for Anorthite composite glass with nucleating agents of tio2 under non isothermal crystallization
    Materials Research Bulletin, 2002
    Co-Authors: Jenqgong Duh, Bishiou Chiou, Wenhsi Lee
    Abstract:

    Abstract The Anorthite-based composite glass doped with TiO2 and B2O3 was prepared by quenching of molten droplets. Phase development and crystals microstructure of glass were investigated under non-isothermal conditions. A glass transition temperature of 770°C and an exothermal peak around 870°C in the DTA trace was associated with Anorthite crystallization (CaAl2Si2O8). For glass specimens under nucleation and crystallization heat-treatment, the final predominant phase was identified as Anorthite. Anorthite crystals show preferential nucleation at specific sites with rutile TiO2 crystals precipitated from the glassy matrix and Anorthite crystallization is governed by heterogeneous volume nucleation. The introduced TiO2 plays the role of nucleating agents to reduce the crystallization temperature lower than 900°C for Anorthite-based glass–ceramics. Chemical compositions could be related to the crystal microstructures on different characteristic regions. It was observed that the sintering aid of B2O3 neither reacted with nor dissolved in the Anorthite or rutile TiO2 crystals, and remained a glassy phase in the matrix. Occurrence of acicular precipitations was attributed to the orientation growth of TiO2 crystals. Anorthite crystals were observed to grow with the forms of feathery-spherical particles, having a tendency to coalescence into a huge domain.

  • low temperature sintering and microwave dielectric properties of Anorthite based glass ceramics
    Journal of the American Ceramic Society, 2002
    Co-Authors: Chunglun Lo, Bishiou Chiou
    Abstract:

    TiO2 nucleated Anorthite-based glass-ceramics were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including apparent bulk density and water absorption, were examined to evaluate the sintering behavior of Anorthite-based glass-ceramic. Results showed that the complete-densification temperature for specimens was as low as 900°C. Sufficient crystallization was achieved by subsequently raising the firing temperature to 950°C, and the dielectric quality factor was promoted to the maximum value. Contents of nucleating agent (TiO2) played an important role in the dielectric constants. The crystallinity was controlled by raising the firing temperature at a constant heating rate. The degree of crystallization affected the dielectric properties of sintered glass-ceramics. At the resonant frequency of 10 GHz, Anorthite glass-ceramics with 5 wt% TiO2 possessed the lowest permittivity of 8 and exhibited appropriate dielectric properties as compared with those with B2O3 and 10 wt% TiO2.

Chang-an Wang - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and growth of Anorthite crystal during in situ preparation of porous Anorthite ceramics by foam gelcasting
    International Journal of Applied Ceramic Technology, 2017
    Co-Authors: Yao Han, Chang-an Wang
    Abstract:

    Pure Anorthite porous ceramics have been fabricated using γ-Al2O3, CaCO3, and SiO2 as raw materials through foam-gelcasting method. XRD, thermal analysis, SEM, and TEM were used to study the synthesis and grain growth of Anorthite during the in situ process. The results indicated that the initiator (ammonium presulfate) took part in the chemical reaction to form CaSO4, which played an effective role during synthesis of Anorthite. Besides, CaO and CaSiO2 were the other intermediate phase during synthesis. Anorthite first occurred at 1050°C, and it was the only phase after it sintered over 1260°C. With sintering temperature increasing from 1300°C to 1450°C, the large sphere pore wall got denser and the Anorthite grains obviously showed platelike. It was deduced that the preferential growth of Anorthite crystals was parallel to the (004) plane.

  • Mullite whisker reinforced porous Anorthite ceramics with low thermal conductivity and high strength
    Journal of the European Ceramic Society, 2016
    Co-Authors: Cuiwei Li, Chao Bian, Yao Han, Chang-an Wang, Linan An
    Abstract:

    Mullite whisker reinforced porous Anorthite ceramics have been fabricated by foam-gelcasting method. Effect of whisker content on thermal conductivity and mechanical strength of the prepared material has been studied. It is found that while thermal conductivity remains almost the same, compressive strength can be significantly improved by increasing whisker content. The results are discussed in terms of microstructures. It suggests that porous Anorthite ceramics with both high mechanical strength and low thermal conductivity can be achieved by reinforcing with mullite whiskers.

  • porous Anorthite ceramics with ultra low thermal conductivity
    Journal of The European Ceramic Society, 2013
    Co-Authors: Cuiwei Li, Chao Bian, Shibo Li, Chang-an Wang
    Abstract:

    Abstract Porous Anorthite ceramics with an ultra-low thermal conductivity of 0.018 W/m K have been fabricated by hydrous foam-gelcasting process and pressureless sintering method using γ-alumina, calcium carbonate and silica powders as raw materials. Microstructure and phase composition were analyzed by SEM and XRD respectively. Properties such as porosity, pore size distribution and thermal conductivity were measured. High porosity (69–91%) and low thermal conductivity (0.018–0.13 W/m K) were obtained after sintering samples with different catalyst additions at 1300–1450 °C. Porosity, pore size, pore structure and grain size had obvious effect on heat conduction, resulting in the low thermal conductivity. The experimental thermal conductivity data of porous Anorthite ceramics were found to be fit well with the computed values derived from a universal model.

  • fabrication and properties of porous Anorthite mullite ceramics
    Key Engineering Materials, 2012
    Co-Authors: Ya Mei Lin, Feng Kun Yang, Chang-an Wang
    Abstract:

    Porous Anorthite/mullite composite ceramics with different mullite content were fabricated by foam-gelcasting, using CaCO3, SiO2, α-Al2O3 as raw material for Anorthite phase and mullite powder for mullite phase. Effects of mullite powder content on bulk density, porosity, compressive strength and thermal conductivity of the porous composite ceramics were researched. It has been shown that mullite powder content has great effect on microstructure and properties of the porous Anorthite⁄mullite composite ceramics. The open porosity of the prepared porous Anorthite⁄mullite composite ceramics is in the range of 58.7 %~77.5 %, the compressive strength is between 4.2 and 30.9 MPa, and the thermal conductivity is in the range of 0.18 ~1.47 W⁄(m·K).

Cuiwei Li - One of the best experts on this subject based on the ideXlab platform.

Hui Wang - One of the best experts on this subject based on the ideXlab platform.

  • dolomite wollastonite and calcite as different cao sources in Anorthite based porcelain
    Ceramics International, 2013
    Co-Authors: Shanjun Ke, Xiaosu Cheng, Yanmin Wang, Qianghong Wang, Hui Wang
    Abstract:

    Abstract Anorthite-based porcelain was fabricated by using ball clay, quartz, alumina, feldspar and three different sources of CaO as raw materials. The effect of CaO sources such as dolomite, wollastonite and calcite on the mechanical, thermal and aesthetical properties of Anorthite-based porcelain was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies were also carried out to analyze the microstructure. Anorthite was formed as major phase in all the samples fired at their optimum sintering temperatures (1200, 1215 and 1230 °C). The sample with dolomite had the highest bulk density but the smallest flexural strength due to formation of substantial glassy phase. The maximum flexural strength (∼110 MPa) was reached in the sample containing wollastonite, which was mainly attributed to the favorable microstructure. Anorthite as the single crystalline phase was found in the sample with calcite and the sample showed the lowest thermal expansion coefficient and the highest whiteness, which was similar to bone china in appearance.

  • dolomite wollastonite and calcite as different cao sources in Anorthite based porcelain
    Ceramics International, 2013
    Co-Authors: Xiaosu Cheng, Yanmin Wang, Qianghong Wang, Hui Wang
    Abstract:

    Abstract Anorthite-based porcelain was fabricated by using ball clay, quartz, alumina, feldspar and three different sources of CaO as raw materials. The effect of CaO sources such as dolomite, wollastonite and calcite on the mechanical, thermal and aesthetical properties of Anorthite-based porcelain was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies were also carried out to analyze the microstructure. Anorthite was formed as major phase in all the samples fired at their optimum sintering temperatures (1200, 1215 and 1230 °C). The sample with dolomite had the highest bulk density but the smallest flexural strength due to formation of substantial glassy phase. The maximum flexural strength (∼110 MPa) was reached in the sample containing wollastonite, which was mainly attributed to the favorable microstructure. Anorthite as the single crystalline phase was found in the sample with calcite and the sample showed the lowest thermal expansion coefficient and the highest whiteness, which was similar to bone china in appearance.

  • fabrication and characterization of Anorthite based ceramic using mineral raw materials
    Ceramics International, 2012
    Co-Authors: Xiaosu Cheng, Qianghong Wang, Hui Wang, Anze Shui, Pingan Liu
    Abstract:

    Abstract The purpose of this study is to design a novel single crystalline phase ceramic based on Anorthite whose properties fulfill the tableware market requirements such as high appearance quality, strength and thermal shock resistance. To obtain the single phase Anorthite ceramic, ball clay, quartz, calcite, feldspar and alumina were used as raw materials. The single phase Anorthite ceramic was fabricated by slip casting and sintering at 1230 °C for 1 h. It has a high flexural strength of 103 MPa, which is higher than that of the conventional porcelain. The single phase Anorthite ceramic had relatively low (4.9 × 10 −6  K −1 ) thermal expansion coefficient which can be matched with applicable glaze easily. Furthermore, the single phase Anorthite ceramic had high degree of whiteness ( L*  = 94) and excellent translucency behavior which could achieve a high-quality decorative effect.

Ahmad Hussain - One of the best experts on this subject based on the ideXlab platform.

  • ca 2 and oh release of ceramsites containing Anorthite and gehlenite prepared from waste lime mud
    Journal of Environmental Sciences-china, 2016
    Co-Authors: Chuanmeng Yang, Jiantao Huang, Ahmad Hussain
    Abstract:

    Abstract Lime mud is a kind of solid waste in the papermaking industry, which has been a source of serious environmental pollution. Ceramsites containing Anorthite and gehlenite were prepared from lime mud and fly ash through the solid state reaction method at 1050°C. The objective of this study was to explore the efficiency of Ca 2 + and OH − release and assess the phosphorus and copper ion removal performance of the ceramsites via batch experiments, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that Ca 2 + and OH − were released from the ceramsites due to the dissolution of Anorthite, gehlenite and available lime. It is also concluded that gehlenite had stronger capacity for Ca 2 + and OH − release compared with Anorthite. The Ca 2 + release could be fit well by the Avrami kinetic model. Increases of porosity, dosage and temperature were associated with increases in the concentrations of Ca 2 + and OH − released. Under different conditions, the ceramsites could maintain aqueous solutions in alkaline conditions (pH = 9.3–10.9) and the release of Ca 2 + was not affected. The removal rates of phosphorus and copper ions were as high as 96.88% and 96.81%, respectively. The final pH values of both phosphorus and copper ions solutions changed slightly. The reuse of lime mud in the form of ceramsites is an effective strategy.

  • recycling of lime mud and fly ash for fabrication of Anorthite ceramic at low sintering temperature
    Ceramics International, 2015
    Co-Authors: Juan Qin, Chuanmeng Yang, Ahmad Hussain, Chong Cui, Xiaoyu Cui, Shihai Yang
    Abstract:

    Abstract Lime mud is a kind of waste generated during causticization reaction of an alkali recycling process in paper industry. Lime mud and fly ash were reused as raw materials to fabricate Anorthite ceramics through solid state reactions. Both sintering temperature and lime mud content influenced the crystalline phases in the prepared ceramics. Anorthite was the major phase in all samples (samples L36, L40, L50 and L60) and it was prominent in sample L36 (containing 36 wt% lime mud). The results also showed that Anorthite ceramic can be synthesized at low sintering temperature (1100 °C). Gehlenite and wollastonite were formed in the samples possessing higher calcium (above 40 wt% lime mud) or at lower sintering temperatures. Bulk density, water absorption and compressive strength were measured. These ceramics were of light weight and had high water absorption. Recycling of lime mud and fly ash as raw materials of Anorthite ceramic is a feasible approach to solve the solid wastes.