Ceramics

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Ceramics

  • al2o3 ceramics
  • alumina ceramics
  • batio3 ceramics
  • calcium phosphate ceramics
  • composite ceramics
  • dense ceramics
  • dental ceramics
  • dielectric ceramics
  • glass ceramics
  • high-strength ceramics
  • lead-free piezoelectric ceramics
  • lu2o3 ceramics
  • microwave ceramics
  • microwave dielectric ceramics
  • nitride ceramics
  • o3 ceramics
  • oxide ceramics
  • phosphate ceramics
  • piezoelectric ceramics
  • polycrystalline ceramics
  • porous ceramics
  • si3n4 ceramics
  • silicon nitride ceramics
  • sintered ceramics
  • structural ceramics
  • zirconia ceramics


  • Selected Abstracts


    ADHESIVE CEMENTATION OF HIGH-STRENGTH CERAMICS

    JOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 5 2007
    Markus B. Blatz DMD, PhD Guest Experts
    [source]


    CERAMICS OF THE SODOHOM PERIOD (1000,1200 AD)

    ACTA ARCHAEOLOGICA, Issue 1 2009
    Article first published online: 5 JUL 2010
    First page of article [source]


    LUSTRE-DECORATED CERAMICS FROM A 15TH TO 16TH CENTURY PRODUCTION IN SEVILLE*

    ARCHAEOMETRY, Issue 1 2010
    A. POLVORINOS DEL RIO
    A set of 17 fragments of ceramics have been uncovered on the occasion of excavations of a workshop in Triana near Seville. These ceramics are typical of objects that are not commonly encountered in present collections in spite of intensive production during the 15th,16th centuries. Chemical and mineralogical analyses have been performed using various techniques (X-ray fluorescence and diffraction, SEM, ion beam analyses). The majority of the ceramic sherds represent the diversity of the Seville production; three fragments recovered in the same archaeological context were not locally produced and belong to the production of eastern Spain (Valence area). The ceramic bodies of the Seville sherds are compatible with the use of clays from the Guadalquivir valley. The glaze and the lustre decoration are comparable to those produced in eastern Spain. These conclusions are based on data that represent the production of a single workshop in Seville; the scatter of the data is due to variations in the processing and/or to alterations during the five centuries of burial of the ceramic fragments. [source]


    RELATIONSHIP BETWEEN THE COLORATION AND THE FIRING TECHNOLOGY USED TO PRODUCE SUSA GLAZED CERAMICS OF THE END OF THE NEOLITHIC PERIOD*

    ARCHAEOMETRY, Issue 5 2009
    S. LAHLIL
    Ancient decorated potteries from Susa (Mesopotamia) dating from 4200 to 3700 bc, were studied in order to determine the origin and the nature of the raw materials used, and to identify the technological processes applied to make the ceramic bodies and their decorations. Bulk compositions were determined by particle induced X-ray emission (PIXE), while the microstructure and the mineralogical phases were studied using scanning electron microscopy (SEM), energy dispersive X-ray analyses (EDX) and X-ray powder diffraction (XRD). The results showed that the raw materials used to elaborate these potteries were similar for all the ceramic bodies (carbonates and iron and magnesium-rich clays containing sand), and for all the decorations (iron oxides, silica, potassic and alumina sources). The variations of coloration of the ceramics and of their decorations were due to different firing temperatures. The ranges of firing temperatures used by potters were evaluated on the basis of mineral stability domains. [source]


    PHYSICOCHEMICAL COMPOSITIONAL ANALYSIS OF CERAMICS: A CASE STUDY IN KENTING, TAIWAN,

    ARCHAEOMETRY, Issue 4 2006
    MAA-LING CHEN
    The composition of ceramics does not just reflect the component of some specific, unprocessed, geological, raw material source, but also certain forms of human behaviour involved in its manufacture. The purpose of this research project is to apply the acid-extraction chemical method, complemented by a thin-section petrographic study, to the compositional analyses of certain local ceramic collections (mainly from several sites in the southern Taiwan area). The results present the raw materials that the ceramic manufacturers of the two cultural traditions (O-laun-pi Phase II and Phase III,IV), which overlapped temporally, used. These materials came from the same sources, but the ceramics were manufactured in different ways. Particularly, the people of O-laun-pi Phase III,IV also procured certain materials from either local sources or from somewhere in eastern Taiwan to make their pots. The results also indicate that there might have been a variation in terms of their manufacture among sites of the same cultural tradition. [source]


    THE ORIGIN OF BLACK-FIGURE GREEK CERAMICS FOUND IN NAUCRATIS (NILE DELTA)*

    ARCHAEOMETRY, Issue 3 2005
    G. HARBOTTLE
    At the site of the Greek trading port of Naucratis, located on the Canopic mouth of the Nile inland from Alexandria, Flinders Petrie and later archaeologists encountered sherds of Classical Greek black-figure pottery. We have characterized the pastes of 14 of these specimens, drawn from the collections of the British Museum and the Ashmolean Museum at Oxford, by neutron activation analysis and numerical taxonomy. The ceramics agree in composition with a reference group centred on Athens. We also investigated a small number of additional black-figure sherds from other sites. One specimen, from Ruvo di Puglia (Italy), actually originated in or near Marseilles. There was no evidence for local manufacture of black-figure pottery at Naucratis. [source]


    CUERDA SECA CERAMICS FROM AL-ANDALUS, ISLAMIC SPAIN AND PORTUGAL (10TH,12TH CENTURIES AD): INVESTIGATION WITH SEM,EDX AND CATHODOLUMINESCENCE*

    ARCHAEOMETRY, Issue 3 2005
    R. CHAPOULIE
    Since little is known about the cuerda seca technique, our aim has been to complete an initial analysis of 11th-century cuerda seca by studying fragments from the 10th century (Pechina, Almera) and the 12th century (Mrtola and Almera), so as to establish the diachronic evolution of this technique. Characteristics specific to cuerda seca ceramic glazes were investigated using scanning electron microscopy (SEM) and quantitative chemical analysis with energy-dispersive X-ray spectrometry (EDX). The chemical compositions of the different-coloured glazes (green, black, yellow and white) have given us valuable indications about the evolution of the technique. The opacification mode and the firing process were also investigated. With the help of cathodoluminescence (CL) and the study of modern ,cuerda seca' glazed ceramics, new hypotheses regarding the number of firing stages, taking into account glaze and paste transformations and their interactions, are put forward. [source]


    Microwave Hybrid Post-Heat Treatment of Reaction Sintered Alumina/Lanthanum Hexaaluminate Composite Ceramics,

    ADVANCED ENGINEERING MATERIALS, Issue 3 2010
    Zahra Negahdari
    One of the main problems in development of in situ reaction sintered alumina/lanthanum hexaaluminate composite ceramics is achievement of simultaneous densification and in situ formation of lanthanum hexaaluminate (LHA) platelets inside the matrix. Microwave hybrid post-sintering was investigated as a method to enhance the solid-state reaction of LHA formation and the densification of composite ceramics with 2.8,80 vol% LHA. Comparison of the conventionally and microwave assisted sintered alumina/lanthanum hexaaluminate composite ceramics revealed that utilization of microwave heating in second stage of sintering could enhance the solid-state reaction, the densification, and the anisotropic grain growth of the LHA platelets in ceramics containing more than 20 vol% LHA and for heat treatment at 1500,C. [source]


    Stress-Dependent Elastic Properties of Porous Microcracked Ceramics,

    ADVANCED ENGINEERING MATERIALS, Issue 12 2009
    Irina Pozdnyakova
    Abstract Although ceramics are considered linear elastic materials, we have observed a non-linear pseudo-elastic behavior in porous cellular microcracked ceramics such as , -eucryptite. This is attributed to the evolution of microstructure in these materials. This behavior is particularly different from that of non-microcracked ceramics such as silicon carbide. It is shown that in microcracked materials two processes, namely stiffening and softening, always compete when a compressive external load is applied. The first regime is attributed to microcrack closure, and the second to microcracks opening, i.e. to a damage introduced by the applied stress. On the other hand rather a continuous damage is observed in the non-microcracked case. A comparison has been done between the microscopic (as measured by neutron diffraction) and the macroscopic stress-strain response. Also, it has been found that at constant load a significant strain relaxation occurs, which has two timescales, possibly driven by the two phenomena quoted above. Indeed, no such relaxation is observed for non-microcracked SiC. Implications of these findings are discussed. [source]


    Microstructure Tailored Functionally Graded Alumina/Lanthanum Hexaaluminate Ceramics for Application as Thermal Barrier Coatings,

    ADVANCED ENGINEERING MATERIALS, Issue 12 2009
    Zahra Negahdari
    The thermal and mechanical properties of a functionally graded lanthanum hexaaluminate-alumina ceramic are described. The gradation of functionality is based on different volume fraction of lanthanum hexaaluminate, varying from 0 to 80 vol% and corresponding porosity from 2 to 32 vol%. The highest volume fraction of lanthanum hexaaluminate enables a five time reduced thermal diffusivity as compared to alumina. The fracture toughness and elastic modulus is highest for a 20 vol% lanthanum hexaaluminate-alumina composite. [source]


    Physical Effects of Multipass Two-Dimensional Laser Machining of Structural Ceramics,

    ADVANCED ENGINEERING MATERIALS, Issue 7 2009
    Anoop N. Samant
    Effect of multiple laser passes on cavities machined in structural ceramics is presented. Multiple laser passes machined cavities with reduced thermal stresses and cracks. Thermal model based on temperature dependent absorptivity and thermophysical properties along with defocusing of laser beam, multiple track induced preheating effect, and heat transfer was developed to incorporate effect of multiple passes on machined cavity. Predicted and experimentally measured values of physical attributes showed decent match. [source]


    Microstructures and Mechanical Properties of Hot-Pressed ZrB2 -Based Ceramics from Synthesized ZrB2 and ZrB2 -ZrC Powders,

    ADVANCED ENGINEERING MATERIALS, Issue 3 2009
    Wei-Ming Guo
    The influence of ZrC on the microstructure and mechanical properties of ZrB2 -SiC ceramics was investigated. SEM observation showed that the presence of ZrC greatly inhibited the grain growth of ZrB2 and SiC phases. With the introduction of ZrC, the Vickers' hardness, fracture toughness, and bending strength of the sintered ceramics increased significantly. [source]


    Improvement in the Specific Strength by Arranging Closed Pores in Fully Densified Zirconia Ceramics,

    ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009
    Akira Kishimoto
    Superplastic-foamed porous ceramics containing numerous closed pores were fabricated. The bending strength of the fabricated ceramics with the smallest pores was close to half that of fully dense ones, even with a porosity of 27%. The smaller pores were introduced selectively between top and bottom surfaces. The resultant dense/porous/dense layered ceramics had a specific mechanical strength greater than that of monolithic dense ceramics. [source]


    3D Powder Printing of ,-Tricalcium Phosphate Ceramics Using Different Strategies,

    ADVANCED ENGINEERING MATERIALS, Issue 12 2008
    E. Vorndran
    Custom made macroporous ,-tricalcium phosphate (,-TCP) bone substitutes were fabricated using 3D powder printing comparing three different preparation strategies. Samples fabricated using a novel hydraulic cement setting reaction showed the best printing resolution and highest mechanical performance. This method is a significant step forward in producing ,-TCP monoliths by rapid prototyping and would decrease processing time for commercial fabrication due to their rapid hardening and ease of handling. [source]


    The Manufacture of Porous Ceramics Using Supercritical Fluid Technology

    ADVANCED ENGINEERING MATERIALS, Issue 3 2008
    S. Matthews
    Supercritical fluid-assisted technology has been combined with conventional polymer processing techniques, such as injection moulding and extrusion to manufacture porous ceramics components. This paper introduces the new process and highlights one of the key benefits of this technique; the ability to control the porous network formed. It was found that by altering the binder formulation and processing conditions the pore size, pore type and pore density could be controlled. [source]


    Tuning the Refractive Index of Polymers for Polymer Waveguides Using Nanoscaled Ceramics or Organic Dyes,

    ADVANCED ENGINEERING MATERIALS, Issue 1-2 2004
    J. Bhm
    Plastic Optical Fibers (POF) show advantageous properties like high flexibility and their cost advantage in comparison to glass fibers. The refractive indices of core and cladding have to be modified in order to get total reflectance. Thus, there is a strong demand for refractive index adjustable polymers with improved transmission properties in the visible and the NIR range. Inorganic nanosized particles or organic dyes homogeniously dispersed or solved in the polymer matrix allow a tailored increase or decrease of the refractive index of various polymers. [source]


    Crystallization and Grain Growth Kinetics for Precipitation-Based Ceramics: A Case Study on Amorphous Ceria Thin Films from Spray Pyrolysis

    ADVANCED FUNCTIONAL MATERIALS, Issue 21 2009
    Jennifer L. M. Rupp
    No abstract is available for this article. [source]


    Crystallization and Grain Growth Kinetics for Precipitation-Based Ceramics: A Case Study on Amorphous Ceria Thin Films from Spray Pyrolysis

    ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009
    Jennifer L. M. Rupp
    Abstract The introductory part reviews the impact of thin film fabrication, precipitation versus vacuum-based methods, on the initial defect state of the material and microstructure evolution to amorphous, biphasic amorphous-nanocrystalline, and fully nanocrystalline metal oxides. In this study, general rules for the kinetics of nucleation, crystallization, and grain growth of a pure single-phase metal oxide thin film made by a precipitation-based technique from a precursor with one single organic solvent are discussed. For this a complete case study on the isothermal and non-isothermal microstructure evolution of dense amorphous ceria thin films fabricated by spray pyrolysis is conducted. A general model is established and comparison of these thin film microstructure evolution to kinetics of classical glass-ceramics or metallic glasses is presented. Knowledge on thermal microstructure evolution of originally amorphous precipitation-based metal oxide thin films allows for their introduction and distinctive microstructure engineering in devices-based on microelectromechanical (MEMS) technology such as solar cells, capacitors, sensors, micro-solid oxide fuel cells, or oxygen separation membranes on Si-chips. [source]


    Multifunctional Composites of Ceramics and Single-Walled Carbon Nanotubes

    ADVANCED MATERIALS, Issue 17 2009
    Nitin P. Padture
    Abstract Polycrystalline ceramic/single-walled carbon nanotube (SWNT) composites possess unique grain boundaries, containing 1D tortuous SWNTs bundles that form 2D tangled embedded nets. This unprecedented grain-boundary structure allows tailoring of multifunctional ceramic/SWNTs composites with unique combinations of desirable mechanical (toughness, strength, creep) and transport (electrical, thermal) properties. A brief discussion and analysis of recent developments in these composites are presented. [source]


    Microstructure and Mechanical Properties of Lu2O3 -Doped Porous Silicon Nitride Ceramics Using Phenolic Resin as Pore-Forming Agent

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2010
    Xiaowei Yin
    The joint process consisting of pressureless sintering and chemical vapor infiltration (CVI) was developed to prepare porous Si3N4 ceramics with controlled microstructure. Lu2O3 and phenolic resin acted as sintering aid and pore-forming agent, respectively. The 5 wt% Lu2O3 -doped ceramics using 12,57 vol% phenolic resin attained a porosity ranging from 46% to 53%. With increasing the resin content, the average pore size increased from 1 to 2 ,m. The porous ceramic infiltrated with CVI Si3N4 had an improved microstructure. The decreased pore size and porosity led to an increase in flexural strength, and the densified surface led to an improved surface hardness. [source]


    Microwave Dielectric Properties of SrO,2CeO2,nTiO2 (n=4 and 5) Ceramics

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2010
    Ramachandran Satheesh
    SrO,2CeO2,nTiO2 ceramics with n=4 and 5 have been prepared through conventional solid-state ceramic route. Structural and microstructural characterizations of the sintered ceramics were carried out using X-ray diffraction, laser Raman, and scanning electron microscopic studies. Microwave dielectric properties have been measured using postresonator and resonant cavity techniques. SrO,2CeO2,4TiO2 and SrO,2CeO2,5TiO2 ceramics showed dielectric constants of 71.3 and 71.7, respectively, around 4 GHz together with a relatively high unloaded quality factor. [source]


    Effect of A-Site Ionic Radius on the Structure and Microwave Dielectric Characteristics of Sr1+xSm1,xAl1,xTixO4 Ceramics

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2010
    Min Min Mao
    SrSmAlO4 microwave dielectric ceramics were modified by Sr/Ti cosubstitution for Sm/Al. The effects of radius difference of A-site ions on the microwave dielectric characteristics were investigated together with the structure. Sr1+xSm1,xAl1,xTixO4 (x=0, 0.05, 0.10, and 0.15) ceramics were prepared by a solid-state reaction approach. X-ray diffraction studies revealed a single-phase K2NiF4 -type solid solution with corresponding peaks shifting to lower 2, as x increased. Minor inhomogeneous grain morphology for x=0.05 and a trace amount of second phases for x=0.10, 0.15 were detected by backscattered-electron microscopy and energy-dispersive X-ray analysis. With increasing Sr/Ti cosubstitution, the dielectric constant ,r increased from 18.4 to 20.4, and the temperature coefficient of resonant frequency ,f was adjusted from ,1.8 to 7.4 ppm/C almost linearly. However, the Qf value decreased from 74,500 GHz at x=0,53,000 GHz at x=0.15. The internal stresses caused by the decreased tolerance factor and the large ionic radii difference between Sr2+ and Sm3+ should be the predominant reasons for such a decrease in the Qf value. The high-resolution transmission electron microscopic results revealed an increase in the lattice distortion with increasing Sr/Ti cosubstitution, and subsequently supported the above conclusion upon the increased internal stresses. [source]


    Cell Proliferation of Human Fibroblasts on Alumina and Hydroxyapatite-Based Ceramics with Different Surface Treatments,

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2010
    Juliana Marchi
    Biocompatibility is an important characteristic of dental implant material, and in vitro tests are required to elucidate the interaction between these materials and human tissues. Cell proliferation assays were done with fibroblasts plated on the surface of alumina and hydroxyapatite sintered samples, each with a different surface treatment (sintered, rectified, or polished). After 1, 2, and three days, the samples were prepared for scanning electron microscopy observations. The data were compared by analysis of variance followed by Tukey's test. It was concluded that neither the hydroxyapatite or alumina substrate is cytotoxic, and hydroxyapatite is more biocompatible than alumina. [source]


    Effects of Rare-Earth Dopants on the Ferroelectric and Pyroelectric Properties of Strontium Barium Niobate Ceramics

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2009
    Yingbang Yao
    Effects of various rare-earth (RE) dopants (Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tm3+, Dy3+, Er3+, and Yb3+) on the dielectric, ferroelectric, and pyroelectric properties of Sr0.5Ba0.5Nb2O6 (SBN50) ceramics were investigated. In the present studies, the doping concentrations of all the RE dopants were fixed at 1 mol%. Their potential usefulness in pyroelectric applications was discussed based on their measured pyroelectric detectivity figure of merit (FOM). On the basis of our studies, for RE dopants with atomic numbers smaller than Nd, their dielectric constants were greatly increased, while for RE dopants with atomic numbers larger than Sm, their dielectric constants as well as dielectric losses became smaller. Among various dopants, Eu-doped SBN showed the most improved ferroelectric properties. Its remnant polarization (Pr) was increased to 4.86 ,C/cm2 as compared with 3.23 ,C/cm2 obtained in undoped SBN50. On the other hand, Gd-doped SBN exhibited the largest pyroelectric coefficient of 168 ,C/m2 K, which was over three times of that of the undoped sample (49 ,C/m2 K). The work shows that Gd-doped SBN exhibits the greatest potential for pyro-applications because it bears the largest FOM of 0.45 10,5 Pa,0.5 [Correction: After online publication on 11/05/2008, an error was found in this article. The original value, 1.3510,5 Pa,0.5, was incorrect. The data has been replaced with the correct value.]. [source]


    The Effect of Dopants on the Dielectric Properties of Ba(B,1/2Ta1/2)O3 (B,=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In) Microwave Ceramics

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2009
    Lamrat Abdul Khalam
    Low-loss dielectric ceramics based on Ba(B,1/2Ta1/2)O3 (B,=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In) complex perovskites have been prepared by the solid-state ceramic route. The dielectric properties (,r, Qu, and ,f) of the ceramics have been measured in the frequency range 4,6 GHz by the resonance method. The resonators have a relatively high dielectric constant and high quality factor. Most of the compounds have a low coefficient of temperature variation of the resonant frequencies. The microwave dielectric properties have been improved by the addition of dopants and by solid solution formation. The solid solution Ba[(Y1,xPrx)1/2Ta1/2]O3 has x=0.15, with ,r=33.2, Quf=51,500 GHz, and ,f,0. The microwave dielectric properties of Ba(B,1/2Ta1/2)O3 ceramics are found to depend on the tolerance factor (t), ionic radius, and ionization energy. [source]


    Tape Casting and Dielectric Properties of Zn2Te3O8 -Based Ceramics with an Ultra-Low Sintering Temperature

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2009
    Johanna Honkamo
    The suitability of dielectric ceramics made of zinc tellurate (Zn2Te3O8) and titanium dioxide (TiO2) with an ultra-low sintering temperature (650C) for tape casting and thus for the multimodule technique with Al electrodes was investigated. The properties of the tape before and after sintering as well as the amount of organic additives for the casting process and a thermal analysis of the tape up to 1000C are reported. In addition, electrodes on a multilayer module made on stacked tapes were prepared using Al paste and postfiring, followed by relative permittivity and loss tangent measurements to verify the electrical performance of the whole structure. The dielectric properties of the stacked module without any electrodes were also measured. The results show that the composition is well suited for the tape process but extra care should be taken especially with the proper sintering temperature for optimized electrical performance. [source]


    Preparation and Thermal Ablation Behavior of HfB2,SiC-Based Ultra-High-Temperature Ceramics Under Severe Heat Conditions

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2009
    Xinghong Zhang
    HfB2,SiC-based ultra-high-temperature ceramics with aluminum nitride (AlN) as a sintering aid were hot pressed at 1850C. The sinterability and mechanical properties were investigated and compared with the composite without a sintering aid. It was shown that the addition of AlN greatly improved the powder sinterability and enabled the production of a nearly full-dense composite. The mechanical properties, especially the flexural strength, were enhanced remarkably through the improvement in the sinterability and microstructure. The oxidation resistance of a composite doped with 10 vol% AlN was evaluated by a plasma arc heater and the ablation mechanism was discussed. [source]


    A Chemical Route to BiNbO4 Ceramics

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2009
    Oleg A. Shlyakhtin
    The liquid phase sintering of fine BiNbO4 powders allows to obtain dense ceramics with excellent microwave dielectric properties (,=44,46; Qf=16,500,21,600 GHz) at T,700C. The thermal decomposition of freeze-dried precursors results in the crystallization of a metastable ,,-BiNbO4 polymorph that transforms into a stable orthorhombic ,-modification at T,700C. The dependence of sinterability on the powder synthesis temperature shows the maximum at 600C, corresponding to the formation of crystalline BiNbO4 powders with a grain size 80,100 nm. Sintering temperature reduction to 700C prevents the deterioration of silver contacts during co-firing with BiNbO4 ceramics. In situ scanning electron microscopy observation of the morphological evolution during sintering shows that the intense shrinkage soon after the appearance of a CuO,V2O5 eutectics-based liquid phase is accompanied by complete transformation of the ensemble of primary BiNbO4 particles. [source]


    Low-Temperature Firing and Microwave Dielectric Properties of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, Ceramics with ZnB2O4 Glass Addition

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2008
    Li-Xia Pang
    Low-temperature sintered Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, microwave dielectric ceramics with ZnB2O4 glass (ZBG) addition were prepared by the conventional solid state reaction method. The sintering behavior, microstructure, and microwave dielectric properties of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, ceramics with ZBG addition were investigated. The ZBG addition lowered the densified temperature of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, ceramics from 1150C to 940C. The dielectric constants of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, ceramics decreased from 40 to 34 and the temperature coefficient of resonant frequency (,f) changed gradually from +12.7 to ,25.7 ppm/C as ZBG addition increased from 0 to 8 wt%. The Qf values increased greatly from 20,500 GHz of pure Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, to 26,900 GHz when 5 wt% ZBG was added. Ca[(Li1/3Nb2/3)0.8Ti0.2]O3,, ceramics with 8 wt% ZBG addition sintered at 940C show good microwave dielectric properties with ,r,32.5, Qf,20,600 GHz, and ,f,,25.7 ppm/C. The relationship between dielectric properties and microstructure was also discussed. [source]


    Preparation of Machinable Fluoramphibole Glass,Ceramics from Soda-Lime Glass and Fluormica

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2008
    Weiyi Zhang
    A novel route, directly mixing fluormica crystals with recycled soda-lime glass powder and then sintering, is proposed to fabricate machinable fluoramphibole glass,ceramics. The effect of fluormica addition on the sinterability, reactive crystallization behavior, strength, and machinability of the material was investigated. The relative densities of the glass,ceramics decreased with increasing fluormica content. An interaction between fluormica crystals and glass powder occurred during the sintering process. Diopside was formed in the glass,ceramics with 20 wt% fluormica, and fluorrichterite was formed in the glass,ceramics with more than 30 wt% fluormica. Machinability and strength of the glass,ceramics were improved with increasing crystalline phase content. [source]