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Liu L.,Nanjing University of Technology | Feng Y.-B.,Nanjing University of Technology | Feng Y.-B.,Nanjing Sanle Electronic Information Industry Group Co. | Qiu T.,Nanjing University of Technology
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2015

The effects of Li2CO3 on sintering and microwave dielectric properties of 0.94Mg2SiO4-0.06Ca0.9Sr0.1TiO3 ceramics synthesized by a traditional solid-state reaction method were investigated. The results show that the addition of Li2CO3 did not change the phase of ceramics. Appropriate Li2CO3 addition could accelerate the sintering process, which could lower the sintering temperature from 1440℃ to 1355℃. Moreover, the addition of Li2CO3 improve the microwave dielectric properties and the Q×f increases apparently. The decrease in density and deterioration of Q×f were observed in the samples with excessive Li2CO3. The optimal microwave dielectric properties: εr=7.96, Q×f=96409 GHz (f=14.571 GHz), τf=+4.62 ppm/℃ were obtained for 0.94Mg2SiO4-0.06Ca0.9Sr0.1TiO3 doped with 0.50wt% Li2CO3 sintered at 1355℃ for 3 h. ©, 2015, Rengong Jingti Xuebao/Journal of Synthetic Crystals. All right reserved.


Ma D.,Nanjing University of Technology | Mu W.,Nanjing Sanle Electronic Information Industry Group Co. | Qiu T.,Nanjing University of Technology
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2013

The effects of B2O3 additive on the sintering and microwave dielectric properties of 0.69CaTiO3-0.31LaAlO3 ceramics prepared by conventional solid-state route were investigated. The results of X-ray diffraction analysis showed that the addition of B2O3 does not change the crystal phase of ceramics. Moderate addition of B2O3 could not only effectively lower sintering temperature and promote the densification but also improve the dielectric properties. The 0.3wt% B2O3-doped 0.69CaTiO3-0.31LaAlO3 ceramic sintered at 1500°C exhibits the optimal dielectric properties: εr≈45.4, Qf≈52800 GHz, τf≈8.78 ppm/°C.


Yu L.,Nanjing University of Technology | Pan L.,Nanjing University of Technology | Yang J.,Nanjing University of Technology | Feng Y.,Nanjing University of Technology | And 3 more authors.
Corrosion Science | Year: 2016

In situ (SiC+ZrB2)/Zr3[Al(Si)]4C6 composites with 0-15vol.% SiC and 15vol.% ZrB2 were prepared. As reinforcements, the incorporation of SiC and ZrB2 shows significant strengthening and toughening effect by the synergistic action of mechanisms including particulate reinforcement, grain-refinement, and grain's pull-out, etc. The oxidation kinetics of the composites at 1000-1300°C in air follows a parabolic law. With the incorporation and increase of SiC, the oxidation resistance of the composites is improved remarkably. It is attributed to the formation of a protective oxide scale containing borosilicate glass and more mullite, which effectively prevents the inward diffusion of oxygen. © 2016 Elsevier Ltd.


Song X.-X.,Nanjing University of Technology | Feng Y.-B.,Nanjing University of Technology | Feng Y.-B.,Nanjing Sanle Electronic Information Industry Group Co. | Qiu T.,Nanjing University of Technology
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2015

Alumina (Al2O3) ceramics were prepared by injection molding with a multi-component binder. The effects of paraffin content, solid loading on the viscosity of feedstock and property of green body were discussed. The effects of sintering temperature on the property and microstructure of sintering body were investigated. The results show the viscosity was suitable for injection molding with paraffin content of 40wt% and solid loading of 52vol%, and the green body presented optimum properties. The green body exhibites a uniform microstructure and mechanical strength as high as 25 MPa, which can fully meet the machining requirement. As the sintering temperature increases from 1560℃ to 1640℃, the relative density increases. Al2O3 sintered at 1600℃ shows the highest flexural strength (422±40 MPa) and high relative density. Also, SEM image shows that crystal grain of sintering bodies was fully developed, which demonstrates that the temperature of 1600℃ is a best sintering temperature. © 2015, Chinese Ceramic Society. All right reserved.


Wan W.,Nanjing University of Technology | Feng Y.,Nanjing University of Technology | Feng Y.,Nanjing Sanle Electronic Information Industry Group Co. | Yang J.,Nanjing University of Technology | And 2 more authors.
Journal of the European Ceramic Society | Year: 2015

Bulk mesoporous silica ceramics with homogeneous microstructure were prepared in this study using a low-toxic aqueous gel-casting method with industry waste as a raw material. The pore size of the porous silica ceramics prepared was about 30nm. The solid loading and sintering temperature showed significant influence on the properties of resultant silica porous ceramics, including porosity, pore size, and pore volume, all of which are easily adjusted by changing the loading and temperature parameters. The addition of glutinous rice flour (GRF) increased the porosity and pore volume of the ceramics while maintaining uniform microstructure and nanoscale pore size. Adding 10 wt% GRF in the slurries increased porosity from 47.5% to 55.1% and pore volume from 0.117cm3/g to 0.141cm3/g. The highly porous silica ceramics also possessed relatively high mechanical strength of up to 34.96MPa, suggesting its promising potential application in catalytics, filter industries, and other relevant fields. © 2015 Elsevier Ltd.

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