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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.


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.


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.


Wan W.,Nanjing University of Technology | Yang J.,Nanjing University of Technology | Feng Y.,Nanjing University of Technology | Feng Y.,Nanjing Sanle Electronic Information Industry Group Co. | Qiu T.,Nanjing University of Technology
Key Engineering Materials | Year: 2016

Highly porous silica ceramics were prepared by in-situ gelation of an aqueous suspension with well dispersed silica particles and N′N-dimethylacrylamide (DMAA) monomer, followed by lyophilization and pressureless sintering. The gelcasting process was imparted by polymerization of DMAA. The silica raw materials used in this experiment are the dusts collected from the exhaust fumes of silicon industry. The as-obtained porous silica ceramics had three-dimensional and hierarchical pore structure and the porosity ranged from 75 to 88 % as the sintering temperature varied from 850 to 1050°C. In addition, the porous silica ceramics appeared to have strong mechanical strength. Compressive strength of the porous silica ceramics was as high as 3.2 MPa even when the porosity was nearly 80%. The gelcasting-lyophilization method was proved to be a novel and promising route for the preparation of highly porous and mechanically strong materials. © 2016 Trans Tech Publications, Switzerland.


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.


Liu L.,Nanjing University of Technology | Feng Y.,Nanjing University of Technology | Feng Y.,Nanjing Sanle Electronic Information Industry Group Co. | Qiu T.,Nanjing University of Technology | Li X.,Nanjing University of Technology
Journal of Materials Science: Materials in Electronics | Year: 2015

The microstructures and microwave dielectric properties of (1 − x)Mg2SiO4–xCa0.9Sr0.1TiO3 (x = 0.05–0.08) composite ceramics, prepared via a conventional solid-state ceramic route, were investigated. As expected, an increase in sintering temperature effectively promoted densification and enhanced the dielectric properties of the (1 − x)Mg2SiO4–xCa0.9Sr0.1TiO3 ceramics used in this study. As the amount of Ca0.9Sr0.1TiO3 increased, temperature coefficient of resonant frequency (τf) increased; with a near-zero τf obtained for samples where x = 0.06. The optimal microwave dielectric properties, a dielectric constant (εr) of 8.01, high quality factor (Q × f) of 58,389 GHz (at 14.6 GHz) and a τf of −3.62 ppm/°C, were obtained for 0.94Mg2SiO4–0.06Ca0.9Sr0.1TiO3 sintered at 1,440 °C for 3 h. © 2014, Springer Science+Business Media New York.


Xu X.,Jiangsu University | Zhang Z.,Jiangsu University | Wang H.,Jiangsu University | Cheng X.,Jiangsu University | And 3 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2011

The finite element dynamic simulation using Deform-3D software and the experimental investigation of a large-scale equal channel angular pressing (ECAP) are carried out, with the special focus on the effect of both the friction coefficient between workpiece and ECAP die and the orifice size in exit channel of ECAP die on maximum pressing load. The finite element simulation results show that the shear friction model can be used in the finite element simulation of ECAP deformation. The friction coefficient between workpiece and ECAP die has very great effect on the maximum pressing load. With the increase of friction coefficient, the maximum pressing load increases considerably. As the friction coefficient varies from 0 to 0.6 (approximately equal to the friction coefficient between aluminum and steel under dry friction condition), the maximum pressing load increases up to 5.1 times. The effect of the orifice size on maximum pressing load is found to be dependent on the magnitude of the friction coefficients. When the friction coefficients are smaller than 0.6, enlarging the orifice size has little effect on the maximum pressing load. On the other hand, when the friction coefficients are bigger than 0.6, the maximum pressing load can be obviously decreased with an enlarged orifice size, but the impact is not always improved with the increase of the orifice size. The experimental results demonstrate that the realization of ECAP scale-up and commercialization strongly depends on finding an approach to effectively reduce friction, and that the maximum pressing loads by the finite element simulation and the experiment are in accordance. © 2011 Journal of Mechanical Engineering.


Wan W.,Nanjing University of Technology | Yang J.,Nanjing University of Technology | Feng Y.,Nanjing University of Technology | Feng Y.,Nanjing Sanle Electronic Information Industry Group Co. | And 2 more authors.
Journal of Alloys and Compounds | Year: 2016

The effect of a small amount of alumina on the mechanical strength, thermal shock resistance, room temperature and high-temperature dielectric, and ultra-high temperature ablation properties of fused silica ceramics prepared by aqueous gelcasting was investigated. Alumina addition promoted the dissolution of silica during slurry preparation. Compared to a pure fused silica sample, the flexural strength and thermal shock residual strength of fused silica ceramics with 0.5 wt% alumina (sintered at 1250 °C) reached 79.9 MPa and 82.0 MPa, showing increases of 19.3% and 19.9%, respectively. In addition, the ablation resistance increased. The mass loss rate and linear recession rate of fused silica ceramics with 0.5 wt% alumina were 0.018 g/s and 0.133 mm/s at 10 s and 0.026 g/s and 0.089 mm/s at 60 s ablation time, respectively. Importantly, the presence of alumina did not decrease the excellent room temperature and high-temperature dielectric properties of fused silica ceramics. © 2016 Elsevier B.V. All Rights Reserved.


Yang W.,Nanjing Sanle Electronic Information Industry Group Co.
Proceedings of 2015 IEEE International Vacuum Electronics Conference, IVEC 2015 | Year: 2015

This paper presents the application of microwave chemistry technology to coal desulfurization. The effects of the dosage and the proportion of oxidant, microwave power and radiation time, as well as coal particle size on the desulfurization process are investigated. Optimizing technological route has been obtained. They are: microwave power: 900W, microwave radiation time 60 second, the best dosage of oxidant: 50mL, oxidizer volume ratio:1/1, coal particle size: 1000μm. Infrared spectra shows that the coal sample after such treatment has no change in its chemical and internal structure. © 2015 IEEE.

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