Papers by Keyword: Sinterability

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Authors: N. Antón, L.E.G. Cambronero, J.M. Ruiz Prieto, Francisco Velasco, José M. Torralba
Authors: Wei Xia Dong, Qi Fu Bao, Xing Yong Gu, Yan Chun Huang
Abstract: The properties of anorthite-based glass/ceramic with different amounts of CeO2 addition had been investigated in this paper. The glass/ceramics with small amounts of CeO2 addition could be well sintered at 850~900°C. The water absorption was examined to evaluate the sintering behavior of the samples. The crystalline phase,microstructure, dielectric properties, thermal expansion and bending strength were characterized by X-Ray diffraction (XRD), scanning transmission electron microscope (SEM), impedance materials analyzer, thermal expansion analyzer and flexural strength analyzer. The results showed the 1wt % CeO2-doped glass/ceramics sintered at 900 °C have optimum properties of ε = 6.282, tanθ = 2.18×10-3 at 1 MHz and a thermal expansion coefficient of 3.32×10-6 °C-1 (25~500 oC) matched with silicon chip (3.4×10-6 °C -1). Obviously, CeO2 could be used as a suitable sintering aid that improves densification of the glass/ceramic composites.
Authors: Qing Chang, Hong Qiang Ru, Dao Lun Chen, Jin Long Yang, S.L. Hu
Abstract: Dense iron-containing hydroxyapatite (HA)/titanium composites were synthesized via pressureless sintering at a relatively low temperature using nanosized HA powders and Ti-Fe mixed powders. XRD analysis showed that desirable Ti phase still remained in the HA matrix. The addition of iron improved the densification by enhancing the sinterability of titanium, and reduced the decomposition rate of HA and the interaction between HA and titanium. The mechanical tests showed that both the flexural strength and fracture toughness of the composites were significantly improved. The Ti-Fe reinforcing particles exhibited plastic stretching and bridged an advancing crack, making a significant contribution to the improvement of mechanical properties of the composites.
Authors: Mafalda Guedes, Alberto C. Ferro, José Maria F. Ferreira
Authors: W.R. Weinand, F.F.R. Gonçalves, W.M. Lima
Abstract: Mechanical alloying (MA) has been successfully used to produce alloys and composites with a high homogeneity degree. In current research, titanium (Ti) powder was mixed with 40, 50% volume of hydroxyapatite (HAp). MA was performed without atmosphere control, at room temperature, for 4.5 hours of milling time, at rotation speed of 300 rpm. Samples of material were compacted in cylindrical form at 350 MPa and sintered in 2.0 flux air (l/min) at 1000, 1100 and 1200oC during 1 hr. The material’s morphological and microstructural characterization, in powder form and in sintered material, was performed by scanning electronic microscope and X-ray diffractometry. Thermal treatments revealed that sintering temperature affects the microstructure, microhardness and the composition of the composites evaluated by EDS.
Authors: Xue Ying Li, Jie Cai Han, Xing Hong Zhang, Xiao Guang Luo
Abstract: In this study, two rare earth oxides, Y2O3 and La2O3, are used as the additives in the sintering of ZrB2-SiC composites to improve the sinterability and control development of microstructure during densification. The results show that the use of rare earth oxides (5vol.%) improves the powder sinterability, hindered excessive growth of matrix particles and increase fracture toughness of ZrB2-SiC composites, in comparison to ZrB2-SiC with additions free. Nearly full dense materials are obtained by hot pressing at 1900°C. XRD analyses indicate that lanthanum-containing phases were formed in the composite with La2O3. Microstructure observations by SEM reveal that the grain size of ZrB2-SiC with Y2O3 and La2O3 composites are less than the sample without additives, which indicates Y2O3 and La2O3 may restrain the grain growth and increase the fracture toughness. The fracture toughness of ZrB2-SiC composites with Y2O3 and La2O3 reached 5.0MPa·m1/2 and 5.5MPa·m1/2 respectively. Therefore, the additive Y2O3 and La2O3 are very effective as sintering aids for the ZrB2-SiC composite.
Authors: Ji Hong Liao, Ying Dai, Ren Zhou Yang, Wen Chen
Abstract: Low-temperature sintered Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ (CLNT) microwave dielectric ceramics with V2O5 and ZnO additives were prepared by the conventional solid state reaction method. The sintering behavior and microwave dielectric properties of CLNT ceramics were investigated. The main diffraction peaks of all the specimens sintered at the temperature under 1150C split due to the coexistence of the non-stoichiometric phase and stoichiometric phase, which all possess CaTiO3-type perovskite structures. ZnO and V2O5 combined additives lowered the sintering temperature of CLNT ceramics from 1150C to 1090C. and the Qf values were improved from 18,210 GHz to 20,740 GHz. The CLNT ceramics with 4 wt% ZnO addition sintered at 1090C showed good microwave dielectric properties with εr ~39.7, Qf ~20,740 GHz, τf ~8.6 ppm/C. The relationship between dielectric properties and the sintering behavior was also discussed.
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