Papers by Keyword: Spark Plasma Sintering (SPS)

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Authors: E. Ayas, Alpagut Kara, Ferhat Kara
Abstract: An effective approach for preparing electrically conductive SiAlON-TiN composites was developed. Granules of a designed composition of α- SiAlON was obtained by spray drying and coated with varying amounts of TiO2 powder homogenously by mechanical mixing. Fully dense composites were obtained by spark plasma sintering (SPS) under a pressure of 50 MPa at 1650°C for 5min. According to the SEM analysis, unique microstructures containing continuously segregated in-situ formed TiN phase in 3-D were achieved. Additionally, XRD studies revealed that all TiO2 was successfully converted to TiN. The resistivity of the α-β SiAlON (1x1011 .m) was drastically reduced with the addition of only 5 vol. % TiO2 (2x10-4 .m).
Authors: Zhou Fang, Zheng Yi Fu, Hao Wang, Wei Min Wang, Qing Jie Zhang
Abstract: A novel approach was developed to prepare Ni-coated TiB2 cermet. Fine Ni particles with mean particle size of about 80 nm were impacted onto coarse TiB2 particles having a mean size of about 5 μm to form Ni-coated TiB2 powder by Hybridization. The conventional blended TiB2-Ni powder, as well as Ni-coated TiB2 powder, was sintered by hot pressing (HP) method and Spark Plasma Sintering (SPS) method. Compared with the conventional blended TiB2-Ni cermet, particle features and mechanical properties of the Ni-coated TiB2 cermet were investigated. The microstructure analysis reveals that the thickness of Ni film is around 4 nm. It is concluded that the mechanical properties of Ni-coated TiB2 cermet are superior to the blended TiB2-Ni cermet.
Authors: J.L. Xu, Khiam Aik Khor, W.N. Chen
Abstract: Hydroxyapatite based biomaterials were prepared by a spark plasma sintering technology. The human limb-derived osteoblasts were cultured on the various biomaterial surfaces (HA, RF21, 1SiHA and 5SiHA) for up to two weeks to investigate the cellular behaviors. The bone gammacarboxyglutamic protein or osteocalcin in the medium were determined at different periods of cell culture. The results indicated that a combined effect of bioceramic surface composition and surface morphology had influenced the osteoblast behaviors. The amount of osteocalcin in the medium increased in the initial periods of culture but decreased in the late periods of culture.
Authors: N. Koide, K. Suzuki, M. Tsuda, Teruo Asaoka
Abstract: Due to the merits of zirconia ceramics such as high strength, toughness, and abrasion resistance, as well as chemical stability in vivo, yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) are currently used in the femoral head of hip prostheses. However, this material has a limited range of use because it is a bioinert material that does not interact with bone tissue and thus does not easily integrate directly with bone. Therefore, addition of a material surface that enables the in vivo formation of a bone-like apatite layer that exhibits bioactivity and facilitates interactions and integration with bone tissue is desired. In addition, by developing a surface structure that enhances mechanical bonding, this material can be expected to be used as an alternative aggregate under load bearing conditions. In the present study, structural design of the material surface, addition of bioactivity using reagents treatment, confirmation of formation of the apatite layer using immersion in simulated body fluid, mechanical assessment, and wettability testing were conducted with the objective of controlling interactions between zirconia ceramics and the body.
Authors: Mehdi Estili, Kenta Takagi, Akira Kawasaki
Abstract: Capability of multiwalled carbon nanotubes (CNTs) to create in-depth gradients in properties and functionalities of conventional materials has been investigated for the first time. Functionally graded material (FGM) concept has also been employed for the first time to bridge conventional materials to their advanced nanocomposites containing a high concentration of CNTs, which is promising for unexplored yet novel structural, electronic and biomaterial applications. In this study, α-alumina ceramics considered as the most challenging case has been used as the matrix. Bulk, layered, nanostructure-controlled, CNT-based, functionally graded α-alumina ceramics have been fabricated employing a recently established powder processing technology. In-depth gradients in microstructure, grain size and hardness have been successfully achieved in alumina ceramic without cracking, delamination or warping, after homogeneous and gradual incorporation of the CNTs within the alumina ceramic matrix. The FGM approach showed promise to successfully bridge conventional ceramics to their nanocomposites containing a high concentration of CNTs.
Authors: Yi Song, Zhao Yao Zhou, Zhi Cheng Chen, Yong Quan Ye
Abstract: This paper proposed an improved thermal-electric-displacement FEM model for spark plasma sintering (SPS), which fully considered the variations of therma-electrical material parameters, contact resistances and contact boundaries due to the densification process. The simulation shows that such an alterable boundary condition builds a remarkable temperature gradient in the axial direction along the inner wall of the die, and the local change of the temperature at the contact interfaces can be described more exactly. The experiment and the simulation are in a great agreement. The developed SPS model can be used as an aiding tool to optimize the SPS process parameters of metal powders.
Authors: Marcelo Bertolete, Izabel Fernanda Machado, Daniel Rodrigues
Abstract: The aim is to analyze the influence of two sintering process parameters concerning the compact densification of WC-Co. The input variables studied were uniaxial pressure (40 and 60 MPa) and holding time (1 and 3 minutes). The output variables monitored were relative density, microstructural features, besides online monitoring of dynamics of sintering. The samples were sintered in a Dr. Sinter-Syntex machine of Spark Plasma Sintering (SPS), which allows heating rate greater than conventional sintering techniques, with the advantage of lower temperature, time and energy consumption. The powder used was a compaction residue of grade K (with content between 3 and 12%Co). The results showed significant influence of pressure on the density and percentage of the porous area; however, the process parameters did not affect the grain size.
Authors: Jun Jie Hao, Xiao Hui Wang, Jian Ling Zhao, Long Tu Li
Abstract: Textured bismuth titanate ceramics were successfully produced by spark plasma sintering, using plate-like Bi4Ti3O12 particles prepared by a molten salt method. The microstructure and electric properties of the samples were investigated. The results show that the textured Bi4Ti3O12 ceramics electric property is anisotropic in different direction, and spark plasma sintering is an effective sintering technology to get textured dense Bi4Ti3O12 ceramics at a low temperature.
Authors: G.A. Suchkova, E.Y. Belyaev, Alexander A. Vlasov, O.I. Lomovsky, Young Soon Kwon
Authors: Naoki Miyano, H. Iwasa, Kazuo Isonishi, S. Tanaka, S. Sugiyama, Kei Ameyama
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