Fabrication of Mg2Si bulk by spark plasma sintering method with Mg2Si nano-powder

2013 ◽  
Vol 1490 ◽  
pp. 63-68 ◽  
Author(s):  
Koya Arai ◽  
Keishi Nishio ◽  
Norifumi Miyamoto ◽  
Kota Sunohara ◽  
Tatsuya Sakamoto ◽  
...  

ABSTRACTMg2Si bulk was fabricated by spark plasma sintering (SPS) nano-powder, and the thermoelectric characteristics of the bulk sample were evaluated at temperatures up to 873 K. A pre-synthesized all-molten commercial polycrystalline Mg2Si source (un-doped n-type semiconductor) was pulverized into powder of 75 μm or less. To obtain nano-sized fine powder, the powder was milled using planetary ball mill equipment under an inert atmosphere. Fine Mg2Si nano-powder with a mean grain size of about 500 nm was obtained. XRD analysis confirmed that no MgO existed in the nano-powder. The fine powder was put in a graphite die to obtain a sintering body of Mg2Si and treated by SPS under vacuum conditions. The resulting Mg2Si bulk had high density and did not crack. However, the XRD analysis revealed a small amount of MgO in it. The thermoelectric properties (electrical conductivity, Seebeck coefficient, and thermal conductivity) were measured from room temperature to 873 K. The microstructure of the sintered body was observed by scanning electron microscopy. The maximum dimensionless figure of merit of a sample made from Mg2Si nano-powder was ZT = 0.67 at 873 K.

2020 ◽  
Vol 16 (4) ◽  
pp. 578-583
Author(s):  
Muhammad Asif Hussain ◽  
Adnan Maqbool ◽  
Abbas Saeed Hakeem ◽  
Fazal Ahmad Khalid ◽  
Muhammad Asif Rafiq ◽  
...  

Background: The development of new bioimplants with enhanced mechanical and biomedical properties have great impetus for researchers in the field of biomaterials. Metallic materials such as stainless steel 316L (SS316L), applied for bioimplants are compatible to the human osteoblast cells and bear good toughness. However, they suffer by corrosion and their elastic moduli are very high than the application where they need to be used. On the other hand, ceramics such as hydroxyapatite (HAP), is biocompatible as well as bioactive material and helps in bone grafting during the course of bone recovery, it has the inherent brittle nature and low fracture toughness. Therefore, to overcome these issues, a hybrid combination of HAP, SS316L and carbon nanotubes (CNTs) has been synthesized and characterized in the present investigation. Methods: CNTs were acid treated to functionalize their surface and cleaned prior their addition to the composites. The mixing of nano-hydroxyapatite (HAPn), SS316L and CNTs was carried out by nitrogen gas purging followed by the ball milling to insure the homogeneous mixing of the powders. In three compositions, monolithic HAPn, nanocomposites of CNTs reinforced HAPn, and hybrid nanocomposites of CNTs and SS316L reinforced HAPn has been fabricated by spark plasma sintering (SPS) technique. Results: SEM analysis of SPS samples showed enhanced sintering of HAP-CNT nanocomposites, which also showed significant sintering behavior when combined with SS316L. Good densification was achieved in the nanocomposites. No phase change was observed for HAP at relatively higher sintering temperatures (1100°C) of SPS and tricalcium phosphate phase was not detected by XRD analysis. This represents the characteristic advantage with enhanced sintering behavior by SPS technique. Fracture toughness was found to increase with the addition of CNTs and SS316L in HAPn, while hardness initially enhanced with the addition of nonreinforcement (CNTs) in HAPn and then decrease for HAPn-CNT-SS316L hybrid nanocomposites due to presence of SS316L. Conclusion: A homogeneous distribution of CNTs and SPS technique resulted in the improved mechanical properties for HAPn-CNT-SS316L hybrid nanocomposites than other composites and suggested their application as bioimplant materials.


2011 ◽  
Vol 306-307 ◽  
pp. 1398-1401 ◽  
Author(s):  
Di Zhang ◽  
Ming Gang Wang ◽  
Zhan Kui Zhao

The porous ZrO2 ceramics was prepared by spark plasma sintering (SPS) at 520 °C. A dense closed micro-cellular ceramic structure was fabricated with micron Al90Mn9Ce1 alloy powders clading by 10 wt% ZrO2 nano-powder. SEM image showed that the thickness of ceramic cell wall was 1.0 - 2.0 μm. After deep corrosion with 10% HCl, an integrity nanocrystalline ZrO2 porous sample was obtained. Based on the experimental results, the transient spark plasma sintering mechanism of micron-nano mixing powder was also studied.


2002 ◽  
Vol 17 (3) ◽  
pp. 575-581 ◽  
Author(s):  
Tomonari Takeuchi ◽  
Claudio Capiglia ◽  
Nalini Balakrishnan ◽  
Yasuo Takeda ◽  
Hiroyuki Kageyama

Dense BaTiO3 ceramics consisting of fine grains were prepared using fine powder (average grain size of 0.06 μm; BT006) as a starting material and the spark plasma sintering (SPS) method. The powder was densified to >95% of theoretical x-ray density by the SPS process, and the average grain size of the resulting ceramics was <0.5 μm; the particle size of the initial powder significantly affects the grain size of the resulting SPS pellets. Fixed-frequency (100 kHz), room-temperature permittivity measurements of the BT006-SPS ceramics showed relatively low values (3000–3500) compared with those (typically 5000) for SPS ceramics consisting of larger grains (approximately 1 μm). Lower permittivity was attributed to poor development of ferroelectric domains in the ceramics, which originated from incomplete development of the tetragonal structure as well as the presence of a local orthorhombic structure.


JOM ◽  
2016 ◽  
Vol 68 (3) ◽  
pp. 908-919 ◽  
Author(s):  
E. S. Dvilis ◽  
O. L. Khasanov ◽  
V. N. Gulbin ◽  
M. S. Petyukevich ◽  
A. O. Khasanov ◽  
...  

2008 ◽  
Vol 403 ◽  
pp. 225-226
Author(s):  
E. Ayas ◽  
A. Kalemtas ◽  
Gürsoy Arslan ◽  
Alpagut Kara ◽  
Ferhat Kara

Si3N4-B4C composites containing fine and coarse B4C particles were produced using Al2O3 and Y2O3 as sintering additives via spark plasma sintering (SPS) technique. Phase assemblages of the produced composites were determined by XRD analysis. Si3N4, B4C and in situ formed SiC, h-BN and Si phases were observed. Even when incorporated in significant amounts, B4C was consumed readily in the Si3N4 based system. Consequently, full densification of these composites was found to be a very difficult task due to the simultaneous in-situ reactions, even in fast sintering process. Electrical resistivity measurements carried out at room temperature indicated that addition of both fine and coarse B4C particles decreased the electrical resistivity by several orders of magnitude due to the formation of electrically conductive in-situ phases, mainly SiC and metallic Si.


2020 ◽  
Vol 17 (3) ◽  
pp. 932-940
Author(s):  
Changchun Lv ◽  
Xiaoyong Ren ◽  
Chengbiao Wang ◽  
Zhijian Peng

2011 ◽  
Vol 485 ◽  
pp. 169-172 ◽  
Author(s):  
Koya Arai ◽  
Hiroyuki Akimoto ◽  
Tohru Kineri ◽  
Tsutomu Iida ◽  
Keishi Nishio

NaCo2O4and 0.5at%-Sb doped Mg2Si have excellent thermoelectric properties. We tried to fabricate a thermoelectric module composed of these materials and using Ni plates as electrodes. The fine powder of NaCo2O4was prepared by metal-citric acid complex decomposition. 0.5at%-Sb doped Mg2Si bulk was ground to powder and sieved to a powder particle size of 75 micrometers or less. These powders were sintered using spark plasma sintering (SPS) to obtain a body of NaCo2O4and 0.5at%-Sb doped Mg2Si. These thermoelectric materials were connected to the Ni plates by using the SPS method. The whole process took a very short time (less than 2 min) and could be done at low temperature (below 873 K). The open-circuit voltagevalues were 82.7 mV, and the maxima,maximum output currentand maximum output power, for the single module were 212.4 mA and 6.65 mW at ΔT= 470 K.


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