Spray freeze granulation of submicron alumina and its sintering behavior via spark plasma sintering

Spray freeze granulation is an improved method based on spray granulation, solving many limitations of spray granulation. In this work, spray freeze granulation of submicron alumina is performed to explore the possibility of industrial-scale production of dense alumina via spark plasma sintering. Powder pretreatment such as sedimentation and the selection of granules with the appropriate size are employed for the maximum use of the high qualified as-prepared granules and granule sliding, which would provide a guidance for the industrial-scale production. Debound granules were densified via SPS and the corresponding sintering behaviors such as the recorded shrinkage and shrinkage rate were discussed. The comparison of sintering behaviors between granulated and as-received powder are conducted to identify the role of spray freeze granulation in sinterability for dense alumina. The Vickers hardness (Hv) and the fracture toughness (KIC) of the freeze granulated body are higher than the corresponding properties of the as-received body due to the more homogenous microstructure with little agglomeration in the particle packing after freeze granulation.

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Spark Plasma Sintering of Hybrid Nanocomposites of Hydroxyapatite Reinforced with CNTs and SS316L for Biomedical Applications

Current Nanoscience ◽

10.2174/1573413715666190130160253 ◽

2020 ◽

Vol 16 (4) ◽

pp. 578-583

Author(s):

Muhammad Asif Hussain ◽

Adnan Maqbool ◽

Abbas Saeed Hakeem ◽

Fazal Ahmad Khalid ◽

Muhammad Asif Rafiq ◽

...

Keyword(s):

Fracture Toughness ◽

Spark Plasma Sintering ◽

Xrd Analysis ◽

Sem Analysis ◽

Hybrid Nanocomposites ◽

Homogeneous Distribution ◽

Sintering Behavior ◽

Stainless Steel 316L ◽

Plasma Sintering ◽

Spark Plasma

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.

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On the Role of the Electrical Field in Spark Plasma Sintering of UO2+x

Scientific Reports ◽

10.1038/srep46625 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 17

Author(s):

Vaclav Tyrpekl ◽

Mohamed Naji ◽

Michael Holzhäuser ◽

Daniel Freis ◽

Damien Prieur ◽

...

Keyword(s):

Spark Plasma Sintering ◽

Electrical Field ◽

Plasma Sintering ◽

Spark Plasma

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Sintering Behavior of TiC-Fe Based Composite Fabricated by Spark Plasma Sintering Using TiH2 Graphite Powders

Materials Science Forum ◽

10.4028/www.scientific.net/msf.534-536.217 ◽

2007 ◽

Vol 534-536 ◽

pp. 217-220 ◽

Cited By ~ 1

Author(s):

Sung Yeal Bae ◽

In Sup Ahn ◽

Ho Jung Cho ◽

Chul Jin Kim ◽

Dong Kyu Park

Keyword(s):

Heat Treatment ◽

Spark Plasma Sintering ◽

Temperature Increase ◽

Metal Matrix ◽

Sintering Behavior ◽

Matrix Composites ◽

Plasma Sintering ◽

Spark Plasma ◽

Particulate Reinforced ◽

Continuous Metal

TiC particulate reinforced Fe matrix composite compacts with controlled interfacial reaction was processed by spark plasma sintering after mechanical alloying. Milled powders were fabricated for 1-5 hours by spex shaker mill with the ball to powder ratio of 25:2. Metal matrix composites (MMCs) based on the Fe-40%TiC system can be synthesized by spark plasma sintering of the D’AE powders with TiH2-graphite powders under vacuum in the temperature range 1273-1473K for 5-20 min. TiC phase was formed by self combustion reaction with temperature increase. The specimen that was formed by sintering Fe-TiC powders displayed a microstructure of uniformly dispersed TiC grain in a continuous metal matrix. The densifications of the TiC-Fe materials were increased as the heat-treatment holding time increasing. In the same time, relative density and hardness of TiC-Fe sintering materials was increased.

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