scholarly journals Microstructure and Sintering Behavior of Fine Tungsten Powders Synthesized by Ultrasonic Spray Pyrolysis

2021 ◽  
Vol 59 (5) ◽  
pp. 289-294
Author(s):  
Hyeonhui Jo ◽  
Jeong Hyun Kim ◽  
Young-In Lee ◽  
Young-Keun Jeong ◽  
Sung-Tag Oh
Keyword(s):  
Particle Size ◽  
Relative Density ◽  
Spray Pyrolysis ◽  
Spark Plasma Sintering ◽  
Hydrogen Reduction ◽  
Ultrasonic Spray Pyrolysis ◽  
Sintering Behavior ◽  
Ultrasonic Spray ◽  
Plasma Sintering ◽  
Spark Plasma

The powder microstructure and sintering behavior of W prepared by ultrasonic spray pyrolysis and spark plasma sintering were investigated. Fine-grained W powders were synthesized by ultrasonic spray pyrolysis using an ammonium metatungstate hydrate solution and hydrogen reduction. The XRD analysis of the powder, pyrolyzed below 600 oC, showed tungsten oxide hydrate and WO3 peaks, while the powder pyrolyzed at 700 oC was composed of only the WO3 phase. As the precursor concentration increased, the particle size of the WO3 powder increased, which was interpreted to be due to an increase in the amount of solute in the droplet. The hydrogen-reduced powder showed a spherical shape with fine pores inside. XRD and XPS analysis revealed that the WO3 powder was completely reduced to metallic W by hydrogen reduction, and some oxide layers existed on the powder surface. The consolidated specimen prepared by spark plasma sintering of hydrogen-reduced W powder exhibited a relative density of 94.1% and a Vickers hardness value of 3.89 GPa. The relative density and hardness of the specimens prepared by ultrasonic spray pyrolysis showed relatively lower values than when commercial W powder, with an average particle size of 1.22 μm, was sintered under the same conditions. These results were explained by the formation of agglomerates in the W powder prepared by the ultrasonic spray pyrolysis method.

A proposed model for spark plasma sintering of SiC-Si nanocomposite with different SiC particle sizes

2020 ◽  
Vol 54 (19) ◽  
pp. 2599-2609
Author(s):  
Abtin Heydarian ◽  
Seyed Abdolkarim Sajjadi ◽  
Mats Johnsson
Keyword(s):  
Particle Size ◽  
Spark Plasma Sintering ◽  
Nano Particles ◽  
Sintering Behavior ◽  
Particle Sizes ◽  
Sic Particles ◽  
Plasma Sintering ◽  
Proposed Model ◽  
Spark Plasma ◽  
Sic Particle

In this study, the effect of SiC particle size on the sintering behavior of SiC-Si nano composites fabricated by spark plasma sintering (SPS) technique was investigated and a model was proposed, accordingly. To this purpose, SiC powders with three different particle sizes of 25 µm, 80 nm and 45 nm were chosen. It was expected that hardness of the composites increase with decreasing the SiC particle size; however, the outcomes were interesting and unpredictable. The composite with 80 nm SiC particles indicated the highest hardness. Hardness of the specimen with 25 µm SiC was low because of the large particle size of its reinforcement. While 80 and 45 nm SiC particles are considered as nano particles, the composite with 45 nm SiC particles showed lower hardness due to the growth of SiC powders during sintering according to a proposed model. Two reasons for the growth of 45 nm SiC particles were defined: (i) the fineness of the SiC particles prevented the Si particles to act as a binder between them thus, they agglomerated; (ii) SiC powders were oxidized during mixing procedure and a layer of SiO2 was formed on their surfaces. During sintering procedure, the reaction between SiC and SiO2 was happened and as a result SiO was formed. It caused vapor transportation during sintering leading to necking between particles and in turn, grain growth.

Synthesis and Densification of Nano-Sized W Powders Prepared by Hydrogen Reduction of Ball-Milled WO3 Powders

2020 ◽  
Vol 20 (7) ◽  
pp. 4521-4524
Author(s):  
Ju-Yeon Han ◽  
Hyunji Kang ◽  
Young-Keun Jeong ◽  
Sung-Tag Oh
Keyword(s):  
Relative Density ◽  
Spark Plasma Sintering ◽  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Applied Pressure ◽  
Average Particle ◽  
Tem Analysis ◽  
Combination Process ◽  
Plasma Sintering ◽  
Spark Plasma

The synthesis and consolidation of nano-sized W powders are attempted with the combination process of hydrogen reduction of ball-milled WO3 powder and spark plasma sintering. The reduction behavior of WO3 is analyzed by temperature-programmed reduction. The reaction peaks for reduction of WO3 are observed in the temperature range of 590–782 °C. XRD and TEM analysis reveals that oxide powder is changed to metallic W with an average particle size of 100 nm by hydrogen reduction at 900 °C for 1 h. The densified specimen by spark plasma sintering at 1700 °C under an applied pressure of 50 MPa using nano-sized W powder shows increased relative density compared with that using micron-sized W powder. The results suggested that the W bulk with increased relative density fine microstructure can be fabricated by spark plasma sintering of hydrogen-reduced WO3 powder, more effectively.

Densification and Microstructure of Monolithic TiN and TiB2 Fabricated by Spark Plasma Sintering

2012 ◽  
Vol 508 ◽  
pp. 38-41 ◽  
Author(s):  
Mettaya Kitiwan ◽  
Akihiko Ito ◽  
Takashi Goto
Keyword(s):  
Relative Density ◽  
Spark Plasma Sintering ◽  
Sintering Behavior ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Increasing Temperature

Sintering Behavior of Monolithic TiN and TiB2 Was Investigated Using Spark Plasma Sintering (SPS) at Temperatures between 1673 and 2573 K. Relative Density of TiN Was Increased from 82.3 to 96.7% while that of TiB2 Increased from 70.1 to 92.8% with Increasing Temperature. At Temperatures between 1673 and 2273 K, TiB2 Was More Difficult to Consolidate Compare to TiN. At 2473 K, TiB2 Densified Rapidly to 92.8%.

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

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.

scholarly journals Microstructure evolution of TC4 powder by spark plasma sintering after hot deformation

2020 ◽  
Vol 39 (1) ◽  
pp. 457-465
Author(s):  
Jiangpeng Yan ◽  
Zhimin Zhang ◽  
Jian Xu ◽  
Yaojin Wu ◽  
Xi Zhao ◽  
...  
Keyword(s):  
Strain Rate ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Hot Deformation ◽  
Tc4 Titanium Alloy ◽  
Weave Structure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Average Relative Density ◽  
Low Strain Rate

AbstractThe cylindrical samples of TC4 titanium alloy prepared by spark plasma sintering (SPS) were compressed with hot deformation of 70% on the thermosimulation machine of Gleeble-1500. The temperature of the processes ranged from 850°C to 1,050°C, and the strain rates varied between 0.001 and 5 s−1. The relative density of the sintered and compressed samples was measured by the Archimedes principle. During hot deformation, the microstructure of the sample was observed. The results show that the average relative density of the samples was 90.2% after SPS. And the relative density was about 98% after the hot deformation of 70%. Under high temperature (>950°C), the sensitivity of flow stress to temperature was reduced. At low strain rate (0.001 s−1), the increase in the deformation temperature promoted the growth of dynamic recrystallization (DRX). At the same temperature, the increase in strain rate slowed down the growth of DRX grains. And the variation tendency was shown from the basket-weave structure to the Widmanstätten structure at a low strain rate (<0.1 s−1), with increase in the strain rate.

Investigation on the Correlations between Droplet and Particle Size Distribution in Ultrasonic Spray Pyrolysis

2008 ◽  
Vol 47 (5) ◽  
pp. 1650-1659 ◽  
Author(s):  
Wei-Ning Wang ◽  
Agus Purwanto ◽  
I. Wuled Lenggoro ◽  
Kikuo Okuyama ◽  
Hankwon Chang ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Spray Pyrolysis ◽  
Size Distribution ◽  
Ultrasonic Spray Pyrolysis ◽  
Ultrasonic Spray

scholarly journals Effect of initial particle size and various composition on the spark plasma sintering of binderless tungsten carbide

2021 ◽  
Vol 1758 (1) ◽  
pp. 012022
Author(s):  
E A Lantsev ◽  
N V Malekhonova ◽  
V N Chuvil`deev ◽  
A V Nokhrin ◽  
M S Boldin ◽  
...  
Keyword(s):  
Particle Size ◽  
Tungsten Carbide ◽  
Spark Plasma Sintering ◽  
Initial Particle ◽  
Initial Particle Size ◽  
Plasma Sintering ◽  
Spark Plasma

Spark Plasma Sintering and Hot Pressing Sintering of Nanocrystalline WC-10CO-0.8VC

2007 ◽  
Vol 534-536 ◽  
pp. 1229-1232
Author(s):  
Li Hui Zhu ◽  
Guang Jie Shao ◽  
Yi Xiong Liu ◽  
Dave Siddle
Keyword(s):  
Relative Density ◽  
Spark Plasma Sintering ◽  
Hot Pressing ◽  
Nanocrystalline Powders ◽  
Microstructure And Properties ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Hot Pressing Sintering

WC-10Co-0.8VC nanocrystalline powders were sintered by spark plasma sintering (SPS) and hot pressing sintering (HPS), and the microstructure and properties were compared. Results show that, sintered at 1300°C, the sample prepared by SPS for only 3 minutes has higher density than that prepared by HPS for 60 minutes. SEM and SPM observation shows SPS at 1200°C has a more uniform and finer microstructure, and most of the WC grains are smaller than 100nm. It has a relative density of 95.1%, HV30 of 1887, and KIC of 11.5 MPam1/2. If a suitable sintering parameter is chosen, SPS is a promising consolidation technique to prepare nanocrystalline WC-10Co-0.8VC with improved properties.

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