scholarly journals Characteristics of Nanophase WC and WC-3 wt% (Ni, Co, and Fe) Alloys Using a Rapid Sintering Process for the Application of Friction Stir Processing Tools

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Daeup Kim ◽  
Young Choi ◽  
Yongil Kim ◽  
Seungboo Jung
Keyword(s):  
Friction Stir Processing ◽  
Average Particle Size ◽  
Milling Process ◽  
Phase Changes ◽  
Average Particle ◽  
Sintering Process ◽  
Friction Stir ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Rapid Sintering

Microstructures and mechanical characteristics of tungsten carbide- (WC-) based alloys, that is, WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe, fabricated using a spark plasma sintering (SPS) method for the application of friction stir processing tools were evaluated. The sintered bodies with a diameter of 66 mm showed relative densities of up to 99% with an average particle size of 0.26~0.41 μm under a pressure condition of 60 MPa with an electric current for 35 min without noticeable grain growth during sintering. Even though no phase changes were observed after the ball milling process the phases of W2C andWC1-xappeared in all sintered samples after sintering. The Vickers hardness and fracture toughness of the WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe samples ranged from 2,240 kg mm2to 2,730 kg mm2and from 6.3 MPa·m1/2to 9.1 MPa·m1/2, respectively.

Spark-Plasma Sintering of Molybdenum Disilicide

2005 ◽  
Vol 287 ◽  
pp. 160-165 ◽  
Author(s):  
Ji Soon Kim ◽  
Young Do Kim ◽  
Choong Hyo Lee ◽  
Pyuck Pa Choi ◽  
Young Soon Kwon
Keyword(s):  
Relative Density ◽  
Spark Plasma Sintering ◽  
Silicon Oxide ◽  
Average Particle Size ◽  
Molybdenum Disilicide ◽  
Milling Process ◽  
Average Particle ◽  
Densification Rate ◽  
Plasma Sintering ◽  
Spark Plasma

The effect of milling on the densification behavior of MoSi2 powder during spark-plasma sintering (SPS) was investigated. MoSi2 starting powder with an average particle size of 10 µm was milled to reduce particle sizes to less than 1 µm. Sintering was performed in a SPS facility, varying the sintering temperature from 1200°C to 1500°C. Changes in relative density and the densification rate were measured as a function of temperature. Additionally, the microstructure of sintered compacts was analyzed by means of SEM and EPMA. The sintered density was lower for ballmilled powder compacts (having 94-95% relative density) than for as-received ones (having 94- 98% relative density) despite a higher densification rate of the former in the early and middle stages of sintering. These apparently contradictory results can be explained by a pick-up of oxygen (from 0.3 to 1.8 wt. % O) during the milling process, leading to the formation of silicon oxide and its decomposition into a gas phase at temperatures above 1200°C.

Mechanical Property of Porous Titanium Produced by Spark Plasma Sintering

2008 ◽  
Vol 385-387 ◽  
pp. 637-640 ◽  
Author(s):  
Yuki Sakamoto ◽  
Shigeaki Moriyama ◽  
Masahiro Endo ◽  
Yuji Kawakami
Keyword(s):  
Elastic Modulus ◽  
Spark Plasma Sintering ◽  
Average Particle Size ◽  
Pure Titanium ◽  
Porous Titanium ◽  
Human Bone ◽  
Average Particle ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Biological Reaction

Titanium has widely been used as a biomaterial because of its excellent corrosion resistance and biocompatibility. However, problems with respect to biological reaction and fitness of elastic modulus for human bone or tooth have yet to be solved. Porous titanium is expected to be a promising material to solve these problems. The aim of this study is to clarify the effect of the porous structure of this material on the biomechanical compatibility. The spherical pure titanium powder, with an average particle size of 100 µm, was sintered by spark plasma sintering. The sintered porous titanium compacts had a porosity of 33 %. The specimens were machined from the sintered compacts for the evaluation of the mechanical properties. The elastic modulus indicated a value close to human bone, while the tensile and compressive strengths showed lower values than those of human bone.

scholarly journals Modification of Densification Mechanisms By The Timing of Mechanical Pressure During Spark Plasma Sintering

2021 ◽  
Author(s):  
David Salamon ◽  
Hua Tan ◽  
Haibo Zhang
Keyword(s):  
Grain Size ◽  
Alumina Powder ◽  
Sintering Process ◽  
Mechanical Pressure ◽  
Vapor Transfer ◽  
Plasma Sintering ◽  
Nano Alumina ◽  
Diffusion Enhancement ◽  
Spark Plasma ◽  
Rapid Sintering

Abstract The application of mechanical pressure during a sintering process is connected with grains sliding and diffusion enhancement. However, the timing of mechanical pressure during the rapid sintering process was not addressed. In the present study, four different timings of mechanical pressure with final pressure 50 MPa starting from the beginning, 600 ℃, 900 ℃ and at sintering temperature, furthermore one pressure-less SPS have been studied during SPS of Nano-Alumina powder (Taimei, Japan) at 1100 ℃, 1150 ℃, 1200 ℃, and 1300 ℃, respectively. The density, hardness, microstructure, and grain size of each sample were measured and calculated carefully. The results show that applying the pressure at 900 ℃ brings high density and small grain size, leading to the best Vickers hardness. The interaction between pressure and vapor, leading to the different vapor transfer rate of the first sintering stage, is considered as a reason for the differences in the microstructure.

Effect of Alumina Additions on Mechanical and Electrical Properties of 8mol% Yttria-Stabilized Zirconia Prepared by Spark Plasma Sintering

2006 ◽  
Vol 317-318 ◽  
pp. 917-920
Author(s):  
Jae Kwang Kim ◽  
Kyung Hun Kim ◽  
Yong Ho Choa ◽  
Jong Won Yoon ◽  
Kwang Bo Shim
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Average Particle Size ◽  
Yttria Stabilized Zirconia ◽  
Average Particle ◽  
Stabilized Zirconia ◽  
Plasma Sintering ◽  
Spark Plasma

Dense 8mol% yttria-stabilized zirconia (8YSZ) consisting of submicrometer-sized grains was prepared using spark plasma sintering (SPS) along with Al2O3 additives. The starting powder with average particle size of 50nm was densified to 98% of the relative density with short sintering time (5min) at 1200 while preserving a submicrometer grain size. The fracture toughness and bending strength showed maximum values of 2.54MPam1/2 and 380MPa at 2vol% alumina-added 8YSZ, due mainly to the higher relative density and small grain size. The electrical conductivity of 2vol% alumina-added 8YSZ was 0.0278 S/cm at 700 in airThus, alumina additions in 8YSZ using the SPS method are an effective process to improve the mechanical strength and electrical conductivity.

Structural and magnetic characterization of spark plasma sintered Fe-50Co alloys

2012 ◽  
Vol 1516 ◽  
pp. 201-207 ◽  
Author(s):  
Mahesh Kumar Mani ◽  
Giuseppe Viola ◽  
Mike J Reece ◽  
Jeremy P Hall ◽  
Sam L Evans
Keyword(s):  
Sintering Temperature ◽  
Average Particle Size ◽  
Average Particle ◽  
Mechanical Pressure ◽  
Plasma Sintering ◽  
Saturation Induction ◽  
Porous Microstructure ◽  
Density Values ◽  
Spark Plasma

ABSTRACTFe-50 wt% Co alloy powders with average particle size of 10 μm were compacted by spark plasma sintering (SPS) at 700, 800, 900 and 950oC by applying 40, 80, 100 MPa uniaxial pressures for 2, 5, 10 minutes. The densities of the samples were found to increase with temperature from 700 to 900oC for constant sintering pressure and time and to decrease for the material sintered at 950oC. The effects of sintering time on density were more significant in samples sintered at 700oC and 800oC than those densified at 900oC. The consequences of small increases in mechanical pressure during sintering on density values were significant for samples sintered at 700oC. The coercivity (Hc) of the compacts decreased significantly with increasing sintering temperature, and with increasing dwell time at sintering temperatures lower than 700oC. The sample sintered at 950oC, which contains the largest grains among the prepared samples and porous microstructure, exhibited the minimum coercivity. Unlike Hc, the remanence (Br) and saturation induction (Bsat) values were more strongly affected by the specimen density than by grain size. Br and Bsat values were found to vary linearly with sintering temperature and pressure owing to increasing density. An increase in soaking time at 800 and 900 oC, although enabling higher density, exhibited contradicting effects on Bsat values. The SPS parameters to obtain maximum density and optimum magnetic properties for Fe-50% Co alloy were found to be 900oC, 80 MPa and 2-5 minutes.

scholarly journals Two-Step Spark Plasma Sintering Process of Ultrafine Grained WC-12Co-0.2VC Cemented Carbide

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2443 ◽  
Author(s):  
Zhenhua Wang ◽  
Jiheng Jia ◽  
Boxiang Wang ◽  
Yulin Wang
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Average Particle Size ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
Average Particle ◽  
Plasma Sintering ◽  
Ultrafine Grained ◽  
Spark Plasma

Ultrafine grained WC-12Co-0.2VC (named UYG12V) cemented carbides were prepared via the two-step spark plasma sintering (SPS) in this study. First, the effects of the sintering temperature on the relative density and WC grain size of UYG12V cemented carbides were studied. The results show that regular WC grains form when sintered at 1300 °C. The sintered body begins to rapidly densify and WC grains grow slowly when sintered at 1200 °C. Thus, the first-step (T1) and the second-step (T2) temperatures in the two-step SPS of UYG12V are 1300 °C and 1200 °C, respectively. The effect of the holding time during the first and second steps on the mechanical properties was also studied. The results show that the UYG12V cemented carbide sintered at 1300 °C for 3 min and then at 1200 °C for 5 min has the best comprehensive mechanical properties, exhibiting the average particle size, Vickers hardness, fracture toughness, relative density, and bending strength of 271 nm, 18.06 GPa, 12.25 MPa m1/2, 99.49%, and 1960 MPa, respectively.

scholarly journals Fabrication and Enhanced Thermoelectric Properties of Alumina Nanoparticle-Dispersed Bi0.5Sb1.5Te3Matrix Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Kyung Tae Kim ◽  
Gook Hyun Ha
Keyword(s):  
Milling Process ◽  
Alumina Nanoparticles ◽  
Sintering Process ◽  
Composite Powders ◽  
Alumina Nanoparticle ◽  
Plasma Sintering ◽  
The Matrix ◽  
High Resolution Tem ◽  
Spark Plasma ◽  
P Type

Alumina nanoparticle-dispersed bismuth-antimony-tellurium matrix (Al2O3/BST) composite powders were fabricated by using ball milling process of alumina nanoparticle about 10 nm and p-type bismuth telluride nanopowders prepared from the mechanochemical process (MCP). The fabricated Al2O3/BST composite powders were a few hundreds of nanometer in size, with a clear Bi0.5Sb1.5Te3phase. The composite powders were consolidated into p-type bulk composite by spark plasma sintering process. High-resolution TEM images reveal that alumina nanoparticles were dispersed among the grain boundary or in the matrix grain. The sintered 0.3 vol.% Al2O3/BST composite exhibited significantly improved power factor and reduced thermal conductivity in the temperature ranging from 293 to 473 K compared to those of pure BST. From these results, the highly increased ZT value of 1.5 was obtained from 0.3 vol.% Al2O3/BST composite at 323 K.

Preparation of Lithium Sulfide-Carbon Composites Using Spark-Plasma-Sintering Process and their Electrochemical Properties

2010 ◽  
Vol 638-642 ◽  
pp. 2184-2188 ◽  
Author(s):  
Tomonari Takeuchi ◽  
Hikari Sakaebe ◽  
Tetsuo Sakai ◽  
Kuniaki Tatsumi
Keyword(s):  
Spark Plasma Sintering ◽  
Carbon Composite ◽  
Milling Process ◽  
Sintering Process ◽  
Rechargeable Lithium Batteries ◽  
Positive Electrodes ◽  
Electrochemical Tests ◽  
Plasma Sintering ◽  
Lithium Sulfide ◽  
Spark Plasma

Lithium sulfide (Li2S)-carbon composite positive electrodes were prepared by the spark-plasma-sintering (SPS) process for use in rechargeable lithium batteries. By the SPS treatment of Li2S and acetylene black (AB) blended powder, the strong binding between the active materials and the carbon powders were formed. Such contact effect improved the electrochemical performance of the cells with liquid electrolytes (1M LiFP6/(EC+DMC)), probably due to the increase in conductivity of the positive electrodes, though the samples prepared by the ball-milling process showed no significant capacity in the electrochemical tests.

MECHANICAL ALLOYING WITH PARTIAL AMORPHIZATION OF FE–CR–CO–NI–MN MULTICOMPONENT POWDER MIXTURE AND ITS SPARK PLASMA SINTERING FOR COMPACT HIGH-ENTROPY MATERIAL PRODUCTION

2018 ◽  
pp. 35-42 ◽  
Author(s):  
N. A. Kochetov ◽  
A. S. Rogachev ◽  
A. S. Shchukin ◽  
S. G. Vadchenko ◽  
I. D. Kovalev
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Powder Mixture ◽  
Average Particle Size ◽  
Solid Solution Phase ◽  
Average Particle ◽  
Chromium Powder ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma

This paper presents the results of studying the mechanical alloying (MA) effect on the surface morphology, microstructure and atomic-crystal structure of multicomponent Fe–Cr–Co–Ni–Mn powder mixture particles. The following materials were used as initial components: radio-engineering carbonyl iron powder (R-10 with an average particle size d = 3,5 μm), nickel powder (NPE-1, d = 150 μm), cobalt powder (PK-1u, d <71 μm), chromium powder (PH-1М, d <125 μm) and manganese powder (MR0, d <400 μm) were used. MA of the prepared mixture was carried out in the AGO-2 water-cooled mechanical activator using 9 mm steel balls with an acceleration of 90 g in air. Alloying time varied between 5 and 90 minutes. The ratio of ball mass to the mass of the mixture was 20 : 1. X-ray patterns of the initial and alloyed mixtures and the sample obtained by sintering were made on the DRON 3M diffractometer on FeKα radiation in the range of angles 2θ = 30°÷100°. The particle microstructure of the mixtures and compact sample section after sintering was studied by scanning electron microscopy. It is found that no peaks of the initial components are present on the X-ray pattern of the mixture after 90 minutes of mechanical activation, but there are peaks corresponding to the γ-Fe-based solid solution phase having a face-centered crystal lattice with an amorphous phase content increased by 20 %. A compact single-phase material was obtained by spark plasma sintering at 800 °С for 10 minutes from the mixture after 90-minute alloying. Material density was 7,49 kg/cm3, specific electrical resistivity was 0,94÷0,96·10–6 ·m, microhardness was 306÷328 kg/mm2, and the phase was distributed uniformly throughout the volume.

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.

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