scholarly journals Electrochemically Exfoliated Graphene-Like Nanosheets for Use in Ceramic Nanocomposites

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2656
Author(s):  
Rosalía Poyato ◽  
Reyes Verdugo ◽  
Carmen Muñoz-Ferreiro ◽  
Ángela Gallardo-López
Keyword(s):  
Graphene Nanosheets ◽  
Ceramic Matrix Composite ◽  
Tetragonal Zirconia ◽  
Microstructural Characterization ◽  
Homogeneous Distribution ◽  
Graphene Layers ◽  
Exfoliated Graphene ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma

In this work, the synthesis of graphene-like nanosheets (GNS) by an electrochemical exfoliation method, their microstructural characterization and their performance as fillers in a ceramic matrix composite have been assessed. To fabricate the composites, 3 mol % yttria tetragonal zirconia (3YTZP) powders with 1 vol % GNS were processed by planetary ball milling in tert-butanol to enhance the GNS distribution throughout the matrix, and densified by spark plasma sintering (SPS). According to a thorough Raman analysis and SEM observations, the electrochemically exfoliated GNS possessed less than 10 graphene layers and a lateral size lower than 1 μm. However, they contained amorphous carbon and vacancy-like defects. In contrast the GNS in the sintered composite exhibited enhanced quality with a lower number of defects, and they were wavy, semi-transparent and with very low thickness. The obtained nanocomposite was fully dense with a homogeneous distribution of GNS into the matrix. The Vickers hardness of the nanocomposite showed similar values to those of a monolithic 3YTZP ceramic sintered in the same conditions, and to the reported ones for a 3YTZP composite with the same content of commercial graphene nanosheets.

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.

Effect of Precursors on Transmittance and Microstructure of Mullite Ceramics

2009 ◽  
Vol 620-622 ◽  
pp. 429-432 ◽  
Author(s):  
Gui Min Zhang ◽  
Zheng Yi Fu ◽  
Yu Cheng Wang ◽  
Hao Wang ◽  
Wei Min Wang ◽  
...  
Keyword(s):  
Spray Drying ◽  
Ethanol Solution ◽  
Spherical Particles ◽  
Plasma Sintering ◽  
The Matrix ◽  
Conventional Drying ◽  
Spark Plasma ◽  
Mean Size ◽  
Dta Curves ◽  
Equiaxed Grains

Two different kinds of mullite precursors with composition 3Al2O3•2SiO2 (3:2) were prepared by conventional drying ethanol solution and spray-drying aqueous solution of aluminum nitrate nanohydrate and tetraethoxysilane, respectively. The results of scanning electron microscope (SEM) indicate that one powder consists of irregular particles with size of 1-10μm, the other powder is made of inhomogeneously sized hollow spherical particles with mean size of 0.5-5μm. The TG-DTA curves indicate the hollow spherical particles are unfavorable to eliminate the decomposed products. After the precursors were sintered by Spark Plasma Sintering at 1450°C for 10min, the microstructures of the former are made of fine equiaxed grains with sizes of around 0.5μm, the latter consist of elongated grains distributed in the matrix of fine grains with imhomogenous size of 0.5~10μm due to the liquid phase forming. The different microstructures lead to the former sintered body is transparent, while, the sample from spray-drying is opaque.

Highly Infrared Transparent Nanometric Tetragonal Zirconia Prepared by High-Pressure Spark Plasma Sintering

2011 ◽  
Vol 94 (9) ◽  
pp. 2739-2741 ◽  
Author(s):  
Haibin Zhang ◽  
Zhipeng Li ◽  
Byung-Nam Kim ◽  
Koji Morita ◽  
Hidehiro Yoshida ◽  
...  
Keyword(s):  
High Pressure ◽  
Spark Plasma Sintering ◽  
Tetragonal Zirconia ◽  
Plasma Sintering ◽  
Spark Plasma

Carbon Vacancy Ordered Non-Stoichiometric ZrC0.6

2014 ◽  
pp. 667-689
Author(s):  
Wentao Hu ◽  
Yongjun Tian ◽  
Zhongyuan Liu
Keyword(s):  
Heating Temperature ◽  
Tetragonal Zirconia ◽  
Zirconium Carbide ◽  
Amorphous Layer ◽  
Plasma Sintering ◽  
Heating Treatment ◽  
Spark Plasma ◽  
Metastable Tetragonal Zirconia ◽  
Average Size ◽  
Oxygen Atoms

The starting nanopowders of non-stoichiometric zirconium carbide (ZrCx) were fabricated via milling Zr powders in toluene for different dwell times. The carbon content was determined to depend on the milling time and the used amount of toluene. The bulk non-stoichiometric ZrCx with different x were prepared by spark plasma sintering of the obtained ZrCx nanopowders. The microstructural features of a sintered ZrC0.6 sample were investigated via the measurements of XRD, TEM, and HRTEM. It was found that the carbon vacancies have an ordering arrangement in C sublattice, forming a Zr2C-type cubic superstructural phase with space group of . Moreover, it was observed that the superstructural phase exists in nano-domains with an average size of ~30 nm owing to the ordering length in nanoscale. During the heating treatment in air, it was recognized that the diffusion of oxygen atoms is significantly facilitated through the ordered carbon vacancies. For the heating treatment at low temperature (<300°C), the oxygen atoms diffuse easily into and occupy the ordered carbon vacancies, forming the oxy-carbide of ZrC0.6O0.4 with ordered oxygen atoms. At the heating temperature higher than 350°C an amorphous layer of ZrC0.6Oy>0.4 was identified to be formed due to the diffusion of superfluous oxygen atoms into Zr-tetrahedral centers. Inside the amorphous layer, the metastable tetragonal zirconia nanocrystals are recognized to be gradually developed.

Microstructural characterization and mechanical behaviours of TiN-graphite composites fabricated by spark plasma sintering

2020 ◽  
Vol 91 ◽  
pp. 105253
Author(s):  
Ojo Jeremiah Akinribide ◽  
Babatunde Abiodun Obadele ◽  
Samuel Olukayode Akinwamide ◽  
Olusola Olaitan Ayeleru ◽  
Mehdi Eizadjou ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Microstructural Characterization ◽  
Plasma Sintering ◽  
Mechanical Behaviours ◽  
Spark Plasma ◽  
Graphite Composites

The Influence of RuO2 Addition on the Thermoelectric Properties of BiSbTe Alloys

2012 ◽  
Vol 512-515 ◽  
pp. 1651-1654 ◽  
Author(s):  
Yu Kun Xiao ◽  
Zhi Xiang Li ◽  
Jun Jiang ◽  
Sheng Hui Yang ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Lattice Thermal Conductivity ◽  
Combined Process ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma ◽  
Xrd Patterns ◽  
Factor Α ◽  
P Type

P-type BiSbTe/RuO2 composite was fabricated using a combined process of melting and spark plasma sintering. The XRD patterns showed that RuO2 reacted with the matrix for the RuO2 content of 1.0 wt% and 4.0 wt% samples. The measured thermoelectric properties showed that the highest electrical conductivity was obtained for the sample with 2.0 wt% RuO2. The power factor (α2σ/κ) decreased with the increase of RuO2 below 450 K. The lattice thermal conductivity was lower than that of BiSbTe over the whole temperature range for BiSbTe/2.0 wt% RuO2.

High Temperature Microstructural Stability of Si3N4 in TiAl Alloys

2007 ◽  
Vol 534-536 ◽  
pp. 1577-1580
Author(s):  
Jee Hoon Choi ◽  
Dong Bok Lee
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Reaction Layer ◽  
Microstructural Stability ◽  
Tial Alloys ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma

Alloys of Ti-50 at.% Al with (3 and 10)wt.% Si3N4 particles were prepared by a mechanical alloying-spark plasma sintering (MA-SPS) method. The matrix consisted primarily of TiAl, Ti2AlN, TiN. Si3N4 was unstable in the matrix and started to decompose forming a Ti5Si3 reaction layer on the surface of former Si3N4 particles during sintering and heat treatment at 1373 K.

Effect of Milling Time on the Properties of Nanocrystalline CuCr50 Alloys

2011 ◽  
Vol 299-300 ◽  
pp. 824-827
Author(s):  
Kun Yu Shi ◽  
Tao Shen ◽  
Li Hong Xue ◽  
Chun Hao Chen ◽  
You Wei Yan
Keyword(s):  
Electrical Conductivity ◽  
Crystallite Size ◽  
Milling Time ◽  
Micro Hardness ◽  
Uniform Microstructure ◽  
High Relative Density ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma ◽  
Bulk Nanocrystalline

Nanocrystalline CuCr50 alloys were fabricated by means of mechanical alloying and spark plasma sintering. The influence of milling time on the as-milled powders and properties of sintered compacts were investigated. The results show that crystallite size of powders decreases gradually with increase of milling time, while the micro-strain increases firstly then decreases correspondingly. The crystallite size is 22 nm at milling 100h.The micro-hardness of the compacts improves greatly with the increase of milling time, reaching 363HV at 150h which is about 3 times as high as that of the industrial standard (120HV), while the electrical conductivity improves gradually decline. The bulk nanocrystalline CuCr50 alloys sintered at 900°C for 5min exhibit high relative density of 96% and uniform microstructure: nanoparticles Cr with size of about 120nm are uniformly dispersed in the matrix.

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