Article

Effect of Drying Methods of Alumina Powder and Graphene Oxide Mixture on the Mechanical and Electrical Properties of Sintered Composites Fabricated by Spark Plasma Sintering

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

This paper presents a study on graphene-reinforced alumina ceramic composites and the resulting mechanical and electrical properties. Three drying methods were chosen for the fabrication of the initial mixtures: spray, freeze, and vacuum. Spark plasma sintering was chosen as a method of consolidating mixtures. A combination of spray drying and spark plasma sintering makes it possible to produce a high-density (99%) ceramic nanocomposite with improved mechanical properties. The hardness and crack resistance values were increased by 6 and 28%, respectively, compared to other materials studied in this work. This improvement is due to an extremely good dispersion of graphene in the composite, which leads to the decrease in the grain size of the ceramic matrix and consequently reduces the probability of crack occurrence. In addition to these exceptional mechanical properties, the sintered composites also showed high electrical conductivity, which allows the compacts to be machined using electrical discharge machining and thus facilitates the fabrication of ceramic components with sophisticated shapes while reducing machining costs.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Thanks to this, many ceramic-based composites that have a certain percentage of nanomaterials are converted into materials with improved mechanical properties. One of these promising nanomaterials is graphene [133,134]. Graphene is a revolutionary material that opens wide perspectives with its use, as an example, for increasing the flexural strength and fracture toughness of ceramic materials [135]. In the following sections, the characteristics and possible applications of graphene-based material, as well as the most popular additive technologies for them will be explained in more detail. ...
Article
Full-text available
In the present work, the state of the art of the most common additive manufacturing (AM) technologies used for the manufacturing of complex shape structures of graphene-based ceramic nanocomposites, ceramic and graphene-based parts is explained. A brief overview of the AM processes for ceramic, which are grouped by the type of feedstock used in each technology, is presented. The main technical factors that affect the quality of the final product were reviewed. The AM processes used for 3D printing of graphene-based materials are described in more detail; moreover, some studies in a wide range of applications related to these AM techniques are cited. Furthermore, different feedstock formulations and their corresponding rheological behavior were explained. Additionally, the most important works about the fabrication of composites using graphene-based ceramic pastes by Direct Ink Writing (DIW) are disclosed in detail and illustrated with representative examples. Various examples of the most relevant approaches for the manufacturing of graphene-based ceramic nanocomposites by DIW are provided.
... Thanks to this, many ceramic-based composites that have a certain percentage of nanomaterials are converted into materials with improved mechanical properties. One of these promising nanomaterials is graphene [173,174]. Graphene is a revolutionary material that opens wide perspectives with its use, as an example, for increasing the flexural strength and fracture toughness of ceramic materials [175,176]. In the following sections, the characteristics and possible applications of graphene-based material, as well as the most popular additive technologies for them, will be explained in more detail. ...
Preprint
Full-text available
In the present work, the state of the art of the most common additive manufacturing (AM) technologies used for the manufacturing of complex shape structures of graphene-based ceramic nanocomposites, ceramic and graphene-based parts is explained. A brief overview of the AM processes for ceramic, which are grouped by the type of feedstock used in each technology, is presented. The main technical factors that affect the quality of the final product were reviewed. The AM processes used for 3D printing of graphene-based materials are described in more detail; moreover, some studies in a wide range of applications related to these AM techniques are cited. Furthermore, different feedstock formulations and their corresponding rheological behaviour were explained. Additionally, the most important works about the fabrication of composites using graphene-based ceramic pastes by Direct Ink Writing (DIW) are disclosed in detail and illustrated with representative examples. Various examples of the most relevant approaches for the manufacturing of graphene-based ceramic nanocomposites by DIW are provided.
Article
Full-text available
The use of graphene as a component for developing electroconductive ceramic composites is being profusely studied. It is a very promising additive as it has excellent mechanical properties, high electrical and thermal conductivities, it is lightweight and its aspect ratio allows reaching percolation with low contents. In the particular case of zirconia, preparation of black coloured materials remains a challenge while many high added value applications are waiting for a solution. Graphene appears as a candidate for fulfilling all these requirements. In this work, 3Y–TZP/rGO composites were prepared by Spark Plasma Sintering Zirconia-rGO mixtures. Simultaneous sintering and in-situ reduction of graphene oxide opens a very interesting technological route for preparing this type of materials. The influence of graphene content on the electrical, mechanical and optical properties was studied. An rGO content as low as 0,29 vol% allows nanostructured black zirconia to be obtained but it has to be increased up to 1 vol% in order to reach electrical resistivity values <100Ωcm, required for electrodischarge machining.
Article
Full-text available
Numerical modeling of the spark plasma sintering of square plates from aluminum-oxide and tungsten-carbide powder is considered. The rounding radius of the plates is 0.8, 1.2, or 1.6 mm. The distribution of the temperature and mechanical stress within each sample and also within the mold is determined. The results are used for preliminary assessment of the possibility of spark plasma sintering of cutting plates.
Article
Full-text available
The method of production nanostructured ceramic Al2O3-SiCw-TiC with high operational properties by spark plasma sintering is developed in this work. The obtained nanoceramic material was compared to Al2O3-SiCw. The homogenous compound of initial nanostructured powders of different phases and sizes was made by the methods of colloid blending and spraying. The microstructure, hardness, fracture strength, phase's analysis, electro conductive properties of the samples were researched. The electro conductivity of sintered nanocomposite Al2O3-SiCw-TiC enables to process it by electrical discharge machining.
Article
Full-text available
This work describes a whole processing route for obtaining dense and nanostructured zirconia-nickel composites with low contents of metallic phase (1-3.5 vol%). For the processing route, a combination of spray-freezing and lyophilization has been proposed. After the calcination and reduction of the resulting powders an X-ray and HRTEM characterization has been performed. This showed the formation of pure zirconia and nickel, well dispersed and homogeneously distributed, nanostructured phases. The obtained powders were subsequently sintered by Spark Plasma Sintering (SPS). As a result, dense ZrO2-Ni composites were obtained, revealing that the sizes of the metal particles were kept in the nanometer range and appear homogeneously and well dispersed into the ceramic matrix. The mechanical behavior of these materials was evaluated by means of the Vickers hardness, showing and increment of about 25% with respect to pure zirconia with only a Ni concentration of 1 vol%.
Article
Full-text available
Using the semiclassical Boltzmann theory, we calculate the conductivity as a function of the carrier density. We include the scattering from charged impurities but conclude that the estimated impurity density is too low in order to explain the experimentally observed mobilities. We thus propose an additional scattering mechanism involving midgap states, which leads to a similar k dependence of the relaxation time as charged impurities. The proposed scattering mechanism can account for the experimental findings such as the sublinear behavior of the conductivity versus gate voltage and the increase of the minimal conductivity for clean samples. We also discuss temperature dependent scattering due to acoustic phonons.
Article
Full-text available
We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.
Article
Full-text available
Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.
Article
Full-text available
We report the measurement of the thermal conductivity of a suspended single-layer graphene. The room temperature values of the thermal conductivity in the range approximately (4.84+/-0.44)x10(3) to (5.30+/-0.48)x10(3) W/mK were extracted for a single-layer graphene from the dependence of the Raman G peak frequency on the excitation laser power and independently measured G peak temperature coefficient. The extremely high value of the thermal conductivity suggests that graphene can outperform carbon nanotubes in heat conduction. The superb thermal conduction property of graphene is beneficial for the proposed electronic applications and establishes graphene as an excellent material for thermal management.
Article
This paper presents a study on graphene-reinforced Al2O3-SiCw ceramic composites and the relationship between graphene oxide (GO) loading and the resulting mechanical and electrical properties. Well-dispersed ceramic-GO powders were fabricated using a colloidal processing route. Dense composites were obtained via spark plasma sintering, a technique that has the ability to reduce GO to graphene in situ during the sintering process. The mechanical properties of the sintered composites were investigated. The composite with only a small amount of graphene (0.5 vol.%) showed the highest flexural strength (904 ± 56 MPa), fracture toughness (10.6 ± 0.3 MPa·m1/2) and hardness (22 ± 0.8 GPa) with an extremely good dispersion of graphene within the ceramic matrix. In addition to these exceptional mechanical properties, the sintered composites also showed high electrical conductivity, which allows the compacts to be machined using electrical discharge machining and thus facilitates the fabrication of ceramic components with sophisticated shapes while reducing machining costs.
Article
Alumina silicon carbide composites have been traditionally considered as one of the most interesting materials to be used for structural applications at high temperatures. The SiC nanoparticle content and its distribution in the alumina matrix are parameters of extreme importance controlling the operating deformation mechanisms at high temperature. Then, the processing of tailor-made microstructures is still challenging in order to find an optimal material. Full dense alumina-nano silicon carbide composites were prepared by using Spark Plasma Sintering at relative low temperatures and sintering times. In this work, different composite microstructures with different SiC content and type of starting alumina powder were obtained by increasing the sintering temperature and dwell time. Different ratios of inter/intra granular alumina positions of SiC particles were controlled by a suitable selection of starting raw materials, composition and sintering conditions.
Article
Spark plasma sintering is a method of consolidating nanostructured powder materials and also composites and gradient materials in the presence of an electromagnetic field, by means of low-voltage sources of powerful current. The main benefit of spark plasma sintering is that previously impossible structures, properties, and compositions may be produced. The finite-element method is used to analyze the consolidation of samples by spark plasma sintering and by a hybrid method in which spark plasma sintering is combined with hot pressing. Corresponding numerical models are tested.
Article
Large Al2O3–SiCw and Al2O3–SiCw–TiC composites disks (150 mm diameter) were prepared in this work by using the spark plasma sintering technique. The main physical and mechanical properties of these composites were measured in different disk zones in order to test out the homogeneity of the sintering process. It has been found that the incorporation of TiC as reinforcing phase to the Al2O3–SiCw composite, improved densification, mechanical strength and hardness. This result was analyzed in terms of SEM microstructure observations showing that the presence of TiC inhibited the alumina grain growth.
Article
Starting from commercially available powders of tetragonal zirconia polycrystals (TZP) doped with 3 mol% yttria (Tosoh grade TZ-3YS-E) and yttria-free monoclinic zirconia (Tosoh grade TZ-0) powders with an overall Y2O3 content of 2 mol% (2Y/TZP) were fabricated by CO2 laser vaporization (LAVA) and wet mixing, respectively. The obtained powders were compacted by spark plasma sintering. The influence of the Y3+ distribution on the mechanical properties and on the low temperature degradation (LTD) of the obtained ceramics was investigated. 2Y/TZP ceramics sintered from LAVA nanoparticles showed significantly enhanced mechanical properties and improved LTD resistance due to the homogeneous yttria and grain size distributions in the ceramic structure. For the first time, the present research has demonstrated the effectiveness and reproducibility of the LAVA process for the preparation of tailored zirconia nanopowders enabling microstructural homogeneity and therefore optimized mechanical properties and degradation resistance of Y-TZP ceramics.
Article
A simple, fast and upscalable method is described to produce graphene/alumina (G/Al2O3) composites by spark plasma sintering (SPS) with a significant improvement on both mechanical and electrical properties of monolithic Al2O3. Graphene oxide (GO) was mixed with Al2O3 using a colloidal method obtaining an excellent dispersion of GO in the alumina matrix. The material was consolidated by SPS that allowed, in one-step, the in situ reduction of the GO during the sintering process. A detailed Raman analysis was found to be very useful to study the orientation of the graphene in the composite and to evaluate and optimise its thermal reduction. Graphene platelets acted as elastic bridges avoiding crack propagation and providing this material with a crack bridging reinforcement mechanism. A very low graphene loading (0.22 wt%) led to a 50% improvement on the mechanical properties of the alumina and to an increase of the electrical conductivity up to eight orders of magnitude.
Article
Ceramic–metal composites based on the Fe–TiC system can be synthesised by reduction of the mineral ilmenite (FeTiO3) with carbon in flowing argon or under vacuum in the temperature range 1100–1400 °C. The ratio of Fe:TiC can be controlled through adjustment of the reactant materials, as can the addition of alloying metals such as Co, Cr or Ni. Dense bodies formed by sintering Fe–TiC powders display a microstructure of uniformly dispersed TiC grains in a continuous metal matrix. The grain size of the TiC can be controlled between 1 and 20 μm by varying the heat treatment schedules. Hardness values of 14 GPa can be achieved through pressureless sintering of unalloyed Fe:3TiC bodies. Technologies have been developed for fabricating a range of compositions from 6 wt% to over 80 wt% TiC in iron alloy matrices, leading to broad suite of potential industrial applications as wear parts or cutting tools.
Cutting properties of the tool equipped by plates from mixed ceramics with a multifunctional coating
  • M N Lazareva
  • E S Sotova
  • A S Vereshchaka
Simulation of power parameters in face milling of hardened steel by a tool with a ceramic cutting part
  • M A Volosova
  • V D Gurin
  • A E Seleznev
Chetyrekhzondovyi metod izmereniya elektricheskogo soprotivleniya poluprovodnikovykh materialov (Use of Four-Terminal Sensing for Measurement of Electrical Resistance of Semiconductor Materials)
  • N A Poklonskii
  • S S Belyavskii
  • S A Vyrko
  • T M Lapchuk
Research of cutting properties of cutting layered composite ceramics with multicomponent functional coatings
  • A S Vereshchaka
  • M A Lazareva
  • K V Kryuchkov
  • D N Lytkin
  • D L Shegai
  • O H Khozhaev