Nano Carbons

Numerical analysis of discs based on carbon-nanofiber/Al2O3ZrO2 nanocomposite materials

Hüseyin Fırat Kayiran — Wed, 06 Dec 2023 13:19:19 +0000

In this study, the behavior of three different discs consisting of AS4 carbon fiber, T-300 carbon, and Al₂O₃ZrO₂ (nanocomposite) materials at constant temperature was investigated by the numerical analysis method. Nanocomposites are formed by the dispersion of nanometer-sized particles in a matrix. With the advantages that nanocomposites bring to the material, they increase heat resistance in general. Carbon fibers, on the other hand, are preferred in the aerospace industry and aircraft industry due to their high strength properties. In this study, it was assumed that the modulus of elasticity does not change with temperature. The temperatures applied to the discs are 45 ℃, 60 ℃, 75 ℃, 90 ℃, and 105 ℃, respectively. It has been observed that the radial and tangential stress values obtained at high temperatures are higher than at low temperatures. The Al₂O₃ZrO₂ nanocomposite materials have found that the stresses occurring in the Al₂O₃ZrO₂ (nanocomposite) disc are higher than the stresses occurring in the AS4 carbon fiber disc. The stresses obtained on the AS4 carbon fiber disc are T-300 carbon discs.

Vibration analysis of functionally graded carbon nanotubes reinforced composite nanoplates

Dang Van Hieu, Nguyen Thi Kim Thoa — Mon, 19 Feb 2024 00:00:00 +0000

This work presents the analytical analysis for free linear vibration behavior of functionally graded-carbon nanotubes reinforced composite (FG-CNTRC) nanoplates in the framework of nonlocal strain gradient theory (NSGT) and the first-order shear deformation plate theory (FSDPT). The nanoplate is considered made of a mixture of an isotropic polymer matrix and reinforced carbon nanotubes (CNTs). Four different distributions of CNTs are examined including uniformly distributed and FG reinforcements (FG-O, FG-X, and FG-V). The governing equations of motion are established based on the Hamilton’s principle. The closed-form analytical solution for the natural frequency of FG-CNTRC nanoplates with simply supported all edges is carried out by using the Navier-type solution. The impact of some key parameters on the natural frequencies of FG-CNTRC nanoplates is also studied and discussed. The result shows that FG-CNTRC nanoplates reveal the softening- or hardening-stiffness effects depending on the relationship between the nonlocal parameter and the material length scale parameter. The aspect ratios of FG-CNTRC nanoplates, the volume fraction, and the distribution pattern of CNTs have also an important impact on the vibration behavior of FG-CNTRC nanoplates.

Functionalization of insulating substrate and its hybridization with carbon fibers

Prashanta Dhoj Adhikari — Thu, 22 Feb 2024 00:00:00 +0000

In this work, surface functionalization of an insulating glass substrate was performed and it was hybridized with conducting carbon fiber materials, carbon coils. Glass substrate was carried out via different chemical treatments, then an amine terminated self-assembled monolayer was introduced on its surface. Carbon coils were also treated with nitric acid. These surface modified carbon coils, glass substrates, and carbon coils immobilized on glass substrates were analyzed through different analytical tools. Finally, hybridization of carbon coils on glass substrates resulted only in functionalized glass (amine terminated) surfaces via chemical bonding, while the un-functionalize glass substrate did not. Thus, such a stable, recognized practice can apply to fabricate simple microarrays to bind carbon materials or biomolecules for further application.

The study of multilayer graphene membrane performance in O2 purification process: Molecular dynamics simulation

Mohammad Pour Panah, Bahman Parvandar Asadollahi, Roozbeh Sabetvand — Tue, 09 Apr 2024 03:05:20 +0000

We use molecular dynamics (MD) method to describe the atomic behavior of Graphene nanostructure for Oxygen molecules (O₂) separation from Carbon dioxide (CO₂) molecules. Technically, for the simulation of graphene-based membrane and O₂-CO₂ gas mixture, we used Tersoff and DREIDING force fields, respectively. The result of equilibrium process of these structures indicated the good stability of them. Physically, this behavior arises from the appropriate MD simulation settings. Furthermore, to describe the purification performance of graphene-based membrane, we report some physical parameters such as purification value, impurity rate, and permeability of membrane after atomic filtering process. Numerically, by defined membranes optimization, the purification value of them reach to 97.31%. Also, by using these atomic structures the CO₂ impurity which passed from graphene-based membrane reach to zero value.

The study of ideal/defected graphene nanosheet roughness after atomic deposition process: Molecular dynamics simulation

Sedigheh Bigom Hoseini, Roozbeh Sabetvand — Thu, 11 Apr 2024 00:00:00 +0000

In this work, molecular dynamics (MD) approach was performed to study the surface roughness of ideal/defected graphene nanosheet after carbon atoms deposition at various temperatures and pressures. In our calculations, the atomic interactions of nanostructures are based on TERSOFF and Lennard-Jones potential functions. The results show that the temperature of simulated structure is an important parameter in atomic deposition process and initial temperature enlarges, intensifies atomic deposition ratio. Numerically, by temperature increasing to 15 K, the surface roughness amplitude increase to 0.98 Å/0.83 Å after atomic deposition in ideal/defected structure. The roughness power in MD simulations converges to 0.64/0.55 in ideal/defected sample at maximum temperature. Furthermore, the pressure effects on dynamical behavior of simulated samples were reported in our study. We conclude that, by increasing initial pressure from 0 to 2 bar, the surface roughness amplitude in ideal/defected atomic arrangement increases to 1.01 Å/0.84 Å after deposition process and the roughness power of simulated structures reaches to larger value. Numerically, by initial pressure setting at 2 bar, the roughness power value converged to 0.72/0.56 in ideal/defected graphene. Reported numeric results in various temperature and pressures predicted the initial condition can be manipulated the atomic deposition process in ideal/defected graphene nanostructures.

Resistance of HVOF-Sprayed Cr3C2-25NiCr and WC-10CO-4Cr coatings to cavitation and erosion by mud jetting

Androw D. H., Ratchagaraja Dhairiyasamy — Mon, 15 Apr 2024 02:07:35 +0000

This study investigates chromium carbide-based coating material’s cavitation and erosion resistance with 25% nickel-chromium. (Cr₃C₂-25NiCr) and Tungsten carbide coating with 10% cobalt and 4% chromium (WC-10CO-4Cr) coatings deposited by high-velocity oxygen fuel (HVOF) thermal spraying. The coatings were characterized by microstructure, porosity, hardness, and fracture toughness. Cavitation tests were performed in distilled water and water-sand mixtures to assess the synergistic effect of erosion and cavitation. Erosion tests were conducted using a mud jet at different impact angles (30°, 60°, 90°). The Cr₃C₂-25NiCr coating exhibited higher cavitation resistance due to its higher fracture toughness and lower porosity. However, the WC-10CO-4Cr coating showed superior erosion resistance, attributed to its finer and more homogeneously distributed carbides. The dominant wear mechanisms were micro grooving, carbide detachment, and cracking. The impact angle significantly influenced the erosion rates, with ductile materials like CA6NM steel being more susceptible at lower angles, while brittle coatings showed the opposite behavior. The findings highlight the importance of coating properties and test conditions on the wear performance, providing valuable insights for selecting suitable coatings for hydropower applications.