Microscale magnetoelectricity: Effect of particles geometry, distribution, and volume fraction

Achieving efficient magnetoelectric coupling of core-shell and particulate multiferroic composites has been a challenging hurdle; however, research has shown unwavering interest to overcome this barrier in pursuit of their implementation into promising potential applications. Herein, a fully coupled computational model of core-shell and particulate composites is developed and verified to investigate the magnetoelectric interactions of the particle and matrix on the microscale. The effects of particle geometry, settling, and agglomeration were exhaustively studied by investigating seven different shapes and a wide range of vertical and lateral particle spacing. Overall, it was found that utilizing particle geometries and positioning that closely resemble a laminate configuration, such as a prolate ellipsoid and horizontal particle alignment, enhances the magnetoelectric coupling of the composite structure. The results coincided with the experimental results concerning settling and agglomeration.

Evaluation on Mechanical Properties of Coated RHA-TIO2-LM24 Aluminium Alloy Composite

In the present research work, liquid state technique is employed to prepare the LM4/RHA/TiO2 composites containing four different mass proportion of RHA and TiO2. The weight proportion of reinforcements ie RHA-1,3&5 and TiO2 2,5&6 respectively. Hybrid composite with 3% of RHA and 6% of TiO2 showed the maximum Tensile strength of 298.37 N/mm².It is found that there is 37 % increase of tensile strength while addition of RHA and TiO2 to LM 24.The aluminium based particulate reinforced composite, the dislocations are generated during solutionizing due to thermal mismatch between the matrix and the ceramic reinforcement particles. It can be inferred that the tensile strength increased with an increase in the weight percentage of rice husk ash and TiO2. Because, the RHA particles act as barriers to the dislocations when taking up the load applied. It has been observed that with changing rate of TiO2 compressive quality increments from 478.83 to 653.79 MPa. The increase in compressive strength is mainly due to the decrease in the inter-particle spacing between the particulates since RHA and TiO2 are much harder than LM24. The presence of RHA and TiO2 resists deforming stresses and thus enhancing the compressive strength of the composite material. The maximum hardness value obtained for 5 wt.% of RHA and 6 wt.% of TiO2 .ie.117 BHN. It was observed that the hardness of the composite linearly increasing with the increase in weight fraction of the rice husk ash particles. This occurs due to increases in surface area of the matrix and thus the grain sizes are reduced. The presence of such hard surface area offers more resistance to plastic deformation which leads to increase hardness.. Keywords: LM4/RHA/TiO2, Tensile testing, Compression, Hardness, Rice husk.

Research on the Inertial Migration Characteristics of Bi-Disperse Particles in Channel Flow

The inertial focusing effect of particles in microchannels shows application potential in engineering practice. In order to study the mechanism of inertial migration of particles with different scales, the motion and distribution of two particles in Poiseuille flow are studied by the lattice Boltzmann method. The effects of particle size ratio, Reynolds number, and blocking rate on particle inertial migration are analyzed. The results show that, at a high blocking rate, after the same scale particles are released at the same height of the channel, the spacing between the two particles increases monotonically, and the change in the initial spacing has little effect on the final spacing of inertial migration. For two different size particles, when the smaller particle is downstream, the particle spacing will always increase and cannot remain stable. When the larger particle is downstream, the particle spacing increases firstly and then decreases, and finally tends to be stable.

Study on the Microstructure and Wear Behavior of In-Situ Al3Ti/Al Composites Under Induction Heating

In the study, Ti fiber (200 μm, 99.8 wt.%) and pure aluminum (99.6 wt.%) were respectively used as the reaction source and matrix to prepare Al-based composites by in-situ synthesis methods. During the stage of preparing the preform, Ti fibers were fixed in the matrix at equal intervals to pre-control the initial position of the product. The preform was heated in an induction heating device finally, at the same time, parameter combinations of different frequencies and currents were applied to promote the in-situ reaction between Al-Ti, thereby the Al matrix composites reinforced by Al3Ti were obtained. The phase composition, microstructure and wear resistance of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and wear testers. The results show that when the frequency and current are 5 kHz and 15 A respectively, the Ti fiber is completely reacted, and the product is the isometric Al3Ti with a size of 1 – 2 μm and a particle spacing of about 5 μm, reaching the optimal microstructure under all parameters. Under the condition of a load of 9.8 N, the wear rate of the composites at 5 kHz and 15 A is 2.325 mg/mm2, indicating the best values in this experiment.

Versatile Silver Nanoparticles-Based SERS Substrate with High Sensitivity and Stability

Surface-enhanced Raman scattering has developed into a mature analytical technique useful in various applications; however, the reproducible fabrication of a portable SERS substrate with high sensitivity and good uniformity is still an ongoing pursuit. Reported herein is a rapid fabrication method of an inexpensive SERS substrate that enables sub-nanomolar detection of molecular analytes. The SERS substrate is obtained by application of silver nanoparticles (Ag NPs)-based ink in precisely design patterns with the aid of an in-house assembled printer equipped with a user-fillable pen. Finite-difference time-domain (FDTD) simulations show a 155-times Ag NP electric field enhancement for Ag nanoparticle pairs with particle spacing of 2 nm. By comparing the SERS performance of SERS substrate made with different support matrices and fabrication methods, the PET-printed substrate shows optimal performance, with an estimated sensitivity enhancement factor of 107. The quantitative analysis of rhodamine 6G absorbed on optimized SERS substrate exhibits a good linear relationship, with a correlation coefficient (R2) of 0.9998, between the SERS intensity at 610 cm−1 and the concentration in the range of 0.1 nM—1μM. The practical low limit detection of R6G is 10 pM. The optimized SERS substrates show good stability (at least one month) and have been effectively tested in the detection of cancer drugs, including doxorubicin and metvan.

Migration and Alignment of Three Interacting Particles in Poiseuille Flow of Giesekus Fluids

Effect of rheological property on the migration and alignment of three interacting particles in Poiseuille flow of Giesekus fluids is studied with the direct-forcing fictitious domain method for the Weissenberg number (Wi) ranging from 0.1 to 1.5, the mobility parameter ranging from 0.1 to 0.7, the ratio of particle diameter to channel height ranging from 0.2 to 0.4, the ratio of the solvent viscosity to the total viscosity being 0.3 and the initial distance (y0) of particles from the centerline ranging from 0 to 0.2. The results showed that the effect of y0 on the migration and alignment of particles is significant. The variation of off-centerline (y0 ≠ 0) particle spacing is completely different from that of on-centerline (y0 = 0) particle spacing. As the initial vertical distance y0 increased, the various types of particle spacing are more diversified. For the off-centerline particle, the change of particle spacing is mainly concentrated in the process of cross-flow migration. Additionally, the polymer extension is proportional to both the Weissenberg number and confinement ratio. The bigger the Wi and confinement ratio is, the bigger the increment of spacing is. The memory of shear-thinning is responsible for the reduction of d1. Furthermore, the particles migrate abnormally due to the interparticle interaction.

Analytical Modeling of Particle Interference in Micro-abrasive Jets

Two existing analytical models of particle interference in non-divergent particle jets were modified to include radial symmetry of the particle jet across the nozzle axis, inter-particle spacing, and more complex rebound geometry. Two novel experimental techniques for obtaining the particle spatial and velocity distributions across a micro-abrasive jet were then devised and rigorously tested. One of the above mentioned analytical models was then chosen to be further modified to include the above-mentioned modifications along with the effect of a divergent jet, the ability to simulate high flux cases, and experimentally obtained particle spatial and velocity distributions. All of the models were tested at various jet conditions. The results of the models were quantitatively compared to a previously developed computer simulation and were found to qualitatively agree with previous experimental observations. The modified models allow the critical flux below which inter-particle interference is likely to occur to be determined.

Analytical Modeling of Particle Interference in Micro-abrasive Jets

Two existing analytical models of particle interference in non-divergent particle jets were modified to include radial symmetry of the particle jet across the nozzle axis, inter-particle spacing, and more complex rebound geometry. Two novel experimental techniques for obtaining the particle spatial and velocity distributions across a micro-abrasive jet were then devised and rigorously tested. One of the above mentioned analytical models was then chosen to be further modified to include the above-mentioned modifications along with the effect of a divergent jet, the ability to simulate high flux cases, and experimentally obtained particle spatial and velocity distributions. All of the models were tested at various jet conditions. The results of the models were quantitatively compared to a previously developed computer simulation and were found to qualitatively agree with previous experimental observations. The modified models allow the critical flux below which inter-particle interference is likely to occur to be determined.

Exploring the α-decay chain of 302122 within relativistic mean field formalism

The ground and first excited state structural properties like binding energy, charge radius, deformation parameter, pairing energy, and two-neutron separation energy for the isotopic chain of Z= 122 are analyzed. The axially deformed relativistic mean-field formalism with NL3* force parameter is used for the present analysis. Based on the analysis of binding energy per particle, chemical potential and single-particle spacing, we predict the isotopes of Z =122 with N = 180. 182 and 184 are the possible stable nuclei over the considered isotopic chain. The α-decay energies and the decay half-lives of ³⁰²122 chains are investigated using four different empirical formulae. The results of our calculations are compared with the available experimental data and Finite Range Droplet Model predictions. We also established a correlation for the decay energy with the half-lives for the considered α-decay chains for various empirical formulae.