Influence Of Interfacial Layer Research Articles

The effects of interfacial layers on dielectric properties of an acrylic co-polymer containing polymer-grafted reduced graphene oxide

In this study, the influence of interfacial layers, in addition to other effective parameters, on the dielectric efficiency of polymer nanocomposites in the rubbery state is presented. For this purpose, reduced graphene oxide (rGO) was grafted by poly (butyl acrylate) chains (rGO-PBA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and incorporated into an acrylic co-polymer matrix with the glass-transition temperature (Tg) well below room temperature. The rGO exhibited poor dispersion and uneven distribution in acrylic co-polymer, whereas polymer grafted-rGO showed excellent dispersion. The grafted chains can penetrate and form entropic interactions with the matrix chains, which results in a strong interfacial region. The immobilized interfacial layer was characterized by DSC and dielectric measurements. The dielectric measurements in different temperatures provided the means to evaluate the contribution of the interfacial layers on dielectric properties. The findings confirmed that there exists an optimum chain mobility in which the chain polarization shows a major contribution to the dielectric properties of polymer nanocomposites. Reduction of temperature to a certain degree exhibited more rise in the dielectric properties of polymer/rGO-PBA nanocomposites than pure matrix which can be correlated to the interfacial region.

Generation mechanism of interfacial layer and its effect on Fe-Cr-Ni/Al-Si-Cu-Ni-Mg composite performance

Fe-Cr-Ni/Al-Si-Cu-Ni-Mg composite was taken as the experimental material. The chemical composition of interfacial layer was tested. The generation mechanism and influence of interfacial layer on the composite were analyzed. The results indicated that the generation of interfacial layer is sensitive to temperature. Interfacial layer will generate rapidly when temperature reaches 500 °C or above. The interfacial layer is mainly composed of Al, Si, Cu, Fe, and Cr, element Ni distributes at the outward of the interfacial layer for the precipitate of Ni later than Si and Cu, and there is almost no diffusion of Ni during the solution treatment. During heat treatment process, unequal quantity changing of metal atom results in disperse or concentrated vacancies or holes near the matrix. The existence of interfacial layer will induce a decrease of compression strength and plasticity at room temperature and an increase of strength at higher temperature comparing with composite without interfacial layer.

Effect of interfacial layer on water flow in nanochannels: Lattice Boltzmann simulations

A novel interfacial model was proposed to understand water flow mechanism in nanochannels. Based on our pore-throat nanochannel model, the effect of interfacial layer on water flow in nanochannels was quantitatively studied using Lattice Boltzmann method (LBM). It is found that both the permeability of nanochannel and water velocity in the nanochannel dramatically decrease with increasing the thickness of interfacial layer. The permeability of nanochannel with pore radius of 10nm decreases by about three orders of magnitude when the thickness of interfacial layer is changed from 0nm to 3nm gradually. Furthermore, it has been demonstrated that the cross-section shape has a great effect on the water flow inside nanochannel and the effect of interfacial layer on the permeability of nanochannel has a close relationship with cross-section shape when the pore size is smaller than 12nm. Besides, both pore-throat ratio and throat length can greatly affect water flow in nanochannels, and the influence of interfacial layer on water flow in nanochannels becomes more evident with increasing pore-throat ratio and throat length. Our theoretical results provide a simple and effective method to study the flow phenomena in nano-porous media, particularly to quantitatively study the interfacial layer effect in nano-porous media.

Investigation of Influence Factors on Residual Stress Determination within Coated Surfaces in Consideration of the Differential and Integral Method

To improve the surface behavior of metal structures, like wear-and heat resistance or hardness, often thermally sprayed ceramic coatings are applied. A modern technology to realize dense layers is the High Velocity Oxygen Fuel (HVOF) technique. The deposition process and necessary pretreatments can cause high residual stresses within the coating and the substrate. While tensile stresses in the brittle coating may cause cracks, compressive stress states can even improve the materials behavior. To guarantee high product quality, it is necessary to know exactly the occurring residual stresses in the metal-ceramic hybrid system. A very common measurement technique is the incremental hole drilling (IHD) method. To determine the residual stresses out of IHD measurements the differential method (DM) or integral method (IM) can be used. To investigate the influence of interfacial layers, nonlinear stresses, cracking, anisotropy, variation of coating thickness and calculation formalisms several FEM models have been build, while case sensitive calibration was used for the coated systems.

Influence of interfacial layers on resonance phonon transport

The resonance transport of phonons considered in the present work is characteristic of heat transport between two media. This effect is essential one, for example, in transmission of heat between solids and liquid helium in the presence of interface layer. The resonance phonon transport permits to control heat flow between two media with introduction of impurity layers weakly bound with contact edges. In the point contacts the molecules of water or solidified inert gases can serve as a resonance layer. The peaks of the reduced heat flow (RHF) were observed in point contacts KBr–KBr, KBr–Cu Si–Cu. We explain the maximum of RHF observed at temperature 5.7 K by the theory of the resonance transport and introduce the model of multichannel resonance phonon transport for the interface of point contact Si–Cu. Phonon transport is calculated using the capillary effects theory. The characteristics of the phonon transmission channels are calculated. The calculated temperature dependence of RHF is in a good agreement with the experimental data.

Current status of silicon carbide based high-temperature gas sensors

Silicon carbide (SiC) based field effect gas sensors can be operated at very high temperatures. Catalytic metal-insulator-silicon carbide (MISiC) Schottky diodes respond very fast to a change between a reducing and an oxidizing atmosphere, and cylinder-specific combustion engine monitoring has been demonstrated. The sensors have also been suggested for high-temperature electronic nose applications. Car applications and other harsh environments put very strong requirements on the long-term stability of the sensors. Here we review the current status of the field of SiC based Schottky diode gas sensors with emphasis on the work in our group. Basic work on understanding of the detection mechanism and the influence of interfacial layers on the long-term stability of the sensors is reviewed. The direction of future research and device development in our group is also discussed.

The Influence of Interfacial Layers on the Ultimate Shear Strength of Copper/Sapphire Interfaces

The Influence of Interfacial Layers on the Ultimate Shear Strength of Copper/Sapphire Interfaces

Reliability of the asperity contact model in determining charge injection across interfaces

Current profiles across mechanically contacted materials usually differ from the ones obtained by corresponding evaporated contacts. The asperity contact model has been brought up to cover such discrepancies. However, there is a lack of experimental evidence concerning its applicability on electronic injection across the interfaces. The work presented in this paper uses I-V curves of a well-documented device, the metal-semiconductor contact, as a tool to examine the validity of the asperity contact model and the implications of the interfacial layer, the axial contact force, the interfacial field and the relative permittivity of the surrounding space, on the injection process. Namely, the influence of interfacial layers has been studied in ultra-high-vacuum (UHV) environment (10/sup -10/ mbar) using cleaved silicon samples, contacted by hemispherical metal electrodes (Au, Cu, In, Al) covered in situ by fresh overlayers. The applied axial forces were controlled by electromagnets which displaced stainless steel electrodes to contact chemically prepared and cleaved [110] Si samples in a UHV environment. The importance of the interfacial fields has been examined by using Si and GaAs samples having specific surface profiles, i.e., mesas with 10 /spl mu/m diameter and 1 /spl mu/m height, fabricated by plasma etching or wet chemistry processes. Finally, the effect of the relative permittivity of the surrounding space has been investigated by applying sinusoidal 50-Hz high current densities on metal-metal contacts in the laboratory and high vacuum (10/sup -6/ mbar) environments. Utilizing the framework of the theory of the asperity contact model, the obtained results are in good agreement with the expected implications of the examined factors. >