Features of Functionalization of the Surface of Alumina Nanofibers by Hydrolysis of Organosilanes on Surface Hydroxyl Groups

Small additions of nanofiber materials make it possible to change the properties of polymers. However, the uniformity of the additive distribution and the strength of its bond with the polymer matrix are determined by the surface of the nanofibers. Silanes, in particular, allow you to customize the surface for better interaction with the matrix. The aim of our work is to study an approach to silanization of nanofibers of aluminum oxide to obtain a perfect interface between the additive and the matrix. The presence of target silanes on the surface of nanofibers was shown by XPS methods. The presence of functional groups on the surface of nanofibers was also shown by the methods of simultaneous thermal analysis, and the stoichiometry of functional groups with respect to the initial hydroxyl groups was studied. The number of functional groups precipitated from silanes is close to the number of the initial hydroxyl groups, which indicates a high uniformity of the coating in the proposed method of silanization. The presented technology for silanizing alumina nanofibers is an important approach to the subsequent use of this additive in various polymer matrices.

Vacuum Brazing of C/C Composite and TiAl Intermetallic Alloy Using BNi-2 Brazing Filler Metal

C/C composite was brazed to TiAl intermetallic compound using a commercial BNi-2 brazing filler metal under vacuum brazing condition. The brazing temperature was 1030~1150 °C and the holding time was 20 min. The joint interfacial microstructures and mechanical properties were studied, and the fracture behavior and joining mechanism were also investigated. The effect of brazing temperature on the joint shear strength was explored. The results showed that a perfect interface joint can be obtained by using BNi-2 to braze C/C and TiAl. During brazing, Ti, Cr, and other carbide forming elements diffused to C/C composite side, forming Cr3C2, Cr7C3, TiC, and other carbides, and realizing metallurgical joining between the brazing filler metal and C/C composite. The microstructure of the interface of C/C composite and TiAl intermetallic compound joint is as follows: TiAl alloy → TiAl + AlNi3 → AlNi2Ti → Ni(s, s) + Ti3Al + Ni3Si → Ni(s, s) + Ni3(Si, B) + CrB → Ni(s, s) + Ni3Si + TiCr2 → (Ti, Cr)C → C/C composite. When the holding time is fixed, with the increase of brazing temperature, the shear strength of the joint increases first and then decreases. The maximum average room temperature shear strength of the brazed joint was 11.62 MPa, while the brazing temperature was 1060 °C and the holding time was 20 min.

Anti-Plane Shear Wave in Microstructural Media

The present chapter encapsulates the characteristic behavior of anti-plane shear wave propagation in a micropolar layer/semi-infinite structural media. Two types of interfacial complexity have been considered at the common interface which give rise to two distinct mathematical models: (1) Model I: Anti-plane shear wave in a micropolar layer/semi-infinite structure with rectangular irregular interface and (2) Model II: Anti-plane shear wave in a micropolar layer/semi-infinite structure with non-perfect interface. For both models, dispersion equations have been deduced in algebraic-form and in particular, the dispersion equation of new type of surface wave resulted due to micropolarity has been obtained. The deduced results have been validated with classical cases analytically. The effects of micropolarity, irregularity, and non-perfect interface on anti-plane shear wave have been demonstrated through numerical study in the present chapter.

Examination of car navigation systems and UX designs – suggestion for a new interface

<p><strong>Abstract.</strong> The need for car-related navigation and the appearance of the vehicles themselves are much the same age – of course. In the early days, paper maps and personal questioning were solved this problem. Nearly 100 years ago, the first built-in car GPS was released – and this is an innovation that is still an important part of car design. Planning the user interface is a very exciting issue, because only in a few seconds the display needs to provide the user with the right amount of information. In this research our goal was to assess Hungarians driving and built-in GPS using habits and based on this try to suggest the “perfect” interface. A questionnaire was made with 19 or 46 questions and more than 1000 respondents completed it. Because of the high number of questions only selected diagrams are represented. Some answers have also been subjected to different statistical tests.</p>

Micromechanics-based homogenization of the effective physical properties of composites with an anisotropic matrix and interfacial imperfections

Micromechanics-based homogenization has been employed extensively to predict the effective properties of technologically important composites. In this review article, we address its application to various physical phenomena, including elasticity, thermal and electrical conduction, electric and magnetic polarization, as well as multi-physics phenomena governed by coupled equations such as piezoelectricity and thermoelectricity. Especially, we introduce several research works published recently from our research group that consider the anisotropy of the matrix and interfacial imperfections in obtaining various effective physical properties. We begin with a brief review of the concept of the Eshelby tensor with regard to the elasticity and mean-field homogenization of the effective stiffness tensor of a composite with a perfect interface between the matrix and inclusions. We then discuss the extension of the theory in two aspects. First, we discuss the mathematical analogy among steady-state equations describing the aforementioned physical phenomena and explain how the Eshelby tensor can be used to obtain various effective properties. Afterwards, we describe how the anisotropy of the matrix and interfacial imperfections, which exist in actual composites, can be accounted for. In the last section, we provide a summary and outlook considering future challenges.

Coupled Extensional and Flexural Motions of a Two-Layer Plate With Interface Slip

The effect of imperfect interface on the coupled extensional and flexural motions in a two-layer elastic plate is investigated from views of theoretical analysis and numerical simulations. A set of full two-dimensional equations is obtained based on Mindlin plate theory and shear-slip model, which concerns the interface elasticity and tangential discontinuous displacements across the bonding imperfect interface. Some numerical examples are processed, including the propagation of straight-crested waves in an unbounded plate, the buckling of a finite plate, as well as the deflection of a finite plate under uniform load. It is revealed that the bending-evanescent wave in the composites with a perfect interface eventually cuts-on to a propagating shear-like wave with cutoff frequency when the two sublayers imperfectly bonded. The similar phenomenon has been verified once again for coupled face-shear and thickness-shear waves. It also has been pointed out that the interfacial parameter has a great influence on the performance of static buckling, in which the outcome can be reduced to classical buckling load of a simply supported plate when the interface is perfect.

MATHEMATICAL MODELLING AND COMPUTER SIMULATION OF TEMPERATURE DISTRIBUTION IN INHOMOGENEOUS COMPOSITE SYSTEMS WITH IMPERFECT INTERFACE

Many studies have been done previously on temperature distribution in inhomogeneous composite systems with perfect interface, having no discontinuities along it. In this paper we have determined steady state temperature distribution in two inhomogeneous composite systems with imperfect interface, having discontinuities in temperature and heat flux using decomposed immersed interface method and performed the numerical simulation on MATLAB.