Materials Science Forum Vols. 654-656

Abstract: The electroless plating composite film Ni-P-Al2O3 was prepared on a mild steel of SS400 with stirring of the plating solution. The composite film became thinner and rougher when Al2O3 particles were blended into the plating solution. The corrosion resistance and the wear resistance of the composite film were largely enhanced in comparision to the Ni-P film.

Abstract: The adhesion enhancement effect of tetraethoxysilane (TEOS) addition to a silica-polyaniline composite film on ITO glass substrate was studied. The composite film was prepared with the silica-polyaniline core-shell composite nanoparticles which were synthesized by a chemical polymerization of polyaniline in a colloidal solution of silica. A small amount of TEOS and acidic water was added to the dispersion solution of composite nanoparticles. The addition of TEOS was intended to increase the adhesion of electrochromic film to substrate without a deterioration of the electrochromic properties such as response time and cycle life. The adhesion of the films was tested by a tape test, and the composite film with TEOS showed a dramatic increase in adhesion to the ITO glass substrate when compared with the film deposited without TEOS. The electrochromic properties of the films were also characterized using the cyclic voltammetry and the optical response measurement.

Abstract: This article presents an inverse analysis method based on an instrumented indention to extract materials properties from multilayer material systems. In this case, a 12-layers system comprising of two alternate materials is considered. Each layer is 1 μm thick. The material properties selected for the layers are within the range of common commercial aluminium alloys. The yield stress and strain hardening exponent of the two layers were identified based on a power law type equation to define the stress-strain relationship. A 2D axis-symmetric indenter having 70.3 half angle was used, which is representative of a Berkovich or a Vickers indenter. The use of finite element analyses was substituted with a fast and equally accurate approach for the iterative optimization procedure. Thus, the computation time was considerably reduced. The robustness is tested using pseudo-experimental results, in terms of indentation curve and imprint on the material, with added random noises of 2.5%, 5.0%, 7.5% and 10.0%. The proposed approach provides a good estimate of the sought material properties. It is envisaged that this approach can become of assistance in the evaluation of the material properties for multilayer coatings and small devices.

Abstract: A series of hybrids (CnH2n+1NH3)2MCl4 with quantum-well energy-band structure were synthesized by chemical reaction in HCl solutions, in which M(Co,Ni,Cu,Zn) and n(2,4,6,8,10,12) varied to adjust the quantum-well depth and the barrier width, respectively. The X-ray diffraction patterns and scanning electron microscopy images of the products demonstrate that they crystallize well with the typical layered structures. However, the analogues of Ni can not be successfully synthesized in the same way. Concerning the energy-band structure, the colors of the products reveal that the quantum-well depth is more important than the barrier width for controlling the properties of the hybrids.

Abstract: This work aims to investigate the effects of carbon black (CB) and carbon nanotube (CNT) on mechanical properties and thermal behaviors of natural rubber (NR)/styrene butadiene rubber (SBR) blend at NR/SBR weight ratio of 80/20. CB loadings from 3-9 phr and CNT with 0.1-0.4 phr loadings were used as fillers in this study. The composites were prepared by latex compounding method. The specimens were examined for their tensile and dynamic mechanical properties and thermal stability using the universal testing machine, dynamic mechanical analyzer and thermal gravimetric analyzer, respectively. The tensile strength and modulus of the composites were improved as a result of the incorporation of CB and CNT. Dynamic mechanical analysis showed that the CB and CNT filled composites possessed high stiffness and low damping characteristics. Thermal stability of the composites was also proved to be better than the unfilled-rubber blend.

Abstract: Fabricating electrolyte with thin film is one of various methods of lowering the operation temperature for solid oxide fuel cell (SOFC). Because the major polarization of SOFCs is ohmic loss, many groups have tried to fabricate a thin film electrolyte – some proton conducting material that has the conductivity of a couple of orders higher than oxygen conducting one. We have investigated the synthesis of Membrane Electrode Assembly (MEA) including Yttria-doped Barium Zirconate(BYZ) thin film electrolyte via thin-film processes such as Pulsed Laser Deposition and Sputtering. Another approach to lower the operation temperature of SOFCs is the bi-layer structure electrolyte. The functional layer via thin film deposition could guarantee minimum power density loss and stable operation. After the study of Atomic Layer Deposition (ALD) condition to deposit Yttria Stabilized Zirconia (YSZ) on Gadonilia doped Cerate (GDC) substrate, GDC/YSZ bi-layered electrolyte button cells showed higher OCV and larger limiting current with 100nm YSZ ultra thin film. The performance improvement might be attributed to the function of electron blocking and cutting off the reducible gas.

Abstract: The oxide dispersion strengthened (ODS) ferritic steel and non-ODS reduced-activation ferritic (RAF) steel were irradiated at 773 K by means of a dual-beam ion irradiation technique to a dose of 0.4 dpa with simultaneous helium implantation up to 1000 appm. Microstructural changes were investigated by transmission electron microscopy. The RAF steel showed a preferential formation of cavities at grain boundaries, precipitate interfaces and dislocations. In contrast, the ODS ferritic steel showed a homogeneous and fine distribution of cavities in the matrix. This paper discusses the superior resistance of the ODS ferritic steel against development of cavities in terms of the effects of nano-oxide particles dispersed in the matrix.

Abstract: A new fabrication process was proposed for half-Heusler type TiNiSn thermoelectric alloys. Based on the result that the TiNiSn phase can be formed easily at the Sn(Liquid)/TiNi(Solid) interface, the liquid-solid reaction-sintering process was developed using TiNi and Sn powders. The TiNi compound powders were prepared by the atomization method using argon gas atmosphere. We have fabrictaed nearly single-phase TiNiSn alloys and evaluated their thermoelectrical properties; the presnt TiNiSn alloys have large electrical power factor of about 3.5 mWm-1K-2, and the maximum value of dimensionless figure of merit, ZT = 0.67, can be achieved at around 700 K even without tuning of the carrier concentration through alloying elements.

Abstract: The certification of retro-fitted structural health monitoring (SHM) systems for use on aircraft raises a number of challenges. One critical issue is determining the optimal means of supplying power to these systems, given that access to the existing aircraft power-system is likely to be problematic. Other conventional options such as primary cells can be difficult to certify and would need periodic replacement, which in an aircraft context would pose a serious maintenance issue. Previously, the DSTO has shown that a structural-strain based energy harvesting approach can be used to power a device for SHM of aircraft structures. Acceleration-based energy harvesting from airframes is more demanding (than a strain based approach) since the vibration spectrum of an aircraft structure varies dynamically with flight conditions, and hence a frequency agile or (relatively) broad-band device is often required to maximize the energy harvested. This paper reports on the development of a prototype vibro-impacting energy harvester with a ~59 gram flying mass and two piezoelectric bimorph-stops. Over the frequency range 29-41 Hz using a continuous-sine 450 milli-g r.m.s. excitation, the harvester delivers an average of 5.1 mW. From a random band-passed 25-45 Hz excitation with r.m.s. 450 milli-g, the average harvester output is 1.7 mW.

Abstract: In this paper, we present the structural design for the development of the floating type photovoltaic energy generation system using pultruded FRP members. Pultruded FRP has superior material properties compared with those of conventional structural materials. Especially, pultruded FRP has an excellent corrosion-resistance along with high specific strength and stiffness, which are highly appreciated for the design and fabrication of the floating type photovoltaic energy generation system. In the paper, investigations pertaining to the mechanical and structural behaviors of FRP structural members based on the experiments are discussed. In addition to the experimental investigation, finite element analysis of the floating type photovoltaic energy generation system composed of pultruded FRP structural shapes has been performed. Finally, we have designed and developed the floating type photovoltaic energy generation system using the results of investigations.