جستجوی مقالات مرتبط با کلیدواژه « composites » در نشریات گروه « مواد و متالورژی »

Ceramic nozzles are unique options in aerospace industry due to their ability to operate at high temperatures. However, their brittleness, structural defects, poor formability, and need for complex methods for measuring their mechanical properties are among the main obstacles to their development. In this study, four different conical nozzles were produced through Plasma Spray Forming (PSF). Given that Yttria-Stabilized Zirconia (YSZ) is one of the most common materials in high-temperature applications, it is considered as the base material. Throughout the research, three YSZ alternatives were investigated by changing the chemical composition (Ceria-Yttria co-Stabilized Zirconia (CYSZ)), by changing the particle size (nanostructured YSZ), and by double layer architecture design. The mechanical properties of the conical nozzles were then evaluated by the nanoindentation test using Oliver and Pharr method. This method can be quick and applicable for evaluation of the mechanical properties of ceramic parts based on the load-depth curve. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were performed for the phase analysis and coating microstructure and porosities investigation. The results highlighted the promising features of nano-structured YSZ that are strongly based on the presence of nano-zones inside the coating structure.

The scientific community has developed new technologies, including solar cells (SCs), to meet global energy demands. SCs convert solar energy into electrical energy, providing renewable, sustainable, and green energy. Despite the availability of PV systems for many years, power generation through SC technology remains costly due to the low conversion efficiency (CE). Their low CE is due to limitations in semiconducting materials. In the present review, the basic mechanism of SC and techniques for modify SC have been discussed. The main focus of this review is to given an overview about the bimetallic materials and their application in SC. Bimetallic materials consist of two metallic components that can be synthesized using different methods. They exhibit exceptional properties, including improved electrical conductivity, tunable electrochemical activity, and high charge capacity compared to monometallic materials, making them promising candidates for use as electrochemical catalysts and photocatalysts. Various types of bimetallic composites and compounds, such as, oxides, phosphide, sulfide and carbon-based bimetallic composites is explained in the context of their compositions, synthesis techniques and their power generation efficiency. In the last portion of review, the importance of bimetallic materials in SC application with their possible promising research direction and challenges are presented.

Nowadays, providing powerful and green energy sources is one of the main challenges for a cleaner environment. Rechargeable lithium-ion batteries (LIBs), as effective energy storage devices, have gained lots of attention because of their relatively low self-discharge rate, high energy density, and rapid response. Since the efficiency of LIBs is significantly dependent on electrode materials; attention has been paid to the design of various electrodes.  carbon materials with their special structural, electrical, and mechanical properties are considered promising anode materials in LIBs. However, more research is still needed to identify suitable carbonaceous materials to improve the properties of anodes. In this regard, transition metals and silicon as high-capacity anodes can combine with carbon to develop LIBs. In this review, the employed carbonaceous materials and their composites as well as their outlook for LIB anodes have been investigated.

Biocompatible ceramics, commonly known as “bioceramics”, are an extremely versatile class of materials with a wide range of applications in modern medicine. Given the inorganic nature and physico-mechanical properties of most bioceramics, which are relatively close to the mineral phase of bone, orthopedics and dentistry are the preferred areas of usage for such biomaterials. Another clinical field where bioceramics play an important role is oculo-orbital surgery, a highly cross- and interdisciplinary medical specialty addressing to the management of injured eye orbit, with particular focus on the repair of orbital bone fractures and/or the placement of orbital implants following removal of a diseased eye. In the latter case, orbital implants are not intended for bone repair but, being placed inside the ocular cavity, have to be biointegrated in soft ocular tissues. This article reviews the state of the art of currently-used bioceramics in orbital surgery, highlighting the current limitations and the promises for the future in this field.

In order to investigate the effect of fiber volume fraction on the mechanical behavior of ultra-high performance concrete composites (UHPCC), five different volume fractions of macro steel fibers (Vf = 0.5, 1, 1.5, 2 and 2.5%) are used within identical mortar matrix. Ultra-high performance fiber reinforced concrete (UHPFRC) mix was designed to achieve a compressive strength of 155 MPa based on the particle packing method. For 12 series of UHPCC mixes, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity at 28 days are determined. Test results showed a significant improvement in splitting tensile and flexural strengths of UHPFRC with the addition of steel fibers. The maximum values of compressive, splitting tensile and flexural strengths were 155.39, 17.76, and 32.50 MPa, respectively. Stress-strain behavior of fiber-reinforced concrete composites is studied and elastic modulus values evaluated are in the range of 39.52-47.99 GPa. Empirical expressions are developed based on the test results in terms of fiber volume fraction to predict the 28-day strengths of UHPFRC. Comparing the experimental values of earlier researchers to the ones predicted by empirical equations, the average absolute error (AAE) value obtained is within 5%. The proposed model's predictions are in good agreement with the experimental values. Relationship between compressive and flexure strengths of UHPFRC isdeveloped with R2=0.99 and validated.

In this paper we report upon the preparation and characterization of electrospun nanofibersof doped polyaniline (PANI)/poly(methyl methacrylate) PANI-PMMA/AgNO3 by electrospinningtechnique. At first, Doped polyaniline (PANI) was obtained by the polymerization of aniline using chemicaloxidative polymerization in the presence of ammonium peroxydisulfate (APS). The doped PANI wasdedoped by ammonia solution. Then, the electrospinning method was applied on the solutions involvingPANI-PMMA, PANI-PMMA-AgNO3. The as-prepared PANI-PMMA and PANI-PMMA-AgNO3 compositenanofibers were investigated for structural characterizations by means of SEM, FTIR and UV-VIS. SEMtechnique was used to investigate the morphology of the accumulated fibers or particles on the Alsurface collector. SEM revealed the nanofibers with the diameter Micro to nanofibers formed a nonwovenmaterial with highly porous and agglomerated structure. The presence of Ag in the case of Agcontaining composite nanofibers was confirmed by EDAX.

This study is aimed to fabricate the Aluminium-graphene oxide (Al-GO) composites with different concentration of GO (0.5, 1, and 2 wt. %) at 300 °C using repetitive upsetting extrusion (RUE) technique. Uniform dispersion of GO nanoplates throughout the matrix was obtained by sequence processes including the ultrasonicating, ball milling and RUE. The microstructure of composites was investigated by X-ray diffraction, scanning electron microscope and Raman analysis. The results confirmed that the Al-1GO illustrated the uniform and homogenous dispersion of GO into the Al matrix. Raman results confirm the absence of aluminum carbide phase formation during the RUE process. The mechanical properties results show the greater hardness, compressive strength and yield strength of Al-1GO than other ones. This 500% enhancement of Al-1GO in mechanical behavior may be related to desired dispersion of GO throughout the matrix. Current density of the Al matrix corrosion significantly increased from 2.65 to 15.21 (μA/cm2), when the amount of GO increased from 0 to 2 wt. % due to galvanic cor-rosion at the presence of the GO reinforcement. ©2021 JCC Research Group.

In this paper we report upon the preparation and characterization of electrospun nanofibersof doped polyaniline (PANI)/poly(methyl methacrylate) PANI-PMMA/AgNO3 by electrospinningtechnique. At first, Doped polyaniline (PANI) was obtained by the polymerization of aniline using chemicaloxidative polymerization in the presence of ammonium peroxydisulfate (APS). The doped PANI wasdedoped by ammonia solution. Then, the electrospinning method was applied on the solutions involvingPANI-PMMA, PANI-PMMA-AgNO3. The as-prepared PANI-PMMA and PANI-PMMA-AgNO3 compositenanofibers were investigated for structural characterizations by means of SEM, FTIR and UV-VIS. SEMtechnique was used to investigate the morphology of the accumulated fibers or particles on the Alsurface collector. SEM revealed the nanofibers with the diameter Micro to nanofibers formed a nonwovenmaterial with highly porous and agglomerated structure. The presence of Ag in the case of Agcontaining composite nanofibers was confirmed by EDAX.

Composites based on polyoxometalates (POMs) have been increasingly attracted by many researchers due to their multitudinous architectures and excellent redox activities as well as outstanding proton and electron transport capacities. Lately, much research has been done on POMs composited with well-porous framework materials (including ZIFs, MOFs) or conducting polymers, carbon quantum dot (CQD), graphene, carbon structures (e.g. carbon nanotubes (CNTs)), and metal nanoparticles (NPs). The results exhibited improved stability and enhanced electrochemical performances. Hence, developing POMs and POM-based composite materials (PCMs) has long been a topic of interest for chemical researchers. Herein, the properties and applications of pristine POMs, doped POMs, and composite-based POMs are reviewed in detail. The various compositions of POMs with sensing ap-plication such as POMs-nanocarbon composites (POMs-graphene composites and POMs-carbon nanotube com-posites), POMs-conductive polymer composites, and POMs-metal composites are also investigated in this review

The construction sector is responsible for relevant environmental impacts and one of its most crucial points is the use of concrete. Geopolymers represent the most promising green and ecological alternative for common Portland cement and cementitious materials, due to its proven durability, mechanical and thermal properties. This work presents an experimental and comparative study of adhesion at the fiber-matrix interface between glass fibers and carbon fibers added to the geopolymer matrix. This analysis was performed by pull-out test, whereby it was found that the greatest efficiency was obtained by reinforcing with the glass fibers, incorporated at 2 mm in the geopolymer matrix. As results, the adhesion between the fibers and the geopolymer structure can be assessed, as well as the optimum length of application.

NThese days, solar cells have attracted considerable attentions because they are environment-friendly sources of electric power. The present review is focused on composites and materials that are used in the solar cells field, including Si-based solar cells, dye-Sensitized solar cells (DSSC), thin film solar cells, Quantum dot solar cells (QDSC) and Perovskite solar cells (PSC). TiO2 based nanocomposites, which are widely applicable in the solar cells are also reviewed.