High Specific Tensile Strength Research Articles

Symbiotic Aerogel Fibers Made via In-Situ Gelation of Aramid Nanofibers with Polyamidoxime for Uranium Extraction.

The uranium reserve in seawater is enormous, but its concentration is extremely low and plenty of interfering ions exist; therefore, it is a great challenge to extract uranium from seawater with high efficiency and high selectivity. In this work, a symbiotic aerogel fiber (i.e., PAO@ANF) based on polyamidoxime (PAO) and aramid nanofiber (ANF) is designed and fabricated via in-situ gelation of ANF with PAO in dimethyl sulfoxide and subsequent freeze-drying of the corresponding fibrous gel precursor. The resulting flexible porous aerogel fiber possesses high specific surface area (up to 165 m2·g−1), excellent hydrophilicity and high tensile strength (up to 4.56 MPa) as determined by BET, contact angle, and stress-strain measurements. The batch adsorption experiments indicate that the PAO@ANF aerogel fibers possess a maximal adsorption capacity of uranium up to 262.5 mg·g−1, and the absorption process is better fitted by the pseudo-second-order kinetics model and Langmuir isotherm model, indicating an adsorption mechanism of the monolayer chemical adsorption. Moreover, the PAO@ANF aerogel fibers exhibit selective adsorption to uranium in the presence of coexisting ions, and they could well maintain good adsorption ability and integrated porous architecture after five cycles of adsorption–desorption process. It would be expected that the symbiotic aerogel fiber could be produced on a large scale and would find promising application in uranium ion extraction from seawater.

Morphology and mechanical properties of the dorsal bony plates in the Chinese sturgeon (Acipenser sinensis).

The morphology, composition, and mechanical properties of the dorsal bony plates in the Chinese sturgeon (Acipenser sinensis) were determined in this study. Scanning electron microscopy images of the bony plates revealed a ridge-like shape similar to that of traditional Chinese architecture and displayed hierarchical microstructures whose the degree of mineralization decreased from the surface layer to the internal layer. Moreover, the crests in the central part of the bony plates displayed porous characteristics. Composition analysis of the bony plates revealed that they were primarily composed of Ca, P, O, and C, demonstrating that hydroxyapatite was the main constituent. Mechanical experiments including nanoindentation, penetration, and tension tests confirmed that the bony plates have excellent mechanical properties and present high specific tensile strength that is comparable to that of 304 stainless steel. This study may provide a new bionic design template for lightweight and high-strength body armor.

Recent advances in carbon-fiber-reinforced thermoplastic composites: A review

Abstract Carbon fibers (CFs) have high specific tensile strength, high modulus, and outstanding wear resistance, and are widely used for the reinforcement of advanced composite materials. CF-reinforced thermoplastic composites have received much attention because of their easy processability and recycling convenience compared with thermosetting composites. Surface treatment of CFs is generally employed to increase the surface functional groups and interfacial adhesion between the CFs and the surrounding polymer matrix. In this review, we explore recent advances in the surface treatment of CFs and preparation of CF/thermoplastic composites. The thermal, mechanical, and electrical properties of the composites are also discussed.

Surface damage mitigation of TC4 alloy via micro arc oxidation for oil and gas exploitation application: Characterizations of microstructure and evaluations on surface performance

Because of its excellent corrosion resistance, high specific strength and high tensile strength, TC4 titanium alloys used as petroleum tubes have received wide interest from material engineers after many technical investigations and estimations. However, because of its low surface hardness values, high coefficient of friction and poor wear resistance, the TC4 alloy is seldom adopted in tribological-related engineering components. In this work, micro-arc oxidation (MAO) coatings were fabricated on TC4 alloys in NaAlO2 and (NaPO3)6 electrolytes with and without ultrasonic assistance. The microstructural characterizations of the produced MAO coatings were investigated. Comparative estimations of electrochemical corrosion in CO2-saturated simulated oilfield brine and tribological behaviours on MAO coatings and TC4 alloys were conducted. The results showed that the introduction of ultrasound increased the thickness of the MAO coatings. The thickness increased by 34% and 15% in the NaAlO2 and (NaPO3)6 electrolytes, respectively. There was no significant discrepancy in phase constitutions when the MAO processes were conducted with and without ultrasonic assistance. Both MAO coatings obtained with and without ultrasonic assistance were found to improve the corrosion and wear resistance of the TC4 alloy. MAO treatments made it possible to ensure the working surface of a TC4 alloy with an enhanced surface performance for oil and gas exploitation applications.

Influences on the formability and mechanical properties of 7000-aluminum alloys in hot and warm forming

Aluminum alloys of the 7000 series possess high lightweight potential due to their high specific tensile strength combined with a good ultimate elongation. For this reason, hot-formed boron-manganese-steel parts can be substituted by these alloys. Therefore, the application of these aluminum alloys for structural car body components is desired to decrease the weight of the body in white and consequently CO2 emissions during vehicle operation. These days, the limited formability at room temperature limits an application in the automobile industry. By increasing the deformation temperature, formability can be improved. In this study, two different approaches to increase the formability of these alloys by means of higher temperatures were investigated. The first approach is a warm forming route to form sheets in T6 temper state with high tensile strength at temperatures between 150 °C and 300 °C. The second approach is a hot forming route. Here, the material is annealed at solution heat treatment temperature and formed directly after the annealing step. Additionally, a quench step is included in the forming stage. After the forming and quenching step, the sheets have to be artificially aged to achieve the high specific tensile strength. In this study, several parameters in the presented process routes, which influence the formability and the mechanical properties, have been investigated for the aluminum alloys EN AW7022 and EN AW7075.

Development, Analysis, and Validation of an Economically Efficient Process Chain for a Rigid CFRP Plate Assembly Using Finger Joints

For the mechanical engineering sector it is crucial to develop cost efficient process chains to produce CFRP components. CFRP material is usually compared to steel due to its high specific tensile strength and high specific rigidity. Thus, joining techniques known from steel are used to join CFRP parts. In contrast, this study focuses on the elements and production processes known from wooden parts. The wood industry uses connection techniques appropriate for the anisotropic material behavior of CFRP. The finger joint was identified as a suitable connection for CFRP components. It transmits forces by form fit and allows for easy assembly.

Technical Properties of Some Plant Fibres Compared with Glass Fibre

The tensile strength, specific tensile strength, breaking force, tenacity and percent elongation of some fibres extracted from eight fibrous plants found in Northern Nigeria were determined with a view to ascertaining their suitability for the replacement of glass fibre in plastic composites. Also the crimp properties and work of rupture with the specific work of rupture for all the plant fibres were analysed. The fibrous plants were Sisal (Agave Sisalana) (ASA), Lalloh (Corchorus Triden L.) (CCR), Dargaza (Grewia Mollis Juss) (GRW), Kenaf (Hibiscus Cannabinus L.) (HCB), Goruba (Hyphaene Thebaica)(HYP), Sukuwa (Sida Acuta) (SDA), Karlgo (Piliostigma Thoningii) (PTA) and Shikuri Tuggah (Urena Lobata) (ULB). Their properties were compared with E-Glass. The results show that whereas the highest tensile strength of the plant fibre (ASB) was about one-third that of the glass fibre, the highest specific tensile strength of the plant fibre (HCB) was about 5 times that of the glass fibre. The percent elongation of the plant fibres except HYB and SDA were at least 5.6 times that of the glass fibre. The specific work of rupture for the plant fibre were also found to be upto 31% higher compared with that of glass. Three of the plant fibres, (HCB, ASA and ULB) were observed to be possible replacements for the classic glass fibre.

Development and Application of New Design Method by High-Strength Composite Material - Fusing of Optimum Strength Evaluation and Product Design

The purpose of this research is the development of new design method for integrating the optimum strength evaluation and the product design which can make the best use of material's characteristics obtained by the experiment and the analysis. Further we do design using high-strength composite material with this developed concept which is different from conventional design. First, to establish this design method of high-strength materials, we examined these materials characteristics and manufacturing methods and the commercialized products. As this research target material, we focus the fiber reinforced materials such as composite with carbon fiber, glass fiber and aramid fiber. Above all, we marked the carbon fiber which has the high specific tensile strength, wear resistance, heat conductivity and conductance. Here, we introduce the fundamental design concept which makes the best use of the design with enough strength.

Strong, Conductive, Lightweight, Neat Graphene Aerogel Fibers with Aligned Pores

Liquid crystals of anisotropic colloids are of great significance in the preparation of their ordered macroscopic materials, for example, in the cases of carbon nanotubes and graphene. Here, we report a facile and scalable spinning process to prepare neat "core-shell" structured graphene aerogel fibers and three-dimensional cylinders with aligned pores from the flowing liquid crystalline graphene oxide (GO) gels. The uniform alignment of graphene sheets, inheriting the lamellar orders from GO liquid crystals, offers the porous fibers high specific tensile strength (188 kN m kg(-1)) and the porous cylinders high compression modulus (3.3 MPa). The porous graphene fibers have high specific surface area up to 884 m(2) g(-1) due to their interconnected pores and exhibit fine electrical conductivity (2.6 × 10(3) to 4.9 × 10(3) S m(-1)) in the wide temperature range of 5-300 K. The decreasing conductivity with decreasing temperature illustrates a typical semiconducting behavior, and the 3D interconnected network of 2D graphene sheets determines a dual 2D and 3D hopping conduction mechanism. The strong mechanical strength, high porosity, and fine electrical conductivity enable this novel material of ordered graphene aerogels to be greatly useful in versatile catalysts, supercapacitors, flexible batteries and cells, lightweight conductive fibers, and functional textiles.

OS1517 カーボンナノチューブプリフォームを用いた高分子基複合材料の機械的特性(OS15-4 複合材料の変形と強度,OS-15 微視構造を有する材料の変形と破壊)

Carbon nanotubes are nano-scale fibers that have high specific elastic modulus and tensile strength. The potential as reinforcement materials for polymers has, however, not been realized so far. In this study, two types of carbon nanotube preforms, unidirectional sheet and spun yarn, were used to achieve high efficiency of reinforcement. Composite specimens were fabricated using epoxy resin, and tensile tests were conducted for investigating tensile properties. The experimental results showed that using carbon nanotube preforms is effective for achieving high mechanical properties.

Evaluation of Perforation Resistance of Magnesium Alloy by Hypervelocity Impact

Magnesium alloy is the lightest metal that is used as a structural material. It has a higher specific tensile strength and specific stiffness than Iron and Aluminum alloy, and the dent is not caused easily from Iron and Aluminum alloy at the impact. Therefore, Magnesium alloy is widely used in many areas, especially as an external shell of a mobile device and automotive parts which replaces iron and plastic, etc., and its demand is expected to grow in the future. In this paper we studied the hypervelocity impact with a ballistic range to clarify the characteristic of Magnesium alloys which had such a characteristic. The effect of impact velocity, temperature and the size of perforation hole were investigated experimentally. The perforation resistance of Magnesium alloys and their impact behavior were characterized.

２軸荷重下におけるコーテッド平織膜材料の力学特性

In this study, biaxial tensile tests of cruciform specimens with open hole were conducted for evaluating the strength of the coated plain weave fabrics composed of high specific tensile strength fibers. In addition to the biaxial tensile tests, uniaxial tensile tests of strip specimens were also carried out to obtain uniaxial fundamental properties of the fabrics. As the results of the biaxial and uniaxial tensile tests, open hole tensile strength of the fabric under biaxial loadings is approximately equal to the strength under uniaxial load irrespective of biaxial load ratio, and warp directional strip specimens exhibit higher strength than that of weft directional specimens in spite of the same densities of yarns in both directions. Experimental results exhibit that misalignment of weft yarns of the membrane partly contributes the loss of the strength in weft direction. The results of observations by microscope and tensile tests of single yarns reveal that the difference of the strength in warp and weft directions is caused by the degradation of weft yarns by heating process of polymer film coating on the fabrics in addition to the misalignment of yarns.

Evaluation Of Surface Treatment Of Ti-6Al-4V Alloy Specimens

As is generally well known, though titanium and its alloys have high specific tensile strength, excellent corrosion resistance, etc., they have not been widely used until now mainly due to their extremely high processing cost. Therefore, it is considered that the above barrier will become smaller if it is possible to improve the mechanical properties of Ti-alloys by applying surface treatments on them. The purpose of this paper is to improve and to evaluate the mechanical properties, especially fatigue strength of about 6 lunds of surface-treated Ti-6A14V alloys. That is, surface treatments by 2 kinds of plasma, 3 kinds of DLC (diamond-like carbon) coating and the electroless plating method, have been studied for Ti-6A1-4V alloy. This study presents an analysis of fatigue behavior from the viewpoint of micro-hardness and adhesion work through a new technique in Ti-6A1-4V alloy. In addition, the specimen's surface has been successively observed by the replica method during tests and it seems clear that the fatigue strength is improved by the DLC treatment in comparison with that of the conventional Ti-6A1-4V alloy by about 20% (fatigue limit improvement by 70 MPa). Though all the hardness value of these specimens increased, the fatigue limit improved only in the cases of two kinds of specimens by DLC coating.

飛行船用高比強度の膜材料の開発

Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured.

Fabrication and characterization of three-dimensional cellular-matrix composites reinforced with woven carbon fabric

A low-density three-dimensional cellular-matrix composite reinforced with woven carbon fabric (3DCMC), was fabricated by means of a pressure-quenching molding technique with nitrogen gas as the blowing agent. Epoxy resins in the interstices of yarns in the 3DCMC samples were vacated during the foaming process and needle shaped voids were also generated between fibers in yarns. The average density of the 3DCMC samples was about 10 3 kg/m 3, and their density reduction was 28–37% compared with a regular matrix composite with the same preform. The 3DCMC has 32–42% higher specific tensile strength, 14–37% greater specific tensile modulus, a lower specific flexure strength but 35% higher specific tangent modulus in 3-point bending, a 30–40% higher specific impact energy absorption at an impact velocity around 120 m/s and a similar specific energy absorption at about 220 m/s. Meanwhile, the 3-point bending and impact test results of 3DCMC showed that they have different fracture mechanisms from that of 3DRMC.

Intermetallic Alloys Based on Orthorhombic Titanium Aluminide

Orthorhombic titanium aluminides represent the youngest class of alloys emerging out of the group of titanium aluminides. These new materials are based on the ordered orthorhombic phase Ti 2 AlNb, which was discovered for the first time in the late 1980s as a constituent in a Ti 3 Al-base alloy. In the 1990s primarily simple ternary Ti-Al-Nb orthorhombic alloys were investigated in countries such as the US, UK, India, France, Japan, and Germany. The drive was mainly provided by jet engine manufacturers and related research labs looking for a damage-tolerant, high-temperature, light-weight material. This follows the aim of further extending the use of lower density titanium-base materials in temperature regimes, where heavy nickel-base superalloys are the only alternative today. The present understanding of microstructure-property relationships for orthorhombic titanium aluminides reveals an attractive combination of low and high temperature loading capabilities. These involve high room-temperature ductility and good formability, high specific elevated temperature tensile and fatigue strength, reasonable room-temperature fracture toughness and crack growth behavior, good creep, oxidation, and ignition resistance combined with a low thermal expansion coefficient. This article reviews the aspects of composition-microstructure-property relationships in comparison to near-a titanium, TiAl, and nickel-base alloys. Special emphasis is also placed on the environmental degradation of the mechanical properties.

High Strength Nanocrystalline Mg-Al-Ca Alloys Produced by Rapidly Solidified Powder Metallurgy Processing

Nanocrystalline magnesium alloy having high specific tensile strength, high Young's modulus, high elevated-temperature tensile strength, high-strain-rate superplasticity and high corrosion resistance has been developed by rapidly solidified powder metallurgy (RS P/M) processing in amorphous forming Mg 70 Al 20 Ca 10 alloy. The density of the nanocrystalline RS P/M alloy was 1.80 g/cm 3 . The compressive yield strength and plastic strain that were dependent on the consolidation temperature were in the ranges of 570 to 930 MPa and 0.5 to 9.2 %, respectively. The tensile yield strength, plastic elongation and Young's modulus of the RS P/M alloy extruded at 673 K were 600 MPa. 1.0% and 50 GPa, respectively, The specific tensile yield strength was four times as high as that of a commercial AZ91-T6 alloy. The RS P/M alloy exhibited excellent elevated-temperature yield strength that was 360 MPa at 473 K. The RS P/M alloy also exhibited superplasticity at a high strain rate of 1. 1x10 0 S -1 and at 723 K. It is expected that the Mg 70 Al 20 Ca 10 RS P/M alloy is applied in some fields that requires simultaneously the high specific strength at ambient and elevated temperatures, high workability and high corrosion resistance.

Structure and Mechanical Properties of Rapidly Solidified Mg-X Alloys

We have investigated the structure and mechanical properties of binary Mg-X (X=Al, Ca, Li or Zn) melt-spun ribbons in n as-quenched and annealed states as the first step of the development of alloy compositions for new Mg-based rapidly solidified powder metallurgy (RS P/M) alloys. The amorphous Mg 90 Ca 10 and Mg 70 Zn 30 (at%) alloys exhibited high specific tensile strength of more than 2.5 X 10 5 Nm/kg and good bending ductility. Solid solubility extension was observed in Mg-Ca, Mg-Li and Mg-Zn RS alloys. The solid solution had a ductile nature for the Mg-Al and Mg-Zn RS alloys, while brittle for the Mg-Ca and Mg-Li RS alloys. The Mg-Ca and Mg-Zn RS alloys exhibited an abrup increase in hardness by small addition of the alloying elements. The Mg 94 Al 6 , Mg 90 Al 10 , Mg 98 Ca 2 and Mg 98 Zn 2 RS alloys exhibited both high hardness and good bending ductility after annealing. It is expected that new magnesium RS alloys will be developed hereafter on the basis of these data.

Superplasticity of whisker reinforced 2024 aluminum alloy composites fabricated by squeeze casting

Some ceramic whisker reinforced aluminum alloy composites having high specific tensile strength, good resistance to thermal fatigue and to wear have been commercialized as components of automobile etc.. However, since ceramic whiskers having high hardness are distributed in soft aluminum alloys, it is extremely difficult to machine them to produce complicated shape components. In order to overcome this difficulty, near-net shape production processes have been employed to produce metal matrix composite components. Squeeze casting is one of the most excellent production methods for near-net shape production in respect of production technique. Most of MMC products commercialized are being produced by squeeze casting. In squeeze casting, a preform made of fibers or whiskers is used as a reinforcement, and a molten metal is infiltrated into it by pressure. However, it is difficult to make a complicated shape preform and to infiltrate a molten metal into it without any damage. Therefore, there is a limit in the application of squeeze casting.

High strain rate superplasticity of AlN particulate reinforced aluminium alloy composites

Ceramic whisker or particulate reinforced aluminium alloy composites have a great potential for automobile engineering components, aerospace structures, semi-conductor packaging and so on, because of the composites ability to exhibit a high specific elastic modulus and specific tensile strength, excellent wear resistance and heat resistance, low thermal expansion and good dimensional stability. A serious problem involving practical application of ceramic whisker or particulate reinforced aluminium alloy composites is due to the low tensile ductility, fracture toughness at room temperature and, also, their hardness qualities that make it difficult to deform by conventional forming processing and machining by ordinary tools. It has been found, however, that aluminium alloy composites reinforced by SiC or Si[sub 3]N[sub 4] whiskers or particulates produce superplasticity at a high strain rate of about 0.1s[sup [minus]1]. Superplastic deformation mechanisms of the ceramic whisker or particulate reinforced aluminium alloy composites are fine grain boundary sliding, interfacial sliding at a liquid phase and dynamic recrystallization. An AlN particulate reinforced aluminium alloy composite exhibits a high elastic modulus and a high thermal conductivity, and their thermal expansion is similar to silicon in that the AlN particulate reinforced aluminum alloy composite is expected to apply to semi-conductor packaging in the aerospacemore » structure. In addition, if the composite could produce superplasticity at high strain rates, the market of aerospace application for superplastic composites could be expanded. The purpose of this study is to make clear if an AlN particulate reinforced aluminium alloy composite can produce superplasticity at high strain rate and the superplastic characteristics.« less