Tensile Strength In Excess Research Articles

Seeking materials from nature for interrupting eye damage: Ultraviolet to blue light blocking clear cellulose films enabled by curcumin

The harms caused by ultraviolet (UV) and blue light to eyes are attracting momentous concern due to growing exposure to artificial illumination and modern IT devices. Herein, a simple and eco-friendly adsorption approach was employed to integrate curcumin, a natural bioactive compound, into the cellulose substrate for the development of flexible and biodegradable filters capable of blocking harmful light. The curcumin/cellulose films demonstrate excellent UV-screening competence and photostability, with UV-A and UV-B screening ratios ranging from 92.8 % to 100 % and 89.2 % to 100 %, respectively. The films could block >96 % of blue light in the wavelength range of 400–500 nm. Meanwhile, the films maintain high transmittance (85.2–89.4 %) and low haze (2.0–2.7 %). The films can efficiently block blue light emanated from sunlight, light-emitting diodes, lighting systems, computer and mobile phone screens. Encouragingly, the incorporation of curcumin led to a substantial increase in the water contact angle, elevating it from 41.6 to 81.3°. Furthermore, the films exhibit excellent antimicrobial properties, biodegradability, and tensile strength in excess of 72 MPa. Therefore, these films fabricated entirely from natural resources have the potential to achieve practical applications such as food packaging and spectacle lens, especially suitable for electronic screen protectors.

Retain strength, gain ductility: tough and transparent nanopapers by mercerisation

Nanocellulose papers offer high tensile strength and modulus but suffer from drawbacks such as their brittle nature. We show that mercerisation of cellulose nanopapers in strong alkaline media for 2 min to 24 h results in the (partial) transformation of native cellulose I into the more ductile cellulose II allomorph. The strain to failure of mercerised nanopapers tripled compared to the original nanopapers while retaining their tensile strength in excess of 100 MPa at the expense of a slight drop in modulus resulting in a significant increase in toughness (total work of fracture). An additional advantage of mercerisation is a reduction in porosity of the nanopapers and increased transparency.

Bioinspired design optimization for pseudo-ductility in platelet fibre laminates

Platelet designs inspired by nacre shell microstructure are a novel approach to confer pseudo-ductile deformation properties to brittle fibre reinforced polymer laminates while retaining high stiffness and strength. Here we present an experimental and finite element modelling study to investigate the effects of tiling pattern, overlapping length and interlaminar toughness of the ply platelets on the tensile properties, pseudo-ductility, and failure modes of platelet laminates inspired by nacre. The findings are then used to optimize the design for maximal pseudo-ductility for a given tensile strength. Experimental results show that unidirectional platelet laminates can possess tensile strengths in excess of 1 GPa while pseudo-ductile deformation accounts for more than ∼ 50% of the ultimate failure strain. Finite element modelling of platelet laminates reveals that the amount of pseudo-ductility can be tailored via the design optimization of the tiling pattern, overlap length, composite thickness and mode II interlaminar toughness of the platelets. The mechanisms controlling the pseudo-ductility effect in the bioinspired platelet laminates is described.

Microstructure and mechanical properties of a 2000 MPa grade ultrahigh strength boron steel

Press hardening steels (PHS) with very high strength are current key materials for lightweight engineering solutions and corresponding CO2 savings. In the present study, the microstructure and mechanical properties of a 2000 MPa grade ultrahigh strength boron steel for hot stamping were reported. Microstructure evolution experiment revealed that the microstructure of the 2000 MPa grade PHS only consisted of martensite when the cooling rate increased to 20 °C/s. The prior austenite grain size was about 6.8 μm when the sample was austenitized at 900 °C for 300 seconds. The appropriate isothermal quenching process should be austenitized between 900 °C and 950 °C during hot stamping because there is an abnormal grain growth of austenite grains at 950 °C. Following the optimal hot stamping condition, the 2000 MPa grade PHS alloy demonstrated yield strength in excess of 1300 MPa and ultimate tensile strength in excess of 2000 MPa together with a total elongation of about 7%.

High-strength steel components produced by hot metal gas forming

Advanced high-strength steels are promising materials for a variety of applications. They can be used in the automotive industry to reduce the car body weight and thus the fuel consumption as well. Very good mechanical properties can be obtained in martensitic steels by the quenching and partitioning process. Making complex-shaped parts using a single forming step is now possible with hot metal gas forming. Several heat treatment sequences were designed. One involved plain hardening to a temperature below the martensite start temperature. Another sequence was intended to explore the influence of the quenching and partitioning process. In this steel with a carbon content of 0.42%, tensile strengths in excess of 1800 MPa with elongations above 15% can be achieved.

Strain rate sensitivity of the aluminium-magnesium-scandium alloy - Scalmalloy®

This work investigates the strain rate sensitivity of the aluminiummagnesium-scandium alloy Scalmalloy, which is used extensively for additive manufacturing of lightweight structures. This high strength aluminium alloy combines very good weldability, machinability and mechanical strength: it can be heat-treated to reach nominal ultimate tensile strengths in excess of 500 MPa. We report tensile tests at strain rates ranging from 10−3 /s to 103 /s at room temperature. It is well known that Al-Mg alloys exhibit a negative strain rate dependency in combination with serrated flow caused by the Portevin-Le Chatelier effect, which describes the interaction of Mg solutes with dislocation propagations. In contrast, in Al-Sc alloys, the flow stress increases with increasing strain rate and displays positive strain rate dependency. Additionally, the presence of Sc in the form of Al3-Sc provides a fine-grained microstructure which allows higher tensile and fatigue strength. This research shows how these combined effects interact in the case of Scalmalloy, which contains both Mg and Sc. Tests are performed at quasi-static, intermediate and high strain rates with a servohydraulic testing machine and a Split-Hopkinson tension bar. Local specimen strain was performed using 2D Digital Image Correlation.

Additive manufacturing of multiple materials by selective laser melting: Ti-alloy to stainless steel via a Cu-alloy interlayer

The ability to combine multiple materials (MM) into a single component to expand its range of functional properties is of tremendous value to the ceaseless optimization of engineering systems. Although fusion and solid-state joining techniques have been typically used to join dissimilar metals, additive manufacturing (AM) has the potential to produce MM parts with a complex spatial distribution of materials and properties that is otherwise unachievable. In this work, the selective laser melting (SLM) process was used to manufacture MM parts which feature steep material transitions from 316L stainless steel (SS) to Ti-6Al-4V (TiA) through an interlayer of HOVADUR® K220 copper–alloy (CuA). The microstructure in both the CuA/SS and TiA/CuA interfaces were examined in detail and the latter was found to be the critical interface as it contained three detrimental phases (i.e. L21 ordered phase, amorphous phase, and Ti2Cu) which limit the mechanical strength of the overall MM part. By making use of the non-homogeneity within the melt pool and limiting the laser energy input, the relatively tougher interfacial α′-Ti phase can be increased at the expense of other brittle phases, forming what is essentially a composite structure at the TiA/CuA interface. During tensile testing, the interfacial α′-Ti phase is capable of deflecting cracks from the relatively brittle TiA/CuA interface towards the ductile CuA interlayer and an overall tensile strength in excess of 500 MPa can be obtained. This method of introducing an interfacial composite structure to improve MM bonding is envisioned to be applicable for the SLM of other metallic combinations as well.

USE OF MULTI-PHASE TRIP STEEL FOR PRESS-HARDENING TECHNOLOGY

Development of high strength or even ultra-high strength steels is mainly driven by the automotive industry which strives to reduce the weight of individual parts, fuel consumption, and CO2 emissions. Another important factor is to improve passenger safety. In order to achieve the required mechanical properties, it is necessary to use suitable heat treatment in addition to an appropriate alloying strategy. The main problem of these types of treatments is the isothermal holding step. For TRIP steels, the holding temperature lies in the field of bainitic transformation. These isothermal holds are economically demanding to perform in industrial conditions. Therefore new treatments without isothermal holds, which are possible to integrate directly into the production process, are searched. One way to produce high-strength sheet is the press-hardening technology. Physical simulation based on data from a real-world press-hardening process was tested on CMnSi TRIP steel. Mixed martensitic-bainitic structures with ferrite and retained austenite (RA) were obtained, having tensile strengths in excess of 1000 MPa.

Fabrication of Surlyn ionomer fibers using a novel coextrusion approach and mechanical property characterization

ABSTRACTWe report the fabrication of poly (ethylene‐co‐methacrylic acid) sodium‐neutralized ionomer (Surlyn 8940) fibers via a forced‐assembly coextrusion and layer multiplication process with polystyrene (PS) as the matrix material. The PS separating materials were removed by toluene extraction to yield independent Surlyn fibers. The tensile properties of Surlyn fiber strands were studied under different strain rates. Surlyn fibers were oriented to 300% strain at different temperatures to study the effect of orientation on the tensile properties. The oriented Surlyn fibers were annealed after orientation to further enhance the mechanical properties. Further drawing of these oriented fiber mats to a draw ratio of 4 at 60 °C followed by annealing at 60 °C can afford moduli in excess of 350 MPa and tensile strengths in excess of 70 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48046.

Laser Based Manufacturing of Ti6Al4V: A Comparison of LENS and Selective Laser Melting

The laser engineered net shaping (LENS) system was used for the laser based manufacturing of a test geometry used to assess the performance of additive manufacturing systems. This system was preferred over a selective laser melting (SLM) system due to certain inherent benefits that would promote the manufacture of the test geometry where the SLM system had failed due to part delamination. The test geometry was successfully manufactured on the LENS system and machined to produce test specimen for mechanical testing and microstructural evaluation. Investigations revealed that the α-β lamellar microstructure was formed via in situ martensitic decomposition of the α’ structure. This resulted in promising yield and tensile strengths in excess of 900 MPa and high tensile elongation up to 13%.

Exploring the low temperature tempering range of low alloy quenched and tempered steels

It is well known that quenched and tempered alloy steel components with ultimate tensile strength in excess of 1400 MPa are seldom employed as mechanical components, due to their not adequate ductility, as ascertained by multiple researches performed during World War II and soon after. Nevertheless, use of low temperature tempered steels in some niche applications, as well as researches performed on surface heat treated high carbon steels and on their behavior upon tempering in the vicinity of 200°C have stemmed into renewed interest in quenched and low temperature tempered low alloy steels. Application to 36NiCrMo16 steel bars is examined here, by means of tensile and hardness tests and fractographic and metallographic examinations after quenching and tempering in the 160 to 440 °C temperature range.

Effect of carbon and microalloy additions on hot-stamped boron steel

ABSTRACTHot stamping was performed with seven novel boron steels, exhibiting various carbon contents and microalloy additions of Mo, V and Ni compared to the standard 22MnB5 boron steel. The lower carbon content of 15MnB5 resulted in total elongation in excess of 11.0%. The higher carbon content of 38MnB5 resulted in ultimate tensile strength in excess of 2000 MPa. The vanadium addition resulted in ultimate tensile strength in excess of 1600 MPa combined with total elongation in excess of 11.0%. The carbon and microalloy additions were concluded to give rise to improved mechanical properties in hot-stamped boron steel for automotive body engineering applications.

Thin zeolite laminates for rapid and energy-efficient carbon capture

Thin, binder-less zeolite NaX laminates, with thicknesses ranging between 310 to 750 μm and widths exceeding 50 mm and biaxial tensile strength in excess of 3 MPa, were produced by pulsed current processing. The NaX laminates displayed a high CO2 adsorption capacity and high binary CO2-over-N2 and CO2-over-CH4 selectivity, suitable for CO2 capture from flue gas and upgrading of raw biogas. The thin laminates displayed a rapid CO2 uptake; NaX laminates with a thickness of 310 μm were saturated to 40% of their CO2 capacity within 24 seconds. The structured laminates of 310 μm thickness and 50 mm thickness would offer low pressure drop and efficient carbon capture performance in a laminate-based swing adsorption technology.

High tensile strength of sputter-deposited ZrB2 ceramic thin films measured up to 1016 K

We report the results of tensile experiments on 900 nm sputter-deposited films of ZrB2, performed at temperatures ranging from ambient to 1016 K. The ZrB2 samples were tested using micromachined sample frames with integrated micro-heaters. Transmission electron microscopy shows that both as-deposited films and films heated above 1000 K consist of two distinct layers, an amorphous layer and a crystalline layer with a very fine columnar structure. The ZrB2 films have a room-temperature tensile strength in excess of 1.2 GPa, far exceeding the tensile strength of bulk ZrB2, but their stiffness is lower and decreases significantly with increasing temperature. The reduction in stiffness is attributed to the presence of the amorphous phase and the high density of transverse grain boundaries in the crystalline region. The fracture toughness of the ZrB2 films was measured by introducing pre-cracks in the tensile specimens with a focused ion beam, and was found to be 2.57 ± 0.03 MPa√m, similar to values reported for bulk ZrB2.

New generation ultrahigh strength boron steel for automotive hot stamping technologies

The automotive industry is under increasing pressure to: (1) reduce the weight of vehicles and (2) improve crash performance. ‘Hot stamped’ mild carbon–manganese–boron steel 22MnB5 has become common place in the body structure of the European vehicle over the past decade. The ultrahigh strength martensitic microstructure resulting from hot stamping (proof strength ∼1200 MPa and ultimate tensile strength ∼1500 MPa) enables down gauging while not compromising crash performance. However, with demands for yet higher strength in the final component so to enable further down gauging, novel grades must be developed. In this paper, development of the novel grade 38MnB5 was reported. Following hot stamping, 38MnB5 demonstrated proof strength in excess of 1400 MPa and ultimate tensile strength in excess of 2000 MPa. Owing to the immense strength, the novel grade 38MnB5 was considered to offer significant down gauging and weight reduction opportunities to the automotive industry.

TOUGHMET 2CX

Abstract ToughMet 2 CX is a Cu-9Ni-6Sn alloy that combines low coefficient of friction with wear resistance. ToughMet alloys are a line of spinodal hardened Cu-Ni antigalling alloys for bearings capable of performing with a variety of shafting materials and lubricants. The alloys combine a high lubricity with wear resistance in these severe loading conditions. ToughMet 2CX in the cast and spinodally hardened (CX) condition exhibits tensile strength in excess of 724 MPa (105 ksi) and hardness exceeding HRC 27 with excellent machinability. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: Cu-819. Producer or source: Materion Brush Performance Alloys.

Formation of polyamide 12 membranes via thermal–nonsolvent induced phase separation

AbstractThe thermal–nonsolvent induced phase separation method was used for the fabrication of porous membranes from polyamide 12 (PA12), an attractive engineering polymer; the water/formic acid (FA)/PA12 ternary system is explored in detail. Scanning electron microscopy, differential scanning calorimetry, X‐ray diffractometry, tensile strength analysis, and water flux were used to characterize the structure and properties of the fabricated membranes. The morphology of the membranes was found to depend on the FA content in the bath. The top surface of the membrane becomes less dense with increasing FA content in the bath. The cross section and bottom surface of all membranes exhibited a cellular morphology, except for the case of the novel procedure of dope precipitation in a cold neat solvent (FA) bath. In all cases membranes exhibited a crystallinity of ca. 38% with a melting point of ca. 179°C; tensile strengths in excess of 10 MPa were found possible in some cases. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of processing variables on production of powder metallurgical titanium

Hydride/dehydride titanium powder has been processed using a conventional die compaction powder metallurgical approach. The effects of various processing parameters have been assessed in terms of the microstructure and mechanical behaviour, including lubricant type and amount, compaction pressure, delubrication atmosphere, and sintering conditions. While low lubricant contents can result in high sintered densities, a minimum lubricant content is required to maintain die life. It was also demonstrated that a compaction pressure of 300 MPa is sufficient to provide high sintered densities, while again minimising potential for die damage. Densities close to 99% of theoretical could be achieved when sintering at 1450°C for 4 h. Tensile strengths in excess of 750 MPa were obtained when sintering at 1300 or 1400°C. The mechanical behaviour was strongly influenced by a combination of intrinsic powder impurities (i.e. oxygen), residual carbon contamination from the lubricant, grain growth and retained porosity.On a traité de la poudre d’hydrure/dé-hydrure de titane en utilisant une approche métallurgique conventionnelle de compaction de la poudre en matrice. On a évalué l’effet des divers paramètres de traitement sur la microstructure et sur le comportement mécanique, incluant le type et la quantité de lubrifiant, la pression de compaction, l’atmosphère de délubrification et les conditions de frittage. Bien que de faibles teneurs en lubrifiant puissent résulter en de hautes densités de frittage, une teneur minimale en lubrifiant est requise pour assurer la survie de la matrice. On a également démontré qu’une pression de compaction de 300 MPa était suffisante pour atteindre de hautes densités de frittage, tout en minimisant encore une fois le potentiel d’endommagement de la matrice. On pouvait obtenir des densités de près de 99% de la valeur théorique lorsque le frittage était effectué à 1450°C pendant 4 heures. On a obtenu des valeurs de résistance à la traction de plus de 750 MPa lorsque le frittage était effectué à 1300 ou à 1400°C. Le comportement mécanique était fortement influencé par une combinaison des impuretés intrinsèques de la poudre (i.e. oxygène), de la contamination de carbone résiduel du lubrifiant, de la croissance de grain et de la porosité retenue.

Cellulose nanofiber-based hydrogels with high mechanical strength

The preparation of high-strength hydrogels from plant-based cellulose nanofibers by simple alkaline treatment is described herein. We isolated the cellulose nanofibers with a uniform width of approximately 15 nm from wood and we prepared two types of hydrogel sheet with different crystal forms (celluloses I and II) in 9 and 15 wt% aqueous sodium hydroxide solutions. Both of the hydrogels exhibited high tensile properties because of the crystalline network in the gels. Especially, the nanofiber hydrogel with a cellulose II crystal structure with the swelling degree of 13.4 achieved a Young’s modulus and tensile strength in excess of 35 and 5 MPa respectively, because it had a continuous and strong nano-network formed via the interdigitation of the neighboring nanofibers during mercerization.

The Ultimate Strength of Glass Silica Nanowires

In the past decade nanowires have attracted an increase interest because of their extraordinary mechanical strength. In fact, material properties in the nanoregime are extremely different from those found in macroscopic samples: few crystalline materials have shown a tensile strength in excess of 10 GPa in the form of nanowires. Still the length of defect-free crystalline nanowires is limited to a few millimeters and the strength of long nanowires is compromised by defects. The strength of glass nanowires is less affected by single defects. In this paper we present the ultimate strength of glass silica nanowires manufactured by a top-down fabrication technique; this is the highest value reported for glass materials. The measured ultimate strength is in excess of 10 GPa and increases for decreasing nanowire diameters. Scanning electron micrographs of the broken fragments showed a fragile rupture.