Search

Dual layer cement-based absorber is synthesized by mixing with graphene nanosheets and manganese-zinc ferrite, to study the effect of absorbing filler content on the mechanical properties, microstructure, electrical resistivity and reflectivity of the paste. The microstructure of the absorber is seen by Scanning Electron Microscope (SEM) images, Fourier Transform Infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD) curves of the absorber. The results show that graphene nanosheets significantly reduce the electrical resistivity of paste, increasing its mechanical properties by improving its pore structure. SEM images indicate that graphene nanosheets promote the increase and coarsening of cement hydration products and produce a large number of dense bulk crystals. Furthermore, reflectivity measurements show that the minimum reflectivity of - 14.1 dB is obtained in the range of 2 ~ 18 GHz and the effective bandwidth of 16 GHz is obtained when reflectivity is less than - 7 dB. This study provides a new method for the preparation of dual layer cement-based absorber. [ABSTRACT FROM AUTHOR]

A novel natural fiber derived from the Cymbopogan citratus plant was investigated for the first time. The characterization of the C. citratus fibers was conducted, and the chemical composition and physical, thermal, mechanical, crystallinity, and morphological characteristics were studied. The chemical composition analysis of Cymbopogan citratus fiber revealed that the suggested fiber was rich in cellulose contents (37.6%). The tensile test of C. citratus fiber demonstrated the fiber’s average tensile strength of 43.81 ± 15.27 MPa and modulus of elasticity of 1.046 ± 0.33 GPa. Further analysis with X-ray diffraction (XRD) confirmed that the crystallinity index of Cymbopogan citratus fiber was 35.2%, and the crystalline size was estimated as 4.28 nm. The Cymbopogan citratus fiber’s thermal stability was investigated via thermogravimetric analysis (TGA) and observed to be thermally stable (230 °C). A morphological investigation was employed on the fiber via a scanning electron microscope (SEM). The morphological study result exhibited that the fiber had a perforated and rough surface with the lumen in the center. Thus, the findings revealed that the Cymbopogan citratus fiber was a promising potential reinforcement for thermoplastic green composite applications. [ABSTRACT FROM AUTHOR]

Graphene-based nanomaterials possess broad applications because of their excellent multi-functional properties. In this work, a facile self-assembling method was presented for preparing one kind of graphene oxide-based paper/hollow microspheres hybrid. It was found that most of the hollow microspheres can strongly anchored on the surface of graphene oxide paper (GOP) by an in-situ scanning electron microscope peeling testing combining with molecular dynamics (MD) simulation. In addition, the uniform distribution of hollow microspheres on the surface of GOP cannot only provide a better surface wettability, but also can effectively improve the interfacial stress-transfer capability between such hybrid and polymer matrix. Our work provides a guidance for the structural designs of graphene-based nanomaterials and broaden their applications. [Display omitted] [ABSTRACT FROM AUTHOR]

This work investigates the effect of different loading of copper alumina nanoparticles (Cu‐Al2O3) on the processing characteristics, crystalline, morphological, mechanical, and thermal properties of natural rubber (NR). The effective reinforcement of Cu‐Al2O3 nanoparticles into NR was carried out using a simple and efficient two roll mill mixing technique and the structural changes were systematically analyzed by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscope (SEM), high‐resolution transmission electron microscope (HR‐TEM), differential scanning calorimetry, and thermogravimetric analysis. The FTIR and XRD of NR/Cu‐Al2O3 showed the characteristic absorption bands and the crystalline peaks of Cu‐Al2O3 in the prepared composites. SEM and HR‐TEM showed the uniform distribution of nano Cu‐Al2O3 in the NR matrix. The processing time of the nanocomposites was significantly decreased with the addition of metal oxide nanoparticles, which indicated the reduction in the cost of the fabrication of elastomer product using Cu‐Al2O3 nanoparticles. Mechanical properties such as modulus, tensile strength, hardness, heat build‐up, glass transition temperature, tear properties, abrasion, and thermal stability were greatly enhanced by the reinforcement of Cu‐Al2O3 into the NR matrix. The swelling behavior of composite with respect to different loading of nano‐filler was also investigated in various aromatic solvents. The addition of nanoparticles reduces the solvent uptake of the composite and the maximum solvent resistance was noted for the composite with 5 phr loading. [ABSTRACT FROM AUTHOR]

The presence of a secondary phase between the fibres and the matrix has proved to be a good approach for interphase tailoring for enhanced load transfer. In this regard, an optimization of the low-temperature hydrothermal growth process of ZnO-nanorods on different basalt substrates as a function of different growth times was performed. Scanning electron microscope and X-ray diffraction analysis revealed the best results in terms of homogeneity and uniformity of the ZnO nanostructures for the longest growth time, i.e., 5 h for basalt fabrics and 120 minutes for single basalt fibres. The presence of ZnO nanostructures induced a hydrophobic behaviour with contact angles up to 116° for 4- and 5-h growth processes. Fibre/matrix adhesion was characterized by single fibre pull-out tests, showing a 16% increase in interfacial strength. ZnOs added also photocatalytic properties to basalt fibres, enabling a selective removal of organic pollutant equal to 37%. [ABSTRACT FROM AUTHOR]

Conductive carbon black Super-P (CSP) is a kind of nanomaterial, which is often used as conductive agent. It has excellent conductivity and low production cost. In this paper, CSP was used as the admixture to prepare composite mortar (with the specific gravity of cementitious material). The consistency, mechanical properties, electrical conductivity and temperature sensitivity of composite mortar were studied. The mechanism of CSP was analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the consistency of composite mortar decreases with the addition of CSP. The mechanical properties of composite mortar first increase and then decrease with the increase of CSP content. The addition of CSP greatly improves the conductivity of mortar. When the CSP content is 0.5–2%, the resistivity decreases rapidly and the seepage threshold appears. When the content of the mixture is large, the influence of different curing conditions on resistivity is small. SEM and XRD analysis show that CSP can fill micro pores and conduct electricity through tunnels, and does not change the composition of hydration products of composite mortar, and the formation of calcium hydroxide can be inhibited when the content is small. This paper explores the properties of CSP composite mortar, which provides theoretical and experimental basis for the preparation and application of conductive mortar. In this paper, conductive carbon black Super-P (CSP) was added into the mortar as an admixture to prepare composite mortar. It is found that when the CSP content was 0.5–2% of the cement quality, the seepage threshold appears and the temperature sensitivity decreases. [ABSTRACT FROM AUTHOR]

The effects of tempering temperatures on microstructure and mechanical properties of the on-line quenched Q690q bridge steel were investigated through optical and scanning electron microscopes and tensile tests. The results show that the microstructure of the on-line quenched steel is primarily the lath bainite. After tempering at 540~650℃, the microstructure is the tempered sorbite. It is also found that with the increase of the tempering temperature, the lath width and the averaged grain size become larger, and the amounts of the carbide precipitations and large-angle grain boundaries increase. Meanwhile, with the tempering temperature increasing, the strength of the tested steel trends to be decreased, in contrast to the plasticity and toughness. At 620℃, the tested steels have the best mechanical properties, in which the yield and tensile strengths are 878 MPa and 992 MPa, the percentage elongation after fracture is 20%, and the impact absorption energy at -40℃ is 143 J. [ABSTRACT FROM AUTHOR]

Spark Plasma Sintering (SPS) is identified as a suitable technique to prepare the alumina titanium carbide composite to overcome the difficulty in fabricating it through other consolidation method. The present work focuses on the fabrication and characterization of a series of titanium carbide reinforced alumina ceramic composites using a spark plasma sintering process. The titanium carbide reinforcement on the alumina matrix is varied between 20 and 35 wt.%, in order to improve the electrical conductivity and fracture toughness of the composites. The particle size of the starting powders at received and ball milled conditions was analysed through Particle size analyser and Scanning Electron Microscope (SEM). Microstructural analysis revealed that the TiC reinforcement is uniformly dispersed in the sintered composite. XRD report showed that a-alumina and titanium carbide were the two dominant phases without the formation of any reaction phases. Further, the correlation between mechanical and physical properties of the prepared composite was investigated as a function of TiC. Various fracture toughening indicators like crack deflection, bridging and branching were analysed by Vicker's indentation method. Electrical resistivity of the sintered compact decreases proportionally with the increase in titanium carbide constituents. Maximum density (98.80%) and hardness (20.56 GPa) was obtained for 30 wt. % reinforced composite. Almost 40% improvement in fracture toughness is noted for 25 wt. % reinforced composite. This work demonstrates the synthesis and fabrication of alumina titanium carbide composites at low temperature via SPS resulted in obtaining an intact compact with improved mechanical and electrical properties. [ABSTRACT FROM AUTHOR]

Bamboo (Arundinaria clarkei) short fibers were treated with 6% conc. NaoH solution for five different durations viz. 3 h, 6 h, 9 h, 12 h and 24 h. Effect on physical properties like diameter and density were studied. Fibers were examined using Scanning Electron Microscope (SEM) to study the effect of alkali treatment on its surface characteristics. Single fiber tensile tests were conducted to assess the tensile strength of the fibers. Comparative study of the SEM micrographs indicated removal of outer layer with the surface irregularities becoming more prominent with increasing duration. The fiber surface was scanned using an Atomic Force Microscope (AFM) to quantify the increase in surface roughness with alkali treatment. Tests results showed positive effect on the strength till 6 h beyond which the tensile strength was observed to reduce. Fourier Transform Infrared (FTIR) spectroscopy results indicated reduction in content of holocellulose along with hemicellulose, lignin and cellulose which explains the variation in tensile strength with increasing duration of treatment. [ABSTRACT FROM AUTHOR]

A 3D architecture carbon fiber preform, specifically fine‐woven cloth and punctured felt preform, is used to manufacture a novel advanced Cf/C‐SiC‐ZrC composite. The composite matrix is produced by chemical vapor infiltration (CVI) plus precursor infiltration and pyrolysis (PIP) process and finalized by using a chemical vapor deposition (CVD) of SiC coating to make the final density of the material reach 1.95 g/cm3. The organic precursors of SiC and ZrC have a weight ratio of 4:1 in a xylene solute. The composite mechanical properties, such as tensile, compression, bending, shear, and Z‐direction load bearing, are introduced under analysis to find possible applications for the composite. What is more, scanning electron microscope (SEM) images are employed to illustrate the failure behavior of the ceramic composite. The results showed that the punctured filament tows will be beneficial, not only for the composite to withstand compression force up to 308.6 MPa and shear strength to 18.14 MPa but also for the alternatively stacked weave piles and short fiber layers to support the punctured bundles, as well as to hold the composite structure under mechanical forces from different orientations, which is believed to reinforce the ceramic matrix for some high pressure and severe ablation applications. [ABSTRACT FROM AUTHOR]

The hardness and toughness of regenerated cemented carbides, in general, are contradictory. Therefore, it is critical to explore regenerated cemented carbides with both high hardness and high toughness. In this study, regenerated WC‐8‐wt% Co cemented carbide with SiC nanowhisker were prepared by low‐pressure sintering. The influence of SiCw contents on the microstructure and mechanical properties of regenerated WC‐8‐wt% Co cemented carbide was investigated. The results indicated that the hardness, density, flexural strength, and fracture toughness of regenerated cemented carbide first increased and then decreased with the addition of SiCw. The Vickers hardness, density, flexural strength, and fracture toughness could reach 1575 HV, 14.6 g/cm3, 2204 MPa, 16.85 MPa·m1/2, respectively, with SiCw content 0.5 wt%, which were increased by 14.4%, 0.7%, 12.2%, and 17.3%, respectively, when compared with the regenerated cemented carbide without SiCw. The lowest friction coefficient and the best wear resistance could be also reached when 0.5‐wt% SiCw was added. The fracture mechanism of the regenerated cemented carbide contained both transgranular and intergranular fracture through the microscopic observation of fracture surface via scanning electron microscope. [ABSTRACT FROM AUTHOR]

Lattice structures are characterized by good mechanical efficiency because their particular geometry confers high strength and stiffness coupled to lightweight. These structures can be produced using a wide range of technologies, but the additive manufacturing ones are the most promising. In this work, the flexural properties of titanium alloy lattice structure made by means of electron beam melting process were investigated through the three‐point bending test, carried out with three different span lengths. It was found that the span length influenced the load–displacement trend; moreover, the lower skin failure was observed in all the test conditions considered, but for the shortest span, the indentation of upper skin was found, too. The scanning electron microscope analysis showed the presence of dimples on the fracture surface, denoting a ductile fracture behavior. [ABSTRACT FROM AUTHOR]

Dental fractures of the anterior teeth are a common form of dental trauma. Reattachment of fractured tooth fragment by means of self‐adhesive resin cement is currently compromised by the poor mechanical properties of these ceramics. Herein, we synthesized zirconium dioxide nanoparticles (nano‐ZrO2) using the Co‐precipitation approach and then mixing it in different concentrations (1.0, 2.0, 3.0, and 5.0 wt%) with the commercially available RelyX™ Unicem self‐adhesive universal resin cement (ARC) forming, nano‐ZrO2/ARC. Both the synthesized nano‐ZrO2 and nano‐ZrO2/ARC were characterized using a high‐resolution transmission electron microscope (HR‐TEM), field‐emission scanning electron microscope, X‐ray diffraction, and Fourier transform infrared technique. The HR‐TEM images revealed that the synthesized nano‐ZrO2 was spherical with a size of ~ 12 nm. The results showed that the addition of nano‐ZrO2 significantly enhanced the mechanical properties as fracture resistance, compressive strength, diametral tensile, and micro‐hardness values of the resin cement. The mixing 3.0 wt% of nano‐ZrO2 with ARC revealed the maximum improvement in the mechanical properties and, consequently, the resin's repair strength. Their incorporation with ARC up to 3.0% wt did not cause significant cell death than ARC alone. We believe that the information discussed here might be relevant to the stability of nano‐ZrO2‐modified resin cement and, therefore, to its clinical usage for fragment tooth reattachment, cementation of dental crowns, bridges, and bands. [ABSTRACT FROM AUTHOR]

The work deals with the fabrication of a joint between AZ31 magnesium alloy and AW-6060 aluminium alloy with the use of a Zn interlayer. The Zn layer was produced on the surface of an AW-6060 alloy insert by diffusion bonding. The insert was then placed inside a steel mould and kept at room temperature. The joint was produced using compound casting by filling the mould with liquid AZ31 alloy, heated to 650 °C. The microstructure of the bonding zone formed between joined alloys was analysed using an optical microscope and a scanning electron microscope equipped with an energy dispersive X-ray spectroscope. The properties of the joint were examined using Vickers microhardness measurements and simple shear strength testing. As a result of the experiment, the 400 μm thick bonding zone with a complex microstructure was formed between the alloys. The microstructural analysis showed that the bonding zone reveals a high concentration of Zn and Mg. The layers of a eutectoid (a MgZn phase + a solid solution of Al and Zn in Mg), a Mg5Al2Zn2 phase and a Mg(Al,Zn)2 phase with fine particles of other phases were observed there. The bonding zone was characterized by relatively high microhardness, which was related to the brittleness of the constituents. The shear strength of the examined joint was 19.6 ± 2.5 MPa. [ABSTRACT FROM AUTHOR]

The aim of the present study is to use microwave sintering technique to fabricate Al-Graphene oxide (Al-GO) composites with different concentration of GO (i.e. 0.5 wt %, 1 wt%, and 2 wt%) at 600°C for 15 min. X-ray diffraction (XRD) and scanning electron microscope (SEM) were utilized to investigate the microstructural development. Uniform dispersion of GO was obtained in Al-0.5GO composite whereas other concentration of Al-GO composites suffered from agglomeration of GO particles. In addition to microstructure, the hardness, compressive strength, and corrosion resistance of the Al-GO composites were also examined. A remarkable improvement in compressive strength (up to 200%) was attained in Al-0.5GO composite while further addition of GO deteriorated the mechanical strength and hardness due to agglomeration and increase of the microporosities. In spite of significant enhancement in compressive strength with optimum amount of GO nanoplatelets (i.e. 0.5%), the corrosion resistance of the Al-GO composites was degraded by the addition of GO nanoplatelets mainly due to the increased amount of microporosities and surface roughness originating from agglomeration of GO nanoplatelets. [ABSTRACT FROM AUTHOR]

Polyurethane/Graphite composite foam samples with different filler loadings were synthesized for application in electromagnetic shielding. The samples were characterized using Fourier transform infra‐red, thermal gravimetric analysis, scanning electron microscope, universal testing machine, and rheometer. Moreover, to adapt and customize this work in the field of aerospace, the measurements were performed in the X‐band at the range of (8–12) GHz. The results showed that the increase in filler content improves the mechanical properties and thermal stability of the composite materials. The electromagnetic interference shielding effectiveness reached (− 45) dB with 30 wt% filler content. It is expected that the polyurethane/graphite composite foamy materials may be considered a promising material to be used in electromagnetic shielding applications. [ABSTRACT FROM AUTHOR]

High‐performance composites reinforced with natural fibers are next‐generation structural materials due to their recyclability and light weight. Manufacturing composites with high strength has been a challenge. Here, we describe the manufacture of novel composites reinforced with wood fibers using densification by hot‐pressing and fixing by curing reaction with phenolic resin. This composite with 1.4 g/cm3 had high mechanical properties, high water stability, and aging‐resistance, and exhibited a flexural strength and internal bonding strength of 102.4 and 7.5 MPa, respectively. The strength and modulus are 1.5–6.0 and 1.3–28.1 times higher than those of most of the wood fibers reinforced composites. After immersing in water for 24 h, the water absorption and thickness swelling are only 1.3% and 0.8%, respectively. Scanning electron microscope characterization indicates that the cell wall is totally collapsed and became complete densification. And the collapsed cells are fixed by phenolic resin. This production strategy for the composites was shown to be universally effective for various species of natural fibers. These novel wood fiber‐reinforced composites were suitable for commercial manufacture in the current production line, making them a low cost and high‐performance alternative to automotive and aerospace industries. [ABSTRACT FROM AUTHOR]

The paper studies the structure and mechanical properties of the copper alloy based on a Cu–Al–Si–Mn system, produced by wire-feed electron-beam additive manufacturing (EBAM). Energy dispersive X-ray spectroscopy on the scanning electron microscope is carried out to investigate the microstructure and composition of the obtained copper alloy specimens. The tensile strength and microhardness of the alloy specimens are studied to determine its mechanical properties. It is shown that the structure of the manufactured material consists of the κ-phase dendrite grains and the γ-phase layers. According to static tension tests, the copper alloy possesses isotropic hardness and anisotropic ductility. Its hardness values also indicate the anisotropy of mechanical properties due to, mainly, a two-phase structure and nonuniform distribution of microhardness in the bulk of the Cu–Al–Si–Mn system-based copper alloy deposited using wire-fed EBAM. [ABSTRACT FROM AUTHOR]

Nanocomposites derived from poly(methyl methacrylate) (PMMA) and poly(ethylene‐co‐vinyl acetate) (EVA) with 30 wt% EVA and 0–10 wt% multi‐walled carbon nanotube (MWCNT) content were prepared. Scanning electron microscope images showed a two‐phase morphology for the unfilled blend in which the EVA droplets were dispersed within the PMMA domain. However, the size of EVA droplets was considerably smaller in the nanocomposites than that of the unfilled blend. The tensile results revealed that the maximum elastic modulus, tensile strength, yield stress, and strain at break were achieved for the nanocomposite containing 5 wt% MWCNT. The electrical conductivity sharply increased for the nanocomposite containing 2.5 wt% MWCNT, in comparison with that of the unfilled blend, beyond which the conductivity was less dependent on the MWCNT content. The rheological characterization showed that the normalized relaxation time increased up to 5 wt% nanofiller and remained reasonably constant for higher amounts of MWCNT. [ABSTRACT FROM AUTHOR]

This study investigated the effect of carbon black (CB) filler loading on mechanical and rheological properties of natural rubber (NR)/styrene-butadiene rubber (SBR)/nitrile butadiene rubber (NBR) ternary rubber nanocomposites. The nanocomposites were prepared using a melt mixing method. Four different samples with different filler loadings namely S2 (15 phr), S3 (30 phr), S4 (45 phr), and S5 (60 phr) were prepared in this work. The mechanical properties of these samples were investigated such as tensile strength, stress at 100, 200, and 300% elongations, elongation at break %, tear strength, compression set, compression stress, and crosslink density. Results indicate that minimum torque, maximum torque, tensile strength, stress at 100, 200, and 300% elongations, elongation at break %, tear strength, compression set, compression stress, and crosslink density were increased while the scorch time, cure time, cure rate index, elongation at break %, swelling coefficient, and filler–rubber interaction decrease with increasing CB loading. The higher value of tensile strength for these samples was S4 (loading with 45-phr CB). Therefore, had higher stiffness compared to the other content ratio. Additionally, S4 showed 233.58% increment in tensile strength. These results showed that the optimum filler loading can increase the compatibility between CB and NR/SBR/NBR. These results were confirmed by scanning electron microscope micrography. [ABSTRACT FROM AUTHOR]

Mechanical properties of vinyl ester hybrid composites reinforced with alkali treated Smilax zeylanica and sisal fibers were studied at wet condition in the present communication. Hybrid composites were fabricated by using a simple hand lay up technique based on three different fiber loading of 25, 35, and 45 wt.% with alkali treated fibers. Hybrid composite specimens were then subjected to the water absorption test to observe the behaviours of composite specimens at wet condition under mechanical loads such as tensile, flexural and impact. The water absorption test was carried out in two ways in the distilled water environment at room temperature. The first way test was conducted for 10 days to observe the percentage of water particle absorption of hybrid composites. The second way test was performed for 5 days to determine the mechanical properties of hybrid composites at wet condition to observe its durability when they are used in outdoor applications. Mechanical properties of hybrid composite specimens at wet conditions were compared with the dry composite specimens. Experimental results showed that the percentage of the water particle absorption in the alkali treated hybrid fiber composites is lower as compared to the untreated hybrid fiber composites. Mechanical properties of alkali treated hybrid fiber composites at wet condition are slightly reduced as compared to the treated hybrid fiber composite at dry condition. As a result, it is observed that the resistance to the penetration of the water particles is higher for the alkali treated smilax zeylanica and sisal fibers reinforced vinyl ester hybrid composites. The fracture surfaces of the hybrid composite specimens were examined by scanning electron microscope to understand the effects of water absorption on the mechanical properties. [ABSTRACT FROM AUTHOR]

The present work aims to study the effect of nano‐TiO2 modified epoxy on the tension, compression, and fracture toughness properties of nano‐doped polymer (NP) and nano‐doped 3D woven (NW) composites. Nanoparticles are dispersed into epoxy using high‐speed shear mixing and ultrasonication processes. Vacuum‐assisted resin infusion molding process is utilized to prepare the woven composites. The results indicate that nanoparticle addition can improve the tensile modulus and compressive strength of NP composites. The best improvement for fracture toughness of NP composites and compressive strength of NW composites appears at 8 wt% addition. No obvious changes are observed for tensile modulus and strength of NW composites in both warp and weft directions. However, the decreasing trend is observed for the tensile strength of NP composites. Scanning electron microscope images are observed to evaluate the failure mechanisms of the NP and NW composites. [ABSTRACT FROM AUTHOR]

To realize the application of xylan based film in food and drug packaging, the poor mechanical property and film-forming property of xylan based film must be overcome. Herein, a good oxygen barrier composite film with desired mechanical properties was prepared based on carboxymethly xylan (CMX), chitosan (CS), and graphene oxide (GO). The results of scanning electron microscope revealed the composite film had a dense and continuous structure, which will endow the composite film with excellent mechanical property. As expected, the composite film with the 0.5% mass fraction of GO exhibited best mechanical property, among which the tensile stress, tensile strain, and Young's modulus of the composite film reached 50.81 MPa, 47.61%, and 1.39 GPa, respectively. The oxygen barrier properties of the composite films significantly increased with the addition of graphene oxide due to the dense, stacked multilayer structure. In addition, these composite films exhibited good antibacterial properties. Therefore, these films show great promise in the field of food packaging and wound dressing due to their excellent mechanical, oxygen barrier and antibacterial properties. • Flexible composite films based on CMX, CS, and GO prepared by casting method. • Desired mechanical properties of the composite films were obtained by adding GO. • The composite films exhibit good oxygen barrier and antibacterial properties. [ABSTRACT FROM AUTHOR]

During the selection of materials for anti-lithium ion corrosion, magnesium aluminate spinel has been found to have good corrosion resistance and low cost. During the preparation of light-weight spinel ceramics, it is considered to be kiln body material. In this work, spinel bubbles were prepared using electrofusion injection process. Bulk density, volume density and pressure resistance of spinel bubbles in different particle sizes were counted. Light-weight spinel bubble ceramics with different densities were prepared by using electrofused spinel bubbles as light aggregates and using ρ-Al 2 O 3 and caustic burnt magnesia powder as matrix powders. The microstructure of spinel bubbles with different particle sizes and light spinel ceramics was analyzed using scanning electron microscope. Results show that the spinel bubble has complete structure, good sphericity, perfect grain crystallization, and clear edges and corners. Although there are some fine cracks and cavities, grains are tightly bound. Compressive strength and bending strength of light-weight spinel ceramics, whose density were found to lie within the range of 0.99–1.63 g cm−3, were found to be 5.19–36.33 MPa and 3.48–12.84 MPa, respectively. [ABSTRACT FROM AUTHOR]

A hybrid composite material was obtained by stacking carbon fiber reinforced plastic (CFRP) onto 7075‐W Al alloy sheet. Mechanical properties of the CFRP/Al hybrid composite material were measured by tensile and flexural tests. To investigate the flow of the epoxy, the thinning was measured using an optical microscope and the defects were observed by a scanning electron microscope. A finite element model was established to predict the thickness and the contact pressure distributions of the CFRP/Al hybrid composite material during the forming process. The results showed that the tensile strength (TS) of the CFRP/Al hybrid composite was increased by 10% and the fracture strain was increased by 24% compared with the single 7075 Al alloy. The flexural strength (FS) and the displacement of the loading nose were improved by 13% and 75%, respectively. According to the microstructure observation, large cracks in the epoxy could be found on the side wall of the U shape part. The results of numerical analysis indicated that the low contact pressure at side wall was the main reason for the decrease of the tensile and FS and the delamination between laminates. [ABSTRACT FROM AUTHOR]

This research focused on the fabrication of flame‐retardant green composites by utilizing inexpensive bio‐waste eggshell powder (ESP) as a flame‐retardant additive to polypropylene (PP)/abaca fibers (AF) composites (AF/ESP‐PP). The optimization of AF reinforcement in composites examines various wt% (5‐20) of fibers in the light of mechanical properties. Fifteen weight percentage of AF reinforcement showing the highest tensile (26 MPa) and flexural (46 MPa) strength compared to the remaining composites. Spectral (Fourier‐transform infrared spectroscopy) and micro (scanning electron microscope) analysis support the improvement of mechanical strength of the composites in connection with the interaction between AF with PP. Besides, different wt% (2, 4, 6, and 8) of ESP were incorporated into the AF/PP composites and examine the thermal and flame‐retardant properties by thermogravimetric analysis, horizontal burn test, and microcalorimetry, respectively. An improvement in thermal stability 9.82 wt% at 700°C, horizontal burn test results and decrement in peak heat release rate to 947 W/g. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of autogenous healing capacity with the addition of expansive and crystalline agents on mechanical and fracture behaviors of fiber-reinforced (FR) mortar specimens with crack mouth opening displacement (CMOD) controlled test set-up. The experimental results of a self-healing approach of FR mortar were analyzed in terms of first cracking peak load (FCPL) increase, index of fracture toughness recovery (IFTR), and index of fracture energy recovery (IFER). Initially, the specimens were pre-cracked at different crack widths ranging from 30 μm to 200 μm after 28-days of curing. After pre-cracking, the specimens were kept in water for 56- and 120-day healing. A controlled three-point bending test (PBT) was applied on prism specimen having a central notch of 40 mm depth for pre-cracking as well as the post-conditioning stage for determining the FCPL. However, the crack surfaces were monitored by a high-range digital microscope and scanning electron microscope (SEM) to examine the nature of healed products near the damaged area. Test results revealed that a significant recovery of small cracks (≤50 μm) could be achieved for self-healing specimens by using healing agents (HA), while for large cracks (≥100 μm) partial recovery could be achieved after the 120-day healing period. [ABSTRACT FROM AUTHOR]

In recent times, polymer composites have played an epochal role in transforming material science. Some of their properties such as toughness, strength, flexibility and rigidity have helped them supplant conventional materials such as iron, steel, and aluminium on several occasions. Apart from this, they are light in weight and more cost-efficient, which make them a viable alternative. They have found their application in several fields such as automobile industry, aerospace industry, construction and pipeline industry. Owing to its excellent impact strength, tensile and hardness, natural fibres serve as an excellent replacement. Natural fibres are an environmental friendly, biodegradable and are readily available. The present investigation uses a new fibre for manufacturing the eco-friendly composite material. Mechanical properties such as tensile strength, shear stress, flexural rigidity, impact strength and hardness of a coconut fibre-reinforced polymer composite material are evaluated as per respective ASTM standards. A surface analysis of the material using a scanning electron microscope is also performed. The results are categorized and tabulated accordingly. The values obtained appear to fall in line with the experimental data and hence can be espoused as an alternative material especially in the automotive sector. [ABSTRACT FROM AUTHOR]

In the present experimental investigation, titanium carbide (TiC) and red mud are reinforced with aluminium 7075 (Al7075) at 3, 6, 9 and 12 percentages by weight of matrix to produce a flat casting with the help of stir casting process. The mechanical properties such as yield strength, ultimate tensile strength, microhardness, and % elongation are tested and compared. The distribution pattern of the reinforced particles of the samples is studied through a Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) technique. Finally, the micrographs of the fractured surface reveal the features, namely dimples, cracks, voids, ridges and particle fracture that characterise the features of the fractured composite. The ultimate tensile strength of Al/TiC metal matrix composite (MMC) is increased by 48%, whereas a 71% decrease was observed with the addition of red mud. Further, the hardness is increased by 6%, and 62% with TiC and Red mud reinforced AMMCs. [ABSTRACT FROM AUTHOR]

Silicon carbon black (SiCB), a kind of biomass carbon material, is a kind of pyrolysis ash prepared by anoxic pyrolysis of rice husk. When filled as an inorganic reinforcement in the composite material basalt fiber (BF) reinforced polyamide 6 (PA6), it has synergetic effect with the POE‐g‐MAH elastomer. Differential scanning calorimetry analysis shows that KSiCB plays a role of heterogeneous nucleation in the composite material, accelerates the nucleation and crystallization speed of PA6, and can increase the strength and rigidity of the composite material. Scanning electron microscope observation of the fracture surface of the composite material shows that the addition of KSiCB can effectively "pin" and inhibit crack propagation. When the content of KSiCB is 2.5 phr, the tensile strength of the composite material KSiCB/POE‐g‐MAH/PA6(BF) reaches a maximum of 125.194 MPa, the tensile modulus is 2791.257 MPa, the bending strength reaches 192.034 MPa, and the impact toughness reaches 23.42 kJ/m2. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of stainless-steel AISI 304 wire mesh--reinforced AlSi9Cu-matrix composite specimens obtained by gravity casting were investigated. Optical and scanning electron microscope analyses were carried out on samples in both as-cast and solution heat treated conditions. The obtained results showed the absence of intermetallic phases at the insert/Al-matrix interface but even a significant fraction of lack-of-filling defects as well as lack-of-bonding areas that weekend the interface itself. The solution heat treatment, on the other hand, induced the precipitation of a thick and brittle intermetallic layer in the areas where a metallurgical bonding formed during casting. Moreover, the silicon particle spheroidization, improved the ductility of the matrix. The resulting microstructure allowed to obtain a slight improvement of elongation at failure of the compound casting compared to that of the aluminum alloy. Finally, basing on the obtained results, improvements are suggested that take into account both the preconditioning of the reinforcement surface and its geometry. [ABSTRACT FROM AUTHOR]

In this work, the properties of yttria-stabilized zirconia-based ceramics, Y-TZP containing Fe 2 O 3 as coloring agent were evaluated. Nanoparticled powder of 3Y-TZP (ZrO 2 - 3 mol.% Y 2 O 3) doped with different amounts of Fe 2 O 3 (0.002–0.136 wt%) were compacted into monolithical or multilayered samples and sintered at 1475 °C - 2 h. The samples were characterized by X-ray diffraction analysis (XRD), relative density, scanning electron microscope (SEM). Hardness and fracture toughness in the color interface were investigated using the Vickers indentation method and the biaxial flexural strength was determined by the piston on 3 balls method (P–3B). Furthermore, optical parameters were measured using spectrophotometry in regard to sample thickness and Fe 2 O 3 content. The results indicated a good adhesion between layers, proven by indentation cracks randomly growing between different regions, because the powders used produced very similar morphological characteristics. The different amounts of Fe 2 O 3 studied in this work did not interfere in densification, phase composition, or microstructure of the sintered ceramics. The fracture toughness and flexural strength did not significantly change due to the addition of Fe 2 O 3 , presenting values close to 7 MPa m1/2 and 1120–1150 MPa, respectively, in all studied compositions. On the other hand, increasing Fe 2 O 3 contents lead to an increase in the hardness of the material (1280–1330 H V), and higher contrast ratios (CR) with a consequent loss of translucency. Color variation (ΔE) depended also on the thickness of the material. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the effect of post-heat treatment and quenching on the hardness, coating thickness, morphology, wear, and microstructure of the coatings made on steel travelers. The test result shows that all the quenched samples have similar hardness. Wear tests of the specimens show that Type-I oil quenched specimens have better wear resistance compared to other specimens. Atomic force microscope results reveal that Type-I oil-quenched travelers have a smoother surface than water and air-cooled travelers. Scanning electron microscope images show that the distribution of plating on the substrate is not uniform. After baking, the coating becomes uniform. However, some small voids are present in the coating due to improper surface activation before the plating process. [ABSTRACT FROM AUTHOR]

In this research, the effect of siliconized chitosan biopolymeric particles and morinda fiber in epoxy composite and their mechanical and machining behavior were studied. The primary aim of this research was to investigate how the silane‐treatment influences the surfaces of natural biopolymeric particle and fiber in epoxy composite and to study the mechanical and machining behavior. The chitosan and morinda fibers were surface‐treated using an amino silane 3‐Aminopropyltrimethoxylane (APTMS) via aqueous solution method. The composites were prepared using the hand lay‐up method followed by post‐curing at 120οC. The mechanical results showed that the silane surface‐treated chitosan and morinda natural fiber‐reinforced epoxy composite gives improved tensile, flexural and impact results of 148 MPa, 163Mpa and 6.9 J respectively. The inter‐laminar shear strength of silane‐treated morinda fiber gave the highest value of 28 MPa. Similarly, in the drilling process, the surface‐treated reinforcements showed the highest adhesion with matrix without any delamination. The drilled hole dimension stability at the top and the bottom surface was significantly high for silane‐treated epoxy composites. The scanning electron microscope images revealed high adhesion of fiber and uniform dispersion of chitosan particle in the epoxy matrix. Hence, this study confirms that silane surface‐treatment is an essential process while making high‐performance natural composites for various engineering applications. [ABSTRACT FROM AUTHOR]

In this study, bamboo and glass fibers were successfully added into bisphenol A–aniline-based benzoxazine resin by hot pressing method. The effect of water absorption on the mechanical properties of the neat benzoxazine and its composites was studied. The composites prepared in this study has been proved to exhibit better water resistance than some conventional natural fiber/polymer composites due to good hydrophobicity of the benzoxazine matrix. From the mechanical tests, the tensile performance of both neat benzoxazine and the composites degraded seriously after prolonged immersion in water. However, neat benzoxazine and the composites maintained relatively higher residual flexural properties (residual mechanical properties refer to the ratio of strength and modulus of the saturated samples to that of the nonaged samples) after 20 days of water immersion. The effect of water molecules on the fracture surface morphologies of the composites was studied using a scanning electron microscope (SEM). The SEM images showed that the interfacial bonding between fibers and the matrix degraded seriously due to the attack of water. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the mechanical (tensile, hardness, impact, elongation), microstructure and wear behaviours of aluminium alloy reinforced with mussel shell powder (MSP) at different weight percentages (0 wt. % to 15 wt. %) at 3 wt. % interval. The mussel shell powder was characterized by X-ray fluorescence (XRF). The matrix and the composites' morphology were studied using a scanning electron microscope attached with energy dispersive spectroscopy for the distribution of mussel shell powder particles within the matrix. The wear behaviour of the alloy and composites produced at various reinforcements were carried out using a Taber abrasion wear-testing machine. The XRF showed the compositions of MSP to contain calcium oxide (95.70 %), silica (0.83 %) and others. Mechanical properties showed that tensile values increase with increases in MSP, hardness value increases from 6 wt. % to 15 wt. % of MSP. The impact energy decreased from 42.6 J at 3 wt. % to 22.6 J at 15 wt. %; the percentage elongation also decreased from 37.4 % at 3 wt. % to 20.5 % at 15 wt. % MSP, respectively. The bending stress results increase with increases in the percentage of reinforcement. The morphologies revealed that uniform distribution of MSP within the matrix resulted to improvement in mechanical properties. The wear resistance of the composites increases with increase in the applied load and decreases with increases in the weight percentage of MSP and can be used in the production of brake pads and insulators in the automobile industry. [ABSTRACT FROM AUTHOR]

Dynamic mechanical properties of the selected laser melting (SLM)-NiCrFeCoMo 0.2 high-entropy alloy (HEA) are further improved by controlling the molten pool structure and the generation of σ-phase precipitation particles. In this study, a split Hopkinson pressure bar (SHPB) was used for testing the dynamical mechanical properties of the quenched SLM-NiCrFeCoMo 0.2 HEA specimens. Microstructure and volume fraction of the σ precipitates were characterized by X-ray diffractometry (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and the small angle neutron scattering (SANS) technique. After heating to 800 ℃, holding for 8 h and water quenching, the molten pool boundary of the SLM-NiCrFeCoMo 0.2 HEA disappear, and the ultimate compressive strength and the impact energy of specimens reach 1970 MPa and of 217.45 MJ·m−3, respectively. Due to the segregation of Mo elements in the molten-pool boundary of the as-build SLM-NiCrFeCoMo 0.2 HEA, more σ precipitates tend to form at the residual molten pool boundary of the quenched SLM-NiCrFeCoMo 0.2 HEA. The σ precipitates play key role in strengthening of the SLM-NiCrFeCoMo 0.2 HEA. • Annealed SLM- NiCrFeCoMo 0.2 HEA has larger ultimate compressive strength and the impact energy. • Lots of σ precipitates generate at the residual molten pool boundary. • Small angle neutron scattering technique is used to analyze the volume fraction of σ precipitates. • The σ precipitates play key role in strengthening of the SLM-NiCrFeCoMo 0.2 HEA. [ABSTRACT FROM AUTHOR]

In this study, an effort was made to enhance the mechanical properties of coal-based synthetic natural gas slag (CSNGS) geopolymer with curing at ambient temperature by incorporating ground granulated blast furnace slag (GBFS). The effects of GBFS content, activator modulus and alkali content on the compressive strength of CSNGS-GBFS (CG) geopolymers were analyzed, and the microstructural characteristics and the compositional evolution of reaction products were also investigated by X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometer (SEM/EDS), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analyzer (TG) tests. It was found that the mechanical properties of CG geopolymers was highly dependent on the of GBFS content. When the GBFS content was 50%, the 1-day and 28-day strengths of the geopolymer were 50.8 MPa and 120.2 MPa, respectively. Increasing alkali content resulted in the strength of geopolymer to increase and then decrease, whereas, the strength of geopolymer increased monotonically with a decrease in activator modulus. The results also showed that with increasing the GBFS contents, the characteristic peaks corresponding to the gels in the XRD patterns became gradually obvious with highly denser microstructures formed by a number of gels in the SEM micrographs, and the Ca/Si ratio and Ca/(Si + Al) ratio of the reaction products were increased, revealing that the gels generated in CG geopolymers was a mixture of N-A-S-H and C-(A)-S-H gels, which corroborated with the observed the stretching vibration of Si–O-T (T = Si or Al) in FT-IR spectrum shifted from 1013 cm−1 to 990 cm−1 and the corresponding temperatures of the mass loss peaks increased form 104 °C–114 °C. In addition, the dissolution of raw materials was promoted owing to the reduction of the activator modulus, but the change of activator modulus had little effect on the thermal stability of the gels. These findings suggest that CSNGS has the potential to prepare high-strength geopolymers at ambient temperature, providing an attractive avenue for reducing the environmental impact of CSNGS and conserving natural resources. [Display omitted] • A novel high-strength geopolymer based on CSNGS was developed at ambient temperature. • The effect of BGFS on the structure of N-A-S-H and C-(A)-S-H gels in geopolymerization was studied. • The thermal stability of geopolymer was improved due to the increase of the alkali content. • The influence of activator modulus on the internal structure of geopolymeric gels was discussed. [ABSTRACT FROM AUTHOR]

Microstructural characteristics and enhanced mechanical properties of 2024 aluminum alloy associated with shot-peening treatment were investigated by optical microscope (OM), scanning electron microscope (SEM), electron backscatter diffraction technology (EBSD), X-ray diffraction (XRD) and tensile test. The results showed that the shot-peening treatment induces a severe plastic deformation within the surface area of alloys and the depth of the affected area caused by the shot-peening treatment is measured to be 600 ± 20 μm. Within the affected area, the formation of twins, curved grain boundaries and the fragmentations of grains were detected. In addition, the microstrain of the shot-peened surface increased to 0.5769% (±0.00215) from 0.2181% (±0.01084) after the shot-peening treatment. Correspondingly, the yield strength, the tensile strength and the uniform elongation were improved to 410.3 MPa (increased by about 11%), 519.4 MPa (increased by about 15.8%) and 19.7% (increased by about 81%), respectively, after the shot-peening treatment. Microstructural characteristics and the variation of microstrain within the affected area mainly account for the enhanced mechanical properties of the shot-peened 2024 aluminum alloys. The results of this work indicate that the shot-peening process is one of the effective ways to simultaneously improve the strength and ductility of alloys. • Enhanced mechanical properties of 2024 aluminum alloy were obtained by a shot-peening treatment. • Shot-peening treatment resulted in a significant affected area with a depth of about 600 μm. • Microstructural change and the variation of microstrain within the affected area mainly account for the enhanced mechanical properties. [ABSTRACT FROM AUTHOR]

• A simplified approach for optimized acid-mechanical treatment of RCA is developed. • The highest quality RCA is obtained through acid-mechanical treatment. • The compressive strength of RAC is obtained around 16.06% higher than NAC. • Other physical, mechanical, or durability properties of RAC are closer to NAC. • Sorptivity of RAC is obtained almost equal to that of NAC. Present research develops an optimized acid-mechanical treatment for recycled concrete aggregate (RCA). RCA prepared in the laboratory jaw crusher is further soaked for 24 h in a mild acetic acid solution. Acid-soaked recycled aggregates (SR) are mechanically treated at a series of charges and drum revolutions using Los Angeles machines. A performance-based quality identification approach is used to compare acid-mechanically treated recycled concrete aggregates (SRij). The VIKOR indices (QI) for each SRij is calculated by applying a multi-criteria decision-making approach. Based on performance, three SRij with the lowest QI are selected for an experimental study. The present research achieves 71.27 MPa compressive strength for concrete composed of a SRij with the lowest QI. This strength is around 16.06% higher than concrete composed of parent aggregate. Flexural strength, split tensile strength, fracture energy, ultrasonic pulse velocity (UPV) values, rapid-chloride penetration test (RCPT) values, water absorption, and abrasion resistance are in the range of what is expected for parent aggregate concrete. The scanning electron microscope (SEM) image analysis shows that the well compacted and uniform surface morphology of aggregate strengthens the newly developed interfacial transition zone (NITZ) and old interfacial transition zone (OITZ). Acid treatment reduces microcrack lengths and widths and mechanical treatment reduces microcracks and pores by reducing adherent mortar optimally. X-ray diffraction (XRD) analysis shows the lower calcium hydroxide (CH) content in the mortar attached to the SR. A reduced CH content lowers the porosity in the adhered mortar. Thus, improved quality of attached mortar and its reduced porosity strengthen the old interfacial transition zone (OITZ) and lowers the sorptivity of the concrete than reported and almost equal to that of parent aggregate concrete. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) allows for manufacturing intricate and accurate component designs that are challenging, expensive, or impossible to achieve using traditional methods. To achieve a high-quality final product with SLM, it is necessary to optimize the process parameters carefully. This optimization helps to minimize internal structural defects and control the microstructure. In this study, the optimum production parameters of Ti6Al4V alloy were determined using the Response Surface Method (RSM). The micro-CT analysis was utilized to calculate the relative densities of the samples fabricated using different production parameters. Furthermore, the influence of heat treatment, conducted below and above the β transformation temperature, on the mechanical properties was examined. The results were analyzed by considering the microstructure images obtained from Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. The optimum production parameters for the SLM method were found to be 80W laser power, 1125 mm/s scanning speed, 25 μm layer thickness, and 45 μm hatch distance. Samples created with these optimized parameters achieved 99.919% relative density, 1050 MPa ultimate tensile stress, and 13.8% elongation, surpassing the minimum standards outlined in ASTM F3001-14. Additionally, the systematic parameter reduction approach used in the study led to savings in both powder consumption and time in SLM, a method that could be applied to various metallic materials. • Ti6Al4V-ELI alloy was manufactured with selective laser melting method. • The response surface method was used to determine the optimum production parameters. • Micro-CT analysis was performed and density ratios were calculated. • Mechanical properties were improved with post processing operation. [ABSTRACT FROM AUTHOR]

Applicability of natural fiber-reinforced composites in automobile, aerospace like sectors has been increasing as more number of research works is concentrating on natural fibers owing to their eco-friendly nature. Biodegradability of natural fibers is main advantage of them over artificial fibers. Natural fiber-reinforced composite possesses good thermal and mechanical properties besides other requirements. For this reason, investigation of one such natural fiber-reinforced composites has been the focus of the present study. In the present work, composites made up of abutilon indicum fiber reinforced with epoxy have been prepared. Mechanical, morphological, thermal, and spectroscopic studies on the test specimens prepared using the above composites were carried out to evaluate their respective strengths. Also, the effect of alkali treatment (NaOH) for the fibers was studied and evaluated. Scanning electron microscope results indicated that the composite made up of alkali-treated fibers possessed better mechanical properties. Using differential thermal analysis–thermogravimetric analysis apparatus thermal behavior of the composites and using Fourier transform infrared spectroscopic studies, the presence of function groups like C–O, C–H was determined. Thus, characterization of abutilon indicum fiber-reinforced epoxy composites has been carried and properties are evaluated for their applicability to automotive, aerospace similar industries. [ABSTRACT FROM AUTHOR]

BACKGROUND: How to enhance the mechanical properties of the chitosan-based hydrogels has become a focus in the field of cartilage tissue engineering. In our previous research, chitosan was modified by citric acid, which led to significant improvement in the tensile and compression strength of the modified hydrogen in wet state. OBJECTIVE: To further enhance the mechanical perfonnance of the citric acid modified chitosan hydrogel (i.e., CC) using the cellulose fibers derived from the natural com husk fibers (CHFs), and to explore the potential of CHFs/CC composite hydrogel for cartilage tissue engineering scaffold. METHODS: A freeze-thawing method was employed to prepare CC and CHFs/CC (mass ratios of cellulose fiber to citric acid modified chltosan: 1 :1 and 2:1 ). The structure and mechanical properties of the prepared hydrogels were characterized. Rabbit chondrocytes were seeded onto the hydrogel surface, and the cytocompatibility of the prepared hydrogels was analyzed by live/dead cell staining, CCK-8 assay, and scanning electron microscopy. The ability of CHFs/CC composite hydrogels in promoting functional expression of chondrocytes was determined by collagen immunofluorescence staining and quantitative analysis of glycosaminoglycans. RESULTS AND CONCLUSION: (1) With the increase in CHFs loading fractions, the porosity, equilibrium swelling rate, and degradation rate of CHFs/CC composite hydrogels were gradually reduced, but the compressive strength and Young's modulus in dry and wet states were significantly enhanced. (2) Live/dead cell staining revealed that at 7 days of culture, chondrocytes proliferated well on the surface of three types of hydrogels. (3) The CCK-8 assay showed that with the increase in CHF loading fractions, the proliferative ability of chondrocytes on CC was gradually decreased. (4) Scanning electron microscope revealed that the chondrocytes on CC remained elliptic and were sparsely distributed, whereas most of the chondrocytes on CHFs/CC showed completely spread morphology. (5) After 28 days of culture, with the increase of CHFs loading fractions within CC, the chondrocytes showed gradually decreased expression of type I collagen, gradually increased expression of type II collagen, and there was no significant change in the content of glycosaminoglycans secreted. (6) These results demonstrate a great potential of the CHFs/CC composite hydrogels with good mechanical strength for cartilage tissue engineering scaffold. [ABSTRACT FROM AUTHOR]

Salt spray corrosion test was carried out on 6061 aluminum alloy, and quasi‐static tensile test at room temperature was carried out on the sample with universal testing machine. The effect of salt spray corrosion on the mechanical properties of 6061 aluminum alloy was studied by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electrochemistry. The corrosion rate of 6061 aluminum alloy was quantitatively characterized by different corrosion parameters. It was found that local corrosion of 6061 aluminum alloy occurred in salt spray environment, mainly pitting corrosion and intergranular corrosion. With the increase of corrosion time, the polarization resistance of 6061 aluminum alloy decreases, and the corrosion rate significantly increases. The average corrosion rate V‾d and the maximum corrosion rate Vdmax of 6061 aluminum alloy were characterized by corrosion weight loss and corrosion pit depth. And they can be transformed into each other. The mechanical properties of 6061 aluminum alloy were mainly affected by the depth of corrosion pit. With the increase of corrosion time, the tensile strength and fracture strain decreased, resulting in poor plasticity of the sample. At the same time, the change of elongation of 6061 aluminum alloy can be accurately predicted by the depth of corrosion pit. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to focus on the development of the three-dimensional (3D) printing filaments based on acrylonitrile butadiene styrene (ABS) copolymer and styrene-ethylene/butylene-styrene (SEBS) block copolymer, with tailored viscoelastic properties and controlled flow during the 3D printing process. Design/methodology/approach: In this investigation, ABS was blended with various amounts of SEBS via a melt mixing process. Then the ABS/SEBS filaments were prepared by a single-screw extruder and printed by the FDM method. The rheological properties were determined using an MCR 501 from Anton-Paar. The melt flow behavior of ABS/SEBS filaments was determined. The morphology of the filaments was studied by scanning electron microscope and the mechanical (tensile and impact) properties, surface roughness and void content of printed samples were investigated. Findings: The rheological results can accurately interpret what drives the morphology and mechanical properties' changes in the blends. The impact strength, toughness, elongation-at-break and anisotropy in mechanical properties of ABS samples were improved concurrently by adding 40 Wt.% of SEBS. The optimal tensile properties of blend containing 40 Wt.% SEBS samples were obtained at −45°/+45° raster angle, 0.05 mm layer thickness and XYZ build orientation. Optimized samples showed an 890% increase in elongation compared to neat ABS. Also, the impact strength of ABS samples showed a 60% improvement by adding 40 Wt.% SEBS. Originality/value: The paper simultaneously evaluates the effects of material composition and 3D printing parameters (layer thickness, raster angle and build orientation) on the rheology, morphology, mechanical properties and surface roughness. Also, a mechanical properties comparison between printed samples and their compression-molded counterpart was conducted. [ABSTRACT FROM AUTHOR]

The aim of this study is to simultaneously improve ultimate tensile strength, elongation, weld length and hardness of Al–Cu welded sheets by optimizing the electromagnetic welding parameters such as voltage, standoff distance and distance between spacers. Finite element analysis was conducted for the electromagnetic welding of Al–Cu sheets, and the results were used to predict the formation of weld. The experimental tests were then executed by response surface methodology in order to extract the regression models for predicting the optimal values of the parameters. The assessment of the weld quality was performed by observation of the microstructure of weld interface using the optical and scanning electron microscopes. The mechanical properties of Al–Cu weld were improved simultaneously using the desirable values of parameters as validated by confirmation experiments. It was also observed from the weld microstructure that the most important potential sources for reducing the weld length and weld strength are the high thickness intermetallic layers with micro-cracks and the entrapped oxides in the weld interface. [ABSTRACT FROM AUTHOR]

The present paper was aimed at understanding the effect of lath martensite submicrostructure quenched at different austenitizing temperature on the crack propagation behaviour. Different techniques were used to characterize the details of microstructure and submicrostructure. In‐situ tensile tests with scanning electron microscope were performed to observe the propagation of the crack. The results illustrated that packet size and block size increase almost linearly with the increasing austenitizing temperature. However, austenitizing temperature has no significant effect on the size of laths. Both of the packet size and the block size match the Hall–Petch relationship well with a correlation coefficient of 0.99. In macro tensile tests and in‐situ tension, the deflection angle of crack encountered with prior austenite grain boundary is higher than 60°, while it is lower than 90° for packet boundary and 60° for block boundary. The deflection angle of crack is relevant to the interface energy of the encountered boundaries. The interface energy of prior austenite grain boundary is higher than that of packet boundary because of the component difference, while the interface energy of packet boundary is higher than that of block boundary because of larger misorientation. [ABSTRACT FROM AUTHOR]

This research work is focused on development of epoxy based fiber metal laminate (FML) that comprised of multi‐walled carbon nano‐tube (MWCNT), glass fiber, and aluminum metal sheet. The hand layup technique was employed to fabricate the sandwich FML with different weight percentages (3, 4, and 5 wt%.) of MWCNT. The mechanical properties of the developed FMLs were determined through tensile, flexural, lap shear, and hardness tests following ASTM and IS standards. The scanning electron microscope (SEM) was used to characterize the failure mechanism of composites. The FML with MWCNT offered superior tensile and shear properties up to the addition of 4 wt%. The MWCNTs were found to be agglomerated in the epoxy when added more than 4 wt%. The FML's showed larger deformation before complete failure in shear mode with respect to the addition of MWCNTs. However, there was no considerable improvement recorded in the flexural and impact behavior of the FML composition. The addition of MWCNT fillers in the epoxy turned it more brittle and exhibited comparatively less deformation before failure in flexural mode. [ABSTRACT FROM AUTHOR]

Herein, direct aging (aged‐490 °C/6 h) and solution heat treatment and subsequent aging (SHT‐940 °C/2 h + 490 °C/6 h) heat treatments are applied to maraging steel (MS1) produced by direct metal laser sintering (DMLS) method. The effects of these heat treatments on microstructure, phase transformations, mechanical properties, and corrosion properties in MS1 are given in comparison with the as‐built state. Optical microscope (OM) and scanning electron microscope (SEM) is used for microstructure measurements, electron dispersion spectroscopy (EDX), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD) methods are used to determine the phase transformations. Potentiodynamic polarization tests are applied to determine the corrosion resistance of the material, and stereo OM and the Tafel extrapolation method is used to examine the corrosion results. The hardness test is carried out with a Rockwell C method to determine the mechanical character of the material. According to the results obtained, it is determined that the applied heat treatments affect the hardness and corrosion resistance of the material by changing the microstructure and phase transformations of MS1 material produced with DMLS. [ABSTRACT FROM AUTHOR]

Hybrid matrices (epoxidized of ethylene–propylene–diene monomer (eEPDM) -g- aminopropyltriethoxysilane (APTES)/hydroxyl terminated polydimethylsiloxane (HTPDMS)/polyurethane (PU)) were developed based on eEPDM with 3-APTES coupling agent and varying weight percentages (0.75, 1.50, 2.25, and 3.00 wt%) of PU prepolymer as coreactant using 7.5 wt% of HTPDMS as chain extender using suitable experimental conditions. The formation of hybrid matrices and their structure were characterized by Fourier transform infrared (FTIR). The thermal and morphological properties of the hybrid matrices were analyzed using differential scanning calorimetry and scanning electron microscope, respectively. Mechanical properties (tensile strength, elongation at break (%), Young's modulus, and hardness) were characterized as per ASTM standards. Data resulted from mechanical studies, it was noticed that the incorporation of 3-APTES, HTPDMS, and PU into eEPDM has improved the elongation at break (%) and lowered the values of tensile strength, Young's modulus, and hardness according to the percentage concentration. Morphological studies indicate the presence of heterogeneous morphology. Data obtained from different studies, it suggested that the hybrid matrices developed in the present work can be used as cable insulates for high-performance industrial and engineering applications. [ABSTRACT FROM AUTHOR]