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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]

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]

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]

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]

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]

ZnS‐reinforced ZnS/ZnSe composites are prepared by chemical vapor deposition. Scanning electron microscope, transmittance, and bending strength are used to characterize the samples. The schematic diagram of the transmittance model of the double‐layer composite window is used to calculate the theoretical transmittance, and the measured value of the transmittance of ZnS/ZnSe composite material is in good agreement with the calculated value. The effects of interface layer on the optical and mechanical properties of materials are studied in detail. It is found that the interface can affect the transmittance of the composites, but it still maintains a high transmittance, and the influence of interface layer on the transmittance of visible band is more serious than that of infrared band. Moreover, the mechanical properties of the new composite material are significantly improved (35%). [ABSTRACT FROM AUTHOR]

In this article, response surface methodology (RSM) has been applied to simultaneously optimize the tensile and impact strength of polypropylene (PP)/nitrile butadiene rubber (NBR)/halloysite nanotubes (HNTs)/maleic anhydride (MA)‐grafted‐PP nanocomposites. Three levels of material parameters, including NBR (10, 20, and 30 wt%), HNTs (1, 3, and 5 wt%), and PP‐g‐MA (3, 9, and 15 wt%) as compatibilizers were used to design the experiments according to Box‐Behnken design. In order to investigate the morphology of nanocomposite samples, a scanning electron microscope was used. The model predicted that both the tensile strength and impact strength of nanocomposite were peaked between middle and high levels of HNTs content. There was also a peak for NBR loading in the main effect plot of impact strength. Two‐way interactions of all parameters were significantly affecting both responses. Based on RSM models using the desirability function, the optimum values of input parameters leading to optimized tensile strength and impact strength were predicted to be 17.87, 4.35, and 15 wt% for NBR, HNT, and PP‐g‐MA, respectively. Confirmation experiments were in good agreement with the predicted values. [ABSTRACT FROM AUTHOR]

In the present study, the reinforcing effect of aluminum silicon carbide (Al‐SiC) nanoparticles and chemically treated nanocellulose fiber on thermomechanical and corrosion characteristics of polymer nanocomposites have been investigated. The experimental design was selected as per response surface methodology (RSM) to optimize the effect of Al‐SiC (1.59 to 18.41 wt%), nanocellulose fiber concentration (1.59 to 18.41 wt%) and sonication time (39.55 to 140.45 minutes). From the analysis of variance (ANOVA) results, it was found that the Al‐SiC, nanocellulose fiber concentration and sonication time played a significant role in the mechanical properties. In order to simultaneously maximize the flexural strength, the optimal values of nanocellulose fiber, Al‐SiC nanoparticles, and sonication time was found to be 5 wt%, 5 wt%, and 120 minutes, respectively. From the normal distribution plot, it is found that there is a good agreement between experimental results and developed RSM model. Addition of Al‐SiC (5 wt%) and nanocellulose fiber (5 wt%) in epoxy polymer improved the physical, mechanical, thermal and corrosion resistance properties. The scanning electron microscope analysis on Al‐SiC and nanocellulose fiber reinforced epoxy nanocomposites revealed uniform dispersion of nanocellulose fiber and Al‐SiC in the polymer matrix, which caused for the improved mechanical, and corrosion resistance characteristics. [ABSTRACT FROM AUTHOR]

The tensile, flexural, and morphological properties of Napier fiber reinforced nanomodified epoxy composites were investigated. Untreated and alkali‐treated Napier fibers, as well as nanoclay and epoxy resin, were used to fabricate Napier fiber reinforced nanomodified epoxy composites by using cold press compression machines. Napier fiber was treated with 5% dilute sodium hydroxide (NaOH) solution for 6 h. Varying amounts of nanoclay filler (3, 5, and 10 wt%) were mixed with the epoxy resin prior to fabricating the Napier fiber reinforced nanomodified epoxy composites. The results of mechanical testing indicated that the alkali‐treated Napier fiber reinforced nanomodified epoxy composites incorporating 5 wt% nanoclay exhibited the highest flexural and tensile properties. Morphological analysis was then conducted to further analyze the fractured specimens following the mechanical tests. The scanning electron microscope images of the Napier fiber reinforced nanomodified epoxy composites that contained 5 wt% nanoclay revealed good interfacial bonding between the matrix and the reinforcement. [ABSTRACT FROM AUTHOR]

The first aim of this study was to compare influences of various contents of the micro‐ (200 nm) and nano (50 nm)‐sized titania (TiO2) particles especially on the mechanical performance of the polylactide (PLA) biopolymer. Micro‐ and nano‐composites were prepared by twin‐screw extruder melt mixing, while the specimens were shaped by compression molding. Scanning electron microscope analyses and mechanical tests revealed that due to the most efficient uniform distribution in the matrix, the best improvements in the strength, elastic modulus, and fracture toughness values could be obtained either by using 5 wt% micro‐TiO2 or by only 2 wt% nano‐TiO2 particles. The second purpose of this study was to investigate influences of using maleic anhydride (MA)‐grafted copolymer (PLA‐g‐MA) compatibilization on the performance of one nanocomposite composition. Due to the improved chemical interfacial adhesion, use of PLA‐g‐MA compatibilization for the specimen of PLA/2 wt% n‐TiO2 composition resulted in the highest improvements in the mechanical performance of neat PLA. The improvements were 14% in tensile strength, 20% in flexural modulus, and as much as 67% in fracture toughness. Thermal behavior of all specimens was also observed by differential scanning calorimetry and thermogravimetric analyses. [ABSTRACT FROM AUTHOR]

In this study, a retrogression process (R) has been applied to AA7075 at 180, 240, and 370°C for 15, 30, 90, and 120 min. After the retrogression, reaging treatment (RA) was reapplied with T6 conditions (120°C for 24 hr). The effect of different temperatures and time periods of retrogression and reaging temper on exfoliation corrosion (EXCO) of the AA7075 is examined. The EXCO solution was prepared in accordance with the ASTM G34‐01 standard and the samples were kept in the solution for 48 hr. Susceptibility of the alloy to EXCO was determined by weight loss detection, macro and microstructure studies, scanning electron microscope, transmission electron microscope, and energy dispersive X‐ray analyses. The mechanical properties of aged samples were determined by hardness, tensile tests, and fractography. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the influence of surface treatments and artificial aging on surface roughness (Ra), phase transformation, and flexural strength of yttria‐stabilized tetragonal zirconia polycrystalline (Y‐TZP) ceramics. Two‐hundred and eighty specimens from four types of Y‐TZP were divided into seven groups, according to the surface treatments and aging used: control, air‐abrasion, air‐abrasion + aging, grinding, grinding + aging, erbium: yttrium‐aluminum‐garnet (Er:YAG) laser, Er:YAG laser + aging. The Ra values were measured using a profilometer. X‐ray diffraction (XRD) analysis was performed to determine phase transformation. Specimens were subjected to a three‐point bending test and loaded until fracture. Scanning electron microscope (SEM) and atomic force microscope (AFM) analyses were performed on one specimen per group. Grinding and air‐abrasion groups exhibited higher Ra values than the others (P < 0.05). The differences in the roughness and flexural strength values between the laser and control groups were not significant. For all materials, the highest amount of monoclinic phase was found after air‐abrasion. Grinding groups showed lower flexural strength values compared with the control groups (P < 0.05), while there was no significant difference between the control and air‐abrasion groups. Aging did not affect the roughness and flexural strength (P > 0.05). The grinding process is not recommended in clinical usage for Y‐TZP because of the remarkable decrease in flexural strength and reliability. [ABSTRACT FROM AUTHOR]

In this study, T651‐applied AA7075 alloy was subjected to retrogression and re‐aging (RRA) process. Various retrogression temperatures (180 °C, 280 °C, 370 °C) and times (15 min, 30 min, 90 min) were used to determine the effects of temperature and time on the mechanical and tribological properties of the AA7075 alloy. All re‐aging stages were performed at 120 °C for 24 hours. Retrogression and re‐aging‐applied specimens were characterized by scanning electron microscope, transmission electron microscope, x‐ray diffraction, Charpy V‐notch impact and tensile tests. Brinell hardness measurements and ball‐on‐disc type tribometer measurements by using AISI 316 ball as a counterpart have also been conducted. Grain boundary precipitates in the T651‐applied specimen was transformed from continuous to the discontinuous structure after retrogression and re‐aging process. Continuous MgZn2 precipitates at grain boundaries were disintegrated and re‐precipitated along the grain boundaries. The sizes of intragranular precipitates have become coarsened by comparison with the T651 condition. Hardness, tensile strength and wear resistance were decreased whereas impact toughness values were increased with increasing retrogression temperature and time. The best wear resistance was obtained in the sample treated at 180 °C for 15 minutes. [ABSTRACT FROM AUTHOR]

Scalable, bottom‐up chemical synthesis and electrospinning of novel Cl‐substituted poly(para‐phenylene terephthalamide) (PPTA) nanofibers are herein reported. To achieve Cl‐PPTA nanofibers, the chemical reaction between the monomers was precisely controlled, and dissolution of the polymer into solvent was tailored to enable anisotropic solution formation and sufficient entanglement molecular weight. Electrospinning processing parameters were studied to understand their effects on fiber formation and mat morphology and then optimized to yield consistently high quality fibers. Importantly, the control of relative humidity during the fiber formation process was found to be critical, likely because water promotes hydrogen bond formation between the PPTA chains. The fiber and mat morphologies resulting from different combinations of chemistry and spinning conditions were observed using scanning electron microscopy, and observations were used as inputs to the optimization process. Tensile properties of single Cl‐PPTA nanofibers were characterized for the first time using a nanomanipulator mounted inside a scanning electron microscope (SEM), and fiber moduli measuring up to 70 GPa, and strengths exceeding 1 GPa were achieved. Given the excellent mechanical properties measured for the nanofibers, this chemical synthesis procedure and electrospinning protocol appear to be a promising route for producing a new class of nanofibers with ultrahigh strength and stiffness. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 563–573 [ABSTRACT FROM AUTHOR]

Poly(N‐acryloyl glycinamide) (PNAGA)/poly(N‐isopropyl acrylamide) (PNIPAAm) interpenetrating network (IPN) hydrogels were made by UV‐light initiated radical polymerization in two‐steps. The IPN hydrogels showed a double thermoresponsive behavior due to the combination of PNIPAAm (thermophobic) and PNAGA (thermophilic) networks. Increasing the content of the thermophobic PNIPAAm network leads to a change from a broad thermophilic volume phase transition temperature of PNAGA to a thermophilic–thermophobic‐type dual transition for the prepared IPN. Due to the double thermoresponsive character of the IPN gels, the mechanical properties are dependent upon temperature as demonstrated by performing tensile tests in water at 15 and 50 °C. Furthermore, the IPN hydrogels were characterized using turbidity measurements, SEM, and the determination of the equilibrium swelling ratio. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 539–544 The preparation and properties of a strong double thermoresponsive interpenetrating network (IPN) consisting of PNAGA and PNIPAAm hydrogels are shown. The IPNs show mechanical as well as thermoresponsive properties dependent on the temperature and weight ratio of the two networks. [ABSTRACT FROM AUTHOR]

Mechanical and fatigue properties of heavy section solution–strengthened ferritic ductile iron (SSF‐DI) castings have been examined in this contribution. Amounts of silicon varying from 3.2 to 3.55 wt% have been used. The effect of antimony on counteracting the formation of chunky graphite has been evaluated. In order to estimate the influence of solidification defects (microshrinkage porosities or degenerated graphite particles) on the fatigue strength of the investigated materials, scanning electron microscope observations of the fracture surfaces and extreme value analysis of the crack initiating defect dimension, √area, have been performed. The propagation of the fatigue crack through the material has been observed by means of microstructural analysis of the cross sections of the fracture surfaces. It has been found that the treatment with Sb is useful to avoid the formation of degenerated graphite particles. Moreover, it has been observed that the most of the fatigue life is spent in the crack initiation stage, where the microshrinkage porosities play a major role. The presence of chunky graphite affects mostly the propagation stage. Finally, mechanical and fatigue properties of SSF‐DI have been compared with those obtained from traditional ductile cast iron specimens taken from the same casting geometry. [ABSTRACT FROM AUTHOR]

Abstract: In this work, TiN‐based cermets with excellent performance and uniform microstructure were successfully manufactured by conventional vacuum sintering with 0‐5 wt% carbon addition at 1500°C. Influence of carbon addition on the microstructure and mechanical properties of cermets was investigated by scanning electron microscope, transmission electron microscope, X‐Ray diffraction, electron probe microanalysis, and mechanical tests. The results showed that small amount of carbon helped to improve significantly the wettability between TiN and Ni/Co, leading to well‐distributed structure and perfect core‐rim phases. As the carbon content increased from 0 to 5 wt%, mechanical properties of cermets increased initially, displayed a maximum and then decreased. For the experimental conditions considered, the cermets with 3 wt% carbon addition revealed best mechanical properties. The relative density, the transverse rupture strength, fracture toughness, and Rockwell hardness of the cermets were 99.78%, 1836 MPa, 14.7 MPa m1/2, and 88, respectively. [ABSTRACT FROM AUTHOR]

In scanning electron microscope tensile testing was carried out to assess the mechanical properties and consequent failure characteristics of dissimilar weld consisting of low alloy steel and low nitrogen austenitic stainless steel. These transition joints find wide spread application in pressurized heavy water reactors. A number of premature failures have been reported in recent past during service exploitation of same joints. Thus, it becomes essential to identify the governing criteria resulting in such type of de-generation. In present endeavour, two types of joints were considered; one weld was fabricated by buttering with 309L stainless steel and the other one was made by buttering with IN82 Ni base alloys. From experimentation, weld strength was evaluated along with uncertainty analysis. Effect of various contributing factors over uncertainty was discussed. It was quantitatively shown that microstructural characteristics influenced more dominantly than physical parameters to the uncertainty of joint efficiency. [ABSTRACT FROM AUTHOR]

This paper aims at improving the mechanical properties of coir fiber reinforced polyester composites through impregnation of rice husk and boiled egg shell in polyester matrix. The composites sheets were manufactured by varying the fabrication parameters such as fiber length, particulate content and fiber content. The mechanical properties of the fabricated composites were determined as per ASTM standards and the effects of fiber length, particulate content and fiber content on mechanical properties of rice husk and boiled egg shells impregnated coir - polyester composites were studied. Scanning electron microscope analysis was used to characterize the fracture behavior of the composites. The investigation witnessed the improvement in mechanical properties on addition of rice husk particulate in coir fiber reinforced polyester composites. Similarly the addition of boiled egg shell in to the composites has enhanced mouldability of the composites. The SEM investigation evidenced the arrest of crack propagation and voids formation on addition of rice husk and egg shell particulates in polyester matrix. This study confirmed the possibility of using rice husk and boiled egg shell impregnated coir fiber reinforced polyester composites in low load bearing applications. [ABSTRACT FROM AUTHOR]

ABSTRACT The fatigue life of ZEK100 magnesium alloy in the phosphate buffered solution for various immersion intervals was investigated by experiments and theoretical predictions. The biodegradable behaviours of ZEK100 magnesium alloy were also studied. Microstructure observation showed that the corrosion behaviours were characterized by pitting corrosion. The corrosion rate decreased a lot in the initial 7 d and then almost stayed unchanged. After 28 d immersion, the elastic modulus almost kept stable, while the yield strength and the ultimate strength decreased a lot, which indicated that corrosion had important effects on the tensile mechanical properties. It showed that the fatigue life of the samples under the same stress conditions decreased with increasing immersion time under the asymmetric stress-controlled cyclic loading. Considering the effect of corrosion on the material failure, a modified fatigue life model was proposed for magnesium alloy under corrosion. [ABSTRACT FROM AUTHOR]