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The main goal of this study is to assess the mechanical, physical and morphological properties of bundle fibers extracted from curaua leaves and pullout testing in cementitious matrix. The mechanical properties of the fibers were analyzed in mechanical testing of four fiber lengths (10, 20, 30 and 40 mm) to observe the influence of the length of the variable's tensile strength, Young's modulus and Weibull modulus. Pullout testing was measured frictional and maximal force. Fibers physical properties were assessed by means of the multipycnometer method. Morphological analyses were conducted through optical and scanning electron microscopes. The results showed that the fiber length does not interfere with the tensile strength (507–638 MPa) and Weilbull modulus (8–12). However, it influences the Young's modulus (19–39 GPa). Curaua bundles present a higher resistance to rupture and Young's modulus than other plant fibers species and it seems to be related to the distribution of faults along the beam. The fibers morphological characterization showed a rough and irregular surface with some impurities which are associated with the surface of the fibrous bundle and low adherence (0,26–0,47 N) with cementitious matrix in pullout testing. [ABSTRACT FROM AUTHOR]

The study deals with the mechanical and thermal characterization of novel composite consisting of vetiver grass fiber (Chrysopogon zizanioides) (VF) and red mud (RM) as reinforcement in epoxy resin. Five types of composites were fabricated using hand lay-up technique by varying the weight percentage (wt%) of vetiver grass and red mud. Various mechanical properties like tensile strength, impact strength, and flexural strength of the said composites were evaluated and discussed. The thermal properties in terms of thermo gravimetric analysis (TGA) were evaluated whereas the chemical composition characteristics were analyzed using FTIR and XRD spectroscopy. The fractured surfaces of the tested specimens were studied using a scanning electron microscope. From the results, it was observed that properties of polymer composites were improved by hybridization with vetiver grass fibers and red mud. The improved mechanical properties of fiber-reinforced composites were noticed in increment of wt% of red mud. Highest tensile strength of 51.78 MPa, flexural strength of 35.92 MPa and impact strength of 29 KJ/m2 was obtained for C5 composite which contains highest wt% of red mud. TGA shows better resistance to thermal degradation for the composites containing higher percentage of red mud. Looking at the results it can be concluded that the developed composites in this work can be an efficient alternative for building and automotive application which requires high strength and thermal stability. [ABSTRACT FROM AUTHOR]

In this study, thermophysical and mechanical tests were conducted on sandstone samples from room temperature to 1000 °C. Based on the test results, the thermophysical properties (such as specific heat capacity, thermal conductivity, and thermal expansion coefficient) of sandstone after high-temperature treatment and the variations of mechanical properties (including peak strength, peak strain, elastic modulus, and whole stress-strain curve) with temperature were analyzed. Indeed, the deterioration law of sandstone after high-temperature treatment was also explored with the aid of a scanning electron microscope (SEM). The results show that with the increase in temperature, the specific heat capacity and thermal expansion coefficient of sandstone samples after high-temperature treatment increase first and then decrease, while the thermal conductivity gradually decreases. The range from room temperature to 1000 °C witnesses the following changes: As temperature rises, the peak strength of sandstone rises initially and falls subsequently; the elastic modulus drops; the peak strain increases at an accelerated rate. Temperature change has a significant effect on the deterioration rules of sandstone, and the increase in temperature contributes to the transition in the failure mode of sandstone from brittle failure to ductile failure. The experimental study on the thermophysical and mechanical properties of sandstone under the action of high temperature and overburden pressure has a guiding significance for the site selection and safety evaluation of UCG projects. [ABSTRACT FROM AUTHOR]

This paper is based on the basic mechanical properties and volume deformation test, as well as the characterization of hydration products and microstructure properties such as x-ray diffraction (XRD), scanning electron microscope (SEM), and mercury injection method (MIP). The effects of CO2 curing on the mechanical properties, hydration product composition, and microstructure of magnesium oxysulfate (MOS) cement were studied. The results show that the carbonation properties of MOS cement are closely related to the standard air curing age after demolding. The CO2 curing immediately after demolding is not conducive to the development of compressive strength of MOS cement, while the compressive strength of MOS cement in standard air curing for 14 or 28 days after demolding is increased during CO2 curing. The CO2 can prevent the continuous hydration of residual MgO to form Mg(OH)2 or 5·1·7 phase, which affects the development of the compressive strength of MOS cement. The appropriate addition of low-calcium fly ash (L-FA) can compensate the effect of CO2 on the mechanical properties of MOS cement. During CO2 curing, some Mg(OH)2 is transformed into an amorphous phase to increase the compactness of its microstructure and a small amount of Mg(OH)2 reacts with CO2 to form MgCO3·3H2O. The results provide an important theoretical and experimental foundation for the further study of the effects of CO2 on the properties of MOS cement and the use of CO2 curing modification. [ABSTRACT FROM AUTHOR]

The present work is focused on the influences of reinforced particles on mechanical, microstructural, and tribological performances of AA7075 hybrid metal–matrix composites (HMMCs). Al2O3 and coconut shell ash (CSA) were reinforced using two-stage stir casting by varying the wt% (0–5) of reinforcement. Microstructural analysis and various phase identifications were examined with the help of scanning electron microscope (SEM) equipped with EDX and optical microscope. Various mechanical testing such as tensile, hardness, 3-point bend test, and tribological behaviors were carried out to know the HMMCs properties. Microstructural images revealed a homogeneous distribution of reinforced particles in the metal–matrix and EDX confirmed the presence of dispersed reinforcements (Al2O3 and CSA) in the HMMCs. It was seen that mechanical properties and tribological behavior have been increased after addition of Al2O3 and CSA reinforced particles whereas slightly decreased in impact strength. Transgranular cleavage facets, micro-void coalescence, dimples, and crack were shown in SEM images of fractured specimens during impact and tensile testing. [ABSTRACT FROM AUTHOR]

The degree of the imidization reaction determines the properties of polyimide (PI) obtained by the thermal curing process. In this paper, amine‐modified graphene (N‐GO) was designed by integrating pyridine structure with graphene and acting as a catalyst to promote the imidization reaction of PI. Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) were then used to confirm the morphology and structure of N‐GO. The catalytic effect of N‐GO in imidization reaction was obtained by FTIR and subsequently characterized by differential scanning calorimetry (DSC) and water contact angle (WCA). Surprising results suggest that the agglomeration of N‐GO can also contribute to solid‐phase reactions in imidization reactions. Lastly, the results of mechanical property tests, thermogravimetric analysis (TGA), and FTIR demonstrated that the composite films showed excellent tensile strength (176.2 MPa) and thermal stability (513.0 °C); at the same content, only 0.5% of N‐GO addition reduced the imidization temperature by 20°C, exhibiting remarkable enhancement effects. This research is a valuable solution to the problem in performance caused by low‐temperature curing agent residues in films, and it is expected to be used in the microelectronics field. [ABSTRACT FROM AUTHOR]

A novel hybridized neodymium iron based-composite consolidated with 5%AIN-5%NI-5%Nb has been fabricated via powder metallurgy (PM). Thus, Taguchi statistical procedure was applied to examine the influence of sintering parametric process namely, sintering temperature, dwell time, pressure, and heating rate, relative densification, and microhardness of the fabricated novel composite. The fabricated composite was successful and subjected to various analyses and characterization. Scanning electron microscope (SEM) was used to investigate the of the microstructural modification of the fabricated composite developed. The SEM morphology shows a bonding neck formation which indicates a uniform dispersion between the matrix and reinforcement phase. The result of the optimized procedure reveals that all the factors significantly contributed to hardness and densification of the composite. However, temperature shows the major that significantly influenced the procedure above 90%. The maximum microhardness value of 680.52 HV was revealed by the material sintered at 700 °C, 30 MPa of pressure, 5 min of dwell time, and heating rate of 300 °C/minute. [ABSTRACT FROM AUTHOR]

To study the effect of SAP incorporation on the early shrinkage of SAP internally cured concrete with the aim to solve the problems of early shrinkage and cracking of bridge leveling-layer concrete, using the SAP incorporation method as a parameter, the mechanical properties test of internally cured concrete, the shrinkage performance test of ring restraint and the scanning electron microscope observation test were carried out. The effects of the SAP content and incorporation method on the flowability, mechanical properties, shrinkage performance and microstructure of internally cured concrete were analyzed. The experimental results show that when the content of the SAP in concrete is 0.2% of the mass of cementitious materials, it has the least influence on the compressive strength of concrete. The addition of preabsorbed water to the SAP can delay early cement hydration, increase the later cement hydration rate and final hydration degree, and improve the concrete strength. Preabsorbed water mixed with an SAP can effectively improve the shrinkage of concrete, and the shrinkage reduction effect is more obvious than that from the dry addition of the SAP; the early cracking risk of concrete without an SAP is high, and it will crack before day 28. The addition of an SAP can strengthen the microstructure of concrete and improve its density and crack resistance, effectively avoiding concrete cracking. It is recommended that the water-absorbent resin be incorporated in a preabsorbent manner, and the SAP preabsorbent ratio is equal to the maximum water storage rate of the SAP. [ABSTRACT FROM AUTHOR]

In this work, mechanical properties of reinforced polypropylene composites were studied. PP in particulates shape with two different melt flow indexes (MFI) was used, i.e., 3 and 23 g/10 min, namely PP3 and PP23, respectively. Three different materials, namely TiO2 nanoparticle (nTiO2, spherical, 0D), micro-size short carbon fiber (SCF, fiber, 1D), and graphite nanoplatelet (GNP, sheet, 2D), were used as reinforcements/fillers. PP and fillers (in the desired composition) were first pre-mixed by a mechanical mixer. The mixture was then fed to a co-rotating twin-screw extruder for melt-compounding, followed by injection molding to fabricate testing samples. The microstructure and fracture surface of the composites were observed by a scanning electron microscope (SEM). Additionally, tensile, flexural, impact, and hardness tests were conducted to evaluate their mechanical properties. The SEM images stipulate that PP23 had better adhesion and dispersion with the fillers. The results from the SEM images support the mechanical testing results. PP23 composites exhibited more significant improvement in mechanical properties in comparison to PP3. At 5 wt. % filler loading, PP/GNP composite exhibited a greater improvement in mechanical properties compared with two other composites, which are PP/SCF and PP/nTiO2 composites for both PPs. [ABSTRACT FROM AUTHOR]

In the present study, a new composite based on epoxy resin reinforced with Lygeum spartum L. fibers was prepared using compression molding technique. Chemical, mechanical as well as morphological analyses were carried out on the Epoxy/Lygeum spartum composite (Epoxy/LS) using ATR-FTIR, tensile and flexural tests, and SEM spectroscopy. An increase in the intensity of several bands associated to the main complements of vegetable fibers (cellulose, hemicellulose, and lignin) was showan using ATR-FTIR analysis. An improvement in the mechanical properties of this new material was observed, with respect to the neat epoxy resin. This was of the order of 117 % and 85 % for tensile and flexural modulus respectively, and of the order of 40 % and 9 % for tensile and flexural strength, correspondingly. A good fiber-matrix adhesion was also observed from tensile fracture surface of composite using scanning electron microscope (SEM). All the obtained results demonstrated the effectiveness of the Lygeum spartum fibers as reinforcement of composite materials. [ABSTRACT FROM AUTHOR]

It is aimed to explain different tensile elongations in 18Cr–8Ni austenitic stainless steel (ASS) with various microstructures having the same yield strength by comparing the deformation mechanisms. The as‐received ASS is cold‐rolled (CR) at room temperature with thickness reductions of 10% and 90% (achieved following 14 passes). The ultra‐fine grain/fine grain (UFG/FG, average grain size (diameter): 0.5–2 μm) structure is developed by annealing the 90% CR structure at 850 °C over 300 s. The optical, scanning and transmission electron microscope, electron backscatter diffraction, and X‐ray diffraction techniques are applied to the microstructural features. The as‐received specimen contained equiaxed austenite and equiaxed dislocation cells, stacking faults, deformation twins (DTs), and strain‐induced martensite (SIM) coexist in the 10% CR and UFG/FG samples. Tensile tests are conducted, and the results reveal that 10% CR and UFG/FG structures exhibited similar yield strengths (550 MPa) under conditions of varying elongation properties, which is attributed to differences in the microstructure‐dependent deformation mechanisms. Dislocation slip (≈10 area%; newly formed), DTs, and SIM (≈44 vol%; newly formed) are observed in the 10% CR structure. The presence of numerous dislocation slips (≈50 area%; newly formed) and a small amount of DTs and SIMs are observed in UFG/FG structure. [ABSTRACT FROM AUTHOR]

In this study, the effect of sonication time on the mechanical properties of graphene nanoplatelets (GnPs) glass fiber composites were discussed. The Sonication process is one of the best techniques to ensure uniform dispersion of nanofillers into the polymer matrix; otherwise, they form agglomerates of multilayers. To fulfill the massive demand for mass production, ultrasonic bath‐type sonication were deployed. In this study, 0, 1, 2, 3, 4, and 5 wt% of GnPs were added with epoxy at different sonication durations, precisely 0, 20, 40, and 60 min. Other sonication process parameters were kept constant with a sonication frequency of 28 KHz. Bidirectional glass fabric materials was used as reinforcement material in the fabrication of the laminates. In total, 21 laminates were fabricated using the hand lay‐up technique in various amalgamations. The tensile and flexural specimens were cut from the laminates as per the standards to determine their mechanical properties. The scanning electron microscope (SEM) images were used for the structural analysis of the glass fiber reinforced GnPs/epoxy composite. Surface morphology of GnPs becomes more wrinkled, resulting in a stronger graphene/epoxy matrix interface, enhancing the tensile strength and tensile modulus performance of the nano‐composites increases up to 37.12% and 66.30%, the flexural strength and flexural modulus performance of the nano‐composites increases up to 55.74% and 91.23% respectively. Based on the investigations, the influence of the GnPs percentage and the sonication duration for the preparation of the nano‐composites with the help of technique for order of preference by similarity to ideal solution (TOPSIS) optimization technique. [ABSTRACT FROM AUTHOR]

The need for eco‐friendly materials has been attracted due to renewability, abundance availability, low cost, and so on. Therefore, the search for bio fillers for the fabrication of bio‐based composite materials is gaining more and more attention in both academic and industry circles because it promotes sustainability. The present study represents the utilization of biomass solid waste in the hybrid form of Tamarind Seed and Date Seed Filler (TSF/DSF) into polymer reinforced composite which has been explored for the first time by a compression molding technique. These fillers are bio‐waste that can be obtained at a minimal cost from renewable sources. An attempt has been made to use these hybrid fillers to reinforce the matrix ranging from 0 to 50 wt%, and their physical, mechanical, and thermal properties were investigated. In general, the inclusion of hybrid fillers increases mechanical properties, although the addition of hybrid fillers had only a minor impact on thermal properties. When compared to the pure vinyl ester resin, the hybrid fillers reinforced composites revealed a significant enhancement in tensile, flexural, impact, and hardness properties, with improvements of 1.51 times, 1.44 times, 1.87 times, and 1.46 times respectively, at 10 wt% filler loading. Filler matrix interaction of fractured mechanical testing samples was evaluated by scanning electron microscope. Based on the findings, hybrid filler reinforced composites may be suitable for applications where cost is a consideration and where minor compromises in thermal qualities are acceptable. [ABSTRACT FROM AUTHOR]

The present work aims to demonstrate the effect of multiwalled carbon nanotube (MWCNT) on mechanical behavior and damage of woven carbon fiber/epoxy composites through experimental characterizations and multi‐scale modeling. Tensile tests were conducted for MWCNT/epoxy nanocomposites, and carbon nanotube (CNT) reinforced laminated open hole composites with different MWCNT weight ratios. The tensile modulus in CNT/epoxy nanocomposite was enhanced by 15.0%, 37.86%, and 22.86% for MWCNT reinforcement of 0.5%, 1.0%, and 1.5% wt, respectively. The corresponding improvement of tensile modulus for woven composites was 3.45%, 10.25%, and 1.53%; whereas tensile strength was increased by 19.76%, 25.78%, and 6.70%. The enhancement of tensile modulus and strength was less for 1.5% wt MWCNT laminates due to the formation of MWCNT agglomeration. The effective elastic isotropic/orthotropic properties for nanocomposite/woven composite were estimated through Mori‐Tanaka approach and numerical homogenization. The finite element simulations were performed with Hashin's damage model and extended finite element method‐based crack growth study. The delaminations between layers have been demonstrated through cohesive zone modeling. Damage propagation, interface delamination, and fiber/matrix failure were demonstrated by numerical simulations in line with scanning electron microscope observations. [ABSTRACT FROM AUTHOR]

The effects of La and Y on the microstructure and mechanical properties of cast Al-Si-Cu alloys were investigated by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM). The results indicated that the addition of La and Y had a great effect on the refinement of α-Al grains, the modification of eutectic Si phase, and the reduction of β-Al5FeSi length in Al-Si-Cu alloys. The A380 + 0.6 wt.% La/Y alloy exhibited the best microstructure and mechanical properties. The UTS and EI of the A380 + 0.6 wt.% La/Y alloy were 215.3 MPa and 5.1%, which were 22.9% and 37.8% higher than those of the matrix alloy, respectively. In addition, neither Al11La3 nor Al3Y generated by the addition of La and Y could not serve as the nucleation core of α-Al grains, so the grain refinement of α-Al originated from the growth limitation and constitutional supercooling. Since La and Y promote twinning generation and constitutional supercooling, the eutectic Si phase also changed from stripe-like to short fibrous or even granular and was significantly refined. Furthermore, thermodynamic calculations indicated that the Al11La3 phase was formed first and the Al3Y phase was generated on the Al11La3 phase. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) impart great multi-functionality when reinforced with a polymer matrix. This paper shows the qualitative and quantitative improvements of the mechanical, electrical, and electromagnetic interference shielding effectiveness properties with the additions of the multiwalled carbon nanotubes (MWCNTs) and functionalized MWCNTs (FMWCNTs) in ethylene methyl acrylate (EMA) polymer. Mechanical characterization is performed through tensile testing, and electromagnetic interference shielding effectiveness (EMI SE) is calculated from the scattering parameters obtained from the vector network analyzer. Both properties improve compared to neat polymer with the reinforcement loadings up to a critical value, from where the properties start to degrade due to the agglomeration of the CNTs. FMWCNTs provide better performance in terms of properties over the MWCNT reinforced nanocomposites. Morphological characterization using a scanning electron microscope justifies a lower percolation threshold of FMWCNT/EMA composite by better electrical conductive network formation. At 10 wt% of FMWCNT loading, the FMWCNT/EMA composite shows 25.1 dB of EMI shielding efficiency combined with excellent mechanical and electrical properties extending its potential use in both industry and academia as an excellent flexible EMI shielding material. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the microtensile bond strength (µTBS) and Knoop hardness number (KHN) of a novel experimental light-cured resin cement (HL). Eighteen flat dentin surfaces of human molars were polished using #600 SiC paper and bonded to CAD/CAM resin blocks with the respective resin cements and composites: HL, Panavia V5 (PV), and Clearfil AP-X (AP). All specimens were stored in distilled water at 37 °C for 24 h and 7 days. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) observations were performed to evaluate filler morphology and to detect the elements. The resin cements had a significant effect on the immediate µTBS (F = 22.59, p < 0.05) and after water storage µTBS (F = 22.83, p < 0.05). Significant differences (p < 0.05) in the KHN between the tested materials were observed, and HL indicated the highest KHN when compared with PV. HL showed a combination of the regular-shaped filler and spherical-shaped filler within the matrix. Silicon was detected in HL from the EDX evaluation. HL exhibited better bonding performance and polymerization, which may have contributed to the improvement of the adhesive strength. [ABSTRACT FROM AUTHOR]

Effect of 2 MeV Ni+ ion beam irradiation with varying fluences on the surface, structural, and mechanical characteristics of titanium will be explored. For this objective, titanium targets were exposed to nickel ions obtained from a pelletron linear accelerator with 2 MeV energy and various fluences extending from 3 × 1012 to 7 × 1015 ions/cm2. Penetration features and damage evolution of 2 MeV Ni-ion in titanium have been estimated by employing SRIM-2013 software. Various characterization tools were employed to confirm the modifications in the ion beam irradiated targets. The surface and crystallographic variations of ion beam irradiated targets were explored by employing a scanning electron microscope (SEM) and X-ray diffractometer (XRD). Tensile testing and microhardness analysis was performed by utilizing a software-controlled 50 KN universal tensile testing machine and Vickers's hardness tester, respectively. The SEM analysis represents random and irregularly distributed sputter morphology for lower ion fluences. With the increase of ion fluence, the pores keep growing radially while the growth rate slows down. At the highest ion fluence, localized melting, evaporation and expulsion of surface material were recorded at the irradiated zone. The X-ray diffraction analysis revealed no additional phases to be developed in the Ni-ion treated titanium. However, a variation in the peak intensity and slight angle/position shifting was reported, which depicts the creation of ion-induced stresses and defects. The mechanical testing results indicated the variations in the mechanical characteristics (yield stress, ultimate tensile stress, hardness etc.) of irradiated titanium. The hardness, yield stress and ultimate tensile strength increased monotonically with the increase of ion fluence. The reported modifications in the mechanical characteristics of irradiated titanium are in good accordance with structural and surface modifications. The stated changes in the irradiated titanium are ascribed to the development of ions induced stress as well to creation, augmentation/expansion, recombination, and annihilation of the ion-induced defects. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the improvement made on the mechanical properties of the composites by the addition of micro- and nanoparticles to aluminium matrix. The micro- and nano-composites having different weight percentages of particles were fabricated using stir-casting and ultrasonic cavitation probe-assisted casting processes, and they were characterized using metallurgical microscope and scanning electron microscope. The mechanical properties of the composites, such as tensile strength, impact strength, and hardness, were analysed as per the ASTM standards. The analysis indicated that the nanoparticles' reinforcement in aluminium matrix composite significantly improved the mechanical properties compared to the micro-particles owing to their high surface energy. [ABSTRACT FROM AUTHOR]

The structure and mechanical properties of non-equiatomic Al8Co30Cr18Fe9Ni31Nb4, Al8Co30Cr18Fe9Ni31Nb2Ti2 and Al8Co30Cr18Fe9Ni31Ti4 high entropy alloys (HEAs) were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), hardness and tensile testing. TEM and XRD analyses revealed the formation of γ''-Ni3Nb/γ (FCC), double FCC and γ'-Ni3Al/γ (FCC) structure for as-cast Al8Co30Cr18Fe9Ni31Nb4, Al8Co30Cr18Fe9Ni31Nb2Ti2 and Al8Co30Cr18Fe9Ni31Ti4 HEAs, respectively. The hardness and yield strength values were found to increase with the addition of Nb while the ductility of alloys increased with the increase in Ti concentration, significantly. The as-cast Al8Co30Cr18Fe9Ni31Ti4 alloy exhibited an excellent combination of ultimate tensile strength of 844 MPa and an elongation of 29.8% due to the coherent phase relation between γ' precipitates and γ matrix. The fractured surfaces of as-cast Al8Co30Cr18Fe9Ni31Nb4, Al8Co30Cr18Fe9Ni31Nb2Ti2 and Al8Co30Cr18Fe9Ni31Ti4 HEAs showed typical dimple type ductile fracture under tension test. [ABSTRACT FROM AUTHOR]

As a by-product of bamboo processing, bamboo powder is incinerated or buried due to its ineffective utilization, which contributes to pollution. The large amount of waste bamboo powder generated during the processing of bamboo products cannot be effectively utilized. Meanwhile, multiple recycling leads to the loss of fiber quality of corrugated cardboard (OCC) pulp, reducing the mechanical properties of paper. In an effort to obtain high value from waste bamboo powder, this study pulped it using the kraft process. Scanning electron microscope (SEM) observations showed that the surface of bamboo fiber had more cracks, which made bamboo fiber have better air permeability. The permeability of bamboo paper was 146% that of the OCC. X-ray diffraction (XRD) analysis showed that the crystallinity of bamboo pulp was 133% that of the OCC pulp. The results of physical testing of paper showed that the tensile strength of bamboo paper was 116% that of the OCC. The tear strength of bamboo paper was 61.7% that of the OCC, and the bursting strength of bamboo paper was 59.1% that of the OCC. Based on the above results, bamboo powder can be used as raw material for making OCC pulp. [ABSTRACT FROM AUTHOR]

HIPS-g-MAH compatibilizer and the other three compatibilizers were prepared and added to the polyamide 66/polyphenylene oxide (PA66/PPO) alloy. The FT-IR spectra showed that the maleic anhydride (MAH) had successfully undergone grafting on the high impact polystyrene (HIPS). The effect of the MAH ratio in the HIPS-g-MAH compatibilizer, the HIPS-g-MAH compatibilizer weight ratio, and the PA66/PPO ratio on the mechanical properties of PA66/PPO alloy was systematically studied. The results showed that the PA66/PPO alloy possessed the optimal mechanical properties when the HIPS-g-MAH compatibilizer weight ratio was 7% and the MAH ratio in HIPS-g-MAH compatibilizer ranged 4% ~ 8%. The fracture morphologies of PA66/PPO alloy with different HIPS-g-MAH compatibilizer weight ratios were characterized by scanning electron microscope (SEM). The PA66/PPO alloy without HIPS-g-MAH compatibilizer showed a typical brittle fracture. The mechanical properties of PA66/PPO alloys with the HIPS-g-MAH compatibilizer were improved. In addition, the crystallization temperature of PA66/PPO alloy decreased with the increase in the HIPS-g-MAH compatibilizer weight ratio. The PA66/PPO ratio also played an essential role in the PA66/PPO alloy properties. The coefficient of friction and wear rate both increased with the increase in the PPO ratio. [ABSTRACT FROM AUTHOR]

The present study aims at to study the effect of chemical composition, intercritical annealing parameters (temperature and holding time) on microstructure and mechanical properties of dual phase steels. Three normalized steels (A, B and C) with different compositions were subjected to inter-critical annealing at 760°C and 810°C for different holding times (3, 6 and 9 min). The microstructural characterization was carried out using a scanning electron microscope (SEM) and mechanical properties were evaluated using micro-hardness measurements and tensile tests. The strength has been found to increase from 500 MPa (steel A) to >1200 MPa (steel C) at the cost of a decrease in elongation from 25% (steel A) to 7.5% (steel C). Results have been analysed and discussed. [ABSTRACT FROM AUTHOR]

This study investigated the microstructure, hardness, tensile and tribological behaviour of a cooling slope Al--Si--Mg alloy following ECAP and T6 heat treatment. The optical and scanning electron microscopes were applied to investigate the microstructure of the as-cast material and heattreated ECAPed Al--Si--Mg alloy. The dry sliding wear test was tested with three different loads of 10 N, 50 N, and 100 N with constant sliding speed and sliding distance at 1.0 m/s and 9000 m, respectively, using the pin-on-disc tribometer. The hardness and tensile properties were evaluated through microhardness, UTS, and YS measurement for the as-cast Al--Si--Mg alloy, both heat-treated with and without ECAPed alloys. Moreover, wear rate and COF in the Al--Si--Mg alloy with different loads were analysed and linked with microstructural and strength behaviour after the ECAP process. Meanwhile, these analyses of results were correlated with the behaviour of the as-cast Al--Si--Mg aluminium alloy and heat-treated non-ECAPed alloy. Results demonstrated that a combination of ECAP processing and T6 heat treatment improves the mechanical behaviour, while the COF and wear rate are improved at a load of 100 N. [ABSTRACT FROM AUTHOR]

The mechanical and thermal characterization of Moringa oleifera fiber and red mud (RM) reinforced chitosan (CS) based hybrid composite is the subject of this research. By varying the percentages of M. oleifera fiber and RM in the hand lay‐up process, seven types of composite samples were developed. Tensile, flexural, compression, and impact testing were performed in accordance with ASTM standards. A scanning electron microscope was used to examine the cracked surfaces of the tested specimens. Hybridization with M. oleifera fiber and RM increased the characteristics of CS composites, according to the findings. Increase in the percentage composition of RM resulted in better mechanical characteristics of fiber‐reinforced composites. C6 type composite revealed maximum tensile strength of 65.59 MPa and impact strength of 24.86 kJ/m2. It also had better dynamic mechanical qualities, while C6 composite had the best static and dynamic mechanical properties. Overall it may be concluded that composites can be utilized in light weight structural applications. [ABSTRACT FROM AUTHOR]

The application of CO2 curing on sludge ceramsite may improve its mechanical properties, and then increase the corresponding corrosion resistance. In this study, the influence of CO2-cured sludge ceramsite on the strength and long-term properties of cement concrete is investigated. CO2 curing time ranges from 0 h to 2 d. The cylinder compressive strength and water absorption rate of CO2-cured sludge ceramsite are first determined. Additionally, the flexural and compressive strengths, the chloride permeability and the freeze—thaw damage, as well as the corresponding thermal conductivity of cement concrete, are tested. Furthermore, the corrosion resistance of reinforcement inner-sludge-ceramsite cement concrete is measured. Finally, the scanning electron microscope photos of sludge ceramsite are obtained. Results show that the cylinder compressive strength of CO2-cured sludge ceramsite is 15.1, ~34.2% higher than that of sludge ceramsite. Meanwhile, the water absorption rate of CO2-cured sludge ceramsite is 39.6, ~82.4% higher than that of sludge ceramsite. The compressive strength and the flexural strength of cement concrete with CO2-cured sludge ceramsite are 11.4 and 18.7, ~21.6% and ~31.5% higher than the cement concrete with sludge ceramsite, respectively. The resistance of NaCl freeze—thaw cycles, determined by comparing the mass loss rate and the loss rates of mechanical strengths, is effectively improved by CO2 curing, while the thermal conductivity of cement concrete is decreased by CO2 curing. The corrosion resistance of inner reinforcement is improved by the application of CO2 curing on sludge ceramsite. [ABSTRACT FROM AUTHOR]

There is a need to develop new construction materials with improved mechanical performance and durability that are low-priced and have environmental benefits at the same time. This paper focuses on the rheological, mechanical, morphological, and durability properties of synthetic and steel fiber reinforced self-compacting concrete (SCC) containing 5–15% metakaolin (M) by mass as a green replacement for Portland cement. Testing of the fresh mixes included a slump-flow test, density, and porosity tests. Mechanical properties were determined through compression and flexural strength. A rapid chloride penetrability test (RCPT) and the chloride migration coefficient were used to assess the durability of the samples. A scanning electron microscope (SEM) with energy dispersion spectrometry (EDS) was used to study the concrete microstructure and the interfacial transition zone (ITZ). The results show that a combination of metakaolin and hybrid fibers has a negative effect on the flowability of SCC. In contrast, the inclusion of M and hybrid fibers has a positive effect on the compressive and flexural strength of SCC. The fracture of SCC samples without fibers was brittle and sudden, unlike the fiber-reinforced SCC samples, which could still transfer a considerable load with increasing crack mouth opening deflection. Overall, the chloride migration coefficients were reduced by up to 71% compared to the control mix. The chloride reduction is consistent with the resulting compact concrete microstructure, which exhibits a strong bond between fibers and the concrete matrix. [ABSTRACT FROM AUTHOR]

The application of epoxy resins in high temperature and thermal protection fields is limited due to their low decomposition temperature and low carbon residual rate. In this paper, epoxy resin (EP)/quartz fiber (QF) ceramifiable composites were prepared using a prepreg-molding process. The thermal stability, phase change and mechanical properties after high-temperature static ablation and ceramization mechanism of EP/QF ceramifiable composites were investigated. The addition of glass frits and kaolinite ceramic filler dramatically increases the thermal stability of the composites, according to thermogravimetric (TG) studies. The composite has a maximum residual weight of 61.08%. The X-ray diffraction (XRD) results show that the mullite ceramic phase is generated, and a strong quartz diffraction peak appears at 1000 °C. The scanning electron microscope (SEM) and element distribution analyses reveal that the ceramic phase generated inside the material, when the temperature reaches 1000 °C, effectively fills the voids in composites. The composites have a bending strength of 175.37 MPa at room temperature and retain a maximum bending strength of 12.89 MPa after 1000 °C treatment. [ABSTRACT FROM AUTHOR]

Titanium alloy extruded profiles with complex cross-section are usually used to manufacture special-shaped structural parts in the aviation industry. In this paper, a Ti-6Al-4 V profile with asymmetric Y shape was manufactured by a direct extrusion process. A comparative study was conducted at the different lubrication conditions, in which the different process deformation mechanisms, resulting microstructures, and mechanical properties of profiles have been investigated by finite element simulation and a series of experiments, i.e., scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). It was revealed that the metal flow is blocked at the narrow die orifice due to the deterioration of lubrication, resulting in the continuous shrinkage defect. The metal deformation coordination mechanism becomes gradually significant due to poor friction contact, which promotes the internal stress in the cross-sectional center to transfer outward to balance the friction at the edge of the orifice, resulting in the reduction of the effective strain in the center. The heat generated by friction weakens the heat exchange behavior between the metal and the die, which helps the profile retain a more uniform temperature field. In the sectional center of the profiles made from the two different lubrications, extrusion with good lubrication results in greater grain/colony refinement due to greater effective strains, and a slightly greater dislocation density was found due to the uniform deformation. The tensile tests revealed that compared with poor lubrication, due to the improvement of Hall–Petch strengthening and dislocation strengthening in the cross-sectional center with good lubrication, the variation range of yield strength and tensile strength is reduced to 11 MPa and 7 MPa, respectively, and the variation range of microhardness is reduced to 44 HV and 32 HV, respectively. The improvement of lubrication not only helps to reduce forming defects but also can obtain uniform mechanical properties. [ABSTRACT FROM AUTHOR]

Laser beam welding (LBW) has found wide applications in several fields, including electronics, aerospace, and automobile industries, owing to its inherent capabilities over existing welding techniques. Dissimilar laser welding is one of the challenging fabrication processes. However, joining of different materials poses challenging issues because material properties of each material interacts to give rise to hybrid system performance. In present study weld of Al-Cu and Cu-Al has been performed using Ytterbium pulsed fibre laser with a maximum laser power of 300 W. The scanning electron microscope (SEM), and energy dispersive x-ray spectroscopy (EDS) has been employed to investigate the microstructural and chemical composition of the welded joints. The EDS analysis showed the presence of possible intermetallic compounds (IMCs) like AlCu and Cu2Al in the fusion zone. The Al-Cu and Cu-Al welded joints had maximum shear strength of 295 N and 84 N, respectively. The results showed the efficacy of Al-Cu joints over Cu-Al joints. The study further demonstrated that the Al-Cu weld had a better microstructure with fewer pores and cracks than the Cu-Al welds by varying the laser powers. [ABSTRACT FROM AUTHOR]

To study the heat-treatment process of a semi-solid copper alloy, a thixotropic back-extruded tin–bronze shaft sleeve was heat-treated at 630 °C, 660 °C, 690 °C and 720 °C for 1 h, respectively. Microstructure changes and mechanical properties under different solution temperatures of shaft sleeve were characterized using a metallographic microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), hardness tester, and tensile tester. The results show that the tensile strength first increases and then decreases; the elongation decreases; and the Brinell hardness increases gradually with increasing solution temperature. When the solution treatment is at 690 °C, the tin–bronze shaft sleeve's microstructure and comprehensive mechanical properties are the best. The shape factor is 0.75, the average grain size is 82.52 μm, the Brinell hardness is 122 HBW, the tensile strength is 437 MPa, and the elongation is 17.4%, which is 3.4 times higher than that before solution treatment. [ABSTRACT FROM AUTHOR]

Polymer composite materials were prepared using kaolinite nanoclay as reinforcement in different weight fractions (3, 5 and 7) %, and blends of epoxy and polymethyl methacrylate (PMMA) as matrices. The current work aims to prepare a composite material with good thermal and acoustic insulation, besides improved mechanical properties, and the investigation of the effect of this nano additive on the compatibility between the two constituents of the blend, and how this compatibility might be beneficial to the performance of the prepared composite. The blend with an optimum mixing ratio (OMR) was chosen via impact test results; thus, the (80:20) percentage of epoxy and PMMA was chosen. The reinforced specimens showed an improvement in mechanical (impact and flexural) properties besides sound insulation and thermal conductivity, with the specimen reinforced with 7% nanoclay having the highest impact strength (97*10−3) KJ/m2 and the highest thermal conductivity value of (0.34) W/m.°C, with a sound intensity value 95.6 decibels at frequency 10,000 Hz. The scanning electron microscope images showed two separate phases in the unreinforced blend. In comparison, the 7% reinforced specimen showed a rough interface between the two polymer phases, suggesting a positive effect of nanoclay addition on compatibility. The differential scanning calorimeter showed two distinct glass transition temperatures for both reinforced and neat specimens, which belong to the glass transitions of both constituents (epoxy and PMMA). The main difference is the lower temperature gradient accompanied with the (nanoclay/blend) composite than the neat one. Although the blend remained immiscible, nanoclay had contributed to the compatibility and improved mechanical properties. [ABSTRACT FROM AUTHOR]

Cost-effective bamboo strip composite materials have been developed with the low energy consumption, excellent product quality, and high utilization rate, due to the refinement, homogenization, and standardization of bamboo strip. However, there is the low interface compatibility between polar hydroxyl groups on the surface of bamboo strips and non-polar resin matrix. The purpose of this study is to fabricate the structural or sub structural bamboo strips composite materials. The alkali solution was used to treat the bamboo strips for the penetration of resin on the interface and the mechanical properties of composite materials. A systematic investigation was made to clarify the effect of NaOH alkali treatment concentration on the properties of bamboo strips and the epoxy resin composites. The bamboo strips were used as the reinforcement phase, whereas, the epoxy resin as matrix phase. The composites with an average content of 75% bamboo strips were then prepared by hot pressing. Four concentration gradients of NaOH solution were set in the treatment. The properties of bamboo strips and their epoxy resin composites were characterized by means of Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TG), and Dynamic Mechanical Analysis (DMA). The experimental results showed that the alkali treatment efficiently removed some impurities, such as lignin, hemicellulose, and wax on the surface of bamboo strips, further to enhance the tensile strength and thermal stability of bamboo strips. SEM results show that the surface fiber morphology of bamboo strips tended to be regular after the proper alkali treatment. Specifically, the fine and smooth microstructure was conducive to the resin penetration. The polarity of bamboo strips first increased and then decreased with the increase of NaOH solution concentration. The crystallinity increased from 60.0% to 63.6% after treatment. The TG analysis demonstrated that there were the lower end degradation temperature of alkali treated bamboo strips, and the lower maximum decomposition rate, indicating the better performance of thermal decomposition. More importantly, the best properties were achieved at the concentration of NaOH solution of 2%, including the tensile property of bamboo strips, the interfacial bonding property with the epoxy resin, and the shear strength. Specifically, the tensile strength of bamboo strips, the shear strength of the composites increased by 52.11%, and 55.24%, respectively. The DMA test results showed that the bamboo strip/epoxy resin composites after the alkali treatment presented the better structural stability under dynamic load in the single frequency (1 Hz) test condition in the range of 30-90 ℃. Once the concentration was 2%, the maximum storage modulus of the bamboo strip/epoxy resin composite was 1.3 times that of the untreated. There was no outstanding difference of storage modulus before and after treatment in the range of 9-140 ℃. A downward trend was found in the loss modulus and loss factor of the composites after alkali treatment in the range of 60-140 ℃. Consequently, the alkali treatment can be expected to enhance the thermal stability and tensile strength of bamboo strips. The interface strength between bamboo strips and epoxy resin was improved, together with the static and dynamic mechanics of bamboo strips reinforced epoxy resin composite resin. The improved composites can also be used in the outdoor agricultural engineering, buildings, and outdoor gardens, in order to reduce the production cost and the comprehensive utilization rate of bamboo strips. [ABSTRACT FROM AUTHOR]

This study employed response surface methodology to optimize the preparation of biocomposites based on whey protein isolate, glycerol, and nanocrystalline cellulose from pineapple crown leaf. The effects of different concentrations of nanocrystalline cellulose as a filler and glycerol as a plasticizer on the thickness, the tensile strength, and the elongation at break on the resulting biocomposite films were investigated. The central composite design was used to determine the optimum preparation conditions for biocomposite films with optimum properties. The regression of a second-order polynomial model resulted in an optimum composition consisting of 4% glycerol and 3.5% nanocrystalline cellulose concentrations, which showed a desirability of 92.7%. The prediction of the regression model was validated by characterizing the biocomposite film prepared based on the optimum composition, at which the thickness, tensile strength, and elongation at break of the biocomposite film were 0.13 mm, 7.16 MPa, and 39.10%, respectively. This optimum composition can be obtained in range concentrations of glycerol (4–8%) and nanocrystalline cellulose (3–7%). Scanning electron microscope images showed that nanocrystalline cellulose dispersed well in the pure whey protein isolate, and the films had a relatively smooth surface. In comparison, a rough and uneven surface results in more porous biocomposite films. Fourier transform infrared spectroscopy revealed that nanocrystalline cellulose and glycerol showed good compatibility with WPI film by forming hydrogen bonds. The addition of nanocrystalline cellulose as a filler also decreased the transparency, solubility, and water vapor permeability and increased the crystallinity index of the resulting biocomposite film. [ABSTRACT FROM AUTHOR]

Herein, the effect of tempering temperature on the microstructure evolution and mechanical properties of a new nitrogen‐containing hot‐work die steel 3Cr7Mo2NiSiVN is investigated. The new type of hot‐work die steel is quenched at 1080 °C and then conducts a double tempering from 200 to 700 °C. The quenching microstructure contains martensite, film‐retained austenite, and undissolved precipitates, and these precipitates play a Zener pinning effect role in prior austenite grains growing. Based on the Thermo‐Calc thermodynamic calculation and experimental results, the die steel contains V‐rich M2N nitride, Cr‐rich M23C6 carbide, Mo‐rich M6C carbide, and (Nb,V)‐rich M(C,N) precipitates. A secondary hardening phenomenon occurs and the brittle fracture turns to ductile fracture under the scanning electron microscope (SEM) field when the tempering temperature is 500 °C. Room strength decreases and the plasticity improves with the continual increase of tempering temperature. Many nano‐size spherical M2N nitride and strip‐like M(C,N) carbonitride precipitate when the tempered temperature exceeds 550 °C with transmission electron microscope (TEM) observation. Finely dispersed M2N nitride and M(C,N) carbonitride are beneficial for stabilizing microstructure at high temperatures and improving high‐temperature strength. Therefore, the high‐temperature strength of the new type of hot‐work die steel is much higher than that of the traditional hot‐work die steel. [ABSTRACT FROM AUTHOR]

Purpose: Bismaleimide (BMI) is a kind of thermosetting resin and its application is usually limited by low toughness. In this paper, two kinds of reinforcement intercalator amino-terminated polyoxypropylene (POP) and octadecyl trimethyl ammonium chloride (OTAC) were designed and synthesized to toughen BMI resin and the toughening effect was compared and analyzed. The purpose of this paper is to toughen BMI resin and analyze the toughening effect of two reinforcements intercalator amino-terminated polyoxypropylene (POP) and octadecyl trimethyl ammonium chloride (OTAC). Design/methodology/approach: Sodium-based montmorillonite (Na-MMT) was modified by POP and OTAC, and the ion-exchange reaction obtained organic montmorillonite (POP-MMT and OTAC-MMT). The polymer matrix (MBAE) was synthesized, in which 4,4'-diamino diphenyl methane BMI was used as the monomer and 3,3'-diallyl bisphenol A and bisphenol A diallyl ether were used as active diluents. And then, POP-MMT/MBAE and OTAC-MMT/MBAE composites were prepared using MBAE as matrix and POP-MMT or OTAC-MMT as reinforcement. The Fourier-transform infrared, X-ray diffraction and scanning electron microscope (SEM) of the filler and microstructure and mechanical properties of the composite were characterized to the better reinforcement. Findings: POP-MMT and OTAC-MMT enhanced BMI-cured products' toughness by generating microcracks in the polymer to absorb more fracture energy. Meanwhile, POP-MMT and OTAC-MMT were the main stress components and the enhancement of the interface interaction was beneficial to transfer the external force from the matrix to the reinforcement and improved the mechanical properties of the composite. Furthermore, with the intercalation rate increasing, the compatibility of the two phases was increased and the performance of MBAE was also elevated. Research limitations/implications: BMI is generally used as aerospace structural materials, functional materials, impregnating paint and other fields. However, high crosslinking density leads to moulding material's brittleness and limits a wider range of applications. Therefore, it has become an urgent priority to explore and improve the mechanical properties of BMI resin. Originality/value: POP and OTAC have successfully intercalated Na-MMT layers to get POP-MMT and OTAC-MMT, and the interplanar crystal spacing and the intercalation rate were calculated, respectively. The results were corresponding with the SEM images of POP-MMT and OTAC-MMT. After that, the morphology of composites illustrated the compatibility was related to the intercalation rate. According to the mechanism of modified MMT toughening epoxy resin, when they were dispersed uniformly in the matrix, the composite's mechanical properties had been significantly improved. Additionally, OTAC-MMT with a higher intercalation rate had better compatibility and interfacial force with the matrix, so that the mechanical properties of OTAC-MMT/MBAE were the best. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure, mechanical properties, and preparation of geopolymer were investigated. The effects of the proportion of slag and fly ash, the modulus of water glass, and the water–binder ratio on the microstructure, mechanical properties, and preparation of geopolymer were analyzed. The research content of this paper is as follows: Taking the 7-day and 28-day compressive strength and flexural strength of the geopolymer specimens as the evaluation criteria, considering the proportion of slag and fly ash, the modulus of water glass, and the water–binder ratio, the three factors and five levels are respectively considered for a total of 25 sets of orthogonal experiments. Through the range analysis and variance analysis, the influence of each factor on the mechanical properties was analyzed, and the best mix ratio was obtained. Using scanning electron microscope and X-ray diffraction analysis and other testing methods, the mechanical properties, microstructure, and phase composition of geopolymers under the influence of various factors were studied and analyzed. [ABSTRACT FROM AUTHOR]

The recycling and reuse of construction waste have not only effectively protected natural resources but also promoted the sustainable development of the environment. Therefore, in this article, waterborne polyurethane (WPU) as a promising new polymer reinforcement material was proposed to reinforce the road demolition waste (RDW), and the mechanical performance of WPU-reinforced RDW (named PURD) was investigated using triaxial unconsolidated and undrained shear (UU) and Scanning Electron Microscope (SEM) tests. The results showed that under the same curing time and confining pressure, the shear strength of PURD increased with the increase in WPU content. When the WPU content was 6%, the WPU presented the best reinforcement effect on RA. The failure strain of PURD increased with the increase in confining pressure, but increased first and then reduced with the increase in WPU content. The specimens with 5% WPU content showed the best ductility. At the curing time of 7 and 28 days, the internal friction angle and cohesion of PURD increased with the increase in WPU content, and they reached a maximum when the WPU content was 6%. The internal friction angle barely budged, but the cohesion increased obviously. The enhancement effect of WPU was attributed to the spatial reticular membrane structure produced by wrapping and bonding particles with the WPU film. Microscopic analysis showed that with the increase in WPU content, the internal pore and crack size of PURD gradually decreased. As the WPU content increased, the WPU film became increasingly thicker, which increased the adhesion between WPU and RA particles and made the structure of PURD become increasingly denser. [ABSTRACT FROM AUTHOR]

The variations in the austenite–ferrite dual-phase structure of hyper-duplex stainless steels subjected to tensile deformation were analysed in the present work. The blocks of ASTM A890 7A hyper-duplex steel were cast and heat treated to obtain a clean dual-phase structure. Unilateral tensile stress was applied on specimens prepared from the blocks. Heat-treated specimens were deformed under a displacement control mode for various percentage elongations. Scanning electron microscope and metallurgical microscope images revealed that the austenite phase was more deformed compared to that of the ferrite phase. X-ray diffraction analysis was carried out to find the crystallographic planes where maximum deformation has occurred and to explain how different phases participated in the deformation process. The austenite phase was found to be far more deformed than the ferrite phase, with the greatest deformations in the (111) and (200) planes. The distribution of constituent alloying elements was evaluated using energy-dispersive X-ray analysis (EDAX) and area-scan techniques and it was found that there were no substantial changes in the concentration of alloying elements as a result of deformation. [ABSTRACT FROM AUTHOR]

Cyanate ester (CE) was employed to modify epoxy resin (EP) by chemical reaction, and the thermal, mechanical, and corrosion properties were systematically studied. Differential scanning calorimetry and Fourier transform infrared spectra were carried out to determine the curing kinetic parameters, suitable curing procedure, and reaction mechanism. The glass transition temperature and thermal stability were investigated employing dynamic mechanical thermal analysis and thermogravimetry measurement. Furthermore, the mechanical and corrosive properties were evaluated, using test techniques such as mechanical testing machine, abrasion tester, axle rod flexibility tester, scanning electron microscope, and electrochemical impedance spectroscopy. Results verified that an appropriate amount of CE could significantly improve the comprehensive performance of EP. However, a satisfactory effect would not be achieved when the modifier is inadequate or excessive. [ABSTRACT FROM AUTHOR]

The TC4 dual-phase titanium alloy was cryogenically treated for different times at -196 ℃ by liquid nitrogen direct cooling, and the grain size was characterized by metallurgical microscope; the volume fraction of α and β phases was measured by scanning electron microscope(SEM); Vickers hardness tester and electronic universal testing machine were applied to characterize hardness and tensile properties respectively. Through the change of grain size and the structure of α phase and β phase, the changes of material hardness and tensile properties were carefully explained. The experimental results show that with the extension of the cryogenic time, the grain size gradually decreases, and the volume fraction of the β phase gradually decreases by transforming into the α phase. After 12 h cryogenic treatment, the crystal grains are obviously refined, and the majority of β phase is transformed to the α phase. The samples shows superior comprehensive mechanical performance. When the cryogenic time exceeds 12 h, the volume fraction of the α phase and β phase have no obvious change. After taken out to room temperature, the recovery effect of the samples cryogenic treated over 12 h was more obvious, and the mean grain size was not significantly refined compared with that of the samples treated for 12 h. Consequently, the strength and hardness of the sample treated over 12 h were slightly lower than those of the sample treated at 12 h. In conclusion, the superior comprehensive mechanical properties can be obtained after cryogenic treated for 12 h in liquid nitrogen. [ABSTRACT FROM AUTHOR]

This research investigates the combined effect of steel and natural fibre on the mechanical properties and spalling resistance of ultra-high performance concrete (UHPC) before and after exposure to elevated temperatures. The effects of two parameters, namely temperature (ambient temperature, 200 °C, 400 °C and 600 °C) and fibre type (solely macro end hooked steel fibre (MHS) and hybrid of micro straight steel fibre (MSS), macro end hooked steel (MHS) fibre and micro jute (MJ) fibre) on the mechanical properties, spalling resistance and mass loss of UHPC were studied. Micrographs from scanning electron microscope (SEM) test were utilized to appraise the steel fibre and jute fibre before and after exposure to elevated temperatures. The test results exhibited that the residual tensile strength and flexural strength were significantly declined after exposure to high temperatures for UHPC specimens reinforced with macro steel fibre only. Moreover, explosive thermal spalling occurred for this group of specimens under 600 °C. Whereas the combined use of jute fibre and micro-macro steel fibre was an effective approach to prevent the explosive thermal spalling under 600 °C and improve the residual tensile strength, flexural strength and toughness of UHPC. Furthermore, preliminary empirical expressions have been developed in this study to predict the residual mechanical properties of UHPC as a function of natural fibre content, steel fibre content and temperature. [ABSTRACT FROM AUTHOR]

During the extraction of geothermal heat, the changes in temperature and pressure environments can alter the mechanical and hydraulic behavior of fractured rock masses, affecting the overall transmissivity and heat extraction efficiency accordingly. This study carried out a series of experiments, including X-ray diffraction (XRD), scanning electron microscope (SEM), uniaxial compression tests, and surface morphological scanning, to explore the influence of reservoir temperature on the mechanical behavior of granite and fracture surface topography. The results indicate that as the temperature increases, the uniaxial compressive strength, elastic modulus, and Poisson's ratio of granite show similar variation patterns that increase as the temperature approaches 200 °C and then decrease. In addition, with the increase in temperature, the overall surface elevation and roughness parameters generally decrease due to surface asperity degradation, with the maximum mean mechanical aperture found at 200 °C. Flow simulations were conducted to further explore the influence of temperature and pressure environments on fracture transmissivity and flow fields. It is found that the normalized equivalent hydraulic aperture B N of the tested fractures decreases progressively as the stress increases, and more scattered distributions of B N are observed under higher compressive stresses. Moreover, with the continuous increase in temperature, the average B N slowly increases to its peak of ~0.78 at 200 °C, then it decreases to ~0.76 at 300 °C and remains nearly constant. These findings can be important for assessing heat production performances during the geothermal extraction process with spatially and temporally varying reservoir temperatures and pressures. • Temperature and pressure effect on granite properties are analyzed. • Surface roughness decreases due to heat-induced asperity degradation. • UCS and transmissivity reach their maximum at 200 °C with increasing temperature. [ABSTRACT FROM AUTHOR]

For the present investigation, Tungsten heavy alloys (WHAs), (90-x)W-6Ni-4Cu-xLa 2 O 3 are synthesized using the powder metallurgy route by liquid phase sintering at 1400 °C for 1 h in hydrogen atmosphere. The effect of variation of La 2 O 3 (Lanthanum oxide) dispersion in W-Ni-Cu alloy (0, 0.1, 0.5, 1.0, 1.5, and 2.0 wt%) on microstructural evolution was investigated using a scanning electron microscope (SEM) and transmission electron microscopy (TEM). The distribution of the tungsten, matrix, and La 2 O 3 were analyzed using X-ray energy dispersive spectroscopy (EDS). The influence of La 2 O 3 content on the densification behavior was also determined. The stereological quantifications were done on particle size and contiguity. The lowest W particle size was observed in sample of 2.0 wt% La 2 O 3 added WHA. However, this sample was found to have more porosity. The W particle size was reduced by about 30% with 2.0 wt% addition of La 2 O 3. The maximum value of bulk hardness of about 320 HV 5 was observed in 1.0 wt% La 2 O 3 content WHA. The three-point bend test was performed to determine the bending behavior of these alloys. The alloy with 1.0 wt% La 2 O 3 showed the maximum compressive strength of 1481 MPa and bending strength of 1021 MPa. Fractography revealed W-W interface de-cohesion fracture mechanism to operate pre-dominantly. W particle cleavage fracture mode was observed to increase with the addition of La 2 O 3 up to 1.0 wt% in the WHAs. • W-Ni-Cu alloys with La 2 O 3 processed via powder metallurgy LPS at 1400 °C. • With 2.0 wt% La 2 O 3 in W-Ni-Cu alloy reduces W particle size by 30 %. • The addition of 1.0 wt% La 2 O 3 turns out to give the best mechanical property. • Quantification of operational fracture modes attempted. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride cement (MOC) as a green cement has superior mechanical properties such as high strength and quick gain of early strength, however the inherent brittleness has limited its applications where ductility is crucial. To enhance the strength and ductility, a novel hybrid fibre-reinforced MOC-based composite (FRMOC) is developed for the first time using polyethylene (PE) fibres and basalt fibres (BF) to reinforce the MOC. A systematic investigation of the effect of fibre dosage on the flowability, rheological properties, compressive strength, and tensile properties of the developed FRMOC is conducted in this study. The results revealed that the addition of fibre reduces flowability while increasing the yield stress and plastic viscosity. The 1-day compressive strength of the FRMOC reached 68.2–85.4% of the corresponding value at 28 days, demonstrating its high early strength characteristic. The mix with 1.25% PE and 0.75% BF exhibited the maximum compressive strength at all curing ages. All the mixes consistently demonstrated excellent tensile strength and tensile strain capability (ductility), with the tensile strength and tensile strain capacity of 10.95 MPa and 4.41% achieved for the mix of 2% PE fibre, and 8.49 MPa and 2.43% for the mix of 1.25% PE and 0.75% BF respectively. Moreover, a decline in strength characteristics and strain capacity was observed as BF percentages increased. Scanning electron microscope (SEM) analysis was further employed to investigate the morphological changes in the FRMOC matrix at the microscale to discover the fibre reinforcing mechanism. • Hybrid fibre reinforced MOC (FRMOC) with enhanced strength and ductility is developed. • FRMOC demonstrates high-early-strength characteristic. • Rheological, physical, and mechanical properties were evaluated. • 1.25% PE and 0.75% BF-reinforced FRMOC exhibited maximum tensile strength and strain capacity. • Microstructural analysis is performed to analyse the morphological alterations. [ABSTRACT FROM AUTHOR]

For facilitating carbon utilization and minimizing carbon emission, steel fiber was coated with polyethyleneimine and subjected to a moist condition to capture carbon dioxide, and the CO 2 captured steel fiber (CPSF) was formed, which was used to prepare ultra-high performance concrete (UHPC). After heat curing, compressive strength and splitting tensile strength of UHPC were determined. The results reveal that, compared to the UHPC with polyethyleneimine-coated steel fiber (PSF), the compressive strength and splitting tensile strength of UHPC with CPSF increased by 16.3% and 3.4%, respectively. The microstructural tests including environmental scanning electron microscope, X-ray diffraction and thermogravimetric analysis prove that, under a combined curing of 90 °C hot water and subsequent 200 °C dry-air heating, carbon dioxide chemically combined in the coating of CPSF can be released during the combined curing and react with calcium hydroxide or cement clinkers in the matrix surrounding CPSF to generate calcium carbonate and calcium-silicate-hydrate (C–S–H) gels, which is responsible for both the refinement of microstructure and enhancement of mechanical properties of UHPC. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) represents one of the promising biodegradable polymers with great potential to replace petroleum-derived plastic. In the last decade, massive efforts have been devoted to overcoming the brittleness of PLA, expecting comparable mechanical properties to traditional polyolefin and polyester. Introducing oriented texture into PLA has recently been reported to be an effective approach to improve ductility without sacrificing their high strength. However, the understanding of the mechanism is absent. Herein, we study the fracture behaviors of anisotropic PLA with oriented lamellar crystal by employing operando synchrotron X-ray scattering and diffraction. It has been found that the cavities generated parallel with stress direction can restrain the fast failure of PLA. Nevertheless, the load-carrying ability of oriented PLA lamella is still limited. On this basis, we further introduce the flexible nanofibers into an oriented PLA matrix that enables crystals to effectively participate in the stress dissipation, resulting in significant enhancement of the ductility of PLA while maintaining their high strength. Combined with morphological study by scanning electron microscope, we propose a qualitative model to describe the detailed fracture behavior of PLA with oriented texture, which may provide a reliable theoretical guideline towards further optimization of the mechanical properties of PLA. [Display omitted] • Synchrotron X-ray techniques was used to study the fracture behaviors of PLA. • Cavity along orientation direction plays important role in fracture process. • A new way for enhancing the ductility of PLA while maintaining high strength. [ABSTRACT FROM AUTHOR]

This work dealt with the fabrication of novel long glass fibre reinforced aluminum metal matrix composite (LGFRAMMC) material for automotive applications. The composite specimens were prepared by incorporating long glass fibre with different fibre volume percentage (50, 66, 80, and 100 vol.%) as reinforcement in aluminium alloy (Al6061) using the friction stir processing (FSP) method. The mechanical behaviour of the composite materials was investigated for their primary loading conditions such as tensile and Izod impact stress. Microstructural characterization and fractured mechanism of the fabricated composites were carried out by scanning electron microscope (SEM) analysis. The tensile strength and elongation of the developed composite specimens decreased with the incorporation of long glass fibre, whereas the Izod impact strength of the developed composite specimens was significantly improved as compared to the conventional base metal (Al6061) body panels used in automobiles. The low tensile strength of LGFRAMMC specimens compared to base metal was because of tunnel defect, brittle fracture and extreme plastic deformation (EPD) as characterized by fibre pull-out, pits, and micro cracks. The synergetic effects of EPD and reinforcing by long glass fibres lead to a remarkable improvement in the impact strength. [ABSTRACT FROM AUTHOR]

In this study, the water hyacinth was used as a reinforcement of green composites. The chemicals for treatment of water hyacinth are solutions of alkaline, soap and water to determine water absorption. The chemical treated process of the water hyacinth fibers ha d important influences t o the chemical structures and mechanical properties of the green composites. Micrographs analyses of scanning electron microscope (SEM) show obviously roughness of fiber surface after the ch emical tr eatment as we ll as ar rangement of st ructures among the water hyacinth fibers. Similarly, the results of analysis by Fourier transform infrared spectroscopy (FT-IR) showed that most of the intensity of the absorbed peaks was decreased markedly at the wavenumbers of 1375 cm-1 and 1542 cm-1. These a r e r e lated t o lignin extraction with alkaline solution, effectively. In particular, the compressive strength of the water hyacinth/roving composite has high value approximately to that of fiberglass composites (unfriendly composites). The water hyacinth/roving composites have significantly improvements in flexural and compressive strengths and this proves that the environmentally friendly composite responded to high requirements for various applications. [ABSTRACT FROM AUTHOR]

To reduce the pollution resulting from discarding waste plastic film and burning straw, a new method of preparing straw-reinforced LLDPE composites was developed to utilize these wastes. The straws were first laid parallel on an LLDPE film and then rolled up. The rolls containing long straws were laid into a mat and then hot-pressed into a long straw composite board (the mass of straw accounted for 60%). Slope-cutting the straw, grinding the straw, and twisting the roll were designed to improve the physical and mechanical properties of long straw composites. Among them, slope-cutting the straw combined with twisting the roll provided the best properties. Compared to the extruded straw particle composite, the composite prepared with the new method improved the tensile strength, bending strength, impact strength, and water resistance by 358%, 151%, 416%, and 81%, respectively. Slope-cutting exposed more inner surface at the end of the straw. Scanning electron microscope observations showed that the straw inner surface was more tightly bonded with the LLDPE matrix than the outer surface. Meanwhile, the integrity of the straw was retained as much as possible, and thus greatly improved the performance of the resulting composites. Dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis show that the viscous deformation of the composites prepared by the new method was reduced and the rigidity was increased, and the combination of straw and LLDPE forms a dense composite material with good interfacial bonding. It greatly slowed down the degree of its pyrolysis. [ABSTRACT FROM AUTHOR]