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This work presents surface nanocomposites of aluminum alloy AA1050, reinforced with zirconium oxide (ZrO2) nanoparticles developed through multipass friction stir processing (FSP). This article attempts to study the effects of the number of passes on the wear rate, microhardness profile, tensile properties, and macrostructure of surface nanocomposites. The results demonstrate that an improved distribution of ZrO2 nanoparticles is obtained following each FSP pass, and that the number of passes increases with a decrease in stir zone (SZ) grain size. Consequently, it was found that applying FSP passes continuously enhances the materials' microhardness and tensile characteristics. In the microstructure development of the stir zone during the ZrO2 nanoparticle FSP, dynamic recrystallization (DRX) was an essential mechanism. The main reason for this is that surface nanocomposites with homogenous ZrO2 particle dispersion and no discernible particle clustering in the stir zone were shown by microstructural studies conducted through FSP, which significantly reduced the matrix grain size. The AA1050 base metal (BM) has an ultimate tensile strength, yield strength, and hardness of 59.2 MPa, 24 MPa, and 30.1 respectively. The nanocomposite generated by 5 FSP passes exhibits improved yield stress (55 MPa), tensile strength (94.5 MPa), and microhardness (86.5 HV), but its tensile ductility decreased from 34% to 23.8% when compared to the base metal. Tensile strength that is higher is the outcome of fine dimples' ability to pin the dislocation movement during tensile loading. According to fractographic studies, the ductile–brittle mode replaced the dimple-shaped ductile fracture mode.Highlights: ZrO2/AA1050 surface nanocomposites were produced by multipass FSP. Significant strength and microhardness are demonstrated by the ZrO2 nanoparticle reinforcement build, along with a refined microstructure. The results demonstrate the potential of FSP in producing composite materials for specific functional requirements. [ABSTRACT FROM AUTHOR]

Electrospinning is a well-established technique for creating submicron polymer fibers to create distinctive functional nanostructures. Electrospinning parameters including solution concentration, tip-to-collector distance and applied voltage are adjusted to produce nonwovens with variable fiber diameter distributions. This research on the response surface methodology (RSM) is being used to model the diameter of a polyamide-6,6 (PA-6,6) nanofiber mat. The experiments were designed using central composite design (CCD) and RSM, which evaluated the interactions between the operating variables (polymer concentration, applied positive voltage, needle tip to collector distance and spinning angle) on the diameter of the PA-6,6 nanofiber. The average nanofiber diameter increased as the concentration of the PA-6,6 polymer solution increased. The model's strong regression coefficient ( R 2 = 0. 9 8) reveals that it did a desirable of predicting the diameter of PA-6,6 fibers. The experimental findings and predicted fiber diameters were in good agreement. The results demonstrate that the optimization of electrospinning process to produce the smallest nanofibers and narrowest diameter distribution (1 8 3 ± nm) combined effects of 10% polymer concentration, 21 kV applied positive voltage, 18 cm needle tip to collector distance and 60 ∘ spinning angle are substantial interacting effects that have an impact on the surface response nanofibers. The results of the research and several mathematical models will offer useful guidelines for choosing parameter settings for electrospinning PA-6,6 to achieve the required fiber diameter. By saving time, effort and money more effectively, this research will expand the field of investigation for the quality of electrospun nanofibers. Electrospinning is an established technique for creating submicron polymer fibers to create distinctive functional nanostructures. For the manufacture of nonwovens with variable fiber diameter distributions, electrospinning variables such as solution concentration, tip-to-collector distance, and the applied voltage were modified. [ABSTRACT FROM AUTHOR]

The present study is an attempt to optimize the electrospinning parameters to fabricate chitosan/polyethylene oxide hybrid nanofiber composite with minimum diameter and coefficient of variation (homogeneity) by using response surface methodology (RSM). Based on central composite design (CCD), four factors (the chitosan/PEO ratio, the applied voltage, the needle-to-collector distance, and the spinning angle) was applied to evaluate the individual and combined effects of the parameters on the average diameter of nanofibers. Chitosan (CH) was blended with Polyethylene oxide (PEO) at weight ratios of 1:1, 2:1, 3:1, 4:1, and 5:1. As the composition ratio of chitosan was reduced, the viscosity of the chitosan/PEO blend solution also dropped. The RSM model identified the following conditions as necessary to produce the desired and most uniform CS/PEO fiber diameter: a CS/PEO blend ratio of 2:1 (w/w), a voltage of 25 kV, a distance of 20 cm, and a spinning angle of 45°. The average nanofiber diameter and homogeneity under these conditions were calculated to be 73 nm and 20.5%, respectively, compared to the predicted values of 71 nm and 15.58%, respectively. [ABSTRACT FROM AUTHOR]

The present study is an attempt to fabricate composite nanofiber mats from polystyrene (PS) loaded with exfoliated graphite nanosheets (EGNS) by using electrospinning technique. EGNS with different weight ratios of 3, 6, and 9 wt.% were added to PS (20 wt.%). The fiber diameter and morphology of the composite nanofiber mats were investigated by scanning electron microscopy (SEM). Results revealed that as EGNS concentration was increased, the average diameter of EGNS/PS electrospun nanofibers decreased. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate the thermal properties. The tensile strengths and Young's modulus of the composites improve with the increasing EGNS concentrations compared to PS nanofiber, which indicates 84% and 88% augmentation, respectively at 6 wt.% of EGNS. Also, the addition of EGNS increased thermal stability of composite nanofiber mats. [ABSTRACT FROM AUTHOR]

In this work, friction stir processing (FSP) was used to successfully embed boron carbide (B4C) particles into an aluminum matrix (AA6061-T6). Four specimens of aluminum 6061 composite reinforced with 4%, 6%, 8%, and 10% volume fraction of B4C were manufactured. The effects of B4C particles volume fraction on microstructure, mechanical and wear properties are investigated. The microstructural investigations demonstrated that a rise in the volume % of reinforcement greatly decreased the matrix grain size. The manufactured AA6061-T6 loaded with B4C surface composites demonstrated homogeneous B4C particle dispersion, with no significant particle clustering in the stir zone. In addition, it was established that increasing the volume fraction of B4C particles promoted grain refinement, increased hardness, and tensile strength. X-ray diffraction (XRD) was used to identify the reinforcement dispersion. For AA6061-T6 with 10% B4C particles, a maximum hardness value of 163 HV was obtained in the stir zone. Maximum yield strength of 165 MPa and ultimate tensile strength of 220 MPa were attained by AA6061-T6 with 10% B4C particles, which is an improvement of 21% over the specimen FSP without reinforcement. The strengthening of the grain refining was attributed for the increase in hardness and strength. The ductility was reduced by the incorporation of more B4C particles. Comparing the surface composite loaded with B4C to unreinforced friction stir processing and AA6061-T6 as received, it demonstrated superior wear resistance. [ABSTRACT FROM AUTHOR]

Basalt fiber was first treated in a mixture of formic acid (FA) and dichloromethane (DCM) to reduce its diameter down to one micrometer. Electrospinning process was utilized to produce treated basalt fiber (TBF)-reinforced nylon 6,6/epoxy (NY/EP) hybrid nanofibril composites. NY/EP polymers have been dissolved in 80:20 mixture of FA/DCM solvent to form a homogenous solution. TBFs with different weight ratios of 5, 10, 15, 20, and 25 wt% were added to NY/EP (ratio of 5:1). The morphology of the hybrid nanocomposites was investigated by scanning electron microscopy and their compositions were analyzed using energy-dispersive X-ray spectroscopy. The thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties of the hybrid nanocomposites, including tensile strength and modulus, are improved with respect to NY/EP hybrid nanofibers. An increase of 76% and 87% in tensile strength and Young's modulus was acquired, respectively, at 15 wt% of TBF. Also, the addition of TBF increased the thermal stability of nanofibril composites. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM),based on five‐level, four variable Box‐Benkhen technique was investigated for modeling the average fiber diameter of electrospun polyacrylonitrile (PAN) nanofibers. The four important electrospinning parameters were studied including applied voltage (kV), Berry's number, deposition distance from nozzle to collector (cm), and spinning angle (Ѳ in degree). The measured fiber diameters were in a good agreement with the predicted results by using RSM technique. High‐regression coefficient between the variables and the response (R2 = 87.74%) indicates excellent evaluation of experimental data by second‐order polynomial regression model. The optimum PAN average fiber diameters of 208 and 37‐nm standard deviation were collected at 19 kV, Berry's number = 10, 25° spinning angle, and 16‐cm deposition distance. The PAN/N,N‐dimethylformamide (DMF) polymer solution with the optimum weight concentration (10 wt.%) was selected to study the effect of dispersing exfoliated graphite nanoplatelets (EGNPs) in PAN/DMF solution on the electrospun EGNP/PAN fibril composite diameter. Five different EGNPs weight concentrations (2, 4, 6, 8, and 10 wt.%) were dispersed in the optimized PAN/DMF polymer solution. Morphology of EGNPs/PAN fibril composites and its distribution were investigated by scanning electron microscopy (SEM) to show the minimum fiber diameter for the above‐mentioned 5 wt. % of EGNPs. A minimum fibril composite diameter of 182 nm was obtained at 10 wt.% of EGNPs. Morphological characteristics of electrospun fibers and their distribution were tested by Raman spectroscopy, SEM, differential light scattering, and high‐resolution transmission electron microscopy. [ABSTRACT FROM AUTHOR]

In this work, electrospinning technique has been used to produce a new ultra-fine hybrid fiber from a solution consists of polystyrene (PS) and epoxy polymers in dimethylformamide (DMF) solvent. Five ratios of different weight percentages of epoxy in PS/DMF solutions of 4 different concentrations; 15, 20, 25 and 30 wt.% were made to obtain the minimum diameter of the produced hybrid fiber. The minimum obtained hybrid fiber diameter was found to be 897 ± 239 nm at a PS/epoxy ratio of 5:1 and 13.33 Berry's number. Adding epoxy to PS has reduced the electrospun fiber diameter from 2.64 ± 0.49 μm for PS only to 1.52 ± 0.72 μm for PS/epoxy hybrid ultra-fine fibers because of the reduction in Berry's number from 12.4 to 11.53, which gives an indication for the effect of adding epoxy on the PS molecular chain entanglement in DMF. Nuclear magnetic resonance spectroscopy results unambiguously reveal the coexistence of both epoxy and PS polymers in the hybrid fiber. We hypothesize that a hydrophopic (π-π) interaction between the benzene rings of PS and epoxy polymers could contribute to the stability of the resulting hybrid fiber under electrospinning conditions. The fact that the lack of functional groups on both of PS and epoxy polymers that can results in covalent bonding or crosslinking between the 2 polymers supports the hypothesis of hydrophopic (π-π) interaction in the stability of the hybrid fiber. Such (π-π) interaction is well known to contribute to DNA single strand helical structure via intrastrand staking of the consecutive purine and pyrimidine nucleobases. [ABSTRACT FROM AUTHOR]