A Review on Friction Stir Processing Over Other Surface Modification Processing Techniques of Magnesium Alloys

An enormous amount of research is conducted on aluminium alloys on friction stir process, despite magnesium alloy reporting severe weight reduction when compared to aluminium alloys; a very slight amount of research was testified by friction stir processing of magnesium alloys. Magnesium is highly reactive and susceptible to corrosion in the presence of an aggressive environment. This highly corrosive nature of magnesium limits its applications. Surface properties like crystal structure, composition, and micro structure influence the corrosion and wear property of the material. Coating and alloying like laser surface modifications are performed to passivate magnesium surface from corrosion. Coating techniques, however were found to be insufficient in corrosion protection due to coating defects like pores, cracks, etc, and adhesion problems caused due to poor surface preparation of the substrate, and also impurities present in coating which provides micro galvanic cells for corrosion. Current study analyses the detailed overview of different types of Surface modification methods such as Physical vapor deposition, Chemical vapor deposition, Chemical conversion coating, Ion implantation coating techniques and also work focuses on few of Alloying or Surface processing methods such as Laser surface modification namely Laser surface melting, Laser surface cladding, Laser Shot Peening, Laser surface alloying and Friction stir processing (FSP). Friction stir processing a novel method derived from friction stir welding is used as surface modification method, which modifies micro structure, composition of surface layer without changing bulk properties, for enhancing corrosion resistance property. FSP enhances the micro structure and homogenizes but it is also eliminating the breaking up of the brittle- network phases and also cast micro structure imperfections. Indeed FSP can produce particle and fiber-reinforced magnesium-based surface composites. FSP empowers the manufacturing of magnesium by adding additives. Comparison of the different methods of coating and surface modification has been compared with FSP

Prediction of permeability of 5-harness satin fabric by a modified kozeny constant determined from experiments

Permeability is a critical parameter not only in flow simulation analysis but also in liquid composite molding (LCM) process. When a liquid resin is infused into a dry preform, the impregnation is mainly characterized by the permeability. The permeability of a dry preform can be obtained through theoretical and experimental methods. In the theoretical estimation of permeability, the effects of fiber arrangement as well as fabric type and form for various types of preforms are not sufficiently reflected in the calculation. Thus, there is a gap between the theoretical and experimental permeability. Recently, experimental determination has been gaining considerable attention as a mean to obtain accurate permeability values; however, it requires a number of trials. In this study, the permeability of the Hexforce G0926 5HS (5-harness satin) carbon fabric preform is estimated using representative theoretical prediction models, the Gebart and Kozeny–Carman equations. In addition to the Kozeny–Carman permeability (using the Kozeny constant values from literature), the Kozeny constant obtained through experiments was used to obtain a modified Kozeny–Carman permeability. All three calculated permeabilities were compared and verified with the fabric manufacturer’s reference value. The results showed that the modified Kozeny–Carman permeability using the experimentally determined Kozeny constant was closest to the reference value at 57% fiber volume fraction. Further, the predicted permeability was compared with other experimental permeability values from literature over the 40%–65% range of fiber volume fraction. We found that the modified Kozeny–Carman permeability once again came closest to the literature values. Finally, an optimized fitting equation was proposed to replace the Kozeny–Carman equation for predicting the permeability of Hexforce G0926 5HS carbon fabric over the 40%–65% fiber volume fraction range.

Boosted dielectric performance of organic‐inorganic nanocomposites based on BaTiO3 via 2D TiO2 templates

Organic-inorganic hybrid dielectrics composed of nanoscale ceramic fillers in polymer matrices have attracted considerable attention because they can overcome the inherent limitations such as the low dielectric constant, high dielectric loss, and low film density associated with mechanically flexible pristine polymer materials. Barium titanate (BaTiO3), a representative perovskite-based material with a high permittivity, is suitable for applications as nanofillers in nanocomposite dielectrics. X-ray diffraction combined with Raman analysis suggest that a two-step hydrothermal synthesis, which uses synthesized TiO2 nanosheets as a template, is an effective method for the synthesis of pure BaTiO3 nanoparticles compared with other methods. Ultrasonic treatment is employed to disperse BaTiO3 nanoparticles with different concentrations in polyvinyl alcohol (PVA) polymer, and the dielectric performance of the nanocomposite films has been examined. In this study, 20 wt% BaTiO3-PVA nanocomposite dielectric showed superior capacitance and dielectric constant performance, i.e., five times higher than that of the pristine PVA.

A new cure kinetics model to simulate thermomechanical behavior of polymeric sealants for automotive applications

Accurate prediction of the cure level of thermoset polymers is essential to simulate the thermomechanical behavior of polymeric thermoset sealants, which is strongly dependent on cure level. Conventional cure kinetics models, however, fail to accurately predict the cure levels of thermoset sealants subjected to a complex temperature program. Herein, we propose a new cure kinetics model that greatly enhances cure level predictability by considering temperature derivatives. The validity of our model was verified by simulating the thermomechanical behavior of a polymeric sealant using a user material subroutine (UMAT) of ABAQUS software. Experimental results from an appropriately designed thermomechanical test were compared with simulation results obtained from the UMAT.

Study the effect of Nano Zro2 and Tio2 and rotation speed on friction behavior of rotary friction welding of HIPS and P.P

the purpose of this project was to introduce a way to improve the mechanical properties of welded dissimilar material, which gives benefits such as affordable, high speed, and suitable bond property. In this experimental project, the friction welding method has been applied, including combining parameters, such as numerical control (NC) machine including two different speeds, and three different cross-sections; including flat, cone, and step surfaces. When the welding process was done, samples were implemented and prepared via bending test of materials. the results have shown that, besides increasing the machining velocity, the surface friction increased, and so did the temperature. By considering the stated experimental facts, the melting temperature of composite materials has increased. This provides the possibility of having a better blend of nanomaterial compared to the base melted plastics. Thus, the result showed that, besides increasing the weight percentage (wt %) of Nanomaterials contents and machining velocity, the mechanical properties have increased on the welded area for all three types of samples. This enhancement is due to the better melting process on the welded area with attendance of various Nanoparticles contents. Also, the results showed that the shape of the welding area could play a significant role, and the results also change drastically where the shape changes. Optimum shape in the welding process has been dedicated to the step surface. The temperature causes the melting process, which is a significant factor in the friction welding process.

Study of mode II interlaminar fracture toughness of laminated composites of glass and jute fibres in epoxy for structural applications

Composites are being used in the place of metals in many industries as they have a lower density and are cheaper than metals. In aerospace industries there is requirement for light weight together with strength, and reinforced fibre composites are superior in some critical properties compared with metals. In this study, laminated composites were fabricated with woven E-glass and jute fibres in an epoxy matrix by a hand layup method. The samples were prepared as per the relevant the America Society for Testing ad Materials (ASTM) standard and tested for mode II interlaminar fracture toughness to investigate delamination resistance. Mode II interlaminar fracture toughness was evaluated by an end-notched flexure test using three-point bending. The fracture toughness G IIC was calculated for a curing temperature range from 40 °C to 70 °C at intervals of 5 °C for different sets of laminated composites. The investigations revealed that when the curing temperature of laminated composites was increased from 40 °C to 70 °C, the interlaminar fracture toughness G IIC was increased in neat woven E-glass laminated composites, decreased in neat jute laminated composites, significantly increased in laminated composites with woven E-glass fibres in compression and jute fibres in tension and slightly increased when woven E-glass fibres were kept in tension and jute fibres in compression.

Interfacial Engineering for Design of Novel 2D Cobalt Sulfide-Mxene Heterostructured Catalyst Towards Alkaline Water Splitting

In this work, we used an interfacial engineering method to investigate a novel hybrid of two-dimensional cobalt sulfide-Mxene (2D CoS-Mo2TiC2) heterostructure supported by a three-dimensional foam substrate. The modification electronic properties caused by unique interfacial interactions resulted in a significant increase in the number of electroactive sites and charge transfer ability, thereby accelerating kinetics of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. The catalyst required overpotential of 248.2 and 310 mV at a current response of 50 mA cm-2 for HER and OER, respectively, along with a remarkable stability. In addition, a two-electrode electrolyzer derived from the developed 2D CoS-Mo2TiC2 catalyst showed a cell voltage of 1.74 V at 10 mA cm-2 and a good stability during 25 h continuous operation. The achieved results were associated to the formation of a unique interfacial heterostructure with the strong interaction between two material phases, which effectively modified electronic structure and surface chemistry, thereby leading to the enhancement of catalytic performance. The study offered a potential route to synthesize new catalyst for green hydrogen production via water splitting.

The influence of Human Hair on Kenaf and Grewia Fibers based Hybrid Natural Composite Material: An Experimental Study

The demand for natural composite products is continuously increasing to make various industrial and commercial products to protect the environment. In this paper, the Hybrid Plant Fiber composite (HPFC) is produced using 64 wt.% of the resin matrix and 36 wt.% of natural fibers (Kenaf, Grewia, and Human hair) by hand layup moulding method. The influences of natural fiber’s weight on tensile, flexural, and impact strengths were investigated by the simplex lattice method. It was revealed that the percentage of contribution of Kenaf and Human hair fibers is higher on Tensile strength, Flexural, and Impact strengths than Grewia fiber. The optimum weight percentage of fibers: 13.5 wt.% of Kenaf, 15.3 wt. % of Human hair and 7.2 wt.% of Grewia of fibers weights have been used to produce desirable mechanical strengths of HPFC. The mechanical properties of HPFC have been compared to HPFC without Human hair. Tensile, flexural, and impact strength of HPFC is 17.95%, 11.1%, and 19.79% higher than the HPFC without Human hair. The predicted optimum HPFC is recommended to make commercial products for fulfilling consumer demand.

Antibacterial and physical characteristics of silver loaded hydroxyapatite/alginate composites

The influence of silver ions on antibacterial properties and morphology of Hydroxyapatite-Ag (HА-Ag) and Hydroxyapatite-Alginate-Ag (HA-Alg-Ag) nanocomposites was studied. The microstructure and phase composition of the obtained nanocomposites were investigated by SEM, TEM, XRD, FTIR methods, and the formation of the crystalline phase of Ag3PO4 was proved. According to the results, silver ions were incorporated into the HA structure, partially replacing calcium ions. The antimicrobial activity assessment was carried out on Gram-negative (Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus) test cultures by the co-incubation and modified «agar diffusion» methods. We have demonstrated that antimicrobial and adhesive properties of both Ag-HA and HA-Alg-Ag are strongly affected by the crystal lattice structure, controlled by silver ions location. The composite materials could be of great interest in the biomedical field, including the design of coatings that prevent or lag the bacterial biofilm development.

Photocatalytic application of Graphene oxide-ZnO nanocomposite for the reduction of methylene blue dye

The Graphene Oxide (GO) and GO-Zinc Oxide (GO-ZnO) nanocomposite were prepared using simplified techniques with modified Hummer’s and solvothermal methods for photocatalytic application. In a comparative study, the optimized geometries, binding energies, electronic properties, non-linear optical properties and density of states of GO-ZnO were calculated using density functional theory (DFT) calculations with B3LYP method at 6-31G (d,p) and LanL2DZ basis sets to examine the binding site of a methylene blue (MB) dye systematically. The result of Natural bond orbital (NBO) analysis revealed the effective charge transfer and also explained the mechanism and efficiency of the photocatalytic activity of GO-ZnO. Density of states supported the strong interaction of MB with the GO-ZnO leading to the degradation of the MB dye. The attained theoretical results depict the existence of n → σ*, n → n* and σ → σ* interactions, improved charge transfer, reduced band gap which establish the use of GO-ZnO in the visible light photocatalytic performance. Characterization methods such as XRD, FTIR and UV were carried out to support our theoretical results. The XRD results confirmed the particle size of 21 nm with inter layer spacing of 0.87 nm. FTIR spectroscopy indicated the characteristic bands related to the elements in GO-ZnO. The higher electrical conductivity is studied using UV-Vis spectral analysis. The calculated results show good agreements with experimental observations reveal that the GO-ZnO has good photocatalytic behavior.