Effects of the Interfacial Bonding Behavior on the Mechanical Properties of E-Glass Fiber/Nanographite Reinforced Hybrid Composites

The nanoparticles are incorporated into the composite to mark their unique properties. This work investigates the hybrid epoxy nanocomposite and the impact of nanographite reinforcement. The composite was prepared by using a mechanical stirring technique. The amount of nanographite was added in different volumes, i.e., 1.0, 1.5, and 2.0 wt.%. Results of mechanical and dynamic loading properties were analyzed in accordance to the quantity of nano-G. The fiber and matrix interfacial bonding enrichments were evident in high-resolution SEM images-tensile fracture surface. Finally, the optimum content of nanoparticle which impacts the sample greatly was found to be 1.5 wt.%.

Study on Micro - Nano Sized Al2O3 Particles on Mechanical, Wear and Fracture Behavior of Al7075 Metal Matrix Composites

Having Low density and being Light weight with better mechanical properties, aluminum is the most significant material and is universally used in highly critical applications like navy, aerospace and particularly automotive activities. This research work is aimed to investigate the effect of micro and nano boron Al2O3 (Alumina Oxide) to aluminium (Al) on the mechanical and wear properties of the Al composites. The micro - nano composites with 1, 2, 3 and 4 % of Al2O3 particulates in Al are fabricated using stircasting processes. It was found that an increase of Al2O3 both as micro and nano particulates content resulted in an improved hardness, enhanced tensile strength and high wear resistance. However, nano Al2O3 reinforced MMCs have better hardness, improved tensile strength and higher wear resistance as compared with micro sized Al2O3 reinforced MMCs. Grain refinement of composite and nano composite materials as compared with pure Al were observed from the microscopic images. Analysis of wornout surface and tensile fracture surface were studied by SEM analysis to examine the nature of wear and tensile fracture mode of composite samples.

Comparison in Deformation Behavior, Microstructure, and Failure Mechanism of Nickel Base Alloy 625 under Two Strain Rates

Tensile deformation behavior and microstructure of nickel-base superalloy Inconel 625 are investigated under different strain rates of 5 × 10−4 s−1 and 5 × 10−5 s−1. According to the experimental results, yield strength and ultimate tensile strength of the alloy increase with the increase in strain rate in room temperature. Microstructure results indicate that the size of dimples is smaller in the tensile fracture surface at low strain rate than the high strain rate, and the number of dimples is also related to the strain rates and twins appear earlier in the specimens with higher strain rates. Apart from Hollomon and Ludwik functions, a new formula considering the variation trend of strength in different deformation stages is deduced and introduced, which fit closer to the tensile curves of the 625 alloy used in the present work at both strain rates. Furthermore, the Schmid factors of tensile samples under two strain rates are calculated and discussed. In the end, typical work hardening behavior resulting from the dislocations slip behavior under different strain rates is observed, and a shearing phenomenon of slip lines cross through the δ precipitates due to the movement of dislocations is also be note.

Static Mechanical, Thermal Stability, and Interfacial Properties of Superheated Steam Treated Oil Palm Biomass Reinforced Polypropylene Biocomposite

In this study, three types of oil palm biomass (OPB) namely, oil palm mesocarp fiber (OPMF), oil palm empty fruit bunch (OPEFB) and oil palm frond (OPF), were studied and compared as the alternative fillers in the biocomposite reinforced polypropylene (PP). The fibers were treated using the optimal condition of superheated steam treatment obtained from previous study. The OPB/PP biocomposites at weight ratio of 30:70 were fabricated by melt blending technique and hot pressed moulding. Results showed that the tensile and flexural properties of optimized-SHS-treated OPB/PP biocomposites were improved by 9 – 30% and 9 – 12%, respectively compared to the untreated OPB/PP biocomposites. The same observation was recorded for thermal stability. Improved surface morphology as shown by the tensile fracture surface indicates better interfacial adhesion between SHS-treated OPB fibers with PP matrix during blending. Overall results showed that OPF/ PP biocomposites had better properties compared to biocomposites prepared from OPMF and OPEFB, suggesting that OPF is a better OPB fiber choice as a filler in PP reinforced biocomposite.

Improved mechanical and viscoelastic properties of CNT-composites fabricated using an innovative ultrasonic dual mixing technique

Carbon nanotube (CNT) acts as the most promising nanofiller due to its high aspect ratio and exceptional nanoscale-level properties. However, the dispersibility of CNTs in the conventional polymer matrices is a very critical issue in developing the high-strength and light-weight polymer-based nanocomposites. In this study, an attempt was made to develop cluster-free and uniform dispersion of multiwalled carbon nanotubes (MWCNTs) in the epoxy matrix using an innovative ultrasonic dual mixing technique. The effect of dispersion of MWCNTs on the mechanical and viscoelastic properties of MWCNT-epoxy nanocomposites was comprehensively studied. Our results reveal that the tensile strength and toughness of epoxy nanocomposites with 0.50 wt.% of MWCNTs improved by 21% and 46%, respectively, as compared to neat epoxy. The nanocomposite samples with the same CNT loading show maximum enhancements of 22% and 26% in the lap shear strength and storage modulus, respectively. The tensile fracture surface examination of MWCNT-epoxy nanocomposites using field emission scanning electron microscopy indicated the cluster-free and uniform dispersion of MWC-NTs in the epoxy matrix.

Microstructure and Mechanical Properties of Tungsten Inert Gas Weld Joints of Sprayed and Cast Aluminium–Lithium Alloy

The weld joints of sprayed 2195-T6 and cast 2195-T8 aluminium–lithium alloy were created using tungsten inert gas with filler wire. The microstructures and mechanical properties of the weld joints were examined. The results of the microstructure analysis showed that the width of the equiaxed grain zone (EQZ) and the amount of the second phase θ’(Al2Cu) was greater in the weld joint of the cast 2195-T8 Al–Li alloy than that of the sprayed 2195-T6 Al–Li alloy. Tensile testing indicated that failures occurred in the EQZ and partially melted zone (PMZ) for both weld joints. The tensile strength and elongation of the weld joints of the sprayed 2195-T6 and cast 2195-T8 Al–Li alloys were about 68.2%, 89.7%, and 50.7% and 28.3% those of the base metal in the joint, respectively. The cast 2195-T8 Al–Li alloy joint had more pores and cracks, resulting in lower tensile strength and elongation than those in the sprayed alloy. Further, the tensile fracture surface morphology indicated that the fracture mode of the sprayed 2195-T6 Al–Li alloy was a mixed fracture mode dominated by plastic fracture and that of the cast 2195-T8 Al–Li alloy joints was a mixed fracture mode dominated by brittle fracture.

Evolution of microstructure and elevated-temperature properties during hot rolling and post-rolling annealing process in Al-Mg-Si 6082 alloys

In the present work, the hot rolling at 400°C and post-rolling annealing at 500°C were applied on heat-treated Al-Mg-Si 6082 alloys with different Mn contents to study the evolution of microstructure and elevated-temperature properties. During the pre-heat treatment before rolling (400°C/2h), a number of fine rod-like dispersoids formed in Mn-containing alloy while only high volume of larger Mg2Si particles was observed in the matrix of base alloy free of Mn. After hot rolling, the morphology of dispersoids was transferred from rod-like to spherical with finer size and increased number density while the dispersoids gradually coarsened during post-rolling annealing in Mn-containing alloy. The full recrystallization was completed after 1-2 h during annealing in the base alloy, while only partial recrystallization was observed in Mn-containing alloy. The micro-hardness at room temperature and the tensile yield strength at 300°C firstly increased from as-rolled condition to the initial stage of annealing (1 h) for both alloys, which was likely attributed to the dissolution of Mg2Si during the beginning of annealing. With further increasing annealing time (2-8 h), both the microhardness at room temperature and the elevated-temperature strengths of the base alloy remained similar, while they were slightly decreased in Mn-containing alloy owing to the partially recrystallization and coarsening of dispersoids. However, the elevated-temperature strengths were always higher in Mn-containing alloy than the base alloy while their differences between two alloys was reducing with prolonging the post-rolling annealing time. The tensile fracture surface was observed to be ductile for all the conditions of both alloys but the dimples in Mn-containing alloy were finer and much more uniformly distributed.

Physico-mechanical properties of bio-composites fabricated from polylactic acid and rice husk treated with alkali and ionic liquid

In the present work, chemically treated rice husk (TRH) and untreated rice husk (UTRH) reinforced polylactic acid (PLA) bio-composites were produced using Haake rheomixer and compression moulding processes. Alkali (NaOH) and ionic liquid (IL: 1-ethyl-3-methylimidazolium acetate) treated rice husk samples are TRHN4 and TRHILN4 respectively. Using UTRH, TRHN4 and TRHILN4 the fabricated bio-composites are UTRH-PLA, TRHN4-PLA and TRHILN4-PLA respectively. The tensile strength (TS), tensile modulus (TM), impact strength (IS) and hardness values of TRHN4-PLA and TRHILN4-PLA were found to be much higher than the corresponding values of the UTRH-PLA bio-composites. The tensile fracture surface morphological features of TRHN4-PLA and TRHILN4-PLA composites, observed by scanning electron microscopy (SEM), revealed less micro voids and fibre agglomerates, which indicates that better filler-matrix interfacial adhesion occurred in the case of chemical treated RH compared to UTRH when blended with PLA. However, composites TRHN4-PLA and TRHILN4-PLA showed lower water uptake capacity compared to UTRH-PLA. From the FTIR spectra of UTRH, TRHN4 and TRHILN4 together with water absorption behaviour of the composite specimens, it appeared that chemical modifications significantly reduced the hydrophilic nature of RH, resulting in improved fibre-matrix interfacial adhesion. The overall physico-mechanical properties of fabricated bio-composites were found to follow this order: TRHILN4-PLA>TRHN4-PLA>UTRH-PLA.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of a Composite Made of Al-Si-Cu-Mg Aluminum Alloy Reinforced with SiC Particles

In this paper, the effect of heat treatment (solution treatment and artificial aging) on the microstructure and properties of as-cast Al5Si1Cu0.5Mg aluminum alloy and its composite reinforced with 1.5 wt.% SiC particles was studied. The results showed that at 520 °C the optimal solution time for the aluminum alloy and its composite is 9 h and 6 h, respectively. After solution treatment, the microstructure of these two materials consists of a uniform distribution of nearly spherical eutectic Si and skeletal γ phase, furthermore, the composite eutectic Si phase is smaller and γ phase is more dispersed. After artificial aging at 175 °C for 6 h, the microstructure of the composite is more dispersed and finer than that of the aluminum alloy on the whole and Al2Cu is precipitated. After heat treatment, the microhardness, ultimate tensile strength, and elongation of the aluminum alloy and its composite are higher than those of the as-casts. At the same time, the morphology of tensile fracture surface changes very much from a large area of cleavage plane to a large number of dimples and the tearing ridges become thicker for both the aluminum alloy and its composite.

Flammability, Smoke, Mechanical Behaviours and Morphology of Flame Retarded Natural Fibre/Elium® Composite

The work involves fabrication of natural fibre/Elium® composites using resin infusion technique. The jute fabrics were treated using phosphorus-carbon based flame retardant (FR) agent, a phosphonate solution and graphene nano-platelet (GnP), followed by resin infusion, to produce FR and graphene-based composites. The properties of these composites were compared with those of the Control (jute fabric/Elium®). As obtained from the cone calorimeter and Fourier transform infrared spectroscopy, the peak heat release rate reduced significantly after the FR and GnP treatments of fabrics whereas total smoke release and quantity of carbon monoxide increased with the incorporation of FR. The addition of GnP had almost no effect on carbon monoxide and carbon dioxide yield. Dynamic mechanical analysis demonstrated that coating jute fabrics with GnP particles led to an enhanced glass transition temperature by 14%. Scanning electron microscopy showed fibre pull-out locations in the tensile fracture surface of the laminates after incorporation of both fillers, which resulted in reduced tensile properties.