Ultimate Tensile Strength Of Composites Research Articles

Regulating the mechanical properties of (μm B4C+nm SiC)/7075Al composites via nano-SiC content

In this study, micron B4Cp (m-B4Cp) and nanometer SiCp (n-SiCp) reinforced 7075Al composites were prepared by high-energy ball milling, hot press sintering, and hot extrusion. The microstructures and mechanical properties of composites were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile testing, and synchrotron radiation computed microtomography (SR-μCT). The results showed that n-SiCp and m-B4Cp were uniformly distributed in the aluminum matrix without interfacial reaction. The optimal grain refinement was achieved by adding 1.5 wt% n-SiCp, improving the strength and ductility of composites. The room temperature yield strength (YS) and ultimate tensile strength (UTS) of M5N1.5 composites were increased from 350 MPa and 401 MPa of 7075Al to 460 MPa and 502 MPa, respectively. The results revealed that the YS and UTS of composites were decreased, but elongation was increased with increasing temperature. When the temperature increased to 200 °C, the elongation of 7075Al and M5N1.5 was increased from 5.9 % and 4.7 % to 8.7 % and 10.9 %, respectively. Quantitative analysis revealed that dislocation strengthening and grain refinement strengthening caused by the addition of n-SiCp are the dominating strengthening mechanisms at both room and high temperature, while the contribution of m-B4Cp to the strengthening of the composites is very small.

In situ synthesis and characterization of TiB2/FeMnAl metal matrix neutron absorption composites

A novel in-situ TiB2/FeMnAl metal matrix composites with different Mn content have been prepared and characterized. The effects of the Mn content on the microstructure evolution and performances were discussed. In all fabricated FeMnAl metal matrix composites, the in-situ TiB2 particles were dispersedly distributed in austenite matrix after hot rolling and annealing. Significantly, no eutectic M2B (M = Fe, Mn) boride formed along grain boundaries in all composites that shows the excellent hot workability. The tensile strength and elongation after fracture of the all composite above 20 wt% Mn are more than 750 MPa and 12 % at room temperature, respectively. The ultimate tensile strength of composites with 20 wt% Mn can maintain above 560 MPa at 500 °C. The shielding properties was also investigated by Monte Carlo method, and this designed composites are expected to be well materials for practical application.

GO/MgO/Mg interface mediated strengthening and electromagnetic interference shielding in AZ31 composite

More requirements of electromagnetic interference (EMI) shielding performance are put forward for lightweight structural materials due to the development of aerospace and 5G communications. Herein, graphene oxide (GO) decorated with SnO2 coating is introduced as reinforcement into AZ31 Mg alloy. During the smelting process, the MgO layer is in situ gernerated at interface between GO and the molten Mg alloy matrix by consuming SnO2. In the solid state, such kind of interface structure can improve the GO-Mg interface bonding intensity, also significantly generate stacking faults. The AZ31 composite reinfoced by trace modified GO (0.1 wt%) exhibits high ultimate strength and almost the same elongation with AZ31 alloy. Compared with AZ31 alloy, the yield strength and ultimate tensile strength of composite are increased by 33.5% and 23.7%, respectively. Meanwhile, the multi-level electromagnetic reflection from the multi-layer structure of GO and the interface polarization caused by the MgO mid-layer can significantly improve EMI shielding performance. The appropriate interface design strategy achieves the effect of “two birds with one stone”.

Design, fabrication, and testing of CVI-SiC/SiC turbine blisk under different load spectrums at elevated temperature

Abstract In this article, design, fabrication, and testing of SiC/SiC turbine blisk with the fiber’s preform of Spider Web Structure (SWS) subjected to different load spectrums at elevated temperature are conducted. Micro-CT scans are conducted to show the fibers preform and defects inside the SWS-SiC/SiC turbine blisk. For 2D plain-woven SiC/SiC composite under monotonic tensile loading at an elevated temperature of T = 900°C in air atmosphere, the composite ultimate tensile strength is σ uts = 200 MPa with the fracture strain ε f = 0.36%. For SWS-SiC/SiC turbine blisk under the rotation testing, the first and second order natural frequency of the SWS-SiC/SiC turbine blisk are tested using the laser vibration meter. Relationships between the rotation speed, internal damage, and the natural frequency degradation of the SWS-SiC/SiC turbine blisk are established. Under the maximum rotation speed of n = 17,000 rpm at the exhaust temperature of T = 930°C, no damage occurred in the SWS-SiC/SiC turbine blisk. However, multiple coating spalling occurred due to the thermal-chemical coupling failure of the coating under flame impingement. The first natural frequency of the SWS-SiC/SiC turbine blisk decreases by 5% with the increase in the rotating speed from n max = 85,000 rpm to n max = 105,000 rpm, which indicates that there is an internal damage in the SWS-SiC/SiC turbine blisk, which leads to the decrease in the stiffness of the blisk.

Tribological Analysis and Characterization of Zinc Rich Al/Si3N4 Composites Fabricated Via Ultrasonic Assisted Stir Casting Technique

ABSTRACT In the present word, there is a need to minimise the fuel consumption because of the limited resources to beat this demand of aluminium metal matrix composite tremendously performing in the automobile sector, aircraft and various industry. In the present research, an attempt has been made to develop a composite using silicon nitride as a reinforcement (2 wt.%, 4 wt.%, 6 wt.%) in aluminium alloy matrix via ultrasonic stir casting route. After characterisation of composite and optimising the wear parameter, the conclusion was drawn as the maximum ultimate tensile strength (UTS) obtained 6 wt.% composite was tested as 157 MPa. There was 23.15% improvement in UTS when addition of 2 wt.% particle in Al alloy and 65.26% increment in strength when compare 6 wt. % composite UTS to pure alloy. The minimum wear rate was found to be 0.0011 mm3/m at the load of 10 N, 6 wt.% Si3N4 reinforcement, 2.094 m/s sliding velocity and sliding distance as 700 m.

Experimental Study on the Axial Tensile Properties of FRP Grid-Reinforced ECC Composites.

The axial tensile properties of FRP mesh-reinforced ECC composites (TRE) were investigated experimentally under the consideration of four influencing factors: grid type, number of reinforcement layers, ECC matrix thickness, and sticky sand treatment on the grid surface. The test results showed that the axial stiffness and tensile strength of the composite were significantly increased, and the tensile properties were significantly improved under the effect of FRP grid reinforcement. Increasing the thickness of the ECC matrix can obviously improve the crack resistance of composites. The ultimate tensile strength of FRP lattice-reinforced ECC composites increased significantly with the increase in the number of lattice layers, but had no significant effect on the crack resistance. The tensile properties of CFRP grid-reinforced ECC composites were slightly better compared to BFRP grid-reinforced ECC composites. The crack resistance and ultimate tensile strength of the composites were slightly improved by impregnating the surface of the FRP grid with adhesive-bonded sand treatment. Based on the experimental data, the tensile stress–strain constitutive model of FRP grid-reinforced ECC composites is established. The calculation results show that the theoretical values of the model agree well with the experimental values. Therefore, it can be used to reflect the stress–strain change state of FRP lattice-reinforced ECC composites during axial tension.

Influence of aging treatment on mechanical properties of CNT/Al–Cu–Mg rolled composites

Influence of aging treatment on mechanical properties was investigated in the CNT/Al–Cu–Mg rolled composites. The tensile strength of composites was strongly dependent on the aging annealing treatment, and stronger aging effect was observed in the composites compared with matrix alloy. The ultimate tensile strength was highest in the CNT/Al–Cu–Mg composites with peak-aging treatment, however, it sharply decreased when samples were over-aged. In addition to the load transfer and grain refinement, CNTs addition introduced strong back stress, and the aging nanoprecipitation strengthening promoted the strain hardening capability, which both significantly improved the ultimate tensile strength of composites.

Improving mechanical properties of nano-sized TiC particle reinforced AA7075 Al alloy composites produced by ball milling and hot pressing

Considering commonly employed carbide particles, titanium carbide (TiC) is regarded as an excellent reinforcement material due to its superior physical and mechanical characteristics and particularly appropriate interfacial bonding (wetting) ability with aluminum. In this study, 5 wt.% nanoparticle titanium carbide (TiCNP) reinforced AA7075 alloy composites were produced by ball milling and hot pressing. The effects of milling time (15 min, 1 h, 1.5 h, 2 h, 10 h) on the morphologic and crystallographic properties of powders were characterized by scanning electron microscopy, particle size analysis, X-ray diffraction, and high-resolution transmission electron microscopy. It was observed that particle size and morphology varied with milling time. The results indicated that the TiCNP were gradually dispersed into the matrix as ball-milling time increased and achieved a uniform dispersion after 2 h of milling. Consolidation of the milled powders was performed via hot pressing under 400 MPa and 430 °C for 30 min. The effect of milling time on the microstructural and mechanical properties of the bulk TiCNP/AA7075 composites was evaluated in terms of grain formation behavior, hardness, tensile strength, and relative density results. The results revealed that three times enhanced hardness value (277.55 HB) was achieved in a 10 h milled and hot-pressed sample than initial AA7075 alloy (94.43 HB) because of the hardened nanoparticles' homogeneous distribution within the matrix along with the increment in milling time. Tensile tests showed that the 1 h milled TiCNP/AA7075 composite's ultimate tensile strength (284.46 MPa) was increased by 40 % compared with the initial AA7075 alloy (210.24 MPa). Considering test results, it was determined that the hardness values increased as a function of the milling time, but the optimum milling time, which means achieving the highest tensile strength value, was determined as 1 h. This continuous increase in hardness is attributed to the homogeneous distribution of nanoparticles within the matrix, and increased hardness of particles originated from the severe plastic deformation due to advancing milling time. However, the incoherent variation of tensile strength values with milling time suggests that the increased hardness of particles and the changes in particle morphology after 1 h of milling deteriorates the sinterability and packing properties of the powders.

High cycle fatigue behavior of in-situ ZrB2/AA6111 composites

In this work, the in-situ ZrB2/AA6111 composites with different particle volume fractions were prepared by direct melt reaction method and followed by hot extrusion deformation and T6 heat treatment. The microstructure characteristics, tensile and fatigue properties were carefully studied. The results showed that the addition of nano-ZrB2 particles made ZrB2/AA6111 composites have finer grains and the ultimate tensile strength of composites increases with the increase of particle volume fraction. The ZrB2/AA6111 composites showed higher fatigue limits than the unreinforced alloy, and the composites with a particle volume fraction of 2 vol% have the highest fatigue limit of 125 MPa, which is a 31.5% increase compared to the unreinforced alloy. Through microstructure analysis, it is found that the fatigue limit was related to the volume fraction and distribution of ZrB2 particles. The initial cracks of composite and unreinforced alloy were both caused by persistent slip bands and the crack propagation of the composites was more complex due to the resistance of reinforcing particles.

Effect of Small Amount SiC on Mechanical Properties Composite Fabricated by Casting and Subsequent Rolling Process

Aluminum matrix composites (AMCs) are promising material to develope for engineering application in last a few decade. Combination between aluminum matrix and reinforced particles was succesfull increase the mechanical properties. Casting method have been used to fabricate the AMCs due to their simple process and low cost, however the nonuniform distribution elements and some defects were often observed in the microstructure by this traditional casting process. Furthermore, these problems have influenced the mechanical properties of composites. In other hand, the thermomechanical treatment and dispertion strengthening by particles such SiC are attractive technique to improved mechanical properties of composite such AMCs. Thermomechanical such rolling process was successfully modified the properties of composite, high energy from rolling machine induced plastic deformation and grain refinement of microstructure. The modification of this microstructure is the important role to enhance the mechanical properties. The aim of this research to investigate the effect of rolling process on microstructure and mechanical properties of aluminum cast reinforced with SiC particles. In the current work, Al-Si alloy ingot used as a matrix and reinforced with SiC particles for different composition (1.5, 2.0, 2.5 wt.%). Remelted ingot and SiC have been done in crucible grafite to prevent from contaminant. Composites material were fabricated by using pressure casting at 35 MPa, 657°C pouring temperature and the permanent mold made from mild steel with holding temperature 300°C. Further, a hot rolling process was performed at 550°C with 20% thickness reduction through multi pass process to obtain the thickess of sheets. The microstructure of composites were investigated by optical microscope (OM) with different magnification. Brinell hardness test was carried out to obtained the hardness on the surface of composites rolled. The impact test was conducted in room temperature by using charpy model. Furthermore, the ultimate tensile strength of composites were perfomed by universal tensile machine. The results shows the increase of SiC particles upto 2.5 wt.% promoted the finer microstructure was observed after rolled. Further, the sligthly increase both of hardness and tensile strength have been achieved after hot rolling with different silicone particle. The maximum hardness 71 HB of composite rolled was obtained for 2.5 wt.% SiC. The impact strength 19 joule was observed in 2.0 wt.% SiC and sligthly decrease with the increasing of silicone carbide. In other hand, the ultimate tensile strength 130 MPa was obtained for 2.5 wt.% SiC, the addition of a small amount SiC promote a slightly change the mechanical properties.

Influence of homogenization and aging on tensile strength and fracture behavior of TIG welded Al6061-SiC composites

The present work deals with fractograph analysis and enhancement of mechanical properties like hardness and tensile strength on Al6061-SiC reinforced composites during homogenization and artificial aging at 100, 150 and 200 °C. Scanning Electron Microscope, followed by high end metallography testing techniques like, SEM, XRD, EDS etc. are used in the present study for characterization analysis. Metal matrix composites having 0, 8, 10 and 12 wt.% fractions of silicon carbide grits of average 25 μm size, are TIG welded using the filler material ER5356. Mechanical tests showed higher hardness and lower tensile strength for Al6061-12 wt.% SiC composite under non-homogenized and artificially aged condition owing to the presence of coarse micro-segregation of β-AlFeSi and α-Al(Fe, Mn) Si phase. Microstructure confirms dendritic segregation in non-homogenized specimen and after homogenizing, dendritic segregations are minimized leading to an improvement in hardness and tensile strength. Fracture surfaces of non-homogenized and artificially aged samples indicated the existence of shrinkage porosity and accordingly failure along the interdendritic regions. Homogenized and age hardened composites failed under combination of brittle and ductile mode as evident by the presence of equiaxial fine dimples. Amongst different kinds of the recently developed composites, particle reinforced metal matrix composites have a great demand and has led to the emergence of numerous structural composite materials as candidates for a wide variety of industrial applications like in marine, aerospace and automobile. Property enhancement is witnessed due to the combined effect of homogenizing and lower temperature aging. 60% escalation in ultimate tensile strength of composites aged at 200 °C and 90% increase in UTS of composites aged at 100 °C is observed when compared with as weld condition after homogenizing and aging.

The improved mechanical properties of Al matrix composites reinforced with oriented β-Si3N4 whisker

The β-Si3N4 whiskers (β-Si3N4w) reinforced Al matrix composites were first fabricated by hot pressing, then treated through hot extrusion. The microstructure characterization demonstrated the preferred orientations of both β-Si3N4w and Al grains in the as-extruded composites. It indicated that β-Si3N4w were aligned along the extrusion direction and Al grains exhibited a distinct <111>Al texture. The interface between β-Si3N4w and Al was in a good bonding status without voids and reaction products. Effects of extrusion process on the mechanical properties of composites were also investigated. The results indicated the extrusion process had a prominent strengthening effect on the mechanical properties of composites. The maximum yield strength and ultimate tensile strength of composites reached up to 170 and 289 MPa, respectively, accompanied by a 12.3% elongation at fracture when the whisker fraction was 15 vol.%. This improvement was collectively attributed to the densification of composites, the strong interface, and the preferred orientation inside composites. The yield strength of the composites reinforced with 5 vol.% β-Si3N4w corresponded well with the theoretical value from different strengthening mechanisms.

Formation of gradient microstructure and mechanical properties of hot-pressed W-20 wt% Cu composites after sliding friction severe deformation

W-based alloys are currently considered promising candidates for high heat flux components in future fusion reactors. In this paper, hot pressed W-20 wt%Cu composites were treated at room temperature using a sliding friction severe deformation (SFD) process, with a moving speed of 0.2 m/s and an applied load of 500 N. Microstructural evolution of composites after the SFD treatment was evaluated and compared with that of the untreated composites. Results showed that there was a gradient structure generated and an obvious refinement in tungsten particles size in the surface layer after the SFD process. The average particle size of tungsten in the SFD treated composites was 2.60 μm, whereas it was 4.5 μm for tungsten in the untreated composites. Fracture surfaces of the composites indicated that the SFD treatment destroyed the W skeleton and changed fracture mode from predominant inter-granular one to trans-granular one due to the decrease in contact area of W-W inter-particles. Yield strength and ultimate tensile strength of composites after the SFD treatment were 308 MPa and 553 MPa, respectively. The treated composites exhibited micro-hardness values with an average reading of about 308 HV. Analysis of the facture microstructures clearly suggested that the tungsten particles in the treated composites are consisted of dislocations and boundaries as well as dislocation tangles. The electrical conductivity of the composites was decreased from 33 IACS% to 28.5 IACS% after the SFD treatment, mainly due to loss or squeezing of copper into the inner surface.

Physical properties of lyocell-reinforced polypropylene composites from intermingled fibre with varying fibre volume fractions

Polypropylene (PP)-cellulose fibre blends exhibit substantial potential for the production of high-performance textile fibre–reinforced composites. The production of reinforced parts from PP-cellulose composites through thermal shaping of intermingled fibre blends is a strategy to form parts which exhibit superior mechanical properties. In this study, the use of intermingled fibre slivers with different ratios of lyocell fibres (CLY) and PP fibres as raw materials for thermally formed composites was investigated. Such a concept will maximize the interface between the reinforcement fibres and polymer matrix. The cellulose fibres remain oriented along the direction in which the drawing process was performed, which forms the basis for tailored fibre placement in technical production. Because of good surface contact between the cellulose fibre surface and PP matrix, no special coupling agents were required to improve the interfacial adhesion between the two different polymers. The share of CLY and PP fibres in the composite varied from 50% w/w CLY content, up to 70% w/w CLY. Besides analysis of the mechanical properties, such as tensile strength and E-modulus, attention was directed towards moisture sorption of the composites. The rate of sorption and amount of water bound in the composite were found to be dependent on the cellulose fibre content. Composites with a higher CLY content exhibited a more rapid and higher moisture uptake. In water saturated state, the ultimate tensile strength of composites reduced from 160 MPa to 90 MPa, which is an indicator for a reduced adhesion between the CLY surface and PP matrix. The results indicate the potential of the intermingled fibre concept blend for the efficient manufacturing of composite parts.

Microstructure and Mechanical Properties of Milled Carbon Fibers Reinforced EN AW 6082 Aluminium Matrix Composites after Hot Extrusion

The microstructure and mechanical properties of carbon fibers reinforced EN AW 6082 aluminium matrix composites after hot extrusion were investigated. The distribution of carbon fibers in matrix was homogenous and their alignment was in the extruded direction. The microstructure of aluminium matrix alloy in the composites was fine grained, without defects. The heat treatment (annealing at 550 °C for 1 hour, water quenching and artificial aging at 170 °C for 8 hours) caused formation of fine solid solution grains of aluminium alloy and dissolution of Mg2Si particles. The highest value of ultimate tensile strength was achieved in composite reinforced with 10 vol. % of carbon fibers, the worst value was achieved in composite reinforced with 20 vol. % of reinforcement. The application of heat treatment led to an increase of 0.2 yield strength and the ultimate tensile strength of composites compared to extruded states in all types of materials. These changes caused precipitation of &beta;''- phase particles.

Effect of extrusion temperature on the microstructure and tensile property of 2D-Cf/Al composites by liquid extrusion infiltration

2D-Cf/Al composites were prepared by liquid extrusion infiltration under the different extrusion temperatures of 570, 585, 600, 615, and 630 °C of infiltration mold. Through the observation and analysis of the microstructure and ultimate tensile strength (UTS) of the composites, it showed that extrusion temperature had important influence on the infiltration effect and tensile property of 2D-Cf/Al composites. When the extrusion temperatures were 570 and 585 °C, very few aluminum alloy liquid was filled into the carbon fiber preform, and the UTS(s) of composites was low. When the temperature reached 600 °C, infiltration effect and UTS had been improved. With the increase of extrusion temperature at 615 °C, the infiltration of aluminum alloy liquid was sufficient, the distribution of carbon fibers was uniform, and defects of casting holes and fiber damage could not be found. UTS had been improved 115.8% more than that of the matrix. However, when extrusion temperature reached 630 °C, infiltration of the alloy was sufficient, but there was fiber damage, which would reduce the UTS of the composites. The increased proportion of UTS was only 21.7%, and this was not satisfied. Through comparison and analysis, 615 °C was a better extrusion temperature than others, and infiltration effect and UTS were more satisfied. It was adverse for preparing ideal 2D-Cf/Al composite to have too low and too high extrusion temperatures.

Enhanced tensile properties of Al matrix composites reinforced with β-Si3N4 whiskers

Al matrix composites reinforced with β-Si3N4 whiskers (β-Si3N4w) were fabricated by hot pressing method. The microstructures showed that the whiskers were uniformly dispersed in the matrix and the Al/β-Si3N4 interface was well bonded without interface reaction. Effects of β-Si3N4w content and sintering parameters on the densification and tensile behavior of composites were investigated. The results indicated that β-Si3N4w could both enhance the ultimate tensile strength (UTS) and maintain the ductility of Al matrix when the whisker content was 5vol%, corresponding to an elongation at break and an UTS of 21.2% and 239MPa, respectively. However, higher whisker content could improve UTS of composites to the maximum value of 312MPa, which was 158MPa higher than pure Al, while reducing elongation of composites. The fracture mechanism changed from ductile fracture to a combination of both ductile and brittle fracture mechanism with the increase of whisker content.

Ponašanje pri zatezanju Al2024 kompozita sa matricom na bazi legure ojačanih B4C česticama

In the present investigation, microstructure study and tensile behavior of B4C particulate reinforced Al2024 alloy composites have been reported. Al2024 matrix composites containing boron carbide were fabricated by conventional stir casting method. The composites containing 3 and 6 wt. % of B4C (80 micron size)particulates were fabricated for the study. The micro- structure of the composite was examined by optical microscopy. Images were taken to identify the presence of B4C particle in aluminum matrix. Further, tensile behavior of as cast Al2024 alloy and Al2024-3 wt. % B4C and 6 wt. % B4C composites were studied. Tensile properties like ultimate tensile strength, yield strength and percentage elongation were evaluated as per ASTM standards. Microstructural observation revealed the uniform distribution of particles in the Al2024 alloy matrix. It was found from the analysis, that the ultimate tensile strength of composite was increased due to increasing amount of boron carbide particle in the composite and the yield strength was increased due to the higher value of boron carbide. Also percentage elongation of the composites decreases with increase of the order of boron carbide. Finally, it was found that in the stress - strain curve, the boron carbide was the main factor in improving the tensile strength of composites because of its high hardness. The composites in the present study have great potential for application as structural materials.

Effect of pectin and hemicellulose removal from hemp fibres on the mechanical properties of unidirectional hemp/epoxy composites

The objective of this study was to investigate the effect of pectin and hemicellulose removal from hemp fibres on the mechanical properties of hemp fibre/epoxy composites. Pectin removal by EDTA and endo-polygalacturonase (EPG) removed epidermal and parenchyma cells from hemp fibres and improved fibre separation. Hemicellulose removal by NaOH further improved fibre surface cleanliness. Removal of epidermal and parenchyma cells combined with improved fibre separation decreased composite porosity factor. As a result, pectin removal increased composite stiffness and ultimate tensile strength (UTS). Hemicellulose removal increased composite stiffness, but decreased composite UTS due to removal of xyloglucans. In comparison of all fibre treatments, composites with 0.5% EDTA+0.2% EPG treated fibres had the highest tensile strength of 327MPa at fibre volume content of 50%. Composites with 0.5% EDTA+0.2% EPG→10% NaOH treated fibres had the highest stiffness of 43GPa and the lowest porosity factor of 0.04.

Design and tensile properties of aluminum borate whiskers reinforced aluminum composite with low whisker volume fraction

ZnO was firstly coated on the surface of aluminum borate whiskers (ABOw) by sol–gel. Then, ZnO-coated ABOw was added into soybean slurry to make a preform with low volume fraction and the preform was sintered at high temperatures to obtain a sufficient strength. ABOw reinforced aluminum composite (ABOw/Al) was fabricated by squeeze casting. Interfacial microstructures, tensile properties, and fracture mechanisms of the ABOw/Al composite were investigated. The results show that the coating of ABOw and the addition of soybean sacrificial filler can effectively decrease the volume fraction of whiskers in the composite. The ultimate tensile strength of composite has not changed much with the decrease of whiskers volume fraction in the composite. However, the elongation to fracture of the composite evidently increases and it can reach 11.1% at room temperature.