Structure and Tribological Property of TiBN Nanocomposite Multilayer Synthesized by Ti-BN Composite Cathode Plasma Immersion Ion Implantation and Deposition

A Ti-BN complex cathode is made from Ti and h-BN powders by the powder metallurgy technology, and TiBN coating is obtained by plasma immersion ion implantation and deposition with this Ti-BN composite cathode. The TiBN coating shows a self-forming multilayered nanocomposite structure while with relative uniform elemental distributions. High resolution transmission electron microscopy images reveal that the multilayered structure is derived from different grain sizes in the nanocomposite. Due to the existence of h-BN phase, the friction coefficient of the coating is about 0.25.

Least Square Finite Element Model for Analysis of Multilayered Composite Plates under Arbitrary Boundary Conditions

Laminated composites are widely used in many engineering industries such as aircraft, spacecraft, boat hulls, racing car bodies, and storage tanks. We analyze the 3D deformations of a multilayered, linear elastic, anisotropic rectangular plate subjected to arbitrary boundary conditions on one edge and simply supported on other edge. The rectangular laminate consists of anisotropic and homogeneous laminae of arbitrary thicknesses. This study presents the elastic analysis of laminated composite plates subjected to sinusoidal mechanical loading under arbitrary boundary conditions. Least square finite element solutions for displacements and stresses are investigated using a mathematical model, called a state-space model, which allows us to simultaneously solve for these field variables in the composite structure’s domain and ensure that continuity conditions are satisfied at layer interfaces. The governing equations are derived from this model using a numerical technique called the least-squares finite element method (LSFEM). These LSFEMs seek to minimize the squares of the governing equations and the associated side conditions residuals over the computational domain. The model is comprised of layerwise variables such as displacements, out-of-plane stresses, and in- plane strains, treated as independent variables. Numerical results are presented to demonstrate the response of the laminated composite plates under various arbitrary boundary conditions using LSFEM and compared with the 3D elasticity solution available in the literature.

Impact Wear Properties of Metal-Plastic Multilayer Composites Filled with Glass Fiber Treated with Rare Earth Element Surface Modifier

The friction and wear properties of metal-plastic multilayer composites filled with glass fiber, which is treated with rare earth element surface modifier, under impact load and dry friction conditions were investigated. Experimental results show that the metal-plastic multilayer composite filled with glass fiber exhibits excellent friction and impact wear properties when using rare earth elements as surface modifier for the surface treatment of glass fiber.

Multilayer aluminum composites prepared by rolling of pure and anodized aluminum foils

Experimental results on processing,structural and mechanical characterization of a multilayer composite based on commercially pure aluminum foils were presented.A multilayer composite was produced by hot-rolling of anodized and non-anodized aluminum foils alternately sandwiched.In addition,the same process was applied for bonding of non-anodized foils.In both cases,obtained multilayer composites were compact and sound.In order to study composites microstructural evolution and mechanical properties,optical and scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),X-ray diffraction(XRD)analysis,hardness,tensile and three-point flexural tests were performed.Microstructural characterization confirmed that the rod-like particles distributed in parallel rows in the composite aluminum matrix with anodized foils correspond to Al2O3.Maximum and minimum peaks of oxygen and aluminum,respectively,suggest that after the final hot-rolling of composite with non-anodized foils,a small amount of coarser particles were formed at boundaries between foils.Hardness,strength,modulus of elasticity and flexural strength of both multilayer composites were much higher than those of pure aluminum,whereas ductility was significantly less.The composite with anodized foils exhibited the highest strength and modulus of elasticity,but lower ductility compared to composite processed from non-anodized foils.Fracture failure corresponded to the change of ductility.

Effect of Rare Earths-Treated Glass Fiber on Impact Wear-Resistance of Metal-Plastic Multilayer Composites

The friction and wear properties under impact load and dry friction conditions of metal-plastic multilayer composites filled with glass fiber, treated with rare earth elements, were investigated. The worn surfaces were observed and analyzed by scanning electron microscopy (SEM). It shows that applying rare earth elements surface modifier to treat the glass fiber surface can enhance the interfacial adhesion between the glass fiber and polytetrafluoroethylene (PTFE), as well as promote the interface properties of the composites. This helps to form a uniformly distributed and high adhesive transfer film on the counterface and abate the friction between the composite and the counterface. As a result, the wear of composite is greatly reduced. The composite exhibits excellent friction properties and impact wear-resistance.

Mechanical Properties and Fracture Behaviour of Multilayer Alumina Composites

Adopting a ceramic/polymer multilayer structure design to simulate the structure of nacre is usually believed to be an effective way to increase the toughness of ceramic composites at the expense of the material’s bending strength. However, in this study, we found that both the bending strength and the toughness could be improved simultaneously when using a certain Al2O3/Kevlar multilayer composite design compared to pure alumina samples with the same dimensions. The fracture behaviour of the Al2O3/Kevlar multilayer composite was studied to find a reason for this improvement. The results showed that the complex and asymmetrical stresses occurring in the Kevlar-reinforced layers were the main reason for the differences in fracture behaviour. We expect our results to open up new ways for the design of future high performance ceramic composites.

Permeation Characteristics of Light Hydrocarbons Through Poly（amide-6-β-ethylene oxide） Multilayer Composite Membranes

In this paper, poly(amide-6-β-ethylene oxide) (PEBA1657) copolymer was used to prepare multilayer polyetherimide (PEI)/polydimethylsiloxane (PDMS)/PEBA1657/PDMS composite membranes by dip-coating method. Permeation behaviors of ethylene, ethane, propylene, propane, n-butane, methane and nitrogen through the multilayer composite membranes were investigated over a range of operating temperature and pressure. The permeances of light hydrocarbons through PEI/PDMS/PEBA1657/PDMS composite membranes increase with their increasing condensability, and the olefins are more permeable than their corresponding paraffins. For light hydrocarbons, the gas permeances increase significantly as temperature increasing. When the transmembrane pressure difference increases, the gas permeance increases moderately due to plasticization effect, while their apparent activation energies for permeation decrease.

Effect of negative permeability on elastic wave propagation in magnetoelastic multilayered composites

With the advent of left-handed magnetic materials, it is desirable to develop high-performance wave devices based on their novel properties of wave propagation. This letter reports the special properties of elastic wave propagation in magnetoelastic multilayered composites with negative permeability as compared to those in counterpart structures with positive permeability. These novel properties of elastic waves are discerned from the diversified dispersion curves, which represent the propagation and attenuation characteristics of elastic waves. To compute these dispersion curves, the method of reverberation-ray matrix is extended for the analysis of elastic waves in magnetoelastic multilayered composites. Although only the results of a single piezomagnetic and a binary magnetoelastic layers with mechanically free and magnetically short surfaces as well as perfect interface are illustrated in the numerical examples, the analysis is applicable to magnetoelastic multilayered structures with other kinds of boundaries/interfaces.

Effects of tilt interface boundary on mechanical properties of Cu/Ni nanoscale metallic multilayer composites

The effect of tilt interfaces and layer thickness of Cu/Ni multilayer nanowires on the deformation mechanism are investigated by molecular dynamics simulations. The results indicate that the plasticity of the sample with a 45° tilt angle is much better than the others. The yield stress is found to decrease with increasing the tilt angle and it reaches its lowest value at 33°. Then as the tilt angle continues to increase, the yield strength increases. Furthermore, the studies show that with the decrease of layer thickness, the yield strength gradually decreases. The study also reveals that these different deformation behaviors are associated with the glide of dislocation.

Tape Casting of Al_2O_3-TiB_2/Al_2O_3-Nano-TiC Multilayer Composites

Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B) and (C), laminating under 10 MPa pressure, eliminating the solvent and burning out the polymer additives. The final green bodies were hot pressed at 1750℃ and 30 MPa. The composite has a bending strength of 568 MPa and a fracture toughness of 5.8 M Pa·m1/2. SEM analysis exhibits that Al2O3 particle growth was inhibited by TiC particles in C. but TiB2 particles could not hinder Al2O3 growth in B. The curves of GTA indicates that all organic additives could be removed completely above 600℃

MEASUREMENT OF INTERNAL STRESSES OF METAL MULTILAYER COMPOSITE COATINGS

The principle, formula and determination of internal stresses of metal multilayer composite coatings by means of the bending strip method were studied. Using this method, internal stresses of ion-plated metal multilayer composite coatings and thick monolayer coating of aluminium bronze, stainless steel and nickel-iron alloy were determined. The reason of decrement in internal stresses of multilayer composite coatings was discussed.

Effect of Aramid/Carbon Hybrid on the Tensile Properties of Multilayered Biaxial Weft Knitted Fabric Reinforced Composites

The effects of aramid/carbon on tensile properties of multilayered biaxial weft knitted( MBWK) fabric reinforced composites are analyzed by experiments. The tensile tests are inducted by the SHIMADZU AG-250 KNE universal material testing machine and Aramis V6 digital image correlation( DIC) technique.More specifically,the composite samples own four hybrid ratios(Na∶ Nc= 12∶ 0,8 ∶ 4,6 ∶ 6 and 4 ∶ 8). The results showed that the aramid/carbon hybrid MBWK fabric reinforced composites showed nearly linear response until reaching the maximum load and the inserting yarns distribution on the surface of MBWK fabrics reinforced composites had a great influence on the strain pattern distribution. Besides,the tensile strength,the tensile modulus and the elongation at breakage of 0° samples and 90° samples increased with the decreasing of aramid/carbon hybrid ratio. In a word,the changes of tensile strength, tensile modulus and elongation at breakage have a lot to do with the difference of aramid/carbon hybrid ratio.

Multilayered Ti-Al intermetallic sheets fabricated by cold rolling and annealing of titanium and aluminum foils

Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.

Electric field-induced stress birefringence in layered composites PbZr_(1-x)Ti_xO_3/Polycarbonate

Electro-optical composites based on the product of electro-strictive and elasto-optical effects are developed. Layered composites of PbZr1-xTixO3 and polycarbonate are synthesised. Their electro-ptical properties are studied. The nominal transverse electro-optical coefficient of the composite is observed to be about 3.6 times larger than that of LiNbO3. Experiments and theoretical analyses show that the electro-optical effect of the composite has a strong ＇size effect＇. With the ratio of thickness/length decreasing or the width of elasto-optical phase increasing, the half-wave electric field intensity increases but the transverse electrc-optical coefficient decreases for the layered composite.

Evolution of microstructure and mechanical properties in multi-layer 316L-TiC composite fabricated by selective laser melting additive manufacturing

In this study,the microstructure and mechanical properties of a multi-layered 316L-TiC composite material produced by selective laser melting(SLM)additive manufacturing process are investigated.Three different layers,consisting of 316L stainless steel,316L-5 wt%TiC and 316L-10 wt%TiC,were additively manufactured.The microstructure of these layers was characterized by optical microscopy(OM)and scanning electron microscopy(SEM).X-ray diffraction(XRD)was used for phase analysis,and the mechanical properties were evaluated by tensile and nanoindentation tests.The microstructural observations show epitaxial grain growth within the composite layers,with the elongated grains growing predominantly in the build direction.XRD analysis confirms the successful incorporation of the TiC particles into the 316L matrix,with no unwanted phases present.Nanoindentation results indicate a significant increase in the hardness and modulus of elasticity of the composite layers compared to pure 316L stainless steel,suggesting improved mechanical properties.Tensile tests show remarkable strength values for the 316L-TiC composite samples,which can be attributed to the embedded TiC particles.These results highlight the potential of SLM in the production of multi-layer metal-ceramic composites for applications that require high strength and ductility of metallic components in addition to the exceptional hardness of the ceramic particles.

Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy.Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites.It is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass.Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load.Strengthening and fracture mechanisms of the composite are analyzed.

Evaluation of diffusion and phase transformation at Ag/Al bimetal produced by cold roll welding

Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced. To create cold weld between A1 and Ag, mating surfaces were specially prepared and various rolling thickness reductions were applied. The minimum critical thickness reduction to begin cold weld was specified as 70% which equals 0.1630 critical rolling shape factors. The bimetallic strips were treated by diffusion annealing at 400 ~C and various annealing time. The A1/Ag interface of strips was observed by scanning electron microscope to investigate the formation of hard and brittle probable phases. The effect of anneal time on diffusion distance and phase transformation was also analysed by EDS analysis and line scan. A diffusion region along the interface in the Ag side was observed and its width increased with prolonging annealing time. Some 8 phases were detected close to the interface after anneal treating for 3 h and 8 phase was thicker and more continuous by increasing annealing time. The microhardness measurement showed that in spite of formation of 8 phase due to diffusion annealing, the interface hardness was reduced.

Selective synthesis of three-dimensional ZnO@Ag/SiO2@Ag nanorod arrays as surface-enhanced Raman scattering substrates with tunable interior dielectric layer

We describe the synthesis of three-dimensional(3D) multilayer ZnO@Ag/SiO2@Ag nanorod arrays by the physico–chemical method. The surface-enhanced Raman scattering(SERS) performance of the 3D multilayer Zn O@Ag/SiO2@Ag nanorod arrays is studied by varying the thickness of dielectric layer SiO2 and outer-layer noble Ag. The 3D Zn O@Ag/SiO2@Ag nanorod arrays create a huge number of SERS "hot spots" that mainly contribute to the high SERS sensitivity. The great enhancement of SERS results from the electron transfer between ZnO and Ag and different electromagnetic enhancements of Ag nanoparticles(NPs) with different thicknesses. Through the finite-difference time-domain(FDTD) theoretical simulation, the enhancement of SERS signal can be ascribed to a strong electric field enhancement produced in the 3D framework. The simplicity and generality of our method offer great advantages for further understanding the SERS mechanism induced by the surface plasmon resonance(SPR) effect.