Papers by Keyword: Layered Composite

Abstract: The aim of this study was to evaluate the biocompatibility of Al₂O₃-Ti functionally graded material (FGM) successfully fabricated by Spark Plasma Sintering (SPS) technology, and to compare with pure Ti and alumina. Pre-osteoblast MC3T3-E1 cells were used to examine cell viability, proliferation and differentiation using lactate dehydrogenase (LDH) cytotoxicity detection kit, MTT assay and Alkaline Phosphatase (ALP) colorimetric test at different time points. Furthermore, ion release from the materials into the culture medium was assessed. The results showed cell viability over 80% for FGM and alumina which dismissed any cytotoxicity risk due to materials or manufacturing. The results of MTT tests identified superiority of FGM than Ti and alumina, particularly in late proliferation. Nevertheless, in cell differentiation, all materials performed similarly with no statistical differences. Furthermore, it was indicated that Ti had no ion release, while alumina had small amount of Al ion dissolution. FGM, however, had more ions detachment, particularly Al ions.

Abstract: Multi-layered metal composites have received considerable attention due to their improved mechanical and physical properties. In this study, Al6061/Al2024 composite was processed by accumulative roll bonding (ARB) as a severe plastic deformation technique. Mechanical properties of processed material were evaluated using the uniaxial tensile test and shear punch test method (SPT). The correlation between the results of the tension experiments and shear strengths was calculated. Experimental results demonstrated that the shear strength enhanced with increased number of ARB passes. However, the elongation under shear manifested a reduction when the number of ARB passes increased. Inspection of the results of tensile tests and SPT revealed that they follow a similar trend for both strength and ductility. Therefore, it can be asserted that the shear punch test represents a useful and complementary tool in the mechanical analysis of the ARB sample.

Abstract: The results of modeling of the influence of layers thickness of the Ni-Cr-Al composite on value of thermal stresses on its interlayer boundaries after diffusion annealing are presented. It is shown that the cooling of the AD1-Cr20Ni80 composite after annealing, which provides formation of a DZ at its interlayer boundary, consisting of three interlayers (CrAl₇, NiAl₃ + CrAl₇ and Ni₂Al₃ + CrAl₇), leads to spontaneous separation of the aluminum layer,due to the action of tensile stresses, exceeding the zone strength of the interlayer boundaries (CrAl₇) - (NiAl₃ + CrAl₇), and at k> 0.3 - (NiAl₃ + CrAl₇) - (Ni₂Al₃ + CrAl₇) with the ratio of layers thickness of aluminum and the alloy Cr20Ni80 - k <0.3, which leads to the formation of layered Cr20Ni80 / ( Ni₂Al₃ + CrAl₇) / (NiAl₃ + CrAl₇) or Cr20Ni80 / (Ni₂Al₃ + CrAl₇) coatings.

Abstract: A mechanism for the formation of the interaction zone at the interlayer interface of the explosively welded Cu-Ti system composite is proposed and experimentally proved; the heat treatment was performed under a contact melting regime.

Abstract: In this study, electro nickel coating was applied and its effect on the interfacial stability and cracking behaviors were investigated in the multi-layered Ni-plated-Cu/Al/Ni-plated-Cu clad composite. Ni plating with 5μm thickness on the Cu sheet before cladding does not form a continuous layer between Cu and Al because of its low ductility. Ni layer covers the part of the Cu/Al interface. In the interface region without Ni layer, CuAl₂, CuAl and Cu₉Al₄ were found to be formed after annealing whereas Al₃Ni₂ and Al₃Ni were found to be formed in the interface region with Ni layer. After bending, interface crack developed initially in the interface region with plated Ni layer. On the other hand, the interface region with no Ni layer, no interface cracks were found to formed, suggesting that the bonding between Al and Ni is not strong enough. After interface crack formation, cracks developed in the Al layer, which may lead to the fatal fracture.

Abstract: An investigation is performed on the influence of the temperature and duration of heating of the explosively welded titanium ВТ1-0+ Steel 20 composite on the phase composition of the diffusion layer formed at the interface. It is shown that after heating to 800 oС the diffusion layer consists of α + α’-Ti , an iron solid solution in titanium and a decarburized zone. When heated at the temperature range from 900 – 1000 oС, the composition of the diffusion layer is as follows: α + α’-Ti acicular structure, Fe₂Ti and FeTi intermetallics, TiC titanium carbide, titanium solid solution in α-Fe and a decarburized zone.

Abstract: Earlier presented the geometrically nonlinear model of a flexible beam (cylindrical bending of a plate) was used for analysis of post-buckling behavior of the layered composite with delamination at compression. In this paper the model is used for more details nonlinear analysis of double cantilever beam (DCB) that used in standard test for determination of the interlaminar fracture toughness composites with delamination-type damage. The main advantage of the model is a precise description of the curved axis of the beam (plate) without linearization or other higher order approximations. The exact solution of bending differential equation finally can be expressed in terms of the incomplete elliptic integrals of the first and second kind. The model describes only geometrically nonlinear effect of DCB arms bending (global effect) and should be combined with the procedure of effective delamination extension to correct DCB arms rotation at delamination front (local effect). First of all the nonlinear model can serve as a tool to estimate the possible error due the geometrical nonlinearity in comparison with linear solution. On the other hand, this model can be effectively used to determine interlaminar fracture toughness using DCB samples at large deflections. Validation of the model is made using data of standard tests of glass/epoxy DCB samples.

Abstract: The composite formation of steel and ceramics is especially for medical applications of great interest. By use of the multicomponent tape casting metal-ceramic composite components like bipolar scissors and other surgical instruments can be produced. A coating technology that comes from the paper industry, allows to apply a very thin insulating layer of a few microns between the electrodes consisting of stainless steel. Until now bipolar surgical instruments are produced by mechanical joining of steel and ceramic parts or by spraying a ceramic layer on the steel instruments. This joining steps can lead to stresses in the sensitive ceramic material and leave fine interstices or pores that are not only avoidable with a force and / or tight fit. Both factors are reasons for premature failure of the instrument, even if the materials are not yet at the limits of their resistance. Through the joint shaping by the tape casting and subsequent co-sintering of both materials, a material bond is achieved in addition to the previously existing mechanisms of force and form fit. This optimizes the composite properties and increases the usage time of metal-ceramic layered composites. Special focus is given to the formation of the interface and the associated changes in properties of the individual components of the laminate. These investigantions illustrate the influence of co-manufacturing on the texture of the laminate materials and the formed interface between them. By x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), x-ray fluorescence analysis (RFA) and thermodynamic calculations (FactSage) of the material bond at the metal-ceramic interface is investigated. In various application areas where steel and zirconia should occur as integral partners, this material combination may be established.

Abstract: By using a elastic mechanics model the transverse magnetoelectric voltage coefficient of magnetostrictive-piezoelectric bilayer is derived according to the constitutive equations. The transverse magnetoelectric coupling of nickel zinc ferrite-lead zirconate titanate (Ni_0.8Zn_0.2Fe₂O₄–Pb (Zr,Ti)O₃, NZFO-PZT) layered composites were calculated by using the corresponding material parameters of individual phases. NZFO samples have been synthesized with sol–gel technique. Layered composites NZFO-PZT and NZFO-PZT-NZFO have been fabricated by binding discs of NZFO and commercially available PZT, and the transverse magnetoelectric effect have been investigated. The peak value of transverse magnetoelectric voltage coefficient for NZFO-PZT-NZFO trilayer reaches 252.4 mV/cmOe under a bias magnetic field of about 320 Oe, which is about three times as large as that of NZFO-PZT bilayer. The interface coupling parameter of trilayer is significantly higher than that of bilayer.

Abstract: Based on taking combustion synthesis in ultrahigh-gravity field to prepare solidified TiC-TiB₂ ceramic, laminated composite of TiC-TiB₂ to Ti-6Al-4V was successfully obtained by fusion bonding, and within the joint there achieved multi-scale (micron-submicron-micro-nano) and multi-level (TiC_1-x-TiB-TiB₂ + TiB₂-Ti-TiC_1-x-TiB + TiB₂-TiC_1-x-TiB-Ti + TiB-TiC_1-x-Ti + TiC_1-x-Ti + Ti) composite structures characterized by size and distribution of TiB₂ and TiB phases. As micro-nano TiB₂, TiB platelets and needle-like nano TiB grains at the joint area initiated residual stress toughening and pinning at crack tip, while Ti phases initiated ductile phase toughening and subsequent bridging in crack-tip wake, a typical delayed fracture under external stress was manifested obviously in the joint of TiC-TiB₂ to Ti-6Al-4V. As a result, the shear fracture of the joint of ceramic toTi-6Al-4V alloy usually occurred in solidified area of Ti alloy rather than the joint, and the shear strength between the ceramic and Ti alloy was maintained at 375 ± 55 MPa.