Characterization of a Bimetallic Multilayered Composite “Stainless Steel/Copper” Fabricated with Wire-Feed Electron Beam Additive Manufacturing

The results of investigating the structure and properties of multilayered bimetallic “steel–copper” macrocomposite systems, obtained by wire-feed electron beam additive manufacturing, are presented in the paper. The features of boundary formation during 3D printing are revealed when changing the filaments of stainless steel and copper. Inhomogeneities in the distribution of steel and copper in the boundary zone were detected. Interphase interaction occurs both in the steel and copper parts of the structural boundary: Cu particles with an average size of 5 µm are formed in the iron matrix; Fe particles with an average size of 10 µm are formed in the copper matrix. It was revealed that such structural elements, as solid solutions of both copper and iron, are formed in the boundary zone, with additional mutual dissolution of alloying elements and mechanical mixtures of system components. The presence of the disc-shaped precipitations randomly located in the matrix was revealed in the structure of the “copper–steel” boundary by transmission electron microscopy; this is associated with rapid cooling of alloys and the subsequent thermal effect at lower temperatures during the application of subsequent layers. The existence of these disc-shaped precipitations of steel, arranged randomly in the Cu matrix, allows us to draw conclusions on the spinodal decomposition of alloying elements of steel. The characteristics of mechanical and micromechanical properties of a bimetallic multilayered composite with a complex formed structure lie in the range of characteristics inherent in additive steel and additive copper.

Determination of effective stiffness properties of multilayered composite beams

Starting from a Cosserat-type model for curved rods, we derive analytical expressions for the effective stiffness coefficients of multilayered composite beams with an arbitrary number of layers. For this purpose, we employ the comparison with analytical solutions of some bending, torsion, and extension problems for three-dimensional beams and rods. The layers of the composite beam consist of different orthotropic or isotropic non-homogeneous elastic materials. We apply the obtained general formulas to calculate exact analytical solutions of some beam problems and compare them with corresponding results of numerical simulations. The numerical study shows a wide range of validity and applicability of the obtained formulas.

Layer-by-Layer Assembly of Cationic Guar Gum, Cellulose Nanocrystals and Hydroxypropyl Methylcellulose based Multilayered Composite Films

Eco-friendly sustainable materials provide an appealing template to replace contemporary synthetic-nonrenewable resource-based materials while maintaining the acceptable material properties to meet the performance requirements. Here, a layer-by-layer (LBL) self-assembly technique was used for fabricating multilayer composite films using all bio-based polymers/polysaccharides, i.e. cationic guar gum (CGg), carboxylated cellulose nanocrystals (cCNCs) and hydroxypropyl methylcellulose (HPMC). A five layered composite film was fabricated by depositing polymeric layers as follows: CGg→cCNCs→HPMC→cCNCs→CGg. The structural analysis of CGg/cCNCs/HPMC multilayered composite films indicated the existence of electrostatic interaction as well as H-bonding between polymeric layers that resulted in homogenous, dense and compact film surface with improved smoothness and strength properties. As compared to pure CGg film, the CGg/cCNCs/HPMC multilayered composite films showed improved tensile strength (84.8% increment) and modulus (29.19% improvement). Importantly, the deposition of HPMC layer contributed in achieving multilayer composite films with more flexible behavior (46.55% improvement in elongation at break). Furthermore, owing to the high transparency (89.5% transmittance), appreciable gas and oil barrier performance and resistance to various solvents (e.g. acetone, THF and DMAc), these multilayer films are promising candidates for various applications including renewable/sustainable packaging materials.