Emin Bayraktar

Manufacturing of Aluminum Matrix Composites Reinforced with Iron Oxide (Fe3O4) Nanoparticles: Microstructural and Mechanical Properties

The purpose of this paper is to demonstrate the low-cost manufacturing of aluminum matrix composites reinforced with nano iron oxide as light and efficient materials for engineering applications. It is very desirable to use reinforced aluminum matrix composites in structural applications (automotive, aeronautical, etc.) because of their outstanding stiffness-to-weight and strength-to-weight ratios. In modern industry, it is increasingly important to develop new composites as alternative materials to fabricate multifunctional pieces. Detailed information is presented on the manufacturing process of this composite, and a preliminary study was performed on the cryogenic-cycling behavior to evaluate the interface between the matrix and the reinforcement. Microindentation tests were carried out to evaluate the micromechanical properties of these materials; a simple and practical finite element model is proposed to predict certain parameters related to the composition of the composite.

Production of Aluminum/SiC/NiAl2O4 MMCs by Thixoforming of Recycled Chips

The work explores the production of Al/SiC and Al/SiC/NiAl2O4 composites by thixoforming compacted mixtures of AA7075 machining chips and reinforcing particles. It is analyzed the influence of processing parameters in the various processing steps, such as mixing, compacting, heating and thixoforming, in the final quality of products. Results showed the general viability of producing composites by the proposed technique; the utilization of recycling material is particularly important in the high demanding energy processing sector, as the Al industry. NiAl2O4 particles and, in less extent, also SiC particles, can penetrate into the liquid phase present in the thixotropic microstructure within the chip, promoting their disaggregation; reinforcement distribution in the composite depends on appropriate choose of processing parameters.

Wear Resistance of Elastomeric Based Composites by Continuous Multi-Cycle Indentation Used in Manufacturing Engineering

Wear resistance is an important rubber compound property related to useful product life. The rubber compound properties that affect wear behavior are very complicated. Wear is related to a rubber compound’s cut resistance, tear resistance, fatigue resistance hardness, etc. The most commonly used test method to determine the wear resistance of rubber materials is abrasion test. Tested compounds are usually compared on a “volume loss” basis which is calculated from the weight loss and density of the compound. This method is known to be variable and doesn’t give additional information for the wear behavior. For this reason we propose alternative approaches for examination of the wear behavior of rubber composites, giving information not only for the wear resistance but also for elastic the modulus, stiffness of the material, damage mechanism, etc. Continuous multi-cycle indentation is used to determine the indentation hardness, elastic modulus and the stiffness with two indenter types –Vickers and sphero-conical. Comparison of both results is made in order to investigate the effect of the indenter type.

Manufacturing and damage analysis of filler reinforced epoxy-based composites

Epoxy matrix composites reinforced with very fine particles were developed and scratch resistance (dynamic tests) was evaluated. Fracture test results were compared depending on the composition (static compression tests). They were conducted for their designed life. In order to improve the toughness of the composites while maintaining a constant volume fraction of different reinforcements, three basic different epoxy matrix composites were manufactured using basically fine Al2O3 and glass fibre as reinforcements (<1 µm) and fine rubber powder (variable between 5–10 µm), respectively. All of the composites were fabricated by mixing the filler particles and epoxy together stirring for 4 h and then placed in an ultrasonic dispersion for 1 h. Microstructural evolution and other detailed damage analyses are carried out on the scanning electron microscope (SEM).

Design of Multifunctional Energetic Structural Composites: A Preliminary Study on an Epoxy-Rubber Matrix with Exothermic Mixture Reinforcements

A new multifunctional energetic structural composite was designed in the frame of a common research project for potential applications as structural energetic materials in aeronautical engineering. A mixture of structural and energetic functions can be achieved using different reinforcements in rubber-epoxy composites and this type of design give an exigent task. The mechanical and physical properties of the various composite systems containing Nickel and extremely fin aluminium and powders in a epoxy-rubber matrix were studied to investigate their mechanical physical properties. Dynamic (impact choc) tests and static compression tests have been carried out to understand failure response of these composites. Microstructural characterization can reveal that micro-sized Ni and Al stayed on homogeneously and intimately mixed within the epoxy matrix. Dielectric properties and dielectric loss angle tangent (tan delta) were investigated using a Dielectric Thermal Analyzer (DETA). Viscoelastic properties have been evaluated by microindentation tester and also surface wear resistance were measured by scratch test device.

Processing of Epoxy-Nickel Matrix Composites Reinforced with Aluminum and Waste Elastomers

A mixture of structural functions can be accomplished using different reinforcements in epoxy-nickel matrix composites. In the frame of the common research project, mechanical and physical properties of the epoxy resin-nickel matrix composites containing extremely fin aluminum and fine waste elastomer powders were studied. A comprehensive study is given with different static and dynamic aspects as a function of composition, frequency and temperature. Two types of waste elastomeric powders were used for the reinforcement: Styrene-Butadyene Rubber SBR and Ethylene Vinyl Acetate (EVA). All of the composites were fabricated by mixing during 4h and then put in an ultrasonic dispersion for 1h. After that, a detail analyses has been carried out by means of Dynamic Mechanical Thermal Analysis (DMTA), microindentation and wear - scratch test. Dielectric properties (Permittivity (ε′)) and dielectric loss angle tangent (tan delta) were investigated using a Dielectric Thermal Analyzer (Rheometric Scientific) at three different frequencies (1 kHz, 10 kHz, 100 kHz) from room temperature up to 280°C. Wear of surface resistance measurement has been carried out by scratch test with a normal of 2.06N load with the frequency of 10Hz in two different number of cycles; 50000 and 100000. After the test, damaged zone were measured by 3D optical roughness meter to characterize damage occurred after the scratch test.

Effect of Interference-Fit on Fatigue Life for Composite Lap Joints

The aim of this study is to examine the effect of the clearance and interference-fit on the fatigue life of composite lap joints in double shear, 3D finite element simulations have been performed to obtain stress (or strain) distributions around the hole due to interference fit using FEM package, Non-linear contact analyses are performed to examine the effects of the clearance and interference for titanium and composite lap joint. Fatigue tests were conducted for the titanium and composite lap joints with clearance fit and interference fit with 0.5, 1, and 1.5% nominal interference fit levels at different cyclic loads. The results shows that interference fit increases fatigue life compared to clearance fit specimens, the titanium and composite lap joint with 1% interference fit level has the better fatigue life.

New Design of Composite Materials Based on Scrap Rubber Matrix Reinforced with Epoxy and SiC

The aim of this study is to examine the influence of the scrap material and the additional elements on the structure and mechanical properties of multi-phase system. All of the composites were fabricated by mixing during 4h and then put in an ultrasonic dispersion for 1h. After that, a detail analyses are carried out by the means of Dynamic Mechanical Thermal Analysis (DMTA), Microindentation and scratch test. The structure was investigated by Scanning Electron Microscopy (SEM). The present study will help to optimize the parameters of this newly designed composite material allowing to find different possibilities for the industrial applications and to contribute in the war with the waste rubber materials.

Investigation on Microstructure and Interfaces in Graded FE50007 / WC Composites Produced by Casting

Graded composites of grade FE50007 nodular ductile iron reinforced with WC granules grinded from recycled cutting tools, were produced by casting, using lost foam technique. Reinforcement granules were forced to be located in a specific region of the part by controlling flow during pouring. Different casting conditions were investigated (reinforcing granules content and dimensions). Resulting microstructures were extensively analysed to investigate eventual phases modifications in the iron matrix among reinforcing particles and interface interactions or possible reactions. Results show that WC granules deteriorates in contact with liquid metal, by diffusion of binder elements, detaching WC individual particles, resulting in a smooth and continuous interface; any kind of reaction is observed in the interface. The presence of the ceramic particles modifies the alloy microstructure within the reinforced region due to thermal and chemical local features. Preliminary studies on wear behaviour for a specific cast product developed (an impact crusher) are also presented, indicated superior performance compared to commercial crushers.

Scrap-Rubber Based Composites Reinforced with Boron and Alumina

Composites made of reinforced scrap rubber are generating interest in transportation industries due to their unique combination of high strength, low density, and limitless availability. Whether the vehicle is an airplane, truck, car, or boat, weight reduction leads directly to reduced fuel consumption and operating costs. In the present study, different composite formulations are prepared by means of a low-cost production process. In this process, fresh scrap rubber is combined with varying amounts of boron and alumina, with the aim of optimizing strength through control of both composition and constituent bonding. Mechanical properties are evaluated by impact testing, bend testing, and nanoindentation. Microstructure is analyzed by scanning-electron microscopy (SEM).