Lygia Maria Policarpio Ferreira

New Design of Aluminium Based Composites through Combined Method of Powder Metallurgy and Thixoforming

The present study deals with a new design of aluminium alloy based composites reinforced with SiC particles and Si/Al2O3 powders through combined methods of powder metallurgy and thixoforming. Moreover, recycled machining chips are used as raw material, specifically AA7075 chips generated in the aeronautical industry. The proposed method is based on forming at high temperatures a compacted mixture of metal chips and reinforcing particles, with the metal in thixotropic semi-solid condition. Composites containing different SiC weight fractions (10, 20 and 30%) were produced and had their microstructure analyzed. Mechanical properties were evaluated by means of micro-indentation tests. General results show the feasibility of producing composites by the proposed route. Products with good mechanical properties could be obtained. The process, even still not completely optimized as some improvement still must be achieved, can bring a new possibility for the production of a noble material from recycled wastes, particularly important in the high energy spending Al industries.

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.

Design and physical properties of multifunctional structural composites reinforced with nanoparticles for aeronautical applications

Abstract The multifunctional structural composites (MSCs) are used in engineering applications mainly in the aeronautical area because they meet the necessary requirements in new multifunctional systems. These composites exhibit good overall mechanical and thermal performance and potentially offer a large variety of functional properties. The present paper discusses the design, manufacturing and characterisation of these multifunctional structural composites. Generally, a combination of structural and energetic functions is achieved using different nanoparticle reinforcements in epoxy–rubber composites This type of material design gives an exigent task to the designers looking to integrate more functionality into the base material of their structure to achieve overall improved system performance. This paper is focused on the design of MSCs reinforced with Ni + Al mixture with Fe304 nanopowders in different ratios in a matrix of epoxy – fresh scrap rubber. We expect this material would be attractive for industrial applications because of the readily available recycled materials that are utilised. The mechanical and some physical properties of these composite systems were studied in this research. Microstructural characterisation revealed that micro- and nano-sized reinforcements were dispersed homogeneously in the epoxy–rubber matrix. Magnetic properties and surface wear resistance have been evaluated in detail as a function of the microstructure obtained for different compositions.

Production of Metal Matrix Composites Using Thixoinfiltration Techniques

The work presents an innovative approach to produce metal matrix composites by using thixoforming techniques. The proposed procedure is based on the infiltration of thixotropic semisolid metal into an assembly of loose particles of reinforcing material. Experiments were performed using Al alloys as base metal and SiC and porous ceramic particles (expanded clay known as cinasite) as reinforcement. Process parameters are investigated to observe their influence in the quality of products. Results demonstrate that the process is flexible for the manufacturing of different distributions of reinforcing agents, such as homogeneous or layered composites. Moreover, it is also shown that metallic chips can be used as raw material, meaning an important possibility for materials recycling. It can be concluded that Thixoinfiltration is a simple and low cost technique to produce different types of MMCs, with advantages upon techniques involving metal powders, which usually require long milling and sintering periods. Thixoinfiltration can be also advantageous upon techniques involving liquid processing, once lower temperatures are involved and so lower energy input, as well as less interface reactions.

New magnetic aluminum matrix composites (Al-Zn-Si) reinforced with nano magnetic Fe3O4 for aeronautical applications

Abstract Aluminum metal matrix composites (AMMCs) are light-weight materials are widely used in structural applications due to their favorable properties such as lightweight, high specific strength and modulus, wear resistance and low coefficient of thermal expansion. Today, new developed magnetic aluminium based composites (Al-Zn-Si) became very attractive due to their improved magnetic, physical and mechanical properties. These composites, depending on final desired properties with different reinforcement types, are very suitable for electrical motors and other usage in aircraft engineering. These promising properties of AMMCs are attributed to the size and distribution of the reinforcement, as well as to the grain size of the matrix. Process that was used in this work is called ‘Sinter-Forging’ during which compacted aluminium specimens were forged just after sintering. A novel near-net shape, low-cost sinter-forging approach to processing particle-reinforced metal matrix composites allow manufacturing parts for high performance applications with short processing time and low energy consumption. The aim of this work is to briefly present the efficient ‘Sinter-Forging Process’ and to summarize properties of new composites developed for aeronautical applications.

Design of Magnetic Aluminium (A356) Based Composites through Combined 2 Method of Sinter + Forging 3

In this work, aluminium matrix composites (AMCs with scrap A356 powder given by French Aeronautical Society) were designed through combined method of powder metallurgy and thixoforming (sinter + Forging). Three different reinforcements (Magnetic iron oxide, Fe3O4 – Hybrid graphene nano-platelets, GNPs, Nickel, Ni) were used and preceded under the constant process parameters such as hot compaction, sinter-forging, sintering time, etc. Mechanical and physical properties of the composites were improved with the combined processing method of powder compacted specimens and reinforcement volume fractions. Static compression tests, Microhardness tests, surface scratch tests, measurement of magnetic permeability showed that the mechanical and physical properties of these composites can be improved with the optimization of process parameters. In the present work, an alternative and a low cost manufacturing process were proposed for these composites. The microstructure and damage analyses have been carried out by Scanning Electron Microscope (SEM).

Scrap Rubber Based Composites Reinforced with Ceramic Oxides and Silica

The paper presents results of investigation on composition of some ceramic oxides used for scrap rubber-based composites. The paper reports results of investigation on the influence of boron, boron oxide (B2O3) and silica presence of Zr2O3 in the composition. Silica is added as the agent controlling the composite transformation. The process of scrap rubber matrix reinforced with certain ceramic reinforcements during heating was examined by DSC/TG technique. Microstructure was evaluated by Scanning Electron Microscope (SEM). Mechanical and wear properties are also studied depending on the composition. The mechanical properties of the composite structure were found to significantly increase with increasing B2O3 and Zr2O3 contents.

Mechanical and Tribological Properties of Scrap Rubber Based Composites Reinforced with Glass Fiber, Al and TiO2

Scrap rubber/Epoxy composites reinforced with Aluminium, Glass Fibre (GF) and TiO2 particles were prepared and mechanical and tribological properties of these composites were investigated. Basically, these composites are aimed to use in automotive and aeronautics applications. A detail microstructure and matrix/reinforcement interface analyze was made by means of Scanning Electron Microscope (SEM) The wear performance of hard particles reinforced composites were evaluated. Quasi static and dynamic compression tests were carried out and damaged specimens were studied by SEM. The hardness (short test) values of the composites were reviewed related to the reinforcement elements, Glass Fibre-fiber and TiO2 added in the matrix.

Mechanical and Tribological Properties of Scrap Rubber Reinforced with Al 2 O 3 Fiber, Aluminium and TiO 2

Scrap rubber/Epoxy composites reinforced with Aluminium, Alumina Fibre and TiO2 particles were prepared and mechanical and tribological properties of these composites were investigated. Basically, these composites are aimed to use in many engineering applications. A detail microstructure and matrix/reinforcement interface analyze was made by means of Scanning Electron Microscope (SEM) The wear performance of hard particles reinforced composites were evaluated in view of micromechanical properties. Quasi static and dynamic compression tests were carried out and damaged specimens were studied by SEM. Degradation behaviour of the structure for each composite was compared after exposing against UV. The hardness (short test) values of the composites were reviewed related to the reinforcement elements.

Influence of nanoparticulate and fiber reinforcements on the wear response of multiferroic composites processed by powder metallurgy

Abstract Nanoparticulates and nanofibres are good candidates to be considered as reinforcements in the design of new multiferroic composites processed by powder metallurgy. As would be expected in any composite material system, the addition of nanoparticles and fibres to the multiferroic composites will influence the wear response of these materials along with other mechanical properties. Also the choice of the processing parameters during the manufacturing of these materials is expected to influence the resulting material properties. The present study reviews the effect of processing parameters such as milling mode, sintering time and temperature on the wear properties of multiferroic composites that can potentially be used in different engineering applications. For this reason, detailed damage analyses due to wear, utilising scratch tests have been carried out on multiferroic composites reinforced with nanoparticles and fibres such as magnetic iron oxide, alumina powder and alumina fibre. Scanning electron microscopy and 3D optical surface scanner were used to assess the damage to the composites.