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Use of Used Graphite Electrodes as Metal Matrix Composites Reinforcement

Łągiewka Małgorzata

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

21--25

EN

The work presents the effect of the addition of graphite from recycled graphite electrodes on the mechanical properties of metal matrix composites (MMC) based on the AlMg10 alloy. A composite based on the AlMg10 alloy reinforced with natural graphite particles was also tested. Further, tests of the mechanical properties of the AlMg10 alloy were performed for comparative purposes. Composites with a particle content of 5, 10 and 15 percent by volume were produced by adding introduction of particles into the liquid matrix while mechanically mixing molten alloy. The composite suspensions were gravitationally cast into metal molds. Samples for the Rm , R 0.2, A and E tests were made from the prepared castings. Photos of the microstructures of the materials were also taken. The research shows that the addition of graphite to the matrix alloy causes minor changes in tensile strength (Rm) and yield strength (R 02), regardless of the type of graphite used. The results of the relative elongation tests showed that the introduction of graphite particles into the matrix alloy had an adverse effect on the elongation values in the case of each of the tested composites. The introduction of graphite particles into the AlMg10 alloy significantly increased the Young’s modulus value, both in the case of composites with flake graphite (natural) and graphite from ground graphite electrodes.

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The role of innovative composite materials in the safe and efficient operation of floating marine structures

Grabian J., Ślączka A., Pawłowska P., Kostrzewa W.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2017

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nr 52 (124)

23--29

EN

This work indicates that new and innovative materials used in the construction of floating and stationary marine structures can contribute to increased operational safety in addition to reduced service costs and frequency and other reduced operating costs, including the costs of staff and running maintenance. Such materials include metal-ceramic composites whose properties, such as high resistance to abrasive wear, favourable coefficient of friction, good thermal conductivity and low thermal expansion, allow them to be used in tribological pairs in mechanisms, control elements and actuators of various devices operating in marine power plants, thereby increasing their operational reliability. Properties of metal-ceramic composite foams, i.e. vibration and noise damping, good thermal insulation performance, dissipation of electromagnetic waves and absorption of explosive energy, make them ideal for use in shipbuilding and construction of drilling towers, at the same time increasing the levels of comfort during operation. Composite metal-ceramic foams can significantly reduce the effects of fires as they are durable, water-resistant and creep resistant thermal insulators which can limit the destruction (deformation) of steel structures. This paper presents proposals for the application of these materials to selected technical solutions in offshore structures.

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Selected problems of electrical discharge machining (EDM) of metal composite materials applied in manufacturing of mechanical vehicles

Perończyk J.

Journal of KONES

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2011

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Vol. 18, No. 1

429-442

EN

The paper presents examples of applications for metal composite materials on Al matrix reinforced with ceramic particles in the form of grains, fibre or whiskers in the automotive industry. Highlighted are the advantages and drawbacks of such composite materials and issues involved in shaping complete parts. Presence of hard and brittle ceramic particles in the Al alloy (given their sufficient concentration) significantly impacts on the physical, chemical and mechanical properties of the material and its suitability for shaping complete parts and constituting a surface layer (SL) with required properties. In making metal composite materials of Al alloys, various (including the latest) methods of casting are applied, often in combination with press molding in semi-fluid state, as well as powder metallurgy (P/M) methods. The final machining of functionally significant surfaces is done by machining (by all ways and variants). With presence of more than 5% (by volume) ceramic reinforcing particles it becomes necessary to use cutting blades of the so-called super hard materials, including composites of polycristalline diamond and diamond. This considerably increases manufacturing costs. Electrical discharge machining has proved to be an effective way for shaping metal parts, in all its variants: sinker (EDM), wire erosion (WEDM), micromachining (ěEDM), shaping by free electrode (REDM), discharge grinding (AEDM) and other. Cited in the paper are the results of own research connected with EDM and WEDM of Al alloys composite cast and reinforced with particles of Al2O3 (AlSi7Mg + 20%Al2O3) and a composite material produced by powder metallurgy methods (P/M) reinforced with various (maximum 10%) concentrations of Al2O3 or SiC or Si3N4. EDM and WEDM technological characteristics were defined for the studied materials in the form of regressive dependencies as statistical models of given indicators allowing for defining impact of machining parameters on shaping the indicators. In addition, there are selected photos of metallographic structures, enabling observation and evaluation of surface layer phase changes and chemical composition after EDM. The highly enlarged SEM micro-photos which are included show the geometric structure of machined surface, micro-cracks on borders of the composite material grains, presence of minor reinforcement particles adhering to the surface. This confirms the complex nature of electrical discharge machining mechanism taking place locally after very high temperatures and in a very short time, in presence of cold dielectric.