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Investment Casting of AZ91 Magnesium Open-Cell Foams

Kapłon Honorata, Dmitruk Anna, Naplocha Krzysztof

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

11--16

EN

The process of investment casting of AZ91 magnesium alloy open-cell porosity foams was analysed. A basic investment casting technique was modified to enable the manufacturing of magnesium foams of chosen porosities in a safe and effective way. Various casting parameters (mould temperature, metal pouring temperature, pressure during metal pouring and solidifying) were calculated and analysed to assure complete mould filling and to minimize surface reactions with mould material. The foams manufactured with this method have been tested for their mechanical strength and collapsing behaviour. The AZ91 foams acquired in this research turned out to have very high open porosity level (>80%) and performed with Young’s modulus of ~30 MPa on average. Their collapsing mechanism has turned out to be mostly brittle. Magnesium alloy foams of such morphology may find their application in fields requiring lightweight materials of high strength to density ratio or of high energy absorption properties, as well as in biomedical implants due to magnesium’s high biocompatibility and its mechanical properties similar to bone tissue.

2

Development of Al-Ti-C porous structures for reinforcing aluminum matrix composites

Dmitruk Anna, Naplocha Krzysztof

Composites Theory and Practice

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2022

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R. 22, nr 3

172--177

EN

Open-porous preforms from Al-Ti-C compounds were successfully ignited and synthesized by combustion synthesis in a microwave field. The reaction course and the temperature were remarkably affected by the preparation method and molarratio of the substrates, as well as the position of the green sample in the microwave field generated by a single mode microwave reactor. The manufactured structures were characterized by SEM investigations. The addition of aluminum powder to the mixture moderates the reaction and temperaturę variations, allowing the course of synthesis in explosive mode to be avoided. Among the reported developed materials the following can be distinguished: Ti-Al intermetallics, titanium carbides and MAX phases belonging to the Ti-Al-C system. The prepared and selected Al-Ti C preforms were subsequently infiltrated with an AlSi12 aluminum alloy by the squeeze casting method. The composite materials exhibit a relatively homogeneous microstructure with low residual porosity and a good reinforcement/matrix interface.

PL

Otwarte porowate preformy ze związków Al-Ti-C z powodzeniem zapalono i zsyntetyzowano poprzez syntezę spaleniową w polu mikrofalowym. Znaczący wpływ na przebieg i temperaturę reakcji miał sposób przygotowania i stosunek molowy sub-stratów oraz położenie próbki w polu mikrofalowym generowanym przez jednomodowy reaktor mikrofalowy. Wytworzone struktury scharakteryzowano za pomocą badań SEM. Dodatek proszku aluminium do mieszaniny łagodzi przebieg reakcji i zmiany temperatury, pozwalając uniknąć przebiegu syntezy w trybie wybuchowym. Spośród wytworzonych materiałów można wyróżnić następujące: fazy międzymetaliczne Ti-Al, węgliki tytanu i fazy typu MAX należące do układu Ti-Al-C. Przygotowane i wyselekcjonowane preformy Al-Ti-C następnie infiltrowano stopem aluminium AlSi12 metodą prasowania ze stanu ciekłego. Materiały kompozytowe wykazują stosunkowo jednorodną mikrostrukturę o niskiej porowatości resztkowej i dobrej granicy faz umocnienie/osnowa.

3

Application of poly amide 6 as a phase change material: Preliminary studies

Raźny Natalia, Naplocha Krzysztof

Zeszyty Energetyczne

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2020

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T. 7

59--69

EN

Phase-change materials (PCMs) have been the subject of numerous studies for many years thanks to their ability to accumulate heat from phase transitions. This group of materials is different to conventional groups, such as metals, polymers or ceramics. A PCM can be any material with specific parameters, such as the temperature of the phase transition suitable for the application, high enthalpy of the transition, easy product availability or a relatively low price. Applications for this type of material are numerous – from construction, where they are used to collect heat for cooling and heating buildings, through water heating, collecting heat from solar panels, creating smart textiles for athletes and people working in changing weather conditions, to planned applications in food packaging to keep food at the right temperature for longer. Corrosion issues with common PCM salts used in a medium temperature range (150–250°C) induced the development of chemically nonaggressive materials. Due to its high availability, satisfactory melting point for use in heat accumulators and relatively low price, polyamide 6 was used in a series of tests. Polymers are not a popular material for PCM due to their low melting enthalpy and fast degradation. Static temperature exposure tests were run and the first cooling curves were examined to determine whether polyamide 6 is a suitable PCM for this application. The results obtained so far are optimistic, but further tests will be required to determine the performance of the material during repeated charging and discharging cycles of the heat accumulator (heating and cooling of the polymer).