Wyniki wyszukiwania - Biblioteka Nauki

1

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

100%

Dmitruk A. , Naplocha K.

Composites Theory and Practice

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2022

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tom 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.

2

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

100%

Raźny N. , Naplocha K.

Zeszyty Energetyczne

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2020

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tom 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).

3

Investment Casting of AZ91 Magnesium Open-Cell Foams

80%

Kapłon H. , Dmitruk A. , Naplocha K.

Archives of Foundry Engineering

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2023

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tom 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.

4

Refinement of the Manufacturing Route and Evaluation of the Reinforcement Effect of MAX Phases in Al Alloy Matrix Composite Materials

80%

Dmitruk A. , Naplocha K. , Żak A. , Strojny-Nędza A.

Archives of Foundry Engineering

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2024

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tom Vol. 24, iss. 1

141--148

EN

Microwave Assisted Self-propagating High-temperature Synthesis (MASHS) was used to prepare open-porous MAX phase preforms in Ti-Al-C and Ti-Si-C systems, which were further used as reinforcements for Al-Si matrix composite materials. The pretreatment of substrates was investigated to obtain open-porous cellular structures. Squeeze casting infiltration was chosen to be implemented as a method of composites manufacturing. Process parameters were adjusted in order to avoid oxidation during infiltration and to ensure the proper filling. Obtained materials were reproducible, well saturated and dense, without significant residual porosity or undesired interactions between the constituents. Based on this and the previous work of the authors, the reinforcement effect was characterized and compared for both systems. For the Al-Si+Ti-Al-C composite, an approx. 4-fold increase in hardness and instrumental Young's modulus was observed in relation to the matrix material. Compared to the matrix, Al-Si+Ti-Si-C composite improved more than 5-fold in hardness and almost 6-fold in Young's modulus. Wear resistance (established for different loads: 0.1, 0.2 and 0.5 MPa) for Al-Si+Ti-Al-C was two times higher than for the sole matrix, while for Al-Si+Ti-Si-C the improvement was up to 32%. Both composite materials exhibited approximately two times lower thermal expansion coefficients than the matrix, resulting in enhanced dimensional stability.