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Microscopic Analysis of the Aluminium Castings Produced with the use of Polymer Composite Patterns

Czarnecka-Komorowska Dorota, Gawdzińska Katarzyna, Popielarski Paweł

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 3

113--117

EN

The paper presents a microscopic analysis of the surface and fracture of aluminium castings produced using the lost-wax method for patterns made of a composite material, i.e. polyethylene with the addition of bentonite. Castings are made of AlSi7 aluminium alloy (silumin) in a plaster mould. A new type of polymer waxes enriched with bentonite was used to obtain new composites, minimizing the defects caused by the casting production process. The castings were made in the centrifugal casting process. The prepared plaster moulds were removed from the furnace and poured with liquid aluminium alloy (AlSi7) at 750°C. The surface and fracture of the castings was analysed using an optical digital microscope type VHX-7000 manufactured by KEYENCE. It has been proven that the studied castings feature surface defects (raw surface defects) in the form of high roughness and the presence of bentonite inclusions classified as casting contamination. During the tests, shape defects related to mechanical damage were also.

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Structural, morphological and photoluminescent properties of annealed ZnO thin layers obtained by the rapid sol-gel spin-coating method

Sypniewska Małgorzata, Szczesny Robert, Popielarski Paweł, Strzałkowski Karol, Derkowska-Zielinska Beata

Opto-Electronics Review

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2020

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Vol. 28, No. 4

182--190

EN

ZnO thin layers were deposited on p-type silicon substrates by the sol-gel spin-coating method and, then, annealed at various temperatures in the range of 573-873 K. Photoluminescence was carried out in the temperature range of 20-300 K. All samples showed two dominant peaks that have UV emissions from 300 nm to 400 nm and visible emissions from 400 nm to 800 nm. Influence of temperature on morphology and chemical composition of fabricated thin layers was examined by XRD, SEM, FTIR, and Raman spectroscopy. These measurements indicate that ZnO structure is obtained for samples annealed at temperatures above 573 K. It means that below this temperature, the obtained thin films are not pure zinc oxide. Thus, annealing temperature significantly affected crystallinity of the thin films.

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Application of instance-based learning for cast iron casting defects prediction

Sika Robert, Szajewski Damian, Hajkowski Jakub, Popielarski Paweł

Management and Production Engineering Review

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2019

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Vol. 10, No. 4

101--107

EN

The paper presents an example of Instance-Based Learning using a supervised classiﬁcation method of predicting selected ductile cast iron castings defects. The test used the algorithm of k-nearest neighbours, which was implemented in the authors’ computer application. To ensure its proper work it is necessary to have historical data of casting parameter values registered during casting processes in a foundry (mould sand, pouring process, chemical composition) as well as the percentage share of defective castings (unrepairable casting defects). The result of an algorithm is a report with ﬁve most possible scenarios in terms of occurrence of a cast iron casting defects and their quantity and occurrence percentage in the casts series. During the algorithm testing, weights were adjusted for independent variables involved in the dependent variables learning process. The algorithms used to process numerous data sets should be characterized by high eﬃciency, which should be a priority when designing applications to be implemented in industry. As it turns out in the presented mathematical instance-based learning, the best quality of ﬁt occurs for speciﬁc values of accepted weights (set #5) for number k = 5 nearest neighbours and taking into account the search criterion according to “product index”.