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Number of results: 41
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Abstract

Contribution gives an overview of knowledge about the method of centrifugal casting with orientate on Tekcast system. Company Tekcast

Industries has developed a device for centrifugal casting, extending the area of production of castings or prototyping of metal or plastic.

Materials suitable for the centrifugal casting with flexible operating parameters may include non-ferrous metal alloy based on zinc or

aluminum or non-metallic materials such as polyester resins, polyurethane resins, epoxy resins, waxes and the like. The casting process is

particularly suitable for a wide range of commercial castings and decorative objects.

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Authors and Affiliations

H. Mäsiar
L. Repka
P. Lipták
O. Híreš
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Abstract

The paper analyses the influence of chemical composition of silicone-based composites on their properties in the aspect of using them as long-term soft denture lining materials. Different concentrations of filler and methylhydrosiloxane-dimethylsiloxane copolymer were used. The filler was introduced into the composite with mechanical mixing combined with ultrasonic homogenization. Scanning electron microscopy was used to investigate the quality of filler dispersion. Shore A hardness, tensile strength, sorption, solubility and tensile bond strength to poly(methyl methacrylate) were measured. Tests show satisfactory results for some experimental composites, which met all the requirements for such materials.

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Authors and Affiliations

E. Jabłońska-Stencel
W. Pakieła
J. Żmudzki
J. Kasperski
G. Chladek
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Abstract

Perovskite solar cells represent the biggest breakthrough in photovoltaics in decades, bringing a chance for affordable and widely available green energy. They are suitable in areas where silicon cells have fallen short.
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Authors and Affiliations

Olaf Szewczyk
1

  1. Saule Technologies in Warsaw
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Abstract

A superior SiC based thermal protection coating process for carbon composite, which can be especially effective in a hot oxidizing atmosphere, was established in this study. A multi-coating process based on a combination of Chemical Vapor Reaction (CVR) and Chemical Vapor Deposition (CVD) was developed. Various protective coating layers on carbon composite were tested in hot oxidizing surroundings and the test results verified that the thermal ablation rate could be dramatically reduced down to 3.8% when the protective multi-coating was applied. The thermal protection mechanism of the coating layers was also investigated.

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Authors and Affiliations

Soo Bin Bae
ORCID: ORCID
Ji Eun Lee
ORCID: ORCID
Jong Gyu Paik
Nam Choon Cho
ORCID: ORCID
Hyung Ik Lee
ORCID: ORCID
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Abstract

The results presented in this paper are a continuation of the previously published studies. The results of hest treatment of ductile iron with

content 3,66%Si and 3,80% Si were produced. The experimental castings were subjected to austempering process for time 30, 60 and 90

minutes at temperature 300o

C. The mechanical properties of heat treated specimens were studied using tensile testing and hardness

measurement, while microstructures were evaluated with conventional metallographic observations. It was again stated that austempering

of high silicone ferritic matrix ductile iron allowed producing ADI-type cast iron with mechanical properties comparable with standard

ADI.

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Authors and Affiliations

A. Krzyńska
A. Kochański
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Abstract

Ductile iron casts with a higher silicone content were produced. The austempering process of high silicone ductile iron involving different

austempering times was studied and the results presented. The results of metallographical observations and tensile strength tests were

offered. The obtained results point to the fact that the silicone content which is considered as acceptable in the literature may in fact be

exceeded. The issue is viewed as requiring further research.

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Authors and Affiliations

A. Kochański
A. Krzyńska
T. Radziszewski
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Abstract

The miner fly Liriomyza sativae (Blanchard) (Diptera: Agromyzidae) is an insect of economic importance for tomato culture. The conventional control with insecticides is complex due to the mining eating habit that provides protection to the larvae inside the leaves. Therefore, farmers can opt for biological control agents, or substances that provide protection to the plant. Thus, the objective of our research was to evaluate the use of silicon to induce resistance in tomato plants against L. sativae. The results showed that in tomato plants treated with SiO2/F and K2SiO3/F there was a reduction in the net reproduction rate (Ro), in the intrinsic rate of increase in number (rm), in the finite rate of increase (λ), in the average interval between generations (IMG), in the doubling time (TD), in the number of eggs/ female/day and the accumulated egg laying of F1 females of L. sativae. The products SiO2/F and K2SiO3/F gave the tomato a protective effect against injuries caused by L. sativae.
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Authors and Affiliations

Adamastor Pereira Barros
1
ORCID: ORCID
Hugo Bolsoni Zago
2
ORCID: ORCID
Dirceu Pratissoli
2
ORCID: ORCID
Paulo Cezar Cavatte
3
ORCID: ORCID
Julielson Oliveira Ataide
2
ORCID: ORCID

  1. Entomology Department, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil
  2. Entomology Department, Universidade Federal do Espírito Santo, Campus Alegre, Alegre, Brazil
  3. Biology Department, Universidade Federal do Espírito Santo, Campus Alegre, Alegre, Brazil
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Abstract

Electrical properties of semiconductor materials depend on their defect structure. Point defects, impurities or admixture contained in a semiconductor material, strongly affect its properties and determine the performance parameters of devices made on its basis. The results of the currently used methods of examining the defect structure of semiconductor material are imprecise due to solution of ill-posed equations. These methods do not allow for determination of concentration of the defect centers examined. Improving the resolution of the obtained parameters of defect centers, determining their concentration and studying changes in the resistivity of semi-insulating materials can be carried out, among others, by modelling changes in the concentration of carriers in the conduction and valence bands. This method allows to determine how charge compensation in the material affects the changes in its resistivity. Calculations based on the Fermi-Dirac statistics can complement the experiment and serve as a prediction tool for identifying and characterizing defect centers. Using the material models (GaP, 4H–SiC) presented in the article, it is possible to calculate their resistivity for various concentrations of defect centers in the temperature range assumed by the experimenter. The models of semi-insulating materials presented in the article were built on the basis of results of testing parameters of defect centers with high-resolution photoinduced transient spectroscopy (HRPITS). The current research will allow the use of modelling to determine optimal parameters of semi-insulating semiconductor materials for use in photoconductive semiconductor switches (PCSS).
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Bibliography

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[3] Pas, J., & Rosinski, A. (2017). Selected issues regarding the reliability-operational assessment of electronic transport systems with regard to electromagnetic interference. Eksploatacja i Niezawodnosc, 19(3), 375–381. https://doi.org/10.17531/ein.2017.3.8
[4] Makowski, L., Dziadak, B., & Suproniuk, M. (2019). Design and development of original WSN sensor for suspended particulate matter measurements. Opto-Electronics Review, 27(4), 363–368. https://doi.org/10.1016/j.opelre.2019.11.005
[5] Górecki, P., & Górecki, K. (2015). The analysis of accuracy of selected methods of measuring the thermal resistance of IGBTs. Metrology and Measurement Systems, 22(3), 455–464. https://doi.org/10.1515/mms-2015-0036
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[7] Kagamihara, S., Matsuura, H., Hatakeyama, T., Watanabe, T., Kushibe, M., Shinohe, T., & Arai, K. (2004). Parameters required to simulate electric characteristics of SiC devices for n-type 4H–SiC. Journal of Applied Physics, 96(10), 5601–5606. https://doi.org/10.1063/1.1798399
[8] Matsuura, H., Komeda, M., Kagamihara, S., Iwata, H., Ishihara, R., Hatakeyama, T., Watanabe, T., Kojima, K., Shinohe, T., & Arai, K. (2004). Dependence of acceptor levels and hole mobility on acceptor density and temperature in Al-doped p-type 4H–SiC epilayers. Journal of Applied Physics, 96(5), 2708–2715. https://doi.org/10.1063/1.1775298
[9] Suproniuk, M., Pawłowski, M., Wierzbowski, M., Majda-Zdancewicz, E., & Pawłowski, Ma. (2018). Comparison of methods applied in photoinduced transient spectroscopy to determining the defect center parameters: The correlation procedure and the signal analysis based on inverse Laplace transformation. Review of Scientific Instruments, 89(4). https://doi.org/10.1063/1.5004098
[10] Suproniuk, M., Kaczmarek, W., & Pawlowski, M. (2019). A New Approach to Determine the Spectral Images for Defect Centres in High-Resistive Semiconductor Materials. Proceedings of the 23rd International Conference Electronics 2019, Lithuania. https://doi.org/10.1109/ELECTRONICS.2019.8765694
[11] Piwowarski, K. (2020). Comparison of photoconductive semiconductor switch parameters with selected switch devices in power systems. Opto-electronics Review, 28(2), 74–81. https://doi.org/10.24425/opelre.2020.132502
[12] Suproniuk, M. (2020). Effect of generation rate on transient photoconductivity of semi-insulating 4H–SiC. Scientific Reports, 10(1). https://doi.org/10.1038/s41598-020-68898-z
[13] Suproniuk, M., Piwowarski, K., Perka, B., Kaminski, P., Kozlowski, R., & Teodorczyk, M. (2019). Blocking characteristics of photoconductive switches based on semi-insulating GAP and GaN. Elektronika ir Elektrotechnika, 25(4), 36–39. https://doi.org/10.5755/j01.eie.25.4.23968
[14] Sze, S. M.,&Kwok, K. Ng. (2006). Physics of Semiconductor Devices.Wiley. https://doi.org/10.1002/ 0470068329
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[16] Kozubal, M. (2011). Effect shallow impurities on the properties and concentrations of deep-level defect centres in SiC. Ph.D. Dissertation. https://rcin.org.pl/dlibra/publication/29712
[17] Zvanut, M. E., & Konovalov, V. V. (2002). The level position of a deep intrinsic defect in 4H–SiC studied by photoinduced electron parametric resonance. Applied Physics Letters, 80(3), 410–412. https://doi.org/10.1063/1.1432444
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[19] Danno, K., & Kimoto, T. (2006). Deep hole traps in as-grown 4H–SiC epilayers investigated by deep level transient spectroscopy. Materials Science Forum, 527–529, 501–504. https://doi.org/10.4028/ www.scientific.net/MSF.527-529.501
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Authors and Affiliations

Marek Suproniuk
1

  1. Military University of Technology, Faculty of Electronics, Institute of Electronic Systems, gen. S. Kaliskiego 2, Warsaw
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Abstract

The structural, morphological and photoluminescent properties of thermally evaporated neodymium oxide (Nd2O3) thin films deposited onto nanostructured silicon (Si-ns) are reported. Si-ns embedded in silicon nitride (SiN) thin films are prepared by plasma-enhanced chemical vapour deposition (PECVD). SiN and Nd2O3 thin films uniformity and Si-ns formation are confirmed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presence of neodymium (Nd), silicon (Si), oxygen (O), and phosphorus (P) is investigated by energy-dispersive spectroscopy (EDS) and secondary ion mass spectrometry (SIMS). Post-annealing SIMS profile indicates an improvement of the homogeneity of activated P distribution in Si bulk. The X-ray diffraction (XRD) combined with Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) have been employed to determine amorphous silicon (a-Si), crystalline silicon (c-Si), Nd2O3 and SiN phases present in the Nd2O3-SiN bilayers with their corresponding chemical bonds. After annealing, a Raman shift toward lower wavenumbers is recorded for the Si peak. XPS data reveal the formation of Nd2O3 thin films with Nd-O bonding incorporating trivalent Nd ions (Nd3+). Strong room-temperature photoluminescence is recorded in the visible light range from the Si-ns. Nd-related photoluminescent emission in the near infrared (NIR) range is observed at wavelengths of 1025–1031 nm and 1083 nm, and hence is expected to improve light harvesting of Si-based photovoltaic devices.
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Authors and Affiliations

Amine Mefoued
1 2
ORCID: ORCID
Bedra Mahmoudi
1
Nasser Benrekaa
2
Faiza Tiour
1
Hamid Menari
1
Abdelyamine Naitbouda
3
Amar Manseri
1
Afaf Brik
1
Salah Mezghiche
1
Moustafa Debbab
4

  1. Centre de Recherche en Technologie des Semi-conducteurs pour l’Énergétique (CRTSE), 02 Bd Frantz Fanon BP140, Alger–7 merveilles, 16027 Algiers, Algeria
  2. Faculté de Physique, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32 Bab-Ezzouar, 16111 Algiers, Algeria
  3. Centre de Développement des Technologies Avancées (CDTA), Cité 20 août 1956, 16081 Algiers, Algeria
  4. Université Abou Bekr Belkaid BP 230, 13000 Chetouane, Tlemcen, Algeria
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Abstract

The wet flashover voltage of medium voltage insulators made of a silicone rubber is 8% lower than the wet flashover voltage of a porcelain insulator with an identical profile. These surprising results, obtained in 2012, were confirmed again in 2019. The flashover development on the composite insulator is very short (less than 30 ms). On the other hand, on the porcelain insulator, the flashover develops longer (1–3 seconds). The Koppelmann equation was modified, and the Obenaus model to calculate the flashover voltage of insulators under the artificial rain was presented. Attention was paid to the importance of insulator diameters and the phenomenon of water cascades.
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Bibliography

[1] Kuhlman K., Hochspannungsisolatoren, Elektrotechnische Zeitschrift (in German), vol. 31, iss. 3, pp. 51–55 (1910).
[2] Lustgarten J., High-tension porcelain line insulators, Journal of the Institution of Electrical Engineers, vol. 49, pp. 235–279 (1912).
[3] IEC 60060-1:2010, High-voltage test techniques – Part 1: General definitions and test requirements, edition 3 (2010).
[4] Gallet G., How to design a rain apparatus for the dielectric tests, IEEE PES Summer Meeting, San Francisco, paper A 75 490-3 (1975).
[5] Huc J., Rowe S.W., Wet testing installation design, 5th Int. Symposium on High Voltage Engineering, Athens, paper 52.03 (1983).
[6] Chrzan K.L., Streubel H., Artificial rain test of outdoor long rod insulators, Int. Symposium on High Voltage Engineering, ISH, Cap Town, paper E-31 (2009).
[7] Rizk F.A.M., Kamel S.I., Modelling of HVDC wall bushing flashover in nonuniform rain, IEEE Trans. on Power Delivery, vol. 6, no. 4, pp. 1650–1662 (1991).
[8] Matsuoka M., Naito K., Irie T., Kondo K., Evaluation methods of polymer insulators under contaminated conditions, IEEE Transmission and Distribution Asia Pacific Conference, pp. 2197–2202 (2002).
[9] Chrzan K.L., Swierzyna Z., Artificial rain test of insulators, Przegl˛ad Elektrotechniczny (in Polish), no. 11b, pp. 218–221 (2012).
[10] Szpor S., Dzierzek H.,WiniarskiW., High voltage engineering, WNT (in Polish),Warsaw, vol. 1, p. 88 (1978).
[11] Estorff W., Cron H., High Voltage insulator as pollution problem, ETZ (in German), vol. 73, iss. 3, pp. 57–62 (1952).
[12] Chrzan K.L., Leakage currents on naturally contaminated porcelain and silicone insulators, IEEE Trans. on Power Delivery, vol. 25, no. 2, pp. 904–910 (2010), DOI: 10.1109/TPWRD.2009.2034665.
[13] Streubel H., Calculation of AC Flashover voltage under rain, Hermsdorfer Technische Mitteilungen (in German), iss. 31, pp. 974–980 (1971).
[14] Lan L., Gorur R.S., Computation of ac wet flashover voltage of ceramic and composite insulators, IEEE Transactions on Dielectrics and Electrical Insulation, vol. 15, no. 5, pp. 1346–1352 (2008), DOI: 10.1109/TDEI.2008.4656243.
[15] Erler F., About AC pollution flashover on thick insulators, Elektrie (in German), iss. 3, pp. 100–102 (1969).
[16] Hao Y., Liao Y., Kuang Z., Sun Y., Shang G., Zhang W., Mao G., Yang L., Zhang F., Li L., Experimental investigation on influence of shed parameters on surface rainwater characteristics of largediameter composite post insulators under rain conditions, Energies, vol. 13, no. 19, 5011 (2020), DOI: 10.3390/en13195011.
[17] Ely C.H.A., Lambeth P.J., Looms J.S.T., The booster shed: prevention of flashover of polluted substation insulators in heavy wetting, IEEE Transactions on Power Apparatus and Systems, vol. PAS-97, no. 6, pp. 2187–2197 (1978).
[18] Yang L., Kuang Z., Sun Y., Liao Y., Hao Y., Li L., Zhang F., Study on Surface Rainwater and Arc Characteristics of High-Voltage Bushing with Booster Sheds under Heavy Rainfall, IEEE Access, vol. 6, pp. 146865–146875 (2020), DOI: 10.1109/ACCESS.2020.3012978.
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Authors and Affiliations

Krystian Leonard Chrzan
1
Henryk Marek Brzeziński
2

  1. Wroclaw University of Technology, Poland
  2. Łukasiewicz Research Network – Institute of Electrical Engineering, Poland
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Abstract

Many variants of thin film technology are nowadays part of the photovoltaic market. The most popular are amorphous silicon, CIS (Copper Indium Selenide)/CIGS (Copper Indium Gallium Selenide)/CIGSS (Copper Indium Gallium Sulphur Selenide), and CdS/CdTe (Cadmium Sulphide/Cadmium-Telluride) cells. All mentioned types allow potentially for a flexible cell structure. Most emitter contacts are currently based on TCOs (Transparent Conductive Oxides), however, wider approach with alternative carbon nanoforms, silver nanolayers and polymer materials, called TCLs (Transparent Conductive Layers) are also in use. Authors decided to investigate influence of mechanical stresses on physical and electrical behaviour of these layers. Consequently, the aim of work is to determine the level and possible mechanisms of flexible a-Si cell parameters degradation due to a deterioration of transparent contact properties.

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Authors and Affiliations

Maciej Sibiński
ORCID: ORCID
K. Znajdek
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Abstract

An optimal design of a slot waveguide is presented for realizing an ultrafast optical modulator based on a 220 nm silicon wafer technology. The recipe is to maximize the confinement and interaction between optical power supported by the waveguide and electric field applied through metallic electrodes. As height of waveguide is fixed at 220 nm, the waveguide and slot width are optimized to maximize the confinement factor of optical power. Moreover, metal electrodes tend to make the waveguide lossy, their optimal placement is calculated to reduce the optical loss and enhance the voltage per unit width in the slot. Performance of an optimally designed slot waveguide with metal electrodes as ultrafast modulator is also discussed.

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Authors and Affiliations

N. Malviya
V. Priye
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Abstract

This paper presents research on the deposition of an indium tin oxide (ITO) layer which may act as a recombination layer in a silicon/perovskite tandem solar cell. ITO was deposited by magnetron sputtering on a highly porous surface of silicon etched by the metal-assisted etching method (MAE) for texturing as nano and microwires. The homogeneity of the ITO layer and the degree of coverage of the silicon wires were assessed using electron microscopy imaging techniques. The quality of the deposited layer was specified, and problems related to both the presence of a porous substrate and the deposition method were determined. The presence of a characteristic structure of the deposited ITO layer resembling a "match" in shape was demonstrated. Due to the specificity of the porous layer of silicon wires, the ITO layer should not exceed 80 nm. Additionally, to avoid differences in ITO thickness at the top and base of the silicon wire, the layer should be no thicker than 40 nm for the given deposition parameters.
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Authors and Affiliations

Grażyna Kulesza-Matlak
1
ORCID: ORCID
Marek Szindler
2
ORCID: ORCID
Magdalena M. Szindler
2
ORCID: ORCID
Anna Sypień
1
ORCID: ORCID
Łukasz Major
1
ORCID: ORCID
Kazimierz Drabczyk
1
ORCID: ORCID

  1. Institute of Metallurgy and Materials Science, Polish Academy of Sciences, ul. W. Reymonta 25, 30-059 Kraków, Poland
  2. Faculty of Mechanical Engineering, Silesian University of Technology, ul. Akademicka 2A, 44-100 Gliwice, Poland
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Abstract

The paper reports the results of a physical modelling study of the production of a hypereutectic aluminium alloy to be used for making an alloy vapour source for operation in the magnetron. Within the study, targets from a hypereutectic aluminium-silicon alloy were made in laboratory conditions. Thus obtained material was subjected to heat treatment, porosity analysis, and the assessment of the microstructure and fitness for being used in the magnetron. The process of melting the hypereutectic Al-Si alloy was carried out at the Department of Foundry of the Czestochowa University of Technology. The investigation into the production of the alloy vapour source for the synthesis of the dielectric material from the hypereutectic aluminium alloy has confirmed.

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Authors and Affiliations

M. Nadolski
ORCID: ORCID
G. Stradomski
K. Zdunek
S. Okrasa
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Abstract

This paper describes successfully formed ohmic contacts to p-type 4H-SiC based on titanium-aluminum alloys. Four different metallization structures were examined, varying in aluminum layer thickness (25, 50, 75, 100 nm) and with constant thickness of the titanium layer (50 nm). Structures were annealed within the temperature range of 800°C - 1100°C and then electrically characterized. The best electrical parameters and linear, ohmic character of contacts demonstrated structures with Al layer thickness equal or greater than that of Ti layer and annealed at temperatures of 1000°C or higher.
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Bibliography

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Authors and Affiliations

Agnieszka Martychowiec
1
Norbert Kwietniewski
1
Kinga Kondracka
1
Aleksander Werbowy
1
Mariusz Sochacki
1

  1. Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw, Poland
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Abstract

The sodium silicate sands hardened by microwave have the advantages of high strength, fast hardening speed and low residual strength with the lower addition of sodium silicate. However, the sodium ion in the sands will absorb moisture from the atmosphere, which would lead to lower storing strength, so the protection of a bonding bridge of sodium silicate between the sands is crucial. Methyl silicone oil is a cheap hydrophobic industrial raw material. The influence of the addition amount of methyl silicone oil modifier on compressive strength and moisture absorption of sodium silicate sands was studied in this work. The microscopic analysis of modified before and after sodium silicate sands has been carried on employing scanning electron microscopy(SEM) and energy spectrum analysis(EDS). The results showed that the strength of modified sodium silicate sands was significantly higher than that of unmodified sodium silicate sands, and the best addition of methyl silicone oil in the quantity of sodium silicate was 15%. It was also found that the bonding bridge of modified sodium silicate sands was the density and the adhesive film was smooth, and the methyl silicone oil was completely covered on the surface of the sodium silicate bonding bridge to protect it.
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Bibliography

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Authors and Affiliations

Huafang Wang
1
ORCID: ORCID
Xiang Gao
1
Lei Yang
1
ORCID: ORCID
Wei He
1
Jijun Lu
1
ORCID: ORCID

  1. School of Mechanical Engineering and Automation, Wuhan Textile University, China
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Abstract

This paper analyses the possibility of applying thermal barrier coatings (TBCs) onto a substrate made of the AlSi7Mg alloy, intended for, among other things, internal combustion engine components. Engine components made of aluminum-silicon alloys, especially pistons and valve heads, are exposed to high temperature, pressure and thermal shock resulting from the combustion of the fuel-air mixture. These factors cause degradation of these components and can lead to damage. To minimize the risk of damage to engine components caused by heat stress, one way is to apply TBCs. Applying TBCs coatings to engine components improves their durability, increases power output and reduces fuel consumption. The research scope includes the application of an Al2O3-TiO3 coating via the APS (Air Plasma Spraying or Atmospheric Plasma Spraying) method onto a substrate of the AlSi7Mg alloy, analysis of the microstructure and chemical composition of the substrate and coating material, and assessment of the quality of the coating's bond with the AlSi7Mg alloy substrate using the scratch test method.
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Authors and Affiliations

Marek Mróz
ORCID: ORCID
Patryk Rąb
ORCID: ORCID

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Abstract

A source of pure silicon was added into an alloy refining system during a refining process with the application of a direct electric current. The effect of the temperature difference between the graphite electrodes and the alloy was decreased. The temperature increase value (ΔT) of the Al-28.51wt.%Si alloy sample caused by Joule heating was calculated by weighing the mass of primary silicon. When the current density was 5.0×105 A/m2, the overall temperature increase in the alloy was about 90°C regardless of the alloy composition. Adequate silicon atoms recorded the footprint of the electric current in the alloy melt. The flow convection generated by the electric current in the melt during the solidification process resulted in the refinement of primary silicon. The Fe impurity content in alloy refining without the electric current density was 2.16 ppm. However, it decreased to 1.27 ppmw with the application of an electric current density of 5.0×105 A/m2.
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Authors and Affiliations

Jiayan Li
1 2
Benson Kihono Njuguna
1 2
Ping Ni
1 2
Liang Wang
2 1
Yi Tan
1 2

  1. Dalian University of Technology, School of Materials Science and Engineering, No. 2 Linggong Road, Ganjingzi District, Dalian 116023, China
  2. Dalian University of Technology, Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province, Dalian 116024, China
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Abstract

This paper presents the results of studies concerning the production and characterization of Al-SiC/W and Cu-SiC/W composite materials with a 30% volume fraction of reinforcing phase particles as well as the influence of corrosion and thermal shocks on the properties of selected metal matrix composites. Spark plasma sintering method (SPS) was applied for the purpose of producing these materials. In order to avoid the decomposition of SiC surface, SiC powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. The obtained results were analysed by the effect of the corrosion and thermal shocks on materials density, hardness, bending strength, tribological and thermal properties. Qualitative X-ray analysis and observation of microstructure of sample surfaces after corrosion tests and thermal shocks were also conducted. The use of PVD technique allows us to obtain an evenly distributed layer of titanium with a constant thickness of 1.5 µm. It was found that adverse environmental conditions and increased temperature result in a change in the material behaviour in wear tests.

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Authors and Affiliations

A. Strojny-Nędza
P. Egizabal
K. Pietrzak
R. Zieliński
K. Kaszyca
A. Piątkowska
M. Chmielewski
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Abstract

The effect of possible modification and refining effect of Al-Cu-P-based pre-alloy combined with Fe on the microstructure and the silicon morphology change in hypereutectic Al-Si cast alloy was studied. The samples in the as-cast state were observed by optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The 3D morphology of both primary and eutectic silicon was observed by using colour and deep etching in detail. The results showed that the AlCu19P1.4 pre-alloy (1.07 wt.%) combined with the addition of Fe (0.02 wt.%) has a significant effect on the change of the amount, size and morphology of primary Si. This is significantly refined and changes the shape from a coarse irregular star-shaped, polyhedral, or plate-like shape to a fine polyhedral shape. The average size of the primary Si is reduced by about of 78 % from 135 μm to 28 μm and the number of primary Si particles increased from 7.4 to 237. No change in the morphology of the eutectic Si was observed; a refinement of the structure from a coarse needle/plate-like to a fine plate-like structure was seen. The depth etching method using HCl was very effective in the study of the 3D silicon morphology observed, which could be observed in detail without the presence of artefacts.
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Authors and Affiliations

Eva Tillová
1
ORCID: ORCID
Mária Chalupová
1
Lenka Kuchariková
1
ORCID: ORCID
Mirosław Bonek
2
ORCID: ORCID
Milan Uhríčik
1
Lucia Pastierovičová
1

  1. University of Žilina, Faculty of Mechanical Engineering, Department of Materials Engineering, Univerzitná 8215/1, 010 26 Žilina, Slovak Republic
  2. Silesian University of Technology, Faculty of Mechanical Engineering, Department of Engineering Materials and Biomaterials, ul. Konarskiego 18A, 44-100 Gliwice, Poland
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Abstract

This paper investigates the preparation of silicon nitride composites with multi-walled carbon nanotubes (MWCNTs). Samples containing 1–10 wt% MWCNTs were ultrasonically processed in non-aqueous suspensions, dried, pressed, and then subjected to non-pressure sintering at 1600 °C for 2 h. The preliminary results showed that the mixture of activated silicon nitride and covered MWCNTs could be sintered. The porosity of the obtained samples ranged from 0.27 to 36.94 vol.%. The microstructure was observed by scanning electron microscopy (SEM), and the mechanical properties (hardness and fracture toughness) were also determined. Good hardness values were obtained for samples prepared by sintering the mechanically activated precursor under a flowing nitrogen atmosphere using the lowest fraction of CNTs. Residual activator reduced the densification of the composites.
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Authors and Affiliations

Marta Mikuśkiewicz
1
ORCID: ORCID

  1. Faculty of Materials Engineering, Department of Advanced Materials and Technologies, Silesian University of Technology, ul. Krasinskiego 8, 40-019 Katowice, Poland
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Abstract

The U-type ferrite is a kind of hexagonal ferrite, and it is known as a microwave absorber in the X-band. The magnetic and dielectric loss of the U-type ferrite change to the composition and coating layer, etc. In this study, the silicon oxide layer was coated on the substituted U-type ferrites to improve microwave absorption characteristics. The complex permittivity and complex permeability were measured using toroidal specimens that were press-molded and the measured frequency range was set from 2-18 GHz. The improvement of the microwave absorption rate was different according to the type of the substituted U-type ferrites. Only in the substituted U-type ferrites with nickel and zinc, an improvement in the microwave absorption rate due to enhancement of magnetic loss was confirmed. The highest microwave absorption was 99.9% at 9.6 GHz, which was S_Z0.5U.

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Authors and Affiliations

Kwang-Pil Jeong
Jeong-Gon Kim
Su-Won Yang
Jin-Hyuk Choi
Seung-Young Park
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Abstract

Phytolith-occluded carbon (PhytOC) is highly stable, and constitutes an important source of long-term C storage in agrosystems. This stored carbon is resistant to the processes of oxidation of carbon compounds. In our research phytolith content in barley (Estonia) and oat (Poland) grain and straw was assessed at field trials, with Si as a liquid immune stimulant OPTYSIL and compost fertilisation. We showed that cereals can produce relatively high amounts of phytoliths. PhytOC plays a key role in carbon sequestration, particularly for poor, sandy Polish and Estonian soils. The phytolith content was always higher in straw than in grain regardless of the type of cereals. The phytolith content in oat grains varied from 18.46 to 21.28 mg∙g−1 DM, and in straw 27.89–38.97 mg∙g−1 DM. The phytolith content in barley grain ranged from 17.24 to 19.86 mg∙g−1 DM, and in straw from 22.06 to 49.08 mg∙g−1 DM. Our results suggest that oat ecosystems can absorb from 14.94 to 41.73 kg e-CO2∙ha−1 and barley absorb from 0.32 to 1.60 kg e-CO2∙ha−1. The accumulation rate of PhytOC can be increased 3-fold in Polish conditions through foliar application of silicon, and 5-fold in Estonian conditions. In parallel, the compost fertilisation increased the phytolith content in cereals.
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Authors and Affiliations

Beata Rutkowska
1
ORCID: ORCID
Peter Schröder
2
ORCID: ORCID
Michel Mench
3 4
ORCID: ORCID
Francois Rineau
5
ORCID: ORCID
Witold Szulc
6
ORCID: ORCID
Wiesław Szulc
1
ORCID: ORCID
Jarosław Pobereżny
7
ORCID: ORCID
Kristjan Tiideberg
8
ORCID: ORCID
Tomasz Niedziński
1
ORCID: ORCID
Evelin Loit
8
ORCID: ORCID

  1. Warsaw University of Life Sciences – SGGW, Institute of Agriculture, Nowoursynowska St, 166, 02-787 Warsaw, Poland
  2. Helmholtz Center for Environmental Health, German Research Center for Environmental Health, Research Unit Environmental Simulation, Ingolstädter Landstraße 1, D-85764 Neuherberg, Munich, Germany
  3. University of Bordeaux, Amphithéâtre 3 à 12, 33000, Bordeaux, France
  4. INRAE – National Research Institute for Agriculture, Food and the Environment, 147 rue de l’Université 75338, Paris, France
  5. Hasselt University, Martelarenlaan 42, 3500, Hasselt, Belgium
  6. Fire University, Słowackiego St, 52/54, 01-629 Warsaw, Poland
  7. University of Science and Technology, Kaliskiego Ave., 7, 85-796 Bydgoszcz, Poland
  8. Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Fr. R. Kreutzwaldi 1, 51006, Tartu, Estonia
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Abstract

For the sake of exploring the thermodynamic characteristics of hybrid ceramic bearings with metal inner rings in the application process, we established the mathematical model of bearings with metal inner rings based on the thermodynamics of bearings. The heat of the bearings, inner and outer raceway, and the deformation of bearings were calculated by the thermodynamic model. We used the bearing life testing machine to test the bearing load and speed. The consequences indicate that the temperature stability time of a hybrid ceramic bearing with the metal inner ring is about 6 hours after loading, and its temperature is about 1–2°C higher than that of a metal bearing. Under the condition of a certain speed, the stable temperature of bearing operation improves with the enlargement of the load. Under the condition of a certain load, the bearing temperature also improves with the enlargement of bearing speed. The overall temperature trend of the bearing outer ring is unanimous with the overall temperature value calculated by the model. The maximum error is between 2.2 and 2.4°C. The thermodynamic analysis of hybrid bearings with metal inner rings is conducive to a better study of the effect of bearing material characteristics on bearing performance.
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Authors and Affiliations

Jian Sun
1
Guangxiang Zhang
1
Junxing Tian
1
Yusheng Zhu
2

  1. School of Mechanical Engineering, Shenyang Jianzhu University, Liaoning, 100084, China
  2. Nanjing Metro Operation Co., Ltd., Nanjing 210000, China

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