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Number of results: 5
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Abstract

The paper addresses the microsegregation of Mn, Mo, Cr, W, V, Si, Al, Cu and P in the white cast iron. Eutectic alloy with the content of 4.25% C was studied. The white cast iron was directionally solidified in the vacuum Bridgman-type furnace at a constant pulling rate v = 83 μm/s and v = 167 μm/s and at a constant temperature gradient G = 33.5 K/mm. The microstructural research was conducted using light and scanning electron microscopy. The microsegregation of elements in ledeburite was evaluated by EDS measurements. Content of elements in ledeburitic cementite and ledeburitic pearlite was determined. The tendency of elements to microsegregation was found dependent on the solidification rate. Microsegregation of elements between pearlite and cementite structural constituents has been specified. The effect of solidification rate on the type and intensity of microsegregation in directionally solidified eutectic white cast iron was observed. A different type of microsegregation was observed in the components of ledeburite in cementite and pearlite.
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Bibliography

[1] Podrzucki, Cz. (1991). Cast iron. Structure. Properties. Application T.1 and T.2, First Edition, Publishing house ZG STOP. (in Polish)
[2] Sękowski, K. (1973). Heterogeneity of the chemical composition of the metal matrix of ductile iron. Foundry Review. 8-9, 205-255413. (in Polish)
[3] Pietrowski, S. (1987). The influence of the chemical composition of nodular cast steel and cast iron and casting cooling rate on the austenite transformation to acicular structures. Scientific Books nr 94: Technical University of Łódź. (in Polish)
[4] Pietrowski, S. & Gumienny, G. (2006). Crystallization of nodular cast iron with additions of Mo, Cr, Cu and Ni. Archives of Foundry. 6(22), 406-413. (in Polish)
[5] Pietrowski, S. & Gumienny, G. (2012). Microsegregation in nodular cast iron with carbides. Archives of Foundry Engineering. 12(4), 127-134. DOI: 10.2478/v10266-012-0120-z.
[6] Sandoz, G. (1968). Recent Research in Cast Iron, H. Marchant, ed. New York: Gordon and Breach, 509.
[7] Malinochka, Ya.N., Maslenkov, S.B. & Egorshina, T.V. (1963). Investigation of microsegregation in cast iron using electron microprobe. Liteinoe Proizvodstvo, 1, 22-25. (in Russ.)
[8] Swindelsand, N. & Burke, J. (1971). Silicon microsegregation and first stag graphitization in white cast irons. Metallurgical Transactions. 2, 3257-3263. DOI: 10.1007/BF02811605
[9] Charbonnier, J. & Margerie, J.C. (1967). Nouvelle contribution al’etude generale des mikrosegregation dans les alliages Fe-C du type ”fonte”. Fonderie. 259, 333-344.
[10] Bazhenov, V.E., & Pikunov, M.V. (2018) Microsegregation of silicon in cast iron. Izvestiya. Ferrous Metallurgy. 61(3), 230-236. DOI: 10.17073/0368-0797-2018-3-230-236 (in Russ.)
[11] Park, J.Y. and other (2002). Effect of Mn negative segregation through the thickness direction on graphitization characteristics of strip-cast white cast iron. Scripta Materialia 46(3), 199-203. https://doi.org/10.1016/S1359-6462(01)01220-9
[12] Dojka, M. & Stawarz, M. (2020). Bifilm defects on Ti-inculated chromium white cast iron. Materials. 13(14), 3124. https://doi.org/10.3390/ma13143124
[13] Trepczyńska-Łent, M. (1997). Spheroidizing annealing of whitened ductile iron. 1st National Scientific Conference "Materials Science - Foundry - Quality", 129-137, Krakow. (in Polish)
[14] Trepczyńska-Łent, M. (1998). Microsegregation of silicon and manganese after spheroidizing annealing in cast iron with spherical graphite. Scientific Journals ATR 216, Mechanics. 43, 217-226. Bydgoszcz (in Polish).
[15] Chang, W.S. & Lin, C.M. (2013). Relationship between cooling rate and microsegregation in bottom-chilled directionally solidified ductile irons. Journal of Mining and Metallurgy, Section B: Metallurgy. 49(3)B, 315-322. https://doi.org/10.2298/JMMB120702034C.
[16] Trepczyńska-Łent, M. Boroński D. & Maćkowiak P. (2021). Mechanical properties and microstructure of directionally solidified Fe-4.25%C eutectic alloy. Materials Science and Engineering A, 822(3) 141644. https://doi.org/10.1016/j.msea.2021.141644.
[17] Trepczyńska-Łent, M. (2017). Interphase spacing in directional solidification of white carbide eutectic, METAL 2017 - 26th International Conference on Metallurgy and Materials, Conference Paper, Conference Proceedings Volume 2017-January 254-260. ISBN: 978-808729479-6.
[18] Trepczyńska-Łent, M. (2017). Directional solidification of Fe-Fe3C white eutectic alloy. Crystal Research and Technology 52(7) July 2017, 1600359, version of record online: 26 JUN 2017. DOI: 10.1002/crat.201600359.
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Authors and Affiliations

M. Trepczyńska-Łent
1
ORCID: ORCID
J. Seyda
1
ORCID: ORCID

  1. Bydgoszcz University of Science and Technology, Poland
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Abstract

The reaction of alkalis with aggregate containing reactive forms of silica (ASR) plays a significant role in shaping the durability of concrete, as the strongly hygroscopic reaction products generated lead to internal stress, causing its expansion and cracking. This study presents an extended analysis of corrosive processes occurring in mortars with reactive natural aggregate from Poland, using computed tomography and scanning microscopy methods. Numerous cracks in the grains and the surrounding cementitious matrix were observed, indicating a high degree of advancement of corrosive processes. Over time, the proportion of pores with reduced sphericity increased, indicating ongoing degradation of the mortars. The usefulness of computed tomography in studying the progress of ASR was demonstrated. Scanning microscopy confirmed that the cause of mortar degradation is the formed ASR gel with a typical composition, located within the volume of reactive grains, cracks propagating into the cementitious matrix, and accumulated in air voids.
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Authors and Affiliations

Justyna Zapała-Sławeta
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Abstract

The subject of the research was the Middle Miocene red algal limestone from the Włochy deposit, which is currently the only place of exploitation of the Pińczów Limestone representing a local type of the Leitha Limestone. The collected samples of this rock belong to the organodetric facies of diverse grain size and sorting of clastic material. Considering the proportions of characteristic skeleton remains, the composition of the coarse-grained organodetric facies is red algal-foraminiferalbryozoic, while of the fine-grained facies is foraminiferal-red algal. The cement of these rocks is predominantly sparite compared to micrite-clay matrix. A complement to petrographic studies was the chemical analysis and identification of mineral phases with X-ray diffraction. Moreover, physical and mechanical properties of samples were analyzed. Porosity of the rock was assessed in the polarizing and scanning microscope (SEM-EDS) observations, as well as with a porosimetric tests. The coarse-detrital limestone with a dominant binder in the form of intergranular cement is characterized by the apparent density sometimes exceeded 1.90 Mg/m3, while fine-grained limestone has the highest water absorbability (above 20%) and total porosity (about 40%). The above properties influenced high water absorption by capillarity, limiting the possibility of using limestone in places exposed to moisture. The observed relationship between the ultrasonic waves velocity and the uniaxial compressive strength gives the possibility of predicting the value of the latter parameter in the future. The limestones from Włochy deposit do not differ in quality from the previously used Pińczów Limestones, and their technical parameters predestine them for use as cladding material with insulating properties.

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Authors and Affiliations

Beata Figarska-Warchoł
Grażyna Stańczak
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Abstract

High temperature vacuum brazing is a well-known and commonly used method for joining of nickel based elements and subassemblies of gas turbines, both for stationary and aviation applications. Despite the fact that currently used brazing filler metals meet stringent requirements of aviation and energetic industries, a lot of effort is spent on improving operational properties of the joints through modification of chemical composition or brazing process parameters. This paper aims for both of these aspects – its purpose is evaluation of the impact of filler metal composition, brazing gap width and process conditions on the microstructure of joints between sheet metal elements made of Hastelloy X nickel superalloy. Two different Ni-based filler materials (BNi-2 and Amdry 915) were investigated, based on the results of light and scanning electron microscopy evaluations, energy dispersive X-ray spectroscopy and hardness measurements.
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Authors and Affiliations

K. Krystek
1 2
ORCID: ORCID
K. Krzanowska
1
ORCID: ORCID
M. Wierzbińska
1
ORCID: ORCID
M. Motyka
1
ORCID: ORCID

  1. Rzeszow University of Technology, Department of Materials Science, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
  2. Pratt & Whitney Rzeszów S.A., 120 Hetmańska Str., 35-078 Rzeszów, Poland
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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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