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The Influence of Riser Shape on Feeding Effectiveness of Solidifying Casting

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Foundry Engineering | 2019 | vol. 19 | No 4 | 91-94 | DOI: 10.24425/afe.2019.129636
Keywords Solidification process Castings defects Numerical simulation Liquid metal flow
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Abstract

The mathematical model and numerical simulations of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity by liquid metal and feeding the casting through the riser during its solidification, are presented in the paper. Mutual dependence of thermal and flow phenomena were taken into account because have an essential influence on solidification process. The effect of the riser shape on the effectiveness of feeding of the solidifying casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of riser shape was made, which is important for foundry practice. Numerical calculations of the solidification process of system consisting of the casting and the conical or cylindrical riser were carried out. The velocity fields have been obtained from the solution of momentum equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. Changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.

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Authors and Affiliations

L. Sowa
ORCID: ORCID
T. Skrzypczak
ORCID: ORCID
P. Kwiatoń
ORCID: ORCID

Experimental Verification of the Cast Iron Solidification Model

J. Mendakiewicz
Archives of Foundry Engineering | 2022 | vol. 22 | No 3 | 91-94 | DOI: 10.24425/afe.2022.140240
Keywords Application of information technology to the foundry industry Solidification process Numerical Techniques Thermal andderivative analysis
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Abstract

The article concerns the experimental verification of the numerical model simulating the solidification and cooling processes proceeding in the domain of cast iron casting. The approximate course of the function describing the evolution of latent heat and the value of substitute specific heat resulting from its course were obtained using the thermal and derivative analysis (TDA) method The TDA was also used to measure the cooling curves at the distinguished points of the casting. The results obtained in this way were compared with the calculated cooling curves at the same points. At the stage of numerical computations, the explicit scheme of the finite difference method was applied. The agreement between the measured and calculated cooling curves is fully satisfactory.
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Bibliography

[1] Mendakiewicz, J. (2011). Identification of the solidification parameters of casting alloys on the example of grey cast iron. Monografia. Gliwice: Wyd. Pol. Śl. (in Polish).
[2] Jiji, L.M. (2009). Heat conduction. Third Edition. Springer.
[3] Mochnacki, B. & Majchrzak, E. (2007). Identification of macro and micro parameters in solidification model. Bulletin of the Polish Academy of Sciences. Technical Sciences. 55(1), 107-113.
[4] Kapturkiewicz, W. (2003). Modelling of cast iron solidification. Cracow: Akapit.
[5] Majchrzak, E., Mendakiewicz, J. & Piasecka-Belkhayat, A. (2005). Algorithm of mould thermal parameters identification in the system casting–mould–environment. Journal of Materials Processing Technology. 162-163, 1544-1549.
[6] Mochnacki, B., Suchy, J.S. (1995). Numerical methods in computations of foundry processes. Cracow: PFTA.
[7] Ciesielski, M. & Mochnacki, B. (2019). Comparison of approaches to the numerical modelling of pure metals solidification using the control volume method. International Journal of Cast Metals Research. 32(4), 213-220. https://doi.org/10.1080/13640461.2019.1607650
[8] Majchrzak, E., Mochnacki, B., Suchy, J.S (2008). Identification of substitute thermal capacity of solidifying alloy. Journal of Theoretical and Applied Mechanics. 46(2), 257-268.

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Authors and Affiliations

J. Mendakiewicz
1
ORCID: ORCID
  1. Department of Computational Mechanics and Engineering, Silesian University of Technology, Konarskiego18A, 44-100 Gliwice, Poland

Facile Synthesis of Bumpy-Structured ZnO-ZnS Core-Shell Microspheres with Enhanced Photocatalytic Performance

Hee Yeon Jeon Mijeong Park Seungheon Han Dong Hoon Lee Young-In Lee
Archives of Metallurgy and Materials | 2024 | vol. 69 | No 1 | 91-94 | DOI: 10.24425/amm.2024.147792
Keywords ZnO ZnS core-shell chemical transformation photocatalyst
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Abstract

Zinc oxide is considered an outstanding photocatalyst candidate, but its low photo-corrosion resistance is a problem to be solved. In the ZnO-ZnS core-shell structure, ZnS acts as a protective layer for the ZnO core, and thus, it can enhance stability and long-term performance. The ZnO-ZnS core-shell structure is synthesized into various nanoscale morphologies with high specific surface areas to improve photocatalytic efficiency. However, they are easily agglomerated and are hard to separate from reaction media. In this study, micro-sized bumpy spheres of ZnO-ZnS core-shell structure were prepared via facile chemical transformation of as-prepared ZnO. After sulfurization of the ZnO template, it was confirmed through SEM, TEM, EDS, and XPS analysis that a uniform ZnS shell layer was formed without significant change in the initial ZnO morphology. The ZnO-ZnS core-shell microsphere has shown superior efficiency and stability in the photocatalytic degradation of Rhodamine B compared with pristine ZnO microspheres
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Authors and Affiliations

Hee Yeon Jeon
1
ORCID: ORCID
Mijeong Park
1
ORCID: ORCID
Seungheon Han
1
ORCID: ORCID
Dong Hoon Lee
1
ORCID: ORCID
Young-In Lee
2
ORCID: ORCID
  1. Seoul National University Of Science and Technology, Department Of Materials Science and Engineering, Seoul 01811, Republic Of Korea
  2. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul 01811, Republic of Korea

Prediction of Ferrite Content in Austenitic Cr-Ni Steel Castings During Production

A. Záděra J. Šenberger V. Pernica V. Kaňa
Archives of Foundry Engineering | 2018 | vol.18 | No 3 | 91-94
Keywords solidification metallography Austenitic steels Austenite ferrite DeLong diagram
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Abstract

Determination of the ferrite content in austenitic steels, which solidified under defined conditions. Ferrite content in austenitic matrix was determined from samples with wall thickness of 60 mm. Measured ferrite contents served to propose the regression equations for the calculation of the ferrite content in steels with Cr content of 18 up to 22 % and Ni of 9 up to 11 %. An additional regression equation was proposed for steels with a higher Ni content. The proposed regression equations have been checked up on the operating melts. In conclusion, the ferrite content in the axis of the casting of wall thickness of 500 mm has been calculated and it was compared to the ferrite determined in the usual way from the cast-on test.
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Authors and Affiliations

A. Záděra
J. Šenberger
V. Pernica
V. Kaňa

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