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Abstract

The article presents the main results of research on plaster samples with different physical parameters of their structure. The basic physical parameter taken into account in the research is plaster aeration. Other physical parameters were also considered, but they play a minor part. The acoustic properties of the modified plaster were measured by the sound absorption coefficient; the results were compared with the absorption coefficient of standard plaster. The influence of other physical, mechanical and thermal properties of plaster was not analyzed. The effect of modified plasters on indoor acoustics was also determined. To this end, an acoustic problem with impedance boundary conditions was solved. The results were achieved by the Meshless Method (MLM) and compared with exact results. It was shown that the increase in plaster aeration translated into an increase in the sound absorption coefficient, followed by a slight decrease in the noise level in the room. Numerical calculations confirmed this conclusion.
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Bibliography

1. Bonfiglio P., Pompoli F. (2007), Acoustical and physical characterization of a new porous absorbing plaster, ICA, 19-th International Congress on Acoustics, Madrid, 2–7 September 2007.
2. Branski A. (2013), Numerical methods to the solution of boundary problems, classification and survey [in Polish], Rzeszow University of Technology Press, Rzeszow.
3. Branski A., Kocan-Krawczyk A., Predka E. (2017), An influence of the wall acoustic impedance on the room acoustics. The exact solution, Archives of Acoustics, 42(4): 677–687, doi: 10.1515/aoa-2017-0070.
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9. ISO 10354-2:1998 (1998), Acoustics – determination of sound absorption coefficient in impedance tube. Part 2: Transfer-function method.
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11. Li W., Zhang Q., Gui Q., Chai Y. (2020), A coupled FE-Meshfree triangular element for acoustic radiation problems, International Journal of Computational Methods, 18(3): 2041002, doi: 10.1142/S0219876220410029.
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19. Predka E., Branski A. (2020), Analysis of the room acoustics with impedance boundary conditions in the full range of acoustic frequencies, Archives of Acoustics, 45(1): 85–92, doi: 10.24425/aoa.2020.132484.
20. Predka E., Kocan-Krawczyk A., Branski A. (2020), Selected aspects of meshless method optimization in the room acoustics with impedance boundary conditions, Archives of Acoustics, 45(4): 647–654, doi: 10.24425/aoa.2020.135252
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26. You X., Li W., Chai Y. (2020), A truly meshfree method for solving acoustic problems using local weak form and radial basis functions, Applied Mathematics and Computation, 365: 124694, doi: 10.1016/j.amc.2019.124694.
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Authors and Affiliations

Edyta Prędka
1
Adam Brański
1
ORCID: ORCID
Małgorzata Wierzbińska
2

  1. Department of Electrical and Computer Engineering Fundamentals, Technical University of Rzeszow, Rzeszów, Poland
  2. Department of Materials Science, Technical University of Rzeszow, Rzeszów, Poland
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Abstract

The work deals with the influence of change in the filling conditions of the ceramic moulds with plaster binder on the presence of gaseous

porosity and the microstructure of the achieved test castings with graded wall thickness. Castings made of EN AC-44000 alloy, produced

either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the Vacumetal

technology), or by counter-gravity casting were compared. The results of examinations concerning the density of the produced castings

indicate that no significant change in porosity was found. The increased size of silicon crystals was found for the increased wall

thicknesses due to the slower cooling and solidification of castings.

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Authors and Affiliations

M. Nadolski
Z. Konopka
M. Łągiewka
A. Zyska
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Abstract

The performed examinations concerning the process of filling the plaster ceramic moulds with aluminium alloys allowed to assess the

influence of various methods of introducing the metal into the mould cavity on the macro- and microstructure of the obtained experimental

castings. The comparison was performed for castings with graded wall thickness made either of EN AC-44000 alloy or of EN AC-46000

alloy, produced either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the

Vacumetal technology), or by counter-gravity casting. It was found that the silicon crystals grow in size with an increase in wall thickness

due to the slower cooling and solidification of castings.

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Authors and Affiliations

M. Nadolski
Z. Konopka
M. Łągiewka
A. Zyska
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Abstract

The method of determining the accuracy of polymer molds in plaster forms has been discussed. Distortion of the surface of molds and

plaster molds has been assessed. It has been found that the presence of monolithic and porous structure in the samples does not change the

accuracy of the surfaces when forms are prepared for removing the material of the model. It has been found that in case of full-mold

casting it is more expedient to form the mold cavity with cellular adjustable structures of molding prototypes.

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Authors and Affiliations

A.A. Shumkov
T.R. Ablyaz
K.R. Muratov
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Abstract

The tensile properties and microstructures of ZL114A alloy component with a complex shape are investigated at room temperature and 200°C, using the tensile tests, scanning electron microscopy and electron backscattering diffraction. Both thin wall and thick structure exhibit excellent properties, of which max ultimate tensile strength and elongation at break reach 314 MPa and 2.5% at room temperature, respectively. The ultimate tensile strengths of thin wall are 40 MPa and 25 MPa greater than those of thick structure at room temperature and 200°C, respectively. Moreover, the eutectic Si phases of thin wall exhibit a predominantly spherical morphology while of the morphology of thick structure are rod-like, resulting in the different mechanical properties between thin wall and thick structure. The fracture morphologies of thin wall and thick structure are studied to explain the difference in performance between thin wall and thick structure.
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Authors and Affiliations

Jianquan Tao
1
Lin Xiang
1
Xidong Chen
1
Jipeng Sun
1
Yanbin Wang
1
Chuanhang Du
1
Feifei Peng
1
Shiqing Gao
1
Qiang Chen
1

  1. Southwest Technology and Engineering Research Institute, Chongqing 400039, China
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Abstract

The paper presents results of influence microwave drying on strength and technological properties of molding sand with gypsum binder researches, which, immediately after making and after the natural initial setting in air for 1, 2 or 5 hours, was heated with 250 W microwave power for 3, 6, 9 and 12 min time periods. The test was carried out on a mass containing (% -wt.): 88% Grudzeń-Las quartz sand, 12% "Dolina Nidy" plaster gypsum and 6% water. The loss of moisture content during natural drying and then microwave drying was determined, significant from the point of view of using the mass with gypsum binder in the production of products, using an environmentally friendly technology without casting incompatibilities. Additionally, the compressive strength of the mass was measured. The influence of both drying methods on the binder crystallization process and the associated mass strength was demonstrated, especially in terms of the possibility of selecting parameters and / or intensifying a specific drying method for use in the technology of manufacturing molds and foundry cores.
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Bibliography

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[12] Granat K., Paduchowicz P., Dziedzic A., Jamka M. & Biały P. (2020). Impact of hardening methods on the moulding sand’s properties with gypsum binder. Archives of Foundry Engineering. 4(20). 13-17. doi: 10.24425/afe.2020.133342.
[13] Nowak D., Gal B., Włodarska A. & Granat K. (2019). The influence of microwave drying parameters on the properties of synthetic moulding sands. Archives of Foundry Engineering. 4(19). 51-54.
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[16] Kaczmarska K., Grabowska B. & Drożyński D. (2014). Analysis of selected properties of microwave-hardened molding sands bound with starch-based binders. Archives of Foundry Engineering. 4(14). 51-54. (in Polish).
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[28] PN-83 / H-11070
[29] PN-83/H-11073

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Authors and Affiliations

P.J. Paduchowicz
1
K. Granat
1
P. Biały
1

  1. Department of Foundry Engineering, Plastics and Automation, Wroclaw University of Technology, ul. Smoluchowskiego 25, 50-372 Wrocław, Poland

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