TY  - JOUR
AU  - Obradović, Nina
AU  - Fahrenholtz, William G.
AU  - Filipović, Suzana
AU  - Kosanović, Darko
AU  - Dapčević, Aleksandra
AU  - Đorđević, Antonije
AU  - Balać, Igor
AU  - Pavlović, Vladimir B.
PY  - 2019
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3133
AB  - Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. MgAl2O4 was produced by solid state reaction between MgO and alpha-Al2O3. The starting powders were mixed by ball milling to homogenize without significant particle size reduction. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 1 h. Powders were compacted at 300 MPa. Heat treatments were performed in air, at temperatures ranging from 1200 to 1600 degrees C with 2 h dwell time, to determine the amount of spinel formation as a function of temperature. Phase composition and microstructure of initial powders and heated samples were determined by means of X-ray diffraction, particle size analysis, and scanning electron microscopy. The influences of milling and consolidation parameters were studied by electrical measurements and mechanical characterization. The main conclusion of this study was that mechanical activation for 60 min initiated a mechano-chemical reaction, resulted in spinel formation at much lower temperatures than within non-activated powders, and indicated that final sintering stage started at much lower temperatures for activated powders. Changes in microstructure parameters, as a consequence of mechanical treatment and subsequent heating of investigated powder mixtures, strongly affect electrical and mechanical properties of the final ceramics.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics
EP  - 12021
IS  - 9
SP  - 12015
VL  - 45
DO  - 10.1016/j.ceramint.2019.03.095
ER  - 

@article{
author = "Obradović, Nina and Fahrenholtz, William G. and Filipović, Suzana and Kosanović, Darko and Dapčević, Aleksandra and Đorđević, Antonije and Balać, Igor and Pavlović, Vladimir B.",
year = "2019",
abstract = "Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. MgAl2O4 was produced by solid state reaction between MgO and alpha-Al2O3. The starting powders were mixed by ball milling to homogenize without significant particle size reduction. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 1 h. Powders were compacted at 300 MPa. Heat treatments were performed in air, at temperatures ranging from 1200 to 1600 degrees C with 2 h dwell time, to determine the amount of spinel formation as a function of temperature. Phase composition and microstructure of initial powders and heated samples were determined by means of X-ray diffraction, particle size analysis, and scanning electron microscopy. The influences of milling and consolidation parameters were studied by electrical measurements and mechanical characterization. The main conclusion of this study was that mechanical activation for 60 min initiated a mechano-chemical reaction, resulted in spinel formation at much lower temperatures than within non-activated powders, and indicated that final sintering stage started at much lower temperatures for activated powders. Changes in microstructure parameters, as a consequence of mechanical treatment and subsequent heating of investigated powder mixtures, strongly affect electrical and mechanical properties of the final ceramics.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics",
pages = "12021-12015",
number = "9",
volume = "45",
doi = "10.1016/j.ceramint.2019.03.095"
}

Obradović, N., Fahrenholtz, W. G., Filipović, S., Kosanović, D., Dapčević, A., Đorđević, A., Balać, I.,& Pavlović, V. B.. (2019). The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics. in Ceramics International
Elsevier Sci Ltd, Oxford., 45(9), 12015-12021.
https://doi.org/10.1016/j.ceramint.2019.03.095

Obradović N, Fahrenholtz WG, Filipović S, Kosanović D, Dapčević A, Đorđević A, Balać I, Pavlović VB. The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics. in Ceramics International. 2019;45(9):12015-12021.
doi:10.1016/j.ceramint.2019.03.095 .

Obradović, Nina, Fahrenholtz, William G., Filipović, Suzana, Kosanović, Darko, Dapčević, Aleksandra, Đorđević, Antonije, Balać, Igor, Pavlović, Vladimir B., "The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics" in Ceramics International, 45, no. 9 (2019):12015-12021,
https://doi.org/10.1016/j.ceramint.2019.03.095 . .

TY  - JOUR
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Marković, Smilja
AU  - Đorđević, Antonije
AU  - Balać, Igor
AU  - Dapčević, Aleksandra
AU  - Rogan, Jelena
AU  - Pavlović, Vladimir B.
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2844
AB  - Corundum (alpha-alumina) is a suiTab. material for usage in various industry fields owing to its chemical stability, electrical and mechanical features. It is known that properties of ceramics could be modified by addition of different oxides, as well as by changing the consolidation parameters. In this respect, alumina was doped with 1 wt.% of Cr2O3, Mn2O3 and NiO, followed by 1 hour of mechanical activation in a high-energy planetary ball mill. A sensitive dilatometer was used for sintering of powder mixtures up to 1400 degrees C and recording the obtained dilatation. The final density varied between cca. 1.9 and 3.3 g/cm(3). Microstructural changes were detected by SEM measurements. Changes in electrical permittivity and loss tangent were associated with the preparation conditions (types of additives, duration of mechanical activation). For a given mixture, the sintering increases the relative permittivity and decreases losses, exhibiting the optimal values of 8.32 and 0.027, respectively, for the sample activated 60 minutes and sintered, with the addition of MnO2. Mechanical measurements indicate significant differences in strength with the addition of different transition metal oxides. Samples with Mn and Ni, activated and sintered, with strength of 121 and 86 MPa, respectively, have a significantly higher tensile strength than the other tested samples, due to their more compact microstructures.
PB  - Međunarodni Institut za nauku o sinterovanju, Beograd
T2  - Science of Sintering
T1  - Physical Properties of Sintered Alumina Doped with Different Oxides
EP  - 419
IS  - 4
SP  - 409
VL  - 50
DO  - 10.2298/SOS1804409F
ER  - 

@article{
author = "Filipović, Suzana and Obradović, Nina and Marković, Smilja and Đorđević, Antonije and Balać, Igor and Dapčević, Aleksandra and Rogan, Jelena and Pavlović, Vladimir B.",
year = "2018",
abstract = "Corundum (alpha-alumina) is a suiTab. material for usage in various industry fields owing to its chemical stability, electrical and mechanical features. It is known that properties of ceramics could be modified by addition of different oxides, as well as by changing the consolidation parameters. In this respect, alumina was doped with 1 wt.% of Cr2O3, Mn2O3 and NiO, followed by 1 hour of mechanical activation in a high-energy planetary ball mill. A sensitive dilatometer was used for sintering of powder mixtures up to 1400 degrees C and recording the obtained dilatation. The final density varied between cca. 1.9 and 3.3 g/cm(3). Microstructural changes were detected by SEM measurements. Changes in electrical permittivity and loss tangent were associated with the preparation conditions (types of additives, duration of mechanical activation). For a given mixture, the sintering increases the relative permittivity and decreases losses, exhibiting the optimal values of 8.32 and 0.027, respectively, for the sample activated 60 minutes and sintered, with the addition of MnO2. Mechanical measurements indicate significant differences in strength with the addition of different transition metal oxides. Samples with Mn and Ni, activated and sintered, with strength of 121 and 86 MPa, respectively, have a significantly higher tensile strength than the other tested samples, due to their more compact microstructures.",
publisher = "Međunarodni Institut za nauku o sinterovanju, Beograd",
journal = "Science of Sintering",
title = "Physical Properties of Sintered Alumina Doped with Different Oxides",
pages = "419-409",
number = "4",
volume = "50",
doi = "10.2298/SOS1804409F"
}

Filipović, S., Obradović, N., Marković, S., Đorđević, A., Balać, I., Dapčević, A., Rogan, J.,& Pavlović, V. B.. (2018). Physical Properties of Sintered Alumina Doped with Different Oxides. in Science of Sintering
Međunarodni Institut za nauku o sinterovanju, Beograd., 50(4), 409-419.
https://doi.org/10.2298/SOS1804409F

Filipović S, Obradović N, Marković S, Đorđević A, Balać I, Dapčević A, Rogan J, Pavlović VB. Physical Properties of Sintered Alumina Doped with Different Oxides. in Science of Sintering. 2018;50(4):409-419.
doi:10.2298/SOS1804409F .

Filipović, Suzana, Obradović, Nina, Marković, Smilja, Đorđević, Antonije, Balać, Igor, Dapčević, Aleksandra, Rogan, Jelena, Pavlović, Vladimir B., "Physical Properties of Sintered Alumina Doped with Different Oxides" in Science of Sintering, 50, no. 4 (2018):409-419,
https://doi.org/10.2298/SOS1804409F . .