Microstructural and electrical properties of cordierite-based ceramics obtained after two-step sintering technique

Obradović, Nina; Filipović, Suzana; Đorđević, Nataša; Kosanović, Darko; Pavlovic, Vladimir; Olćan, Dragan I.; Djordjević, A.R.; Kachlík, Martin; Maca, Karel

doi:10.2298/sos1602157o

Cited by 15 publications

(19 citation statements)

References 13 publications

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“…In general, the additives lowered the dielectric constant, while the mechanical activation increased it, but the permittivity is still below 10. The loss tangent is below 0.1, except for AC-0-1400 where it is 0.116, which could be correlated with the lowest density and shrinkage rate [31]. As it is well known, the microstructure has a significant impact on mechanical properties.…”

Section: Resultsmentioning

confidence: 91%

Physical properties of sintered alumina doped with different oxides

et al. 2018

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Corundum (α-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 Cr 2 O 3 , Mn 2 O 3 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 o 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 MnO 2. 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.

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Section: Resultsmentioning

confidence: 91%

Physical properties of sintered alumina doped with different oxides

et al. 2018

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“…At the beginning of the milling process, the powder particles become reactive, capable to form new phases, and then, with additional energy transfer, they are practically forced to make agglomerates. Those agglomerates could be a disadvantage during sintering [14].…”

Section: Resultsmentioning

confidence: 99%

Shungite - a carbon-mineral rock material: Its sinterability and possible applications

Obradović

Gigov

Ðordjevic

et al. 2019

PAC

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The paper presents results of the influence of mechanical activation of shungite, a carbon-mineral rock material rich in silica and carbon, on its sintering behaviour, and obtaining of pure SiC ceramics. The mechanical activation of the starting powder was performed in a high-energy ball mill in time intervals from 30 to 480 min. The phase composition of the starting powders and sintered samples was analysed by the X-ray diffraction method. The first traces of SiC were detected after sintering at 1350°C for 2 h in an Ar atmosphere, along with traces of unreacted SiO 2 . The scanning electron microscopy was performed in order to determine changes in the microstructure. Sintering was performed at various temperatures for 2 h, in an Ar atmosphere and a vacuum. Dielectric properties of the sintered samples were measured in the frequency range from 1 to 500 MHz. The obtained results indicate that the sintered powder is a good candidate for applications as an absorber of electromagnetic waves in microwave engineering.

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“…Refractory coatings and their production processes were designed according to the works [3,8,22], our works [24,26] and domestic norms [43,44]. Based on the analysis of the mechanical activation influence on the filler grain size and shape [27,[28][29][30][31][32][33] as well as of the filler grain size influence on coating suspension sedimentation stability [3,7], cordierite-based, mechanically activated fillers were chosen: first filler C 2 (100% -20 x10 -6 m) and the second combination of fillers C 2 (100% -20x 10 -6 m) and C 3 (100% -12 x10 -6 m). In reference to the filler grain size chosen, two series of the Lost Foam refractory coatings were designed as follows: coating with filler C 2 (marked: A) and coating with combination of fillers C 2 + C 3 (marked: B), which were corrected according to test results for the coating suspensions obtained.…”

Section: Synthesis Of Lost Foam Refractory Coatings With Activated Fimentioning

confidence: 99%

“…Design of cordierite-based refractory coatings and choice of production method were carried out in accordance with the analysis of the influence of mechanical activation of non-metallic mineral raw materials on the filler's quality, i.e. on the grain size and shape of the filler, according to the works [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Influence of mechanical activation of a cordierite -based filler on sedimentation stability of lost foam refractory coatings

Pavlović¹,

Andrić

Radulović

et al. 2019

Sci Sintering

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For the development of the Lost Foam refractory coatings with controlled rheologic properties, the influence of the mechanical activation process on the cordierite-based filler's properties change was examined. First of all, the test referred to the change of filler particles' size and shape, as well as to dispersion ability and stability of the coating suspension. Cordierite was obtained by synthesis in a solid state, out of the mass consisting of kaoline, alumina, quartz, sepiolite. For characterization purposes, the following methods were used: X-ray diffraction, differential thermal analysis, SEM and optical microscopy. Mechanical activation of filler was performed in a vibrating mill. The upper boundary of the grain size was 100%-30 x 10-6 m, the times were (min): 15; 30; 60. The new composition of Lost foam refractory coatings has been developed with a change of the coating production process, as well. These newly synthesized coatings proved to be effective in terms of a positive influence on a surface quality, structural and mechanical properties of aluminium castings. Test results may be useful to have the Lost Foam refractory coatings specified together with other process parameters used for the production of castings according to this casting method.

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Microstructural and electrical properties of cordierite-based ceramics obtained after two-step sintering technique

Cited by 15 publications

References 13 publications

Physical properties of sintered alumina doped with different oxides

Physical properties of sintered alumina doped with different oxides

Shungite - a carbon-mineral rock material: Its sinterability and possible applications

Influence of mechanical activation of a cordierite -based filler on sedimentation stability of lost foam refractory coatings

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