Dilatrometric sintering study and characterization of alumina-nickel composites

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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“…4c). This could be a consequence of hard agglomerates presented in the activated AC-60 sample, which was also previously reported [29].…”

Section: Resultssupporting

confidence: 82%

Physical properties of sintered alumina doped with different oxides

et al. 2018

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“…The result of the hardness measurements showed that composites from Series I (Al 2 O 3 + 10 vol% metallic phase) were characterized by the hardness value equal to 5.52 ± 0.56 GPa, whereas the hardness of the Series II (Al 2 O 3 + 15 vol% metallic phase) composites was 4.88 ± 0.84 GPa. Compared to the hardness of samples created from pure alumina TM-DAR [26] obtained, the result is lower ca. 11 GPa.…”

Section: Methodsmentioning

confidence: 75%

Thermoanalytical and dilatometric studies of the Al2O3–Cu–Mo hybrid composite

Zygmuntowicz

Piątek

Wachowski

et al. 2020

J Therm Anal Calorim

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The present research is focused on the characterization of the composites from Al 2 O 3-Cu-Mo system. The composites were prepared by slip casting method and subsequent sintering of green bodies in a reduced atmosphere. Two series of samples with different volume content of metallic powders were produced in the work: 10 vol% and 15 vol% of metal content with respect to the total solid-phase content. The sintering process of the composites was analyzed in detail. The linear shrinkage of the composites was measured. The shrinkage curves were obtained by dilatometry test in a heating mode. The composites were characterized by DTA/TG analyses and thermal conductivity. The composites were characterized by XRD, SEM, and EDX. The hardness was measured by Vickers hardness tester. Moreover, the Brazilian test was performed to determine the tensile mechanical properties of the composites. Fractography investigation was carried out as well. Dilatometric tests showed that the increase of the metallic phase volume in the ceramic matrix causes a decrease in the starting temperature of densification. Simultaneously, dilatometric experiments indicated that an increasing amount of metallic particles into the ceramic matrix increases the temperature of maximum densification and decreases the total shrinkage of the composites during sintering. The DTA/TG showed the characteristics of the dispersant decomposition to the atmosphere during thermal treatment and increase of mass connected with the oxidation of metals. Fractography results revealed good adhesion between Al 2 O 3 matrix and the metallic phase. The observation allowed to conclude that the Al 2 O 3 matrix surface is characterized by the brittle fracture mechanism.

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“…Figure 6 presents the dilatometer curves for pellets with 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.% BBSZ glass containing pellets along with the temperature differential of DL/L 0 , where L 0 is the original length, and DL is change in length. 31 The lowering of sintering temperature with increasing glass content indicates liquid-phase sintering. Evidence of liquid-phase sintering assisting in the reduction in sintering temperature has also been presented by Kim et al for the sintering of BaTi 4 O 9 pellets using zinc borate glass.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Microwave Dielectric Properties of BBSZ-Zinc Silicate Based Material for LTCC Applications

Deshmukh

Chaware

Ratheesh

et al. 2021

Journal of Elec Materi

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The microwave dielectric properties and microstructures of zinc silicate (Zn 2 SiO 4) ceramic with the addition of 5-20 wt.% B 2 O 3-Bi 2 O 3-SiO 2-ZnO (BBSZ) glass have been studied for low-temperature co-fired ceramic (LTCC) applications. BBSZ glass helps in reducing the sintering temperature of zinc silicate (ZS) from about 1350°C to around 900°C in the form of ZS-glass composites. The zinc silicate powder was prepared following solid-state reaction technique, while BBSZ glass was prepared by standard melting and quenching method. Expectedly, the sintering studies indicate increasing sintered density between 91% and 97% with increasing sintering temperature from 875°C to 950°C. The sintering density is also seen to increase with increasing content of BBSZ, indicating liquid-phase sintering of the composites. Higher glass content in the composite leads to increased dielectric constant as well as dielectric loss. The results indicate that ZS with the addition of 5 wt.% of BBSZ glass, sintered at 925°C for 3 h, exhibits good microwave dielectric properties with a dielectric constant (e r) of 6.5 and quality factor (Q 9 f) of 20,754 GHz, which is suitable for LTCC applications.

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Dilatrometric sintering study and characterization of alumina-nickel composites

Cited by 18 publications

References 19 publications

Physical properties of sintered alumina doped with different oxides

Physical properties of sintered alumina doped with different oxides

Thermoanalytical and dilatometric studies of the Al2O3–Cu–Mo hybrid composite

Synthesis and Microwave Dielectric Properties of BBSZ-Zinc Silicate Based Material for LTCC Applications

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