Synthesis and characterization of alkaline earth and rare earth doped sialon Ceramics by spark plasma sintering

Hakeem, Abbas Saeed; Khan, Majad; Ahmed, Bilal Anjum; Ghanim, Ahmed Al; Patel, Faheemuddin; Ehsan, Muhammad Ali; Ali, Sharafat; Laoui, Tahar; Ali, Sharafat

doi:10.1016/j.ijrmhm.2021.105500

Cited by 21 publications

(20 citation statements)

References 67 publications

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“…In the case of MgO having the highest melting temperature of 2852 • C, the solution-precipitation state started at around 1357 • C. In contrast, for Nd 2 O 3 (having the lowest melting temperature), the solution-precipitation stage started at around 1185 • C. Furthermore, despite the difference observed in the onset temperature of various stages, the initiation of the final coalescence stage remained the same for all the samples. A similar observation was reported by Hakeem et al in their study on the densification behavior of alpha SiAlON ceramics [61].…”

Section: Methodssupporting

confidence: 88%

“…For instance, with the change in rare earth cationic size (La (250 pm) having clear discrete cationic size as compared to Nd (229 pm)) the alpha reflexes shifted to a slightly lower 2-theta value, indicating higher accommodation of stabilizing cation within the alpha unit cell. Furthermore, AlN polytype (ICD# 00-042-0161 and ICD# 00-042-0160) reflexes were also observed in some of the samples, as was reported in previous studies as well [61]. Other than this, a few additional reflexes were observed in the sample synthesized using BaO.…”

Section: Phase Evolution and Microstructure Analysissupporting

confidence: 84%

“…Other than this, a few additional reflexes were observed in the sample synthesized using BaO. The additional reflexes were identified as Ba 2 Si 10 Al 2 O 4 N 14 (ICDD# 00-057-0526) phase [61]. BaO having the lowest melting temperature of 1923 • C resulted in the formation of the additional phase.…”

Section: Phase Evolution and Microstructure Analysismentioning

confidence: 96%

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Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics

et al. 2021

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Oxygen-rich SiAlON ceramics doped with various nanosized metal oxide (MO) stabilizers were synthesized with a view to examine their effect on thermal and mechanical characteristics. The nanosized starting powder precursors comprising Si3N4, AlN, Al2O3, and SiO2 along with oxides of Ba, Y, Mg, La, Nd, Eu, Dy, Er, and Yb as the MO charge stabilizer were employed in developing different SiAlON samples. Ultrasonic probe sonication was utilized to develop a homogenous mixture of initial powder precursors followed by spark plasma sintering (SPS) of the samples at the low temperature of 1500 °C coupled with 30 min of isothermal treatment. Sample compositions (according to general formula of alpha SiAlON: Mm/vv+Si12−(m+n)Alm+nOnN16−n) selected in the present study are represented by m value of 1.1 and n value of 1.6. The synthesized samples were evaluated for their physical behavior, microstructural and crystal structure evolution, and thermal and mechanical characteristics. More specifically, the sintered ceramics were examined by X-ray diffraction and electron microscopy to comprehend and relate the structural characteristics with the densification, thermal conductivity, hardness, and fracture toughness. The high reactivity of the nanopowders and the localized heating provided by SPS resulted in densified ceramics with relative densities in the range of 92–96%. Vickers hardness values were found to be in the range of 12.4–17.0 GPa and were seen to be profoundly influenced by the grain size of the alpha SiAlON (primary) phase. The fracture toughness of the samples was measured to be in the range of 4.1–6.2 MPa·m1/2. SiAlON samples synthesized using Er and Yb charge stabilizers were found to have the highest fracture toughness of 5.7 and 6.2 MPa·m1/2, primarily due to the relatively higher content of the elongated beta phase. While there was no obvious relationship between the thermal conductivity and the alpha SiAlON metal charge stabilizers, the values were seen to be influenced by the grain size of alpha phase where Dy-SiAlON had the lowest thermal conductivity of 5.79 W/m⋅K and Er-SiAlON showed the highest value of thermal conductivity (6.91 W/m⋅K). It was concluded that scientifically selected metal oxide charge stabilizers are beneficial in developing SiAlON ceramics with properties tailored according to specific applications.

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Section: Methodssupporting

confidence: 88%

Section: Phase Evolution and Microstructure Analysissupporting

confidence: 84%

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Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics

et al. 2021

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“…At high temperatures, the α-phase, specifically with high x (x is typically between 0.3 and 1.0) is stable, but during the thermal processing, it can transform to β-phase sialon or other crystalline or glassy phases. The α-SiAlONs is used due to its high hardness and temperature resistance due to a decrease in the amount of the residual glassy phase, but for the same reasons, these materials have increased fragility, which requires the introduction of materials with improved fracture toughness but without a significant decrease in hardness [139][140][141][142][143]. In his study, Ekström [144] carried out a series of experiments with α-SiAlON, from which a number of conclusions can be drawn as follows:…”

Section: α-Sialons Can Be Presented By the Chemical Formula M V+mentioning

confidence: 99%

Ceramic Cutting Materials and Tools Suitable for Machining High-Temperature Nickel-Based Alloys: A Review

Seleznev

Pinargote

Smirnov

2021

Metals

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Nickel-based superalloys are attractive to many industrial sectors (automotive, military, energy, aerospace, etc.). However, their physical properties make them difficult to machining using traditional tools. Therefore, new materials for the machining of Ni-based alloys are required. Ceramic-based composites could act as a tool to replace the current materials. The incentives for this paper are to provide an overview of existing ceramic composites and draw some conclusions that will help in solving the problem of choosing materials for the processing of Ni-based superalloys. Despite the diversity of ceramic composites in this work, the possibility of using the SiAlON ceramic for Ni-based alloy machining is highlighted.

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“…The intensity of the opaqueness is not incessantly attributed to high nitrogen content in the glass network [ 11 , 12 ]. The transparency issue of oxynitride glasses has been investigated [ 13 , 14 , 15 , 16 ], but with no significant progress toward obtaining nitrogen-enriched glasses with fully transparency [ 17 , 18 , 19 ]. One of the most common reasons for the opacity of the oxynitride glasses is the alleged precipitation of silicon [ 13 , 16 , 20 ], which is due to the decomposition of Si 3 N 4 [ 21 ] at a temperature above 1600 °C.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evaluation and Impurities in La Containing Silicon Oxynitrides

et al. 2021

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Oxynitride glasses are not yet commercialised primarily due to the impurities present in the network of these glasses. In this work, we investigated the microstructure and instinctive defects in nitrogen rich La-Si-O-N glasses. Glasses were prepared by heating a powder mixture of pure La metal, Si3N4, and SiO2 in a nitrogen atmosphere at 1650–1800 °C. The microstructure and impurities in the glasses were examined by optical microscopy, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy in conjunction with electron energy-loss spectroscopy. Analyses showed that the glasses contain a small amount of spherical metal silicide particles, mostly amorphous or poorly crystalline, and having sizes typically ranging from 1 µm and less. The amount of silicide was estimated to be less than 2 vol. %. There was no systematic relation between silicide formation and glass composition or preparation temperature. The microstructure examination revealed that the opacity of these nitrogen rich glasses is due to the elemental Si arise from the decomposition reaction of silicon nitride and silicon oxide, at a high temperature above ~1600 °C and from the metallic silicide particles formed by the reduction of silicon oxide and silicon nitride at an early stage of reaction to form a silicide intermetallic with the La metal.

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Synthesis and characterization of alkaline earth and rare earth doped sialon Ceramics by spark plasma sintering

Cited by 21 publications

References 67 publications

Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics

Spark Plasma Sintering of SiAlON Ceramics Synthesized via Various Cations Charge Stabilizers and Their Effect on Thermal and Mechanical Characteristics

Ceramic Cutting Materials and Tools Suitable for Machining High-Temperature Nickel-Based Alloys: A Review

Microstructure Evaluation and Impurities in La Containing Silicon Oxynitrides

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