Microstructural evolution mechanism of porous reaction bonded silicon nitride ceramics heat-treated in two powder beds

Nikonam, M Raheleh; Pugh, Martin; Drew, R. A. L.

doi:10.1016/j.ceramint.2019.07.213

Cited by 13 publications

(4 citation statements)

References 45 publications

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“…Although several alternatives of structural ceramics have been proposed, silicon nitride (Si 3 N 4 )-based ceramics remain competitive due to their superior properties, involving high strength and hardness at elevated temperatures, high resistance to oxidation and chemical attack, low coefficient of tribological friction and thermal expansion, and low dielectric permittivity, etc. [1][2][3][4][5][6][7][8][9][10]. As important multifunctional materials, Si 3 N 4 ceramics have found wide range of successful application towards gas turbine engine components [10][11][12][13][14], cutting tools [11,15], radomes [2], and even integrated circuit [16,17], optical devices [18,19], etc.…”

Section: Introductionmentioning

confidence: 99%

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

Luo

Deng

et al. 2020

Materials

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In situ grown C0.3N0.7Ti and SiC, which derived from non-oxide additives Ti3SiC2, are proposed to densify silicon nitride (Si3N4) ceramics with enhanced mechanical performance via hot-press sintering. Remarkable increase of density from 79.20% to 95.48% could be achieved for Si3N4 ceramics with 5 vol.% Ti3SiC2 when sintered at 1600 °C. As expected, higher sintering temperature 1700 °C could further promote densification of Si3N4 ceramics filled with Ti3SiC2. The capillarity of decomposed Si from Ti3SiC2, and in situ reaction between nonstoichiometric TiCx and Si3N4 were believed to be responsible for densification of Si3N4 ceramics. An obvious enhancement of flexural strength and fracture toughness for Si3N4 with x vol.% Ti3SiC2 (x = 1~20) ceramics was observed. The maximum flexural strength of 795 MPa for Si3N4 composites with 5 vol.% Ti3SiC2 and maximum fracture toughness of 6.97 MPa·m1/2 for Si3N4 composites with 20 vol.% Ti3SiC2 are achieved via hot-press sintering at 1700 °C. Pull out of elongated Si3N4 grains, crack bridging, crack branching and crack deflection were demonstrated to dominate enhance fracture toughness of Si3N4 composites.

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Section: Introductionmentioning

confidence: 99%

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

Luo

Deng

et al. 2020

Materials

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show abstract

“…Although a number of alternatives of structural ceramics have been proposed, silicon nitride (Si3N4)-based ceramics remain competitive due to their superior properties, involving high strength and hardness at elevated temperatures, high resistance to oxidation and chemical attack, low coefficient of tribological friction and thermal expansion, and low dielectric permittivity, etc. [1][2][3][4][5][6][7][8][9] . As important multifunctional materials, Si3N4 ceramics have found wide range of successful application towards gas turbine engine components [10][11][12][13] , cutting tools [10,14] , radomes [2] , and even integrated circuit [15,16] , optical devices [17,18] , etc.…”

Section: Introductionmentioning

confidence: 99%

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

Luo

Deng

et al. 2020

Preprint

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In-situ grown C0.3N0.7Ti and SiC, which derived from non-oxide additives Ti3SiC2, are proposed to densify silicon nitride (Si3N4) ceramics with enhanced mechanical performance. Remarkable increase of density from 79.20% to 95.48% could be achieved for Si3N4 ceramics with 5vol% Ti3SiC2. The capillarity of decomposed Si from Ti3SiC2, and in-situ reaction between nonstoichiometric TiCx and Si3N4 were believed to be responsible for densification of Si3N4 ceramics. An obvious enhancement of flexural strength and fracture toughness for Ti3SiC2 doped Si3N4 ceramics was observed. The maximum flexural strength of 795 MPa for Si3N4 composites with 5vol% Ti3SiC2 and maximum fracture toughness of 6.97 MPa.m1/2 for Si3N4 composites with 20vol% Ti3SiC2 are achieved when mixed powders are hot-press sintered at 1700℃. Pull out of elongated Si3N4 grains, crack bridging, crack branching and crack deflection were demonstrated to dominate enhance fracture toughness of Si3N4 composites.

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“…Besides the two morphologies of α-matte grains and elongated β-rods, Si 3 N 4 may form whiskers randomly distributed throughout the pore channels [24,25]. These interlocked whiskers with high aspect ratio improve the mechanical strength and fracture toughness of the load-bearing materials while decreasing the interconnectivity of channels and permeability and size of pores in filtration membranes [22,26,27]. Growth of granular grains on the pore walls in contrast leads to the formation of large cavities and enhanced channel interconnectivity suitable for interpenetrating ceramic-metal composites [22,26,27].…”

Section: Introductionmentioning

confidence: 99%

“…Many detailed studies have explained the growth mechanism of Si 3 N 4 grains in porous RBSN [26,27]; nevertheless, achieving a designed grain morphology and thus a controlled pore microstructure is the major challenge of this route as multiple processing variables are simultaneously involved [28][29][30][31]. As an illustration, porosity provides more reactive area per unit mass and encourages surface reactions such as dissociation and silicon oxidation.…”

Section: Introductionmentioning

confidence: 99%

A comparative study on nitridation mechanism and microstructural development of porous reaction bonded silicon nitride in the presence of CaO, MgO and Al₂O₃

Mofrad

Pugh

Drew

2020

Journal of Asian Ceramic Societies

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During the in-situ nitridation of Si in the presence of CaO, MgO and Al 2 O 3 formation of reaction bonded silicon nitride ceramics (RBSN) having various microstructures indicated the possibility of different nitridation mechanisms operating. Experimental evidence suggested that, whereas the morphology of pores was controlled by nitridation of Si(g) in CaO-RBSN and SiO(g) in Al 2 O 3-RBSN, a combination of these two reactions occurred during the nitridation of the MgO-RBSN. By inhibiting the growth of whiskers and maximizing the α/β ratio, the CaO addition led to the formation of matte grains creating clean spherical cavities with d < 40 µm and flexural strength of 0.8 MPa. In contrast, when using Al 2 O 3 additions, a microstructure with a very low α/β ratio, fine inter-particle pores and 2.4 MPa flexural strength, reinforced with interlocking whiskers, was produced. The highest porosity (85%) and the lowest strength (0.3 MPa) occurred in the MgO-RBSN, which was composed of both matte grains and fine whiskers. Local supersaturation and low content of β-nuclei led to the formation of anisotropic β-grains with a bimodal microstructure in heat-treated CaO-RBSN while a unimodal microstructure was observed in heat-treated MgO-RBSN. No porosity loss or β-grain growth occurred in the heat-treated Al 2 O 3-RBSN.

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Microstructural evolution mechanism of porous reaction bonded silicon nitride ceramics heat-treated in two powder beds

Cited by 13 publications

References 45 publications

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

C<sub>0.3</sub>N<sub>0.7</sub>Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti<sub>3</sub>SiC<sub>2</sub>

A comparative study on nitridation mechanism and microstructural development of porous reaction bonded silicon nitride in the presence of CaO, MgO and Al₂O₃

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Microstructural evolution mechanism of porous reaction bonded silicon nitride ceramics heat-treated in two powder beds

Cited by 13 publications

References 45 publications

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

C<sub>0.3</sub>N<sub>0.7</sub>Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti<sub>3</sub>SiC<sub>2</sub>

A comparative study on nitridation mechanism and microstructural development of porous reaction bonded silicon nitride in the presence of CaO, MgO and Al2O3

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A comparative study on nitridation mechanism and microstructural development of porous reaction bonded silicon nitride in the presence of CaO, MgO and Al₂O₃