Causes and Effects of Fe‐Bearing Inclusions in Sintered Si<sub>3</sub>N<sub>4</sub>

Pasto, A.E.

doi:10.1111/j.1151-2916.1984.tb19612.x

Cited by 25 publications

(8 citation statements)

References 5 publications

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“…This high value was attributed to a mixed control for the reaction, the ceramic decomposition and the diffusion in the metal. The values found in the present work are higher than the activation energy for Si diffusion in α-Fe (240kJmol -1 ) [22], but closer to 400kJmol -1 , a value reported for the Si 3 N 4 densification kinetics [24] and for the Si-N bond energy [25]. This is a first indication that the ceramic decomposition, dissolution and diffusion in the intergranular glassy phase are among the slowest steps of the overall reaction kinetics.…”

Section: Resultssupporting

confidence: 77%

Interacción químico entre nitruros de silicio y aleaciones de acero

Oliveira¹,

Silva²,

Vieira³

2000

Bol. Soc. Esp. Ceram. Vidr.

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Metal/ceramic diffusion experiments are helpful to study bonding mechanisms or the effect of metal composition on the chemical wear of ceramic cutting tools. The reaction kinetics of Fe alloys/Si 3 N 4 ceramic diffusion couples was investigated in the temperature range 1050ºC-1250ºC, for 0.5h to 80h, under inert atmosphere. Optical microscopy, SEM and EPMA were carried out in cross sections of the reacted pairs. Si 3 N 4 decomposes into Si and N that dissolve and diffuse through the metal. Both the diffusion zone on the metal side and the reaction zone on the ceramic side obey parabolic growth laws of time, with activation energies in the range Q=310-460kJmol -1 . The amount of dissolved Si, the length of the diffusion zone and thus the reactivity of the ceramic increase as the alloy carbon content decreases. Due to Si accumulation, the α-Fe solid solution is stabilised at the reaction temperature and a steep decrease in the Si concentration is observed beyond the diffusion zone. The reinforcement of the Si 3 N 4 composites with A1 2 O 3 platelets enhances the chemical resistance of the ceramic due to the inertness of this oxide and to the partial crystallisation of the intergranular phase. Other dispersoids such as HfN, BN and TiN do not improve the chemical resistance of the matrix by iron attack. Keywords: silicon nitride, steels, diffusion couples, interface kinetics Interacción químico entre nitruros de silicio y aleaciones de aceroLos experimentos de difusión metal/cerámica permiten estudiar mecanismos de unión y analizar el efecto de la composición del metal en el desgaste químico de herramientas de corte cerámicas. En este trabajo se investigó la cinética de reacción en pares de difusión aleaciones de Fe/Si 3 N 4 a temperaturas entre 1050ºC-1250ºC, tiempos entre 0.5h a 80h, en atmósfera inerte. Las secciones transversales de los pares de difusión se analizaron mediante microscopía óptica, SEM y microsonda electró-nica. El Si 3 N 4 se descompone en Si y N que se disuelven y difunden en el metal. Tanto la zona de difusión en el metal como la zona de reacción en la cerámica obedecen una ley parabólica de crecimiento, con energías de activación de 310-460 KJ.mol-1. La cantidad de Si disuelto, el tamaño de la zona de difusión y, por lo tanto, la reactividad de la cerámica aumenta al diminuir el contenido de carbón de la aleación. Debido a la acumulación de Si, la solución sólida de a-Fe se estabiliza a la temperatura de reacción, y se observa un descenso significativo en la concentración de Si más allá de la zona de difusión. El reforzamiento del Si 3 N 4 con plaquetas de Al 2 O 3 aumenta la resistencia química del Si 3 N 4 debido a la inercia de este oxido y a la cristalización parcial de la fase intergranular. La incorporación de HfN, BN y TiN no mejoran la resistencia química de la matriz al ataque por Fe. Palabras clave: nitruro de silicio, aceros, pares de difusión, cinética de interfases

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Section: Resultssupporting

confidence: 77%

Interacción químico entre nitruros de silicio y aleaciones de acero

Oliveira¹,

Silva²,

Vieira³

2000

Bol. Soc. Esp. Ceram. Vidr.

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“…Therefore, possessing low density and excellent thermomechanical properties, ceramics materials provide a means for producing heat engines with very efficiency ceiling far above what is presently possible with today's super alloys. Silicon nitride (Si 3 N 4 ), has received considerable attention due to its high decomposition temperature (approximately 1880 • C) as well as excellent creep properties [3,52,53]. Today, commercially available Si 3 N 4 powders are prepared by means of various routes, already in use for production on a technical scale because these powders are the starting point for dense materials, namely:…”

Section: Manufacture Of Silicon Nitride Powdersmentioning

confidence: 99%

Dense and near-net-shape fabrication of Si3N4 ceramics

Bocanegra‐Bernal

Matović

2009

Materials Science and Engineering: A

120

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“…during densification) between the Si 3 N 4 and any Fe, which may be present, from grinding or compounding or injection molding processes. The propensity to form a range of Fe silicides during this reaction leaves large metallic Fe-Si chunks in the matrix, as well as high-pressure gaseous nitrogen bubbles, which act as strength limiters (Pasto, 1984).…”

Section: Shape Makingmentioning

confidence: 99%

Synthesis/Processing of Silicon Nitride Ceramics

Pasto¹

2014

Comprehensive Hard Materials

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Causes and Effects of Fe‐Bearing Inclusions in Sintered Si₃N₄

Cited by 25 publications

References 5 publications

Interacción químico entre nitruros de silicio y aleaciones de acero

Interacción químico entre nitruros de silicio y aleaciones de acero

Dense and near-net-shape fabrication of Si3N4 ceramics

Synthesis/Processing of Silicon Nitride Ceramics

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Causes and Effects of Fe‐Bearing Inclusions in Sintered Si3N4

Cited by 25 publications

References 5 publications

Interacción químico entre nitruros de silicio y aleaciones de acero

Interacción químico entre nitruros de silicio y aleaciones de acero

Dense and near-net-shape fabrication of Si3N4 ceramics

Synthesis/Processing of Silicon Nitride Ceramics

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Causes and Effects of Fe‐Bearing Inclusions in Sintered Si₃N₄