Silicon Carbide‐ and Boron Carbide‐Based Hard Materials

Schmalzried, C.; Schwetz, Karl A.

doi:10.1002/9783527631735.ch4

Cited by 16 publications

(10 citation statements)

References 290 publications

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“…This results in a weakness in Si 3 N 4 ceramics similar to that found in other silicate materials in fluorine‐containing solutions. This behavior contrasts with that of solid‐phase–sintered SiC, which is even stable in HF‐containing solutions …”

Section: Corrosion Of Additive‐free Si3n4 Materialsmentioning

confidence: 74%

“…The solubility of the Si 3 N 4 or SiAlON grains under hydrothermal conditions is higher than for SiC grains. Therefore, Si 3 N 4 materials are less stable than LPSSiC and SSiC materials are under these conditions . The stability of the grains in the silicon nitride ceramics therefore limits the maximum application temperature to 200°C–250°C in water‐based systems.…”

Section: Corrosion Of Si3n4 Materials With Sintering Additivesmentioning

confidence: 99%

“…This behavior contrasts with that of solid-phase-sintered SiC, which is even stable in HF-containing solutions. 31,44…”

Section: Corrosion Of Additive-free Si 3 N 4 Materialsmentioning

confidence: 99%

“…Therefore, Si 3 N 4 materials are less stable than LPSSiC and SSiC materials are under these conditions. 9,31,44 The stability of the grains in the silicon nitride ceramics therefore limits the maximum application temperature to 200°C-250°C in water-based systems. For thin Si 3 N 4 -films or nanocrystalline Si 3 N 4 materials, the maximum application temperature could be lower.…”

Section: (4) Corrosion Under Hydrothermal Conditionsmentioning

confidence: 99%

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Corrosion of Silicon Nitride Materials in Aqueous Solutions

Herrmann

2013

J. Am. Ceram. Soc.

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Silicon nitride ceramics are used under conditions where high strength, hardness, and wear resistance are necessary. The increasing use of Si3N4 ceramics in different environments demands an understanding of the relationships between microstructure and corrosion behavior. This study gives an overview of the behavior of silicon nitride in acids, bases, and hydrothermal conditions. It not only summarizes the literature data but also attempts to explain the mechanisms and to give some guidelines for the use of the materials in different environments. The stability of the ceramics against corrosion in acids and bases up to the boiling point is mostly controlled by the stability of the grain boundary. The stability can be predicted using the glass network theory. Materials with grain boundaries exhibiting a strong network, i.e., a high amount of SiO2 in the grain boundary, are stable in acids, but less stable under hydrothermal conditions and in basic solutions. Therefore, tailoring the grain boundaries can change the corrosion stability by several orders of magnitude. At temperatures above 200°C–250°C, the dissolution of the Si3N4 grains becomes a decisive factor determining the stability.

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Section: Corrosion Of Additive‐free Si3n4 Materialsmentioning

confidence: 74%

Section: Corrosion Of Si3n4 Materials With Sintering Additivesmentioning

confidence: 99%

“…This behavior contrasts with that of solid-phase-sintered SiC, which is even stable in HF-containing solutions. 31,44…”

Section: Corrosion Of Additive-free Si 3 N 4 Materialsmentioning

confidence: 99%

Section: (4) Corrosion Under Hydrothermal Conditionsmentioning

confidence: 99%

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Corrosion of Silicon Nitride Materials in Aqueous Solutions

Herrmann

2013

J. Am. Ceram. Soc.

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“…The properties and preparation route of silicon carbide‐ and boron carbide‐based materials is described extensively in Ref. These composites combine good thermal shock resistance and oxidation resistance. The typical processing route involves pressureless sintering followed by posthiping to produce 100% dense SiC–B 4 C, or SPS processing at a temperature of 1950°C under 100 MPa for 5 min …”

Section: Introductionmentioning

confidence: 99%

Flash Spark Plasma Sintering (FSPS) of α and β SiC

et al. 2016

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A novel processing methodology that allows combined preheating and Flash-SPS (FSPS) of silicon carbide-based materials has been developed. Beta-SiC (+10 wt% B 4 C) powders were densified (Ф 20 mm) up to 96% of their theoretical density in 17 s under an applied pressure of 16 MPa (5 kN). The flash event was attributed to the sharp positive temperature dependence of the electrical conductivity (thermal runaway) of SiC, and a sudden increase in electric power absorption (Joule heating) of the samples after a sufficient preheating temperature (>600°C) was reached. The microstructural evolution was analyzed by examining materials densified by FSPS in the range of 82%-96% theoretical densities. FEM modeling results suggest that the FSPS heating rate was of the order of 8800°C/min. A comparative analysis was done between FSPS and reference samples (sintered using conventional SPS in the temperature range of 1800°C-2300°C). This allowed for a better understanding of the temperatures generated during FSPS, and in turn the sintering mechanisms. We also demonstrated the scalability of the FSPS process by consolidating a large aSiC disk (Ф 60 mm) in about 60 s inside a hybrid SPS furnace equipped with an induction heater, which allowed us to achieve sufficient preheating (1600°C) of the material to achieve FSPS.

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Anodic dissolution of solid‐state sintered silicon carbide at high current densities

Schneider

Schubert

Michaelis

2016

Materials & Corrosion

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The electrochemical behavior of solid-sintered silicon carbide was investigated under high current densities in alkaline solutions. The use of potentiodynamic as well as chronoamperometric measurements show that the anodic dissolution takes place as a transpassive mechanism under formation of a metastable passive layer. At high polarization potentials (≈150 V), the dielectric breakdown of the passive layer which was primarily formed on the surface initiates an anodic dissolution of sintered silicon carbide at high current densities. Complementary material diagnostics (optical microscopy and SEM/EDX investigation) clearly show significant material removal as well as remaining oxide layer thicker than the native oxide film

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Silicon Carbide‐ and Boron Carbide‐Based Hard Materials

Cited by 16 publications

References 290 publications

Corrosion of Silicon Nitride Materials in Aqueous Solutions

Corrosion of Silicon Nitride Materials in Aqueous Solutions

Flash Spark Plasma Sintering (FSPS) of α and β SiC

Anodic dissolution of solid‐state sintered silicon carbide at high current densities

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