Mechanical properties of silicon carbide—in situ zirconium carbonitride composites

Malik, Rohit; Jang, Seung Hoon; Kim, Young‐Wook; Nishimura, Toshiyuki

doi:10.1111/ijac.13213

Cited by 13 publications

(9 citation statements)

References 53 publications

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“…Preceramic polycarbosilane polymers are commonly used as precursors to make ceramic fibers 10,39 and ceramic matrix. [7][8][9]40,41 The chemical and volume changes that accompany ceramization of the polymer during pyrolysis have been documented in several studies.…”

Section: Resultsmentioning

confidence: 99%

“…29,30 The physics of resin under pressure is similar to the seepage pr lar approaches have been used also to mod into a mold containing fiber mats. 23,[31][32][33][34][35][36][37][38] T in these cases to determine the resin flow ing times corresponding to different infilt Preceramic polycarbosilane polymers as precursors to make ceramic fibers 10,3 trix. [7][8][9]40,41 The chemical and volume ch pany ceramization of the polymer during documented in several studies.…”

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confidence: 99%

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Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B₄C and C

Malik

Kim

2021

J Am Ceram Soc.

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SiC ceramics can be pressureless solid-state (PSS) sintered with elemental B or B-compounds and C as sintering aids. The sintering mechanism is a solid-state diffusion process where B segregates at the grain boundaries and reduces the grain boundary energy (γ gb ) 1−3 and C increases the surface energy (γ sv ) of SiC by removing the native SiO 2 film via a carbothermal reduction process. The combined action reduces γ gb /γ sv to a subcritical value and the densification process becomes thermodynamically feasible. 1,2 PSS SiC ceramics exhibit high oxidation and corrosion resistance, high hardness, excellent wear resistance, good strength retention at elevated temperatures, high creep resistance, high thermal conductivity, and low thermal expansion. 2−7 Unlike liquid-phase sintered SiC ceramics where the mechanical, thermal, and electrical properties can be tuned using a wide range of additive systems, 8−11 the scope of PSS SiC ceramics is constrained by the limited choice of sintering additives. To harness the full potential of PSS SiC ceramics, it is important to explore new additives and processing strategies to tailor the properties of PSS SiC ceramics.One potential strategy is to add AlN to PSS SiC. AlN at 2-100 wt% is known to form a solid-solution with SiC. 12 Recently, Li et al. 5 and Zhang et al. 7 investigated the effect of AlN addition on the mechanical and thermal properties of SiC ceramics pressureless sintered with B 4 C and C. SiC-4.6 wt% AlN exhibited the highest flexural strength (392 MPa) and fracture toughness (4.5 MPa‧m 1/2 ) among the SiC-0.9-22.3 wt% AlN ceramics sintered at 2130°C in Ar with 0.7-0.9 wt% B 4 C and 2.7-3.6 wt% C. 5 The optimal AlN content was a trade-off between improved densification caused by AlN addition and increased residual porosity due to partial decomposition of AlN during sintering. The thermal conductivity monotonically decreased (123 → 46 Wm −1 K −1 ) with increasing (0.5 → 10 wt%) AlN

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confidence: 99%

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Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B₄C and C

Malik

Kim

2021

J Am Ceram Soc.

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“…The critical flaw sizes (c), calculated using K 1C = 1.35‧σ‧c 1/2, were approximately 39, 45, 68, 83, and 112 μm for SBN1, SBN2, SBN3, SBN4, and SBN5, respectively. Given that the critical flaw sizes (39-112 μm) were much larger than the average grain size (~2.3 μm), the fracture is thought to have originated from the processing defects [28]. The typical fracture origins of SBN1 and SBN5 were residual pores near the tensile surfaces in bending bars (Figure 7).…”

Section: Resultsmentioning

confidence: 99%

Pressureless solid-state sintering of SiC ceramics with BN and C additives

Malik

Kim

2021

Journal of Asian Ceramic Societies

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This study proposes BN as a new sintering aid for pressureless solid-state sintering of SiC ceramics. The full densification of SiC ceramics for 0.5-2.7 wt% BN addition showed the composition tolerance of the newly developed ceramics. The electrical resistivity decreased by an order of magnitude (10 7 →10 6 Ω•cm) as BN content increased from ~0.5 to ~0.9 wt% because of the increased BN-derived B doping in the SiC lattice. A further increase in BN content had no significant effect on the electrical resistivity, which is attributed to the limited solubility of B in the SiC lattice. The thermal conductivity decreased with increasing BN content owing to increased phonon scattering at B-doped sites and the thermally insulating BN phase located at the grain boundaries. The fracture toughness increased with increasing BN content owing to interfacial debonding at the weak SiC-BN interfaces. However, intrinsically weak BN grains with low hardness were responsible for reduced flexural strength and hardness with increasing BN content.

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“…The residual thermal stresses ( σ th ) in SiC and SiO 2 can be estimated using the following equation: 20

σ_{th} = Δ α Δ T (\frac{E}{1 ‐ ν}),

where

Δ α

Δ T

, E , and ν denote the CTE mismatch, temperature difference (between the oxidation temperature and room temperature), elastic modulus, and Poisson's ratio, respectively. Using α α‐SiC 21 = 2.5 × 10 −6 °C −1 , α β‐SiC 21 = 1.2 × 10 −6 °C −1 , α SiO2 19 = 0.5 × 10 −6 °C −1 , E α‐SiC 21 = 409 GPa, E β‐SiC 21 = 465 GPa, E SiO2 19 = 72 GPa, ν α‐SiC 19 = 0.19, ν β‐SiC 22 = 0.19, ν SiO2 19 = 0.19, and

Δ T

= 600°C, the residual thermal stresses in the specimen sintered at 600°C with the β‐SiC‐SiO 2 interface were calculated to be 679 and −662 MPa for β‐SiC and SiO 2 , respectively. The corresponding residual stresses for an α‐SiC‐SiO 2 system were reduced to 212 and − 207 MPa for α‐SiC and SiO 2 , respectively.…”

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confidence: 99%

Intrinsic microstructures of silica‐bonded porous nano‐SiC ceramics

2020

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Porous SiC-based ceramics are extensively used in various industrial applications such as the purification process of air and water, bio-implants, thermoelectric energy conversion devices, catalytic supports, and thermal insulation, owing to their excellent mechanical properties, high corrosion and oxidation resistances, and tunable thermal and electrical properties. 1-7 Recently, we reported silica-bonded porous nano-SiC ceramics (hereafter, referred to as porous SiC-SiO 2 composites), which exhibited extremely low thermal conductivities (~0.05 Wm −1 K −1). 8,9 The high thermal insulation performance was attributed to the high interfacial thermal resistance of the SiC-SiO 2 interface. The porous SiC-SiO 2 composites exhibited a β-to-α (3C → 6H) polytypic phase transformation at a temperature as low as 600°C. 8,9 In this study, high-resolution transmission electron microscopy (HRTEM) characterization was performed to (a) reveal the intrinsic microstructure and (b) confirm the low-temperature polytypic transformation in the porous SiC-SiO 2 composites. Moreover, the HRTEM images revealed the precipitation of non-graphitic carbons in a porous SiC-SiO 2 composite sintered at 1200°C. This study reveals the underlying mechanisms for the oxidation-induced low-temperature polytypic phase transformation and non-graphitic carbon precipitation. These findings are crucial for the development of SiC-SiO 2-based thermal insulators and metal oxide semiconductor field-effect transistors (MOSFETs). The polytypic phase boundaries (α-β interface) and non-graphitic carbon-SiC heterophase boundaries act as phonon scattering sites. Thus, the thermal insulation performance of the porous SiC-SiO 2 composites could be improved by controlled polytypic phase transformation and non-graphitic carbon precipitation. Similarly, the electrical characteristics of SiC-SiO 2 MOSFETs could be tuned by a polytypic phase transformation and precipitation of the electrically conductive (~10 5 Ω −1 cm −1) 10 non-graphitic carbon phase. 2 | MATERIALS AND METHODS Nano-β-SiC (~50 nm, 97.5 +%, Nanostructured & Amorphous Materials, Inc) and carbon black (∼70 nm, N774,

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Mechanical properties of silicon carbide—in situ zirconium carbonitride composites

Cited by 13 publications

References 53 publications

Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B₄C and C

Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B₄C and C

Pressureless solid-state sintering of SiC ceramics with BN and C additives

Intrinsic microstructures of silica‐bonded porous nano‐SiC ceramics

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Mechanical properties of silicon carbide—in situ zirconium carbonitride composites

Cited by 13 publications

References 53 publications

Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B4C and C

Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B4C and C

Pressureless solid-state sintering of SiC ceramics with BN and C additives

Intrinsic microstructures of silica‐bonded porous nano‐SiC ceramics

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Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B₄C and C

Effect of AlN addition on the electrical resistivity of pressureless sintered SiC ceramics with B₄C and C