Effect of diamond content on microstructure and properties of diamond/SiC composites prepared by tape-casting and CVI process

Liu, Yongsheng; Hu, Chenghao; Men, Jing; Feng, Wei; Cheng, Laifei; Zhang, Litong

doi:10.1016/j.jeurceramsoc.2015.02.009

Cited by 33 publications

(15 citation statements)

References 28 publications

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“…Simulations listed in Table 2 consider different phase content among bulk grains, matrix regions, and GB layers encasing 170 diamond grains with average size of 20.5 µm, as explained in Section 3.2 . The 70% diamond fraction corresponds to the experimental sample, while the 39.4% diamond fraction is an excursion to investigate the response of a material with less diamond [ 13 ]. Partitioning of SiC into 9.4% grains and 9.0% matrix is likewise consistent with the real sample, while other choices are excursions that are convenient based on mesh geometry.…”

Section: Phase Field Results: Bulk and Layer Composition Effectsmentioning

confidence: 99%

“…In these prior results,

was chosen appropriately based on the fracture energy of lowest-energy planes for each crystal type. In contrast, in the present simulations, fractures in material elements of matrix regions are assumed to be intergranular, i.e., along SiC-SiC grain boundaries [ 19 , 69 ] or diamond-SiC phase boundaries [ 13 ]. Fracture energy

is assigned to the appropriate material phase based on distributions of GB energies calculated from MD in Section 5 .…”

Section: Phase Field Simulations: Grain Boundary Energy Distributimentioning

confidence: 99%

“…Those SiC matrix regions not bordering diamond crystals are nominally assumed to fracture by separation along SiC-SiC grain boundaries [ 19 , 69 ]. Matrix regions of SiC contiguous to diamond are assumed to fracture by separation along diamond-SiC phase boundaries [ 13 ]. Fractions of SiC-SiC versus diamond-SiC boundaries vary among microstructures addressed in simulations.…”

Section: Phase Field Simulations: Grain Boundary Energy Distributimentioning

confidence: 99%

“…The material consists of diamond and silicon carbide (SiC) crystals with complex spatial and size distributions of grains. Representative microstructures and processing routes for this material system can be found in [ 10 , 11 , 12 , 13 , 14 , 15 ]. In the material studied herein, disparities exist in typical grain sizes among the primary (diamond) and secondary (SiC) phases, with diamond grains tending to be at least an order of magnitude larger, with mean sizes in tens of microns.…”

Section: Introductionmentioning

confidence: 99%

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A Multi-Scale Approach for Phase Field Modeling of Ultra-Hard Ceramic Composites

et al. 2021

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Diamond-silicon carbide (SiC) polycrystalline composite blends are studied using a computational approach combining molecular dynamics (MD) simulations for obtaining grain boundary (GB) fracture properties and phase field mechanics for capturing polycrystalline deformation and failure. An authentic microstructure, reconstructed from experimental lattice diffraction data with locally refined discretization in GB regions, is used to probe effects of local heterogeneities on material response in phase field simulations. The nominal microstructure consists of larger diamond and SiC (cubic polytype) grains, a matrix of smaller diamond grains and nanocrystalline SiC, and GB layers encasing the larger grains. These layers may consist of nanocrystalline SiC, diamond, or graphite, where volume fractions of each phase are varied within physically reasonable limits in parametric studies. Distributions of fracture energies from MD tension simulations are used in the phase field energy functional for SiC-SiC and SiC-diamond interfaces, where grain boundary geometries are obtained from statistical analysis of lattice orientation data on the real microstructure. An elastic homogenization method is used to account for distributions of second-phase graphitic inclusions as well as initial voids too small to be resolved individually in the continuum field discretization. In phase field simulations, SiC single crystals may twin, and all phases may fracture. The results of MD calculations show mean strengths of diamond-SiC interfaces are much lower than those of SiC-SiC GBs. In phase field simulations, effects on peak aggregate stress and ductility from different GB fracture energy realizations with the same mean fracture energy and from different random microstructure orientations are modest. Results of phase field simulations show unconfined compressive strength is compromised by diamond-SiC GBs, graphitic layers, graphitic inclusions, and initial porosity. Explored ranges of porosity and graphite fraction are informed by physical observations and constrained by accuracy limits of elastic homogenization. Modest reductions in strength and energy absorption are witnessed for microstructures with 4% porosity or 4% graphite distributed uniformly among intergranular matrix regions. Further reductions are much more severe when porosity is increased to 8% relative to when graphite is increased to 8%.

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Section: Phase Field Results: Bulk and Layer Composition Effectsmentioning

confidence: 99%

“…In these prior results,

is assigned to the appropriate material phase based on distributions of GB energies calculated from MD in Section 5 .…”

Section: Phase Field Simulations: Grain Boundary Energy Distributimentioning

confidence: 99%

Section: Phase Field Simulations: Grain Boundary Energy Distributimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Multi-Scale Approach for Phase Field Modeling of Ultra-Hard Ceramic Composites

et al. 2021

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“…In the past few decades, diamond particles have been applied as effective thermal fillers and reinforcement phases for ceramics and metal matrix materials due to their high strength and excellent thermal conductivity. The thermal conductivity and flexural strength of SiC ceramics can be obviously improved by introducing diamond particles . Diamond‐modified Cu and Cu alloy composites also exhibit enhanced thermal conductivity and are regarded as promising thermal management materials .…”

Section: Introductionmentioning

confidence: 99%

Improved Thermal Conductivity and Ablation Resistance of Microdiamond‐Modified C/C Composites after Diamond Graphitization

et al. 2019

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C/C composites with diamond addition are prepared, and a 1600 °C heat treatment is conducted to investigate the effects of diamond graphitization on the ablation resistance and thermal conductivity of the composites. With diamond content increasing, a higher degree of stress graphitization occurs to the surrounding pyrolytic carbon (PyC) due to the enhanced stress accumulation in the diamond stacking region during graphitization process. After heat treatment at 1600 °C, the single diamond/PyC interface is substituted by complex diamond/graphite and graphite/PyC interfaces which results in a more compact structure and enhanced interface strength. Benefiting from the optimized interface microstructure and reduced closed pores after diamond graphitization, higher thermal conductivities are achieved for C/C–diamond composites. The ablation performance of the composites is improved due to the better oxidation resistance of diamond particles, increased compactness of diamond stacking region, and optimized thermal properties of the composites.

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Microstructure and Properties of Diamond/SiC Composites Via Hot Molding Forming and CVI Densifying

et al. 2018

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In order to improve the mechanical properties and thermal conductivity, diamond/SiC composites are fabricated using hot molding forming and chemical vapor infiltration (CVI) densifying. The effects of diamond particle size and grain gradation (maximum particle size of 50–500 µm) on microstructure, mechanical properties, and thermophysical properties of diamond/SiC composites are investigated. The results indicate that the thermal conductivity of composites can be obviously enhanced and the maximum value is 257 W · m−1 · K−1 using large diamond particle size and grain gradation. The value is 2.22 times higher than that of the diamond/SiC composites prepared using tape‐casting and CVI process (116 W · m−1 · K−1). The maximal density, flexural strength, and fracture toughness are found to be 3.16 g cm−3, 248.33 MPa, and 4.65 MPa.m1/2, respectively. The fracture mechanism of the composites is transferred from diamond particles’ trans‐granular fracture to interfacial debonding due to stronger combination between the diamond and the CVI‐SiC matrix. Furthermore, JD50 sample has the highest flexural strength (248.33 MPa), fracture toughness (4.65 MPa · m1/2), and equivalent CTE (4.0 × 10−6 K−1) compared with other samples. Additionally, its thermal conductivity is also relatively high, making it a suitable high thermal conductivity material.

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Effect of diamond content on microstructure and properties of diamond/SiC composites prepared by tape-casting and CVI process

Cited by 33 publications

References 28 publications

A Multi-Scale Approach for Phase Field Modeling of Ultra-Hard Ceramic Composites

A Multi-Scale Approach for Phase Field Modeling of Ultra-Hard Ceramic Composites

Improved Thermal Conductivity and Ablation Resistance of Microdiamond‐Modified C/C Composites after Diamond Graphitization

Microstructure and Properties of Diamond/SiC Composites Via Hot Molding Forming and CVI Densifying

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