The effect of the pyrolytic carbon(PyC)interface thickness on the heat-stability of CansasⅡSiC_(f)/SiC composites under Ar up to 1500℃was studied in detail.After the heat treatment at 1500℃for 50 h,the interface bo...The effect of the pyrolytic carbon(PyC)interface thickness on the heat-stability of CansasⅡSiC_(f)/SiC composites under Ar up to 1500℃was studied in detail.After the heat treatment at 1500℃for 50 h,the interface bonding strength of the thin interface(about 200 nm)decreases from 74.4 to 20.1 MPa(73.0%),while that of the thick interface(about 2μm)declines from 7.3 to 3.2 MPa(52.7%).At the same time,the decline fraction of strength of the composites with the thin interface is 12.1%,less than that with the thick interface(42.0%).The fiber strength also decreases after heat treatment,which may be due to the significant growth ofβ-SiC grains and critical defects.The different heat-stability of the interface with the thin and thick thickness might be related to the inconsistency of the degree of the graphitization of PyC.Compared with the composites with the thick interface,the composites with the thin interface remained higher tensile strength after heat treatment due to the better interface bonding strength.The interface with strong bonding strength could protect the fiber by postponing the decomposition of amorphous phases SiC_(x)O_(y) and hindering the generation of fiber defects.展开更多
Abstract When interfacial layers are viewed as a separate phase, the interface thickness plays an essential role in assessing physico-mechanical properties of particulate materials. However, the interface thickness fr...Abstract When interfacial layers are viewed as a separate phase, the interface thickness plays an essential role in assessing physico-mechanical properties of particulate materials. However, the interface thickness from sectional analysis is often overestimated, due to the irregularity of surface textures of grains in opaque materials that gives rise to the normal of a cross-sectional plane non-perpendicular to the surface of grains. Hence, the determination of the overestimation degree is very critical to precisely obtain the interface thickness. This article develops a numerical model for the overestimation degree of the interface thickness around an ellipsoidal grain with an arbitrary aspect ratio, by applying an accurate sectional analysis algorithm, and quantitative stereology and geometrical probability theories. Furthermore, on the basis of the developed numerical model, the influence of ellipsoidal particle shape on the overestimation degree is quantitatively charac-terized.展开更多
The average thickncss of the interface layer wrapped about sols usually is determined by fitling the Porod curve that shuws anegative deviation from Porod's law.In this paper we show.that it could also be determin...The average thickncss of the interface layer wrapped about sols usually is determined by fitling the Porod curve that shuws anegative deviation from Porod's law.In this paper we show.that it could also be determined by a new method that includes the ful-lowing steps;(1)determining the average radius R,of the sol particles ineluding intlerface layer from the small angle X-ray scat-lering data in which shows negalive deviation from Porod's law;(2)detemining the average rardius R2 of the sol particlks not in-cluding the interface layer from the seattering daia in which las been correeted the negative deviation from P'orod'a law;(3)thedifference AR Lelwcen R1 and R2,i.e,AR=R1-R2,is just the average thieknoss of thr intcrfuce layer wrapperd alunt swuls,By using tlhe:above methol,the average thickness of tie interface layer wrapped about SiO2 wols prepared under dilferent runli-tions were determined.展开更多
electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which ar...electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which are highly dependent on the thickness. Thus, understanding the formation mechanism and the SEI thickness is of prime interest. First, we apply dimensional analysis to obtain an explicit relation between the thickness and the number density in this study. Then the SEI thickness in the initial charge-discharge cycle is analyzed and estimated for the first time using the Cahn-Hilliard phase-field model. In addition, the SEI thickness by molecular dynamics simulation validates the theoretical results. It has been shown that the established model and the simulation in this paper estimate the SEI thickness concisely within order-of-magnitude of nanometers. Our results may help in evaluating the performance of SEI and assist the future design of Li-ion battery.展开更多
基金Funded by the National Science and Technology Major Project(No.2017-IV-0005-0042)the China Postdoctoral Science Foundation(No.2021M691566)。
文摘The effect of the pyrolytic carbon(PyC)interface thickness on the heat-stability of CansasⅡSiC_(f)/SiC composites under Ar up to 1500℃was studied in detail.After the heat treatment at 1500℃for 50 h,the interface bonding strength of the thin interface(about 200 nm)decreases from 74.4 to 20.1 MPa(73.0%),while that of the thick interface(about 2μm)declines from 7.3 to 3.2 MPa(52.7%).At the same time,the decline fraction of strength of the composites with the thin interface is 12.1%,less than that with the thick interface(42.0%).The fiber strength also decreases after heat treatment,which may be due to the significant growth ofβ-SiC grains and critical defects.The different heat-stability of the interface with the thin and thick thickness might be related to the inconsistency of the degree of the graphitization of PyC.Compared with the composites with the thick interface,the composites with the thin interface remained higher tensile strength after heat treatment due to the better interface bonding strength.The interface with strong bonding strength could protect the fiber by postponing the decomposition of amorphous phases SiC_(x)O_(y) and hindering the generation of fiber defects.
基金supported by the Natural Science Foundation Project for Jiangsu Province(BK20130841)National Science Foundation Project for Distinguished Young Scholars(11125208)the Ministry of Science and Technology of China(973 Project)(2009CB623203 and 2010CB832702)
文摘Abstract When interfacial layers are viewed as a separate phase, the interface thickness plays an essential role in assessing physico-mechanical properties of particulate materials. However, the interface thickness from sectional analysis is often overestimated, due to the irregularity of surface textures of grains in opaque materials that gives rise to the normal of a cross-sectional plane non-perpendicular to the surface of grains. Hence, the determination of the overestimation degree is very critical to precisely obtain the interface thickness. This article develops a numerical model for the overestimation degree of the interface thickness around an ellipsoidal grain with an arbitrary aspect ratio, by applying an accurate sectional analysis algorithm, and quantitative stereology and geometrical probability theories. Furthermore, on the basis of the developed numerical model, the influence of ellipsoidal particle shape on the overestimation degree is quantitatively charac-terized.
文摘The average thickncss of the interface layer wrapped about sols usually is determined by fitling the Porod curve that shuws anegative deviation from Porod's law.In this paper we show.that it could also be determined by a new method that includes the ful-lowing steps;(1)determining the average radius R,of the sol particles ineluding intlerface layer from the small angle X-ray scat-lering data in which shows negalive deviation from Porod's law;(2)detemining the average rardius R2 of the sol particlks not in-cluding the interface layer from the seattering daia in which las been correeted the negative deviation from P'orod'a law;(3)thedifference AR Lelwcen R1 and R2,i.e,AR=R1-R2,is just the average thieknoss of thr intcrfuce layer wrapperd alunt swuls,By using tlhe:above methol,the average thickness of tie interface layer wrapped about SiO2 wols prepared under dilferent runli-tions were determined.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11372313, U1562105, and 11611130019)the Chinese Academy of Sciences (CAS) through CAS Interdisciplinary Innovation Team Project, the CAS Key Research Program of Frontier Sciences (Grant No. QYZDJ-SSW-JSC019)the CAS Strategic Priority Research Program (Grant No. XDB22040401)
文摘electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which are highly dependent on the thickness. Thus, understanding the formation mechanism and the SEI thickness is of prime interest. First, we apply dimensional analysis to obtain an explicit relation between the thickness and the number density in this study. Then the SEI thickness in the initial charge-discharge cycle is analyzed and estimated for the first time using the Cahn-Hilliard phase-field model. In addition, the SEI thickness by molecular dynamics simulation validates the theoretical results. It has been shown that the established model and the simulation in this paper estimate the SEI thickness concisely within order-of-magnitude of nanometers. Our results may help in evaluating the performance of SEI and assist the future design of Li-ion battery.
