Both high thermal conductivity(K)and large cross-sectional area are essential for thermal dissipation materials to maximize their heat transfer capability.However,the drastic decrease of K values with the increased th...Both high thermal conductivity(K)and large cross-sectional area are essential for thermal dissipation materials to maximize their heat transfer capability.However,the drastic decrease of K values with the increased thickness makes the existing graphite/graphene films less favored for practical applications.In this work,graphite film with both large thickness and high K value is produced based on an in-situ com-position strategy between nanographene(G)and pyrocarbon(PyC)via chemical vapor deposition(CVD)using CH_(3) OH/C_(2)H_(5)OH mixed precursors.It’s found that an optimized O/C ratio of precursors facilitates the construction of ordered G skeletons within the deposited G/PyC composites.Such G/PyC compos-ites can be completely graphitized at a lower temperature than the existing products.After 2400℃ an-nealing,dense,thick,and highly aligned graphite films were prepared.Their K values reach 1350 and 1010 W m^(-1) K^(-1) at the thickness of 40 and 120μm,respectively,surpassing the existing records with similar thicknesses.More importantly,the proposed method is insensitive to the deposition substrates,and the G/PyC can be infiltrated into large-size fiber preforms as a matrix for preparing centimeter-thick high K materials.Besides,the G/PyC also exhibits better mechanical and electromagnetic shielding per-formances than the existing products,indicating a promising multifunctional application prospect.展开更多
基金financially supported by the National Natu-ral Science Foundation of China(Nos.51872234,52222204,and 52002322)the Natural Science Basic Research Plan in Shaanxi(No.2020JQ-154)+1 种基金the Key R&D Program of Shaanxi Province(No.2019ZDLGY04-02)the China Postdoctoral Science Foundation(No.2020M683556).
文摘Both high thermal conductivity(K)and large cross-sectional area are essential for thermal dissipation materials to maximize their heat transfer capability.However,the drastic decrease of K values with the increased thickness makes the existing graphite/graphene films less favored for practical applications.In this work,graphite film with both large thickness and high K value is produced based on an in-situ com-position strategy between nanographene(G)and pyrocarbon(PyC)via chemical vapor deposition(CVD)using CH_(3) OH/C_(2)H_(5)OH mixed precursors.It’s found that an optimized O/C ratio of precursors facilitates the construction of ordered G skeletons within the deposited G/PyC composites.Such G/PyC compos-ites can be completely graphitized at a lower temperature than the existing products.After 2400℃ an-nealing,dense,thick,and highly aligned graphite films were prepared.Their K values reach 1350 and 1010 W m^(-1) K^(-1) at the thickness of 40 and 120μm,respectively,surpassing the existing records with similar thicknesses.More importantly,the proposed method is insensitive to the deposition substrates,and the G/PyC can be infiltrated into large-size fiber preforms as a matrix for preparing centimeter-thick high K materials.Besides,the G/PyC also exhibits better mechanical and electromagnetic shielding per-formances than the existing products,indicating a promising multifunctional application prospect.
