化学气相沉积低温各向同性热解炭微观结构及沉积机制
Microstructure and deposition mechanism of low temperature isotropic pyrocarbon prepared by chemical vapor deposition

为了研究低温各向同性热解炭（LTIC）的微观结构及沉积机制，采用不同体积分数的丙烷为碳源，在不同的沉积温度下进行稳态流化床化学气相沉积实验制备LTIC，借助SEM和TEM对不同沉积条件下制备的LTIC微观结构进行表征和分析。结果表明：不同沉积条件下制备的LTIC由类球形颗粒状和片层状炭结构组成，沉积温度升高，降低了热解炭在气相中的形核势垒，LTIC中类球形颗粒数量增多，尺寸变小，且类球形颗粒内包围炭黑颗粒的炭层织构逐渐降低；丙烷体积分数升高，热解炭沉积过程逐渐由以表面生长机制为主转变为以气相形核机制为主，所制备的LTIC中类球形颗粒形貌越来越明显，而片层状炭结构逐渐减少甚至完全消失。 For investigating microstructure and deposition mechanism of the low temperature isotropic pyrocarbon(LTIC), LTIC was prepared by a steady-state fluidized bed chemical vapor deposition experiments at different deposition temperatures with propane as carbon source of different volume fractions. Microstructure of the LTIC obtained at different deposition conditions was characterized using SEM and TEM. The results show that the LTIC obtained at different deposition conditions is composed of globular-like granular and laminar carbon structure. Increasing the deposition temperature is propitious to decrease the nucleation barrier forming pyrocarbon in vapor, which causes the quantity of globular-like particles with a smaller diameter increasing and the texture of the carbon layer around carbon black particles inside globular-like particles decreasing gradually. With increasing the volume fraction of propane, pyrocarbon deposition process is mainly dominated by surficial growth mechanism, and transforms to the gaseous nucleation mechanism. The globular-like particle morphology in obtained LTIC is more obviously and laminar carbon structure gradually decreases and even disappear completely. 国家自然科学基金（50975070）；浙江省自然科学基金（LY12E05002）