沉积工艺对致密热解炭密度及显微组织的影响

The effect of deposition process on the density and microstructure of isotropic pyrolytic carbon

以乙炔、丙烯为碳源气体,采用流化床-化学气相沉积工艺于燃料颗粒表面沉积致密热解炭包覆层,在1150~1230℃沉积温度及碳源气体体积分数为7%~21%下开展正交实验,研究沉积温度及碳源气体浓度对致密热解炭密度的影响。采用阿基米德原理测量致密热解炭密度,用场发射扫描电镜观察致密热解炭微观结构。研究结果表明,致密热解炭密度随着沉积温度的升高而降低,随碳源气体浓度的增大先降低再升高;微观结构上,致密热解炭由类球形颗粒组成,在较低的沉积温度或碳源气体浓度下,显微组织以片层结构为主,而在较高的沉积温度或碳源气体浓度下,显微组织以"团聚体"结构为主。

The isotropic pyrolytic carbon is deposited on the surface of fuel particles by fluidized bed chemical vapor deposition process with the mixtures of ethanol and propylene as precursors.The effects of deposition temperature and precursor concentration on the density of the isotropic pyrolytic carbon are studied with the orthogonal experiments at 1150~1230℃and 7%~21%precursor concentrations.The density of isotropic pyrolytic carbon is measured by Archimedes principle and its microstructure is observed by a field emission scanning electron microscopy.The results show that the density of isotropic pyrolytic carbon decreases with the increase of deposition temperature,and first decreases and then increases with the increase of the precursor concentration.The isotropic pyrolytic carbon is composed of nearly spherical particles.And at lower deposition temperature or lower precursor concentration,the microstructure mainly shows a lamellar structure,while at higher deposition temperature or higher precursor concentration,the microstructure mainly shows an agglomerate structure.