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Development of New Fluidized-bed processes for Si-based Materials

硅基材料新型流化床工艺的开发

基本信息

批准号：
03555174
负责人：
KOJIMA Toshinori
金额：
$ 6.91万
依托单位：
Faculty of Engineering, Seikei University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

For the development of novel particle processing such as particle coating, utilization of fluidizing phenomena of particles under plasmatic conditions is available. Coating of SiC on the surface of particles from SiH_4 and CH_4 was studied using a D.C.plasma jetting fluidized bed reactor, consisting of fluidized bed superimposed on a D.C.plasma generator. SiH_4 and CH_4 were introduced through the ports forming vortex flow around the plasma jet. Two types of gas injection methods, premix and diffusion-mix methods, were compared. The diffusion-mix method gave high conversions of SiH_4 and CH_4, compared with the premix method. Though fine beta-SiC powder was trapped in the filter installed on the way of exit line, deposition of SiC on the bed particles was not confirmed by X-ray diffraction, probably due to the coating of amorphous or very thin SiC.The elemental analysis along the cross section of the coated particles showed that most silicon was deposited inside the particles and not near the surface. It can be speculated that the reaction gases excited in plasma were diffused into the particles and deposition occurred inside the particles.Fundamental characteristics of a microwave plasma-fluidized bed reactor for particle processing were also investigated. Alumina or polycrystalline silicon was used as a bed material. Fluidizing phenomena and stability of plasma state seem to depend on the kinds of plasma gas and the level of dielectric loss of particles. Optical observation showed that plasma was generated within bubbles in the bed. Methane conversion was carried out as a model reaction. Although the level of methane conversion in the presence of particles was lower than that in the absence of particles, methane was effectively converted to carbon in the microwave plasma-fluidized bed.

为了开发新型颗粒加工（例如颗粒涂层），可以利用等离子体条件下颗粒的流化现象。使用直流等离子体喷射流化床反应器研究了SiH_4和CH_4颗粒表面的SiC涂层，该反应器由叠加在直流等离子体发生器上的流化床组成。 SiH_4和CH_4通过端口引入，在等离子体射流周围形成涡流。对预混法和扩散混合法两种气体注入方法进行了比较。与预混法相比，扩散混合法SiH_4和CH_4的转化率较高。尽管细小的 β-SiC 粉末被捕获在安装在出口管线上的过滤器中，但 X 射线衍射未证实 SiC 沉积在床颗粒上，这可能是由于无定形或非常薄的 SiC 涂层所致。沿涂层颗粒横截面的元素分析表明，大多数硅沉积在颗粒内部而不是表面附近。可以推测，等离子体中激发的反应气体扩散到颗粒中，并在颗粒内部发生沉积。还研究了用于颗粒处理的微波等离子体流化床反应器的基本特性。使用氧化铝或多晶硅作为床材料。流化现象和等离子体状态的稳定性似乎取决于等离子体气体的种类和颗粒的介电损耗水平。光学观察表明，床中的气泡内产生了等离子体。甲烷转化作为模型反应进行。尽管存在颗粒时甲烷转化水平低于不存在颗粒时的甲烷转化水平，但甲烷在微波等离子体流化床中有效地转化为碳。