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Development of a Large-Diameter Thermal Plasma Processing Device and its Application to Synthesis of Thermoelectric Materials

大直径热等离子体加工装置的研制及其在热电材料合成中的应用

基本信息

批准号：
07558066
负责人：
FUKUMASA Osamu
金额：
$ 4.29万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Thermal plasma jet operated under reduced pressure has a great potential for synthesizing new materials, because of its high speed, high gas temperature and large plasma volume. Therefore, we have newly designed the plasma reactor composed of the forced constricted type plasma jet generator and the feed ring. In order to clarify the application feasibility of this reactor to fine plasma processing for materials, the behavior of the plasma jet has been discussed.Findings are as follows :(1) Under low pressure, high temperature and high velocity regions of the plasma jet are expanded. With the use of this expanding plasma jet, the dense film without vesicles is obtained and the film thickness is easily controlled.(2) Under low pressure, the hardness and the adhesion strength of functionally gradient materials are found to be high.(3) Under not only atmospheric pressure but also low pressure, thin-films of beta" -alumina are successfully synthesized from the powder mixtures, i.e.alpha-Al_2O_3, Na_2CO_3 and MgO.Synthesis of beta" -alumina depends on jet power and the distance from the feed ring exit to the substrate.(4) When pure diamond films are synthesized, the ratio of CH_4 flow rate to H_2 flow rate is lower than a certain critical value. Namely, the intensity of CH/H_<alpha> in the vicinity on the substrate has strong effect on pure diamond film deposition.(5) The computer tomography technique should be applicable to the diagnostics of asymmetric plasma jets.

减压热等离子体射流具有速度快、气体温度高、等离子体体积大等优点，在合成新材料方面具有很大的潜力。为此，我们设计了一种由强制收缩式等离子体射流发生器和进给环组成的新型等离子体反应器。为了阐明该反应器应用于材料精细等离子体加工的可行性，对等离子体射流的行为进行了讨论。结果表明：(1)在低压条件下，等离子体射流的高温和高速区域得到扩展。利用这种膨胀等离子体射流，可以得到致密的无囊泡膜，膜厚易于控制。(2)在低压下，发现功能梯度材料的硬度和粘附强度较高。(3)在常压和低压条件下，用α - al_2o_3、Na_2CO_3和MgO的粉末混合物成功合成了β " -氧化铝薄膜。β " -氧化铝的合成取决于喷射功率和进料环出口到基体的距离。(4)制备纯金刚石膜时，CH_4流速与H_2流速之比低于某一临界值。即衬底附近CH/H_< α >的强度对纯金刚石膜的沉积有很强的影响。(5)计算机断层扫描技术应适用于非对称等离子体射流的诊断。