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Study on the synthesis of Spray Coating Composed of Refractory Boride Ceramics by Electrothermal Explosion of powders

粉末电热爆炸合成耐火硼化物陶瓷喷涂层的研究

基本信息

批准号：
07805066
负责人：
TAMURA Hideki
金额：
$ 1.22万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
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

The subject of this research is to find the spraying process to produce the coating composed of refractory carbide ceramics due to electrothermal explosion of the ceramic powders. In addition, it is also expected to research a new technique suitable for the enlargement of this process.The electrothermal explosion of conductive powders has been applied to produce spray coatings of refractory boride ceramics without any additives. The powder of conductive zirconium boride was pluged in a container made of an inner insulating tube and an outer metal cylinder having a window for ejection of molten paticles. Such a container was holded between a pair of electric contacts in a vacuum chamber. The spray of the ceramics was done by the explosion caused by electrical rapid heating due to high voltage application and large current discharge. In order to obtaine dense and adhessive coatings of novel functional boride ceramics, the explosion and spray of ceramic powders was observed by Sclieren photography which was composed of a high speed camera and high power argon ion laser. It was found that high power electrical discharge caused the production of a high speed jet containing molten particles. The representaive velocity of the jet was estimated 3000m/s of more on the basis of one dimensional approximation of intense shock wave formation. The electric energy supplied to the powder was twice to three times the one needed to melt just the powder. Thus it was revealed that this spray technique is chracterized with high temperature and speed jet which have not been obtained in other techniques yet. The coatings obtained was also as unique so that it had no pore and lamella, and that it mixed with the top layr of a substrate over the range of 50mum. Thus the coatings are expected to be highly dense and adhesive. For the large-scaled spraying, the shapes of the powder container and other equipment were evaluated.

本研究的目的是探索陶瓷粉末电热爆炸制备难熔碳化物陶瓷涂层的喷涂工艺。此外，还有望研究适合于该工艺扩大的新技术。导电粉末的电热爆炸已应用于无任何添加剂的耐火硼化物陶瓷喷涂层的生产。导电硼化锆粉被塞进一个容器中，该容器由一个内部绝缘管和一个外部金属圆柱体组成，该圆柱体具有一个喷射熔融颗粒的窗口。这样的容器被夹在真空室中的一对电触点之间。陶瓷的喷涂是由高压大电流放电产生的电快速加热引起的爆炸造成的。为了获得致密、附着力良好的新型功能硼化物陶瓷涂层，利用高速摄像机和高功率Ar+激光组成的Sclieren照相技术，对陶瓷粉末的爆炸和喷雾过程进行了观察。研究发现，在高功率放电作用下，会产生含有熔融颗粒的高速射流。在强激波形成的一维近似基础上，估算出喷流的代表速度为3000m/S以上。提供给粉末的电能是仅熔化粉末所需电能的两到三倍。结果表明，该喷雾技术具有其他喷雾技术所没有的高温、高速喷雾的特点。所获得的涂层也同样独特，它没有气孔和薄层，并且它与基材的顶层混合在50微米的范围内。因此，涂层应具有高度的致密性和粘附性。对于大规模喷涂，对粉料容器和其他设备的形状进行了评估。