自蔓延反应火焰喷涂TiC-TiB_2复相陶瓷涂层的水淬熄试验

Water Quenching Experiments of SHS Reactive Flame Sprayed TiC-TiB_2 Multiphase Ceramic Coatings

用水淬熄法研究了Ti-B4C-C系自蔓延高温合成(SHS)反应火焰喷涂TiC-TiB2复相陶瓷涂层的反应过程与机理。结果表明,在喷涂过程中喷涂团聚颗粒各组元间、各组元与环境间存在多种反应的竞争,团聚颗粒飞行距离不同,反应得到的产物不同。喷涂的最佳距离为180mm,此处获得的球形粒子(陶瓷液滴)数量最多,团聚粉熔融最充分,获得的球形陶瓷液滴数量最多,形成的目标产物最理想。陶瓷液滴的形成始于钛粉的熔化,并通过扩散和毛细管作用向B4C和C颗粒渗透和浸润,经过自蔓延反应能量积累,最后SHS爆燃完成。当陶瓷液滴遇水淬熄后将以柱状方式结晶成毛线团状,可以用熔渣正规离子溶液模型描述液滴的结构。

Using the self-propagating high-temperature synthesis （SHS） technology, the procedure and mechanism of reactive flame spraying TiC-TiB2 multiphase ceramic coatings with Ti-B4C-C system were studied by means of water quenching method. The results show that different reaction and change take place at different spraying distance, there exist competition of various reactions in the particles, and as a result muhiphase ceramic particles can be got. At the optimal spraying distance 180mm, the agglomerated particles have the fullest melts, the final products are the best, and the most quantities of spheroid particles （ ceramics droplets） are formed. The formed process of the ceramics liquid drop is that the SHS reaction begin with the melting of Ti powders, and then the space among the B4C and C powders is wet and permeated by the liquid Ti through the diffusion and capillary mechanism, pass by the energy backlog, finally the SHS deflagration is completed. When water quenching takes place, the liquid particles will be crystal with pillar crystal way and form knitting wool ball shape. The structure of the ceramics droplets can be described by slag regular solution model.