TiB2-SiC粉末喷雾造粒及其等离子喷涂沉积机理研究

利用喷雾干燥对TiB_2-SiC复合粉末进行造粒,研究了浆料固含量、粘结剂含量及SiC含量对喷雾干燥粉体颗粒形貌等的影响。采用大气等离子喷涂技术,以抛光的石墨为基体,在不同预热温度和不同喷距下对TiB_2-SiC粉末进行粒子收集,研究不同工艺参数对TiB_2-SiC粒子铺展形貌的影响,并制备了TiB_2-SiC涂层。结果表明:当浆料固含量为50%,粘结剂含量为5%,SiC含量为10%时,喷雾造粒获得球形度高、流动性好的TiB_2-SiC粉末;随着基体预热温度的升高,喷距的增大,扁平粒子的溅射逐渐减弱,形成规则的圆盘状粒子;在等离子焰流作用下,TiB_2-SiC粒子熔化加速并与基体发生碰撞,熔融粒子扁平化,急速冷却凝固,不断堆叠、搭接为宏观涂层。

Research on Spray Granulation and Plasma Spraying Deposition Mechanism of TiB2-SiC Powders

TiB2-SiC composite powders were prepared by spray-drying, and the influence of slurry solid content, binder content and SiC content on the particle morphology of the spray-dried powder were investigated. TiB2-SiC flattening splats were collected on the polished graphite substrate by air plasma spraying under different substrate temperature and spray distance. The influence of coating parameters on the splat morphology were investigated. Besides, TiB2-SiC coatings were prepared by air plasma spraying. The results indicate that TiB2-SiC powder with high sphericity, and good fluidity is obtained by spray-drying when the solid content of the slurry is 50wt.%, the binder content is 5wt.%, and the SiC content is 10wt.%. With the increase of the substrate temperature and spray distance, the flat particles gradually decreases to form regular disc-shaped particles. Under the flame of plasma, TiB2-SiC particles melting accelerate and collide with the substrate. The molten particles are flattened, rapidly cooled and solidified. Therefore, the TiB2-SiC particles are continuously stacked and connected as a macroscopic coating.