Plasma spraying of fine particles promises uniform microstructure and improved properties for ceramic coatings due to the formation of small splats with reduced residual stress and pore size. Although spraying fine particles is challenging due to the poor rheological properties of particles (e.g., low flowability and agglomeration), the potential improvements to the coatings make it an attractive option. In this study, we discussed the feasibility of fine particle spraying via three different spraying techniques, namely low-power direct current (DC) plasma spraying, axial suspension plasma spraying (ASPS), and plasma-assisted aerosol deposition or hybrid aerosol deposition (HAD). Low-power DC plasma was sufficient to melt and deposit fine particles in an ambient atmosphere without using a liquid carrier. The fabricated coatings had similar features to those of ASPS coatings of small splats (5–8 µm in diameter without internal cracks). The fabricated coatings by the low-power DC plasma showed almost equivalent properties to that of the conventional plasma-sprayed coating while providing low energy consumption. Fine particles deposited via the HAD process led to the coatings with improved microstructure without pores or cracks. During the HAD process, particle melting was not required for deposition, and using the plasma assisted the surface activation and improved the deposition efficiency of the aerosol deposition process. The fabricated HAD coating revealed improved microstructure with the highest hardness, Young’s modulus, and adhesion strength and lack of pores or cracks compared to the coatings fabricated by other plasma spray techniques. In addition, similarities and differences among the techniques for spraying fine ceramic particles were investigated.

中文翻译：

---

通过不同喷涂工艺由细颗粒沉积的陶瓷涂层

细颗粒的等离子喷涂保证了陶瓷涂层的均匀微观结构和改进的性能，因为形成了具有减小的残余应力和孔径的小碎片。尽管由于颗粒的流变性能较差（例如，低流动性和团聚性），喷涂细颗粒具有挑战性，但涂层的潜在改进使其成为有吸引力的选择。在这项研究中，我们讨论了通过三种不同的喷涂技术进行细颗粒喷涂的可行性，即低功率直流 (DC) 等离子喷涂、轴向悬浮等离子喷涂 (ASPS) 和等离子辅助气溶胶沉积或混合气溶胶沉积 (HAD) ）。低功率直流等离子体足以在环境气氛中熔化和沉积细小颗粒，而无需使用液体载体。制造的涂层具有与小碎片（直径 5-8 µm，无内部裂纹）的 ASPS 涂层相似的特征。低功率直流等离子体制备的涂层表现出与传统等离子喷涂涂层几乎相同的性能，同时提供低能耗。通过 HAD 工艺沉积的细颗粒导致涂层具有改善的微观结构，没有孔隙或裂纹。在HAD过程中，沉积不需要粒子熔化，并且使用等离子体辅助表面活化并提高了气溶胶沉积过程的沉积效率。与通过其他等离子喷涂技术制造的涂层相比，制造的 HAD 涂层显示出改进的微观结构，具有最高的硬度、杨氏模量和粘附强度，并且没有孔隙或裂纹。