目的 研究粉末粒径对微束等离子喷涂羟基磷灰石（HA）扁平粒子形貌和涂层的微观组织结构的影响。方法 选取三组不同粒径范围（25~38 μm、38~45 μm、45~63 μm）HA球形粉末，采用微束等离子喷涂方法在经镜面抛光的Ti-6Al-4V基体上收集扁平粒子，在经过喷砂处理的Ti-6Al-4V基体上沉积HA涂层。利用冷场发射扫描电子显微镜和X射线衍射仪，对扁平粒子形貌，以及涂层的形貌、相组成和择优取向进行分析。通过激光共聚焦显微镜（LSCM）观察扁平粒子的三维相貌，并对比分析扁平粒子的差异。结果 微束等离子喷涂过程中，可形成几种典型形貌特征的扁平粒子，一是中间区域较厚，边缘位置较薄的扁球形；二是中间区域较薄，边缘位置较厚的圆盘状，该种扁平粒子相比于扁球形，其厚度较薄，直径较大；三是边缘位置存在“指状”溅射的圆盘状，其厚度与圆盘状扁平粒子厚度相当，但其直径范围较大。HA涂层的结晶度随着粉末粒径的减小而减小，HA的分解和非晶化逐渐增强，涂层的择优取向强度减弱，涂层中柱状晶比例减少。结论 微束等离子喷涂过程中，粉末粒径对扁平粒子形貌和涂层相结构有显著影响。随着粒径的增加，扁平粒子由扁球形转变为边缘有少量“指状”溅射的圆盘状。粒径较小的HA粉末在等离子焰流中的熔化程度较高，导致涂层中分解相和非晶相含量增多，择优取向程度减小。

The work aims to study the effects of hydroxyapatite (HA) particle size on the splat morphology and coating mi-crostructure during micro-plasma spraying. Three groups of HA particles with different sizes (25~38 μm, 38~45 μm, 45~63 μm) were selected and the splat particles were collected on the bright finished Ti-6Al-4V substrates and then adopted to deposit HA coatings on sandblasted Ti-6Al-4V substrates by micro-plasma spraying method. The morphologies of splat and coatings were observed by cold field emission scanning electron microscopy (SEM). The phase composition and preferred orientation of the as-sprayed coatings were analyzed through X-ray diffraction (XRD). The three-dimensional morphology characteristics of HA splats were observed by laser scanning confocal microscope (LSCM) and the difference between splats was compared and ana-lyzed. Splats formed during micro-plasma spraying showed distinct morphology characteristics: (i) Oblate spheroid with thicker central area and thinner edge areas; (ii) Disk shaped splats with thinner central area and thicker edge areas, exhibiting a thinner thickness and a larger average diameter compared with oblate shaped splats; and (iii) Disk shaped splats with finger splashing at the rim, having a larger diameter but thickness as same as the disk shaped splats. With the decreasing particle sizes, both the crystallinity and texture intensity of the coatings decreased, while the tendency of HA decomposition and amorphous phase for-mation increased. Meanwhile, the preferred orientation intensity and the ratio of columnar grains decreased. The morphology of the collected splats and as-sprayed coatings was strongly influenced by the particle sizes during micro-plasma spraying. As the particles sizes increase, the splat morphology was transformed from the oblate spheroid into the disk shape with a small amount of splashing at the rim. The melting degree of the fine powders were better, so the coatings contained more amorphous and de-composed phases with less preference in orientation.