微束等离子喷涂制备羟基磷灰石涂层微观结构的特征研究

Investigations on Microstructure of Micro-plasma Sprayed Hydroxyapatite Coating

目的通过与大气等离子喷涂和超音速火焰喷涂的对比,研究微束等离子喷涂制备的羟基磷灰石涂层的微观组织特点。方法以高结晶度的羟基磷灰石粉末为原料,采用三种不同的喷涂方法(微束等离子喷涂、大气等离子喷涂和超音速火焰喷涂),在Ti-6Al-4V基体上制备羟基磷灰石(HA)涂层。利用冷场发射扫描电子显微镜和X射线衍射仪,对三种涂层的形貌、相组成和择优取向进行分析。结果与大气等离子喷涂及超音速火焰喷涂制备的涂层相比,应用该设备制备的羟基磷灰石涂层表面平整致密,无大量的气孔存在;涂层截面呈典型的层状结构,在近三分之一表面处观察到柱状晶;涂层中仅有少量的非晶相及分解相,结晶度高达90%以上。这些特征均有利于羟基磷灰石涂层在体液环境中的稳定性。结论比较三种喷涂方法,采用微束等离子喷涂制备的羟基磷灰石涂层致密,结晶度高,杂相少,且存在择优取向的柱状晶。

Objective By comparison with atmospheric plasma spraying and high velocity oxygen fuel spraying, the microstructure characteristics of the HA coating deposited by micro-plasma spraying were investigated. Methods High crystallinity hydroxyapatite powders were used as initial material, which were deposited onto Ti-6Al-4V substrate by three different spraying technol-ogies： micro-plasma spraying（MPS）, atmospheric plasma spraying（APS） and high velocity oxygen fuel（HVOF） spraying in this research. The morphology, phase composition and preferred crystal orientation of HA coatings were characterized by scanning electron microscopy（SEM） and X-ray diffraction（XRD）. Results Compared with the other two counterparts, micro-plasma sprayed HA coating exhibited flat and dense surface without obvious porosity and void, the cross section of which exhibited a typical lamellar structure, with the emergence of columnar crystal near coating surface. Besides, the coating had high crystallinity（90%） with only a small amount of amorphous phase and decomposition phase, which was assumed to be related to the stability of the coating in the body fluid environment. Conclusion Compared with APS and HVOF, HA coating deposited by MPS exhibited denser structure, higher crystallinity with less decomposition phase, and columnar microstructure was observed within coating.