等离子喷涂钛基羟基磷灰石（HA）涂层材料既有金属的强度和韧性，又具有表面生物活性，已广泛应用于骨骼的替代和修复。但是等离子的高温会降低涂层的结合强度，同时HA分解为磷酸三钙(TCP)、磷酸四钙(TTCP)等，涂层在体内易溶解、脱落、失效。超音速氧焰喷涂（HVOF）有非常高的焰流速度和相对较低的火焰温度，是一种较为合适的HA涂层制备方法。
本文采用HVOF的方法在Ti6Al4V基体上制备HA涂层，考察了不同燃气流量对HA颗粒熔化程度、相组成及在涂层表面形貌的影响。结果表明：增加燃气流量，颗粒表面的熔化程度提高，但颗粒整体熔化比例仅有微小增加，从12.79%增加到18%，原因是增大燃气流量提高火焰温度的同时加快了颗粒的飞行速度，降低了粉末在火焰中的滞留时间。X射线衍射(XRD)图谱表明：三种燃气流量下颗粒中均只有HA结晶相，说明喷涂过程中，HA分解很少。三种颗粒的结晶度计算显示：提高燃气流量降低了HA颗粒的结晶度，从91.4%降至73.8%；扫描电镜观察发现：三种燃气流量下的HA颗粒在涂层表面形成了三种典型结构。
涂层中只有HA晶相，结晶度较高，可能存在早期生物活性不高的问题，因此，本文制备了羟基磷灰石/生物玻璃（BG）复合涂层，分析添加生物玻璃对涂层的相组成、表面形貌及生物活性的影响。XRD结果显示：添加生物玻璃不影响涂层的相组成，对HA的分解没有影响或影响很小；SEM结果表明：BG颗粒以球形方式镶嵌在涂层表面，含量小于粉末中的比例；将涂层浸泡在一倍模拟体液（SBF）中7天后发现：添加20%wtBG的涂层表面有明显的类骨类磷灰石生成，说明添加BG可以提高涂层的生物活性。
针对涂层在模拟体液中发生剥落的问题，本文采用在HA涂层表面涂覆聚乳酸（PLA）的方法改善其在水溶液中的稳定性。考察了不同浓度及涂覆次数对涂层稳定性的影响。实验发现，涂层表面涂覆聚乳酸后，在水溶液中的稳定性增强，因为疏水的聚乳酸可以防止水渗入涂层。超声过程中涂层表面以点状方式掉落，与涂层表面聚乳酸膜存在微小的孔洞有关。涂覆浓度及次数对涂层的影响较为明显，浓度低时，涂层易掉落。涂覆次数少，薄膜易破裂，涂覆次数多了，涂层与薄膜间的结合强度降低，导致两者整体分离。本文认为3g/100ml的浓度，涂覆次数以三次为佳。1g/100ml时，涂覆五次效果要好于三次。

Hydroxyapatite (HA) coatings deposited on titanium alloy substrates using air plasma spray (ASP) is being widely used in medical bone prostheses and substitutions.However,due to the extremely high temperature of the plasma jet, the bond strength is low,and the degradation of HA involves the formation of tricalcium phosphate (TCP), tetracalcium phosphate (TTCP) will cause the coating dissolution and desquamation. High volecity oxy-fuel (HVOF) spray has extraordinary high particle velocity and comparatively low temperature and can be an appropriate method to produce HA coating.
HA coatings was prepared by HVOF and the effects of three flow rates on the properties of phases composites, melting state of sprayed HA particles and surface morphology of coatings were investigated in this paper. The results showed that the increase of fuel flow rates could enhance the melting degree in the surface of HA particles, the calculation of melt fraction of HA particle revealed that the melt fraction increased a little from 12.79% to 18.00% as the fuel rate risen. The reason is that larger flow rate result in higher temperature of the flame as well as accelerated the velocity of HA particles and reduced the time of particle during in the flame. Qualitative phase analysis with X-ray diffraction (XRD) showed that the coating is mainly crystalline HA and the crystallinity of HA decreased from 91.4% to73.8% when the flow rates increased, it is caused by the different melt fraction between the HA particles. As the scanning electronic microscopy (SEM) observation shown, HVOF sprayed coatings exhibited three typical morphologies and microstructures after the HA particles impinged on the substrates.
HA/ bioactive glass (BG) coatings were produced to improve the bioactivity of the coating. The effect of BG addition on properties of as-sprayed coatings in terms of phase composites, surface morphology and bioactivity were investigated. XRD showed that the coatings were mainly crystalline HA and exhibited no secondary phase. The addition of BG had no effect on phase’s composites. As the SEM showed, the spherical BG particles studded in the HA coating. The content of BG in the surface of coating is less than the content of the input powder. Soaked in simulate body fluid (SBF) after 7 days showed only the coating with 20wt% BG precipitated bone-like apatite, it means BG increased the coating’s bioactivity.
Since the HA coating desquamated in the SBF, it was coated with polylactic acids polymer(PLA)in order to improve the stability of the coating in water. The effect of PLA concentration and coating times were investigated.The result showed that: the residual area of coating without PLA was less than 1% after ultrasoniced 30 seconds in water while it is more than 8% with PLA coated. Because PLA is hydrophobic, it protected HA coating from water filtered. The PLA concentration and coating times both significantly affected the coating’s stability. The films invalidated in the form of punctate desquamation, it is probably because the films is porous.Low concentration resulted in flaky films, easy to be broken when the coating times was low, but if it was coated too many times the bond strength between PLA films and HA coating became weaker, and the film would apart from coating.The suitable coating time was three, when the PLA concentration is 3g/100ml. In the condition of 1g/100ml, the effect was better when coated five times.