工艺参数和热处理对纯钛表面激光熔覆原位合成羟基磷灰石涂层中物相组成的影响

Effects of Processing Parameters and Heat Treatment on Phase Structure of the Hydroxyapatite Coating on Pure Ti Surface by Laser Cladding in-situ Synthesis

使用CaCO3和CaHPO4混合粉末,在纯钛表面通过激光熔覆原位合成的方法制备羟基磷灰石(Ca10(PO4)6(OH)2,HA)涂层,研究了激光功率,扫描速度和热处理对涂层物相的影响,以期提高涂层中HA的含量。结果表明,低功率下,涂层的主要组成物相为磷酸四钙(Ca4(PO4)2O,TTCP),同时有少量的HA,α-磷酸钙(α-Ca3(PO4)2,α-TCP),CaO和CaTiO3;随功率的增加,涂层中的TTCP,HA和CaO逐渐减少,只剩下α-TCP和CaTiO3。与功率相比,扫描速度对涂层物相的影响较小。当激光功率为400W时,不同扫描速度下涂层的物相没有发生明显的变化,主要物相均为TTCP。将涂层在800℃下保温5h,然后随炉冷却,可以使涂层中的TTCP和α-TCP全部转变为HA,进而得到含HA较多的涂层。

Hydroxyapatite （Ca10（PO4）6（OH）2, HA） coatings were prepared on pure Ti substrates by laser cladding （LC） in situ synthesis using mixed powders of CaCO3 and CaHPO4. In order to increase the amount of HA in the coatings, the effects of processing parameters including laser power and scanning velocity and heat treatment on the phase structure of the coatings were investigated. The results show that the coatings consist of large amount of tetracalcium phosphate （Ca4（PO4）2O, TTCP） as well as a little HA, α-tricalcium phosphate （α-Ca3（PO4）2, α-TCP）, calcium oxide（CaO） and CaTiO3 when the laser power is low. As the laser power increases, the amount of TTCP, HA and CaO in the coatings decreases gradually, and finally only α-TCP and CaTiO3 remain. Compared with the laser power, the effect of scanning velocity on the phase structure of the coatings is much weaker. At the laser power of 400 W, there is no obvious difference for the phase structures at different scanning velocities and the main phase is always TTCP. It is found that the amount of HA can be increased greatly by heat treatment at 800 oC for 5 h followed by furnace cooling, due to the total transformation from TTCP and α-TCP to HA.