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使用碳酸钙(CaCO3)和二水磷酸氢钙(DCPD,CaHPO4·2H2O)混合粉末在纯钛表面利用激光熔覆的法制备羟基磷灰石HA,Ca5(PO4)3(OH)涂层,研究CaCO3和DCPD的质量比对涂层相组成和微观组织的影响。研究发现,CaCO3和DCPD之间的反应不仅在涂层中生成结晶度较高的HA,同时还生成了一定量的磷酸四钙(TTCP,Ca4P2O9),α-磷酸钙(α-TCP,α-Ca3(PO4)2),β-磷酸钙(β-TCP,β-Ca3(PO4)2)和焦磷酸钙(Ca2P2O7),且各相的含量与混合粉末的钙磷原子比有较大关系。HA只有在混合粉末的钙磷原子比大于1.54的情况下才能生成,其含量随钙磷原子比的升高而缓慢增加;当混合粉末的钙磷原子比达到2.0时,涂层中的HA的含量达到25%(质量分数),同时涂层中还存在大量的TTCP,因此制备的涂层需要进行一定的后续热处理以增加其中HA的含量。由于制备过程中粉末之间的反应会生成大量的气体,因此制备的涂层均为多孔结构,其中用钙磷原子比为2.0的混合粉末制备的涂层中,孔隙的尺寸在100~300μm之间。粉末钙磷原子比还能影响涂层的结合强度、孔隙率和裂纹数量。随钙磷原子比的升高,涂层的结合强度和孔隙率随之下降,裂纹数量逐渐增加。
Hydroxyapatite HA and Ca5 (PO4) 3 (OH) coatings were prepared on the surface of pure titanium by laser cladding using mixed powders of calcium carbonate (CaCO3) and calcium hydrogen phosphate dibasic (DCPD, CaHPO4 · 2H2O) Effect of Mass Ratio of CaCO3 and DCPD on Coating Phase Composition and Microstructure. It was found that the reaction between CaCO3 and DCPD not only produced HA with high crystallinity in the coating, but also produced a certain amount of tetracalcium phosphate (TTCP, Ca4P2O9), α-calcium phosphate (α-TCP, α- (PO4) 2, β-TCP, β-Ca3 (PO4) 2 and calcium pyrophosphate (Ca2P2O7), and the content of each phase has a great relationship with the ratio of Ca and P in the mixed powder. HA is only formed when the Ca / P ratio of the mixed powder is greater than 1.54, and the content of HA increases slowly with the increase of Ca / P ratio. When the Ca / P ratio of the mixed powder reaches 2.0, Content of 25% (mass fraction), while the coating is still a large number of TTCP, the coating prepared by the need for some follow-up heat treatment to increase the content of HA. Since a large amount of gas is generated due to the reaction between the powders during the preparation, the prepared coatings are all porous, and in the coating prepared with the mixed powder having the calcium-phosphorus atomic ratio of 2.0, the size of the pores is in the range of 100 to 300 μm between. Powder calcium phosphorus atomic ratio can also affect the bonding strength of the coating, porosity and the number of cracks. With the increase of calcium-phosphorus atomic ratio, the bonding strength and porosity of the coating decrease, and the number of cracks gradually increases.