钛和Ti-40Nb合金的微弧磷酸钙涂层结构与性能

摘要

The microstructure, physical and mechanical, and chemical properties of micro-arc calcium phosphate (CaP) coatings deposited under different process voltages in the range of 150?400 V on the commercially pure titanium (Ti) and Ti?40%Nb (Ti?40Nb)(mass fraction)alloy were investigated by the SEM, TEM, XRD and EDX methods. The coating thickness, roughness, and sizes of structural elements were measured and showed similar linear character depending on the process voltage for the coatings on both substrates. SEM results showed the porous morphology with spherical shape structural elements and rough surface relief of the coatings. XRD and TEM studies exhibitedtheamorphous structureofthe CaP coating. With increasing the process voltage to 300?400 V,the crystalline phases,such as CaHPO4andβ-Ca2P2O7,were formedonto the coatings. The annealing leads to the formation of complex poly-phase structure with crystalline phases: CaTi4(PO4)6,β-Ca2P2O7, TiP2O7, TiNb(РО4)3, TiO2, NbO2, and Nb2O5. The applied voltage and process duration in the ranges of 200?250 V and 5?10 min, respectively, revealed the coating formed on Ti and Ti?40Nb with optimal properties: thickness of 40?70mm, porosity of 20%?25%, roughness (Ra) of 2.5?5.0mm, adhesion strengthof 15?30 MPa, and Cа/Рmoleratio of 0.5?0.7.%采用 SEM、TEM、XRD 和 EDX 等试验手段对经150~400 V 电压微弧氧化处理后工业纯钛(Ti)和Ti?40%Nb(Ti?40Nb)(质量分数)合金表面磷酸钙(CaP)涂层的显微组织、物理和力学性能以及化学特性进行研究。结果表明：在两种基体上所得到的涂层厚度、粗糙度和结构元尺寸显示出相似的线性特征且与处理电压有关。扫描电镜(SEM)分析表明，磷酸钙涂层为多孔形态，表面呈粗糙浮雕状。XRD和TEM分析结果表明，微弧磷酸钙涂层呈非晶态结构。当氧化电压增加至300~400 V时，涂层中形成了结晶相，如CaHPO4、β-Ca2P2O7。经过退火处理，涂层中形成复杂的多相结构，如CaTi4(PO4)6、β-Ca2P2O7、TiP2O7、TiNb(РО4)3、TiO2、NbO2和Nb2O5。当氧化电压为200~250 V、处理时间为5~10 min时，在工业纯钛和 Ti?40Nb 合金表面形成的涂层显示出最佳特性，其厚度为40~70μm，孔隙率为20%~25%，粗糙度(Ra)为2.5~5.0μm，粘合强度为15~30 MPa，Ca与P最佳摩尔比为0.5~0.7。