FABRICATION OF HYDROXYAPATITE/ALUMINUM OXIDE COMPOSITE COATINGS BY THE COMBINATION OF ELECTROPHORETIC DEPOSITION AND REACTION BONDING PROCESS
- 化学化工－已发表论文 
在金属表面用电泳沉积(electrophoretic deposition,EPD)法制备羟基磷灰石(hydroxyapatite,HA)涂层的主要问题是结合强度较低。为了提高HA涂层与基体的结合强度,先采用EPD在钛表面制得羟基磷灰石/铝(hydroxyapatite/aluminum,HA/Al)复合涂层,然后采用反应结合方法(reaction bonding process)制备羟基磷灰石/氧化铝(hydroxyapatite/aluminum oxide,HA/Al2O3)复合涂层,并与相同条件下制备的HA单一涂层进行比较研究。用扫描电镜表征涂层的表面和横截面形貌。用能量散射X射线衍射(X-ray diffraction,XRD)谱分析HA/Al2O3复合涂层的化学组成。用XRD仪研究涂层的物相组成和热稳定性。通过黏结–拉伸实验测定HA涂层与基体的结合强度。结果表明:通过850℃热处理,HA/Al复合涂层中的Al粉发生氧化反应生成Al2O3,经反应结合得到HA/Al2O3复合涂层;反应结合提高了HA涂层的致密化程度且降低了基底钛表面的氧化程度;与单一HA涂层相比,HA/Al2O3复合涂层与基底间的结合强度得到明显提高。The major problem in fabricating hydroxyapatite (HA) coating on metal substrate by electrophoretic deposition is the low bonding strength between the coating and substrate. In order to improve the bonding strength,hydroxyapatite/aluminum oxide (HA/Al2O3) composite coating was fabricated on titanium substrate using the combination of electrophoretic deposition and reaction bonding process. The HA single coating was prepared in the same conditions for comparison. Scanning electronic microscope was employed to characterize the surface and cross-sectional morphologies of the as-prepared coatings. The chemical compositions of the composite coating were analyzed through energy dispersive X-ray spectroscopy. X-ray diffraction was used to study the phase com-position and thermal stability of the as-prepared coatings. The bonding strength between the coating and substrate was tested by a shear strength testing experiment. The results show that the Al in HA/Al green coating prepared by the EPD was oxidized to Al2O3,and HA/Al2O3 composite coating was obtained using the reaction bonding process by heat treatment at 850 ℃. The reaction bonding process promotes the coating's sintering densification and improves the substrate's oxidation resistance during the heat treatment. In comparison with the HA single coating,the HA/Al2O3 composite coating exhibits much higher bonding strength.