促進骨癒合之水熱合成壓電 BaTiO3 塗層技術開發

Abstract

骨組織本身具有壓電特性，當骨骼受到力學刺激時可產生局部電位變化，進而活化細胞訊號傳遞並促進骨修復。基於此，本研究旨在於Ti-6Al-4V骨科植入物表面製備具壓電特性之BaTiO3（BTO）塗層，藉由材料本身之壓電效應，建立有利於骨癒合之電生理微環境。研究首先以陽極處理於 Ti6Al4V 基板表面形成TiO2前驅層，後續利用水熱法於180°C下以Ba(OH)2與KOH反應液原位成長BTO塗層，並進一步結合退火與極化處理，以調控材料之晶相結構與偶極排列，提升其壓電性能。 結果顯示，不同陽極處理厚度中，以T2M組別可形成較適合BTO成長之TiO2前驅層；水熱反應條件方面，0.5M Ba(OH)2與1.5M KOH 可使BTO塗層形成更為緻密且均勻之珊瑚狀結構，並獲得較佳之結晶表現。退火部分則發現600°C可在不明顯損傷Ti-6Al-4V基材之情況下，有效提升BTO之四方相特徵與局部壓電響應，其中PFM量測顯示其d33值可達約98 pm/V。相較之下，800°C以上退火則會造成塗層剝落與基材氧化，降低材料完整性。至於極化處理，雖然電暈極化與熱電暈極化後之塗層形貌與晶相仍可維持，但在本研究所採用之條件下，壓電響應未獲顯著提升，顯示後續仍需進一步優化極化參數。 綜合而言，本研究成功透過水熱法於Ti-6Al-4V基板上製備具壓電潛力之BTO塗層，並建立陽極處理、水熱濃度、退火溫度與極化條件之製程關聯。此結果不僅提供一套可應用於骨科植入物之壓電塗層製備策略，亦為未來開發低溫、簡化且具生醫應用潛力之功能性陶瓷塗層奠定基礎。

Bone exhibits intrinsic piezoelectricity, and mechanical loading can generate localized electrical potentials that promote cellular signaling and bone repair. Based on this concept, this study aimed to fabricate a piezoelectric BaTiO3 (BTO) coating on Ti-6Al-4V orthopedic implants in order to create a bioelectrical microenvironment favorable for bone healing. A TiO2 precursor layer was first formed on the Ti-6Al-4V substrate by anodization. BTO was then grown in situ by hydrothermal synthesis at 180°C using an aqueous Ba(OH)2/KOH solution, followed by annealing and polarization to regulate crystal structure and dipole alignment and thereby improve piezoelectric performance. The results showed that the T2M anodization condition produced the most suitable TiO2 precursor layer for BTO growth. For hydrothermal synthesis, 0.5 M Ba(OH)2 and 1.5 M KOH yielded a denser and more uniform coral-like BTO coating with improved crystallinity. Among the annealing conditions investigated, 600°C provided the best overall performance, enhancing the tetragonal phase characteristics and local piezoelectric response of BTO without noticeable damage to the Ti-6Al-4V substrate; PFM analysis showed a maximum d33 value of approximately 98 pm/V. In contrast, annealing above 800°C caused coating delamination and substrate oxidation, leading to degraded structural integrity. Although corona poling and thermo-corona poling preserved the coating morphology and phase structure, no significant improvement in piezoelectric response was observed under the conditions used in this study, indicating that further optimization of the poling parameters is required. In summary, this study demonstrates the successful fabrication of a BTO coating with piezoelectric potential on Ti-6Al-4V substrates by hydrothermal synthesis and establishes the relationships among anodization, hydrothermal solution concentration, annealing temperature, and polarization conditions. These findings provide a practical strategy for piezoelectric coatings on orthopedic implants and lay the foundation for future development of low-temperature, simplified, and bio-functional ceramic coatings for biomedical applications.