医用新型梯度多元纳米复合涂层的组成结构设计与腐蚀-磨损耦合损伤机制研究

Due to the urgent need for high performance bioactive coating materials of modern bioindustry, the potential advantages of bioinert carbon-based coatings and bioactive hydroxyapatite coatings in bio-tribological applications in simulated body environment, this project puts forwards to optimize the nanocrystalline/amorphous microstructure, multi-element doping and 2D interface structure as the main design concept for fabricating nano-composite coating by multi-function plasma deposition technology. The key breakthrough for the multilayer composite coating is that the microstructure, composition and transition layer could be controlled precisely. Based on the mathematical foundation of synergistic effect between corrosion and wear, to reveal the evolutionary process of chemical constituent and microstructure of coatings in friction test under simulated body fluid (SBF) environment, and especially pay more attention to degradation mechanisms of coating under the conditions of interactive-coupling effects of body fluid, corrosion, wear, abrasives and variable stress, etc. The action relationships of the composition and microstructure features on the corrosion-wear properties of coatings in SBF environment are clarified with emphasis, the composition and structure design principles of functional gradient composite coatings for the Functionality and corrosion resistant and anti-wear operations in SBF are establish at last. The outputs of this project would provide scientific foundations and technical supports for design and fabrication of high performance “structure-functional protective integration surface” on surfaces of key tribo-pairs in SBF environment. The applicant and the research group have accumulated rich experiences and obtained some important results in the corresponding field, and the required foundations and conditions of this project are ready.

鉴于当前生物产业对高性能生物活性涂层的迫切需求以及生物惰性碳基涂层和骨诱导生物活性羟基磷灰石的独特生物优势，本项目从涂层纳米晶/非晶结构、多元功能特性协同和二维界面结构优化三方面入手，采用多功能等离子沉积技术为制备手段，重点突破金属基体表面梯度多元纳米复合涂层纳米晶/非晶多元微结构及层间过渡结构的可控构筑；结合腐蚀-磨损协同作用模型，全面揭示模拟体液环境下复合涂层摩擦过程中成分和微结构演化过程，尤其是体液、腐蚀磨损、磨粒、多变应力等耦合作用下复合涂层的损伤机理，阐明复合涂层组成结构特征与其模拟体液环境下腐蚀磨损性能之间的构效关系，最终建立人体环境用功能性耐磨蚀复合涂层的组成结构设计原则，为人体环境医用生物材料摩擦副表面高性能“结构-功能防护一体化表层”的设计和制备提供科学基础和技术支撑。申请人及其团队在相关领域内已积累丰富的研究经验并取得重要阶段性研究成果，已具备完成此项目的基础和条件。

Ti6Al4V合金耐磨性差，表面不具生物活性，且Al、V等有害离子释放等造成的骨溶解、无菌性松动，无法形成骨性结合，诱发感染等问题仍亟待解决。因此本项目开展了Ti6Al4V合金表面新型梯度纳米复合涂层的构筑及性能研究。针对钛合金所面临的关键性问题，建立了纳米复合涂层不同尺度/维度结构特征与人体环境生物摩擦学行为之间的构效关系；基于人体环境用摩擦副表面涂层与基体材料的弱结合，提出了层间过渡梯度结构设计多种二维界面，阐明了不同界面过渡结构对复合涂层在模拟液环境中的摩擦学作用规律；通过控制工艺参数调控了梯度过渡层的结构致密性，达到有效屏蔽Al、V等有害离子的释放；基于人体模拟液环境复合涂层的腐蚀磨损过程中的组织结构演变，提出了复合涂层体外矿化机理；通过人体模拟环境下纳米复合涂层微观结构和腐蚀矿化机理的深入分析，提出了人工关节耐蚀抗磨及功能性纳米复合涂层的多尺度结构设计原则。研究结果表明，通过磁控溅射技术构筑的复合涂层结构均匀、致密，无裂纹等缺陷，与基体结合强度高达40N；热处理能够恢复HA涂层缺失的羟基（-OH），提高涂层的结晶度；涂层界面缺陷减少，晶粒尺寸增加，粗糙度增加，改善涂层的纳米力学性能、生物降解性能；涂层接触角减小到更加接近细胞粘附角度。提高负偏压，可明显提高涂层的结晶度；高致密度的梯度过渡层涂层可以阻止体液的渗入，也可阻挡有害离子的释放，降低幅度高达88%，有效提高基体的耐蚀性能；涂层内应力随氩气压强增大而降低，随偏压增加先增大后降低；梯度过渡层引入后基体耐腐蚀性明显优于无涂层和单一过渡层；溅射偏压增大，氩气压强降低，复合涂层的磨损量降低；静态浸泡实验可获得连续的HA矿化涂层，具有优异的生物相容性。研究成果对提高人工关节用医用金属的耐磨蚀和生物相容性具有非常重要的意义。