医用钛合金表面改性研究进展

钛合金作为人体硬组织替代物和修复物的首选材料在临床上得到广泛的应用.分析了目前医用钛合金存在的主要问题:生物活性、耐磨性和耐腐蚀性有待进一步提高,指出表面改性是改善上述问题的有效途径;综述了人体植入钛合金表面改性的研究进展,并展望了钛合金表面改性的发展趋势.     

医用钛及钛合金表面改性技术的研究进展

随着现代医学和材料科学的快速发展,植介入治疗技术在临床的应用越来越广泛。作为植入医疗器械的重要材料,医用钛及钛合金已广泛应用于骨科、口腔科等临床医学领域。然而,钛元素活泼的化学特点使得医用钛及钛合金的表面极易形成一层惰性的钝化膜,虽然具有优异的耐蚀性能,但是其表面不具有生物活性,从而影响了植入器械与软硬组织的结合。此外,医用钛及钛合金作为关节器械,其在体液环境下的摩擦磨损性能不佳,磨损情况下的腐蚀也不理想,因此亟需有效的改性技术来改善医用钛及钛合金的表面性能。基于此,本文针对近期开展的医用钛及钛合金表面改性技术研究,综述了物理气相沉积、等离子喷涂、离子注入、激光熔覆、溶胶-凝胶合成等表面改性手段在改善医用钛及钛合金表面性能的研究现状,并对医用钛及钛合金表面改性技术的研究进行了展望。     

医用钛合金表面改性的研究进展

从金属植入体与生物环境的界面反应,以及钛植入体表面现阶段存在的主要问题出发,叙述了近年来钛表面生物活性、生物相容性、血液相容性、抗菌性涂层的制备、结构及性能,重点总结了应用等离子体喷涂技术制备羟基磷灰石涂层、硅酸盐陶瓷涂层、纳米ZrO2涂层、纳米TiO2涂层,以及采用等离子体浸没离子注入/沉积技术对钛合金表面进行离子注入和薄膜沉积的研究结果.最后,基于钛硬组织植入体表面需求,指出钛硬组织植入体表面改性设计与制备应注重改性层的综合生物学性能及力学安全性.     

合金激光表面改性的研究进展

介绍了激光表面改性的方法,综述了几种表面激光改性的研究现状.激光表面改性方法主要包括激光表面合金化、激光表面熔凝、激光熔覆、激光冲击硬化及激光诱导沉积技术,利用激光表面处理技术可改善合金表面耐磨和耐蚀等性能.     

钛合金生体材料及其表面改性

介绍了新型钛合金生体材料的研究开发,探讨了人工关节的失效机理,综述了对钛合金在表面生物活性、耐磨性、耐蚀性三个方面的表面改性的研究进展。     

人工晶体材料的表面改性研究

人工晶体材料由最初的聚甲基丙烯酸甲酯发展到今天的丙烯酸酯多聚物等,一直在不断的改良变化.人工晶体表面性能与其植入术后的临床并发症密切相关,故选择一种合适的人工晶体对白内障复明手术具有重要意义.总结了常用人工晶体材料的表面修饰技术,并着重评述了不同修饰技术对人工晶体性能的影响,对这些性能的了解可为临床医师选择人工晶体材料时提供一定的指导,并为研究人员改进人工晶体性能时提供必要的参考.     

材料表面改性技术

将表面技术分为湿法及干法，并做了详尽论述。湿法有电镀、化学镀、阳极氧化及化学转化等。干法有ＰＶＤ、ＣＶＤ、喷射。着重论及了新技术溶胶－凝胶法在改进材料表面性能方面的应用。     

医用钛合金及其表面改性

目前钛合金被广泛应用于医学领域，如矫形用种植体。简要综述了新型医用钛合金的开发以及钛合金表面改性提高其表面生物活性和耐磨性能的研究进展。     

医用钴合金表面改性技术的研究进展

钴合金具有优异的生物力学特性、耐磨损性能和耐腐蚀性能,在医学植入领域有着广阔的应用前景,其表面改性技术已成为医用金属材料的研究热点和重点。本文简述了钴合金材料表面改性技术的优势,包括钴合金材料的生物力学特性、耐磨性能、耐腐蚀性能等。同时归纳了钴合金材料因人体体液腐蚀和摩擦磨损会释放出Co、Cr等金属离子而导致生物致敏等问题。在上述基础上,重点综述了近年来钴合金表面改性技术的研究进展,包括离子注入技术、选区激光熔化技术、真空沉积技术。其中,离子注入技术主要包括氮离子注入、钇离子注入、镧离子注入和钛镍离子注入等;选区激光熔化技术主要包括粉层厚度、激光功率、组分含量、扫描方式和扫描速度等;真空沉积技术主要包括物理气相沉积和化学气相沉积。针对不同钴合金表面改性技术,分别从钴合金材料的生物力学特性、耐磨性、耐腐蚀性和生物相容性等方面进行了归纳分析。最后分析了钴合金表面改性的发展趋势,认为钴合金表面改性技术应朝着高生物相容性、无金属离子释放、生物功能化、高耐腐蚀性和高耐磨性的方向发展。     

医用NiTi合金表面改性的研究进展

近等原子比NiTi合金具有独特的力学性能,如形状记忆效应、超弹性和高阻尼效应,已成为一种新型的整形外科植入材料.但是,镍元素在生理条件下可能溶出,诱发毒性和炎性反应,限制了其在临床的广泛应用.分类介绍了几种可行的表面改性方法,均能有效地抑制镍离子的溶出,改善NiTi合金的抗腐蚀性和生物相容性,包括表面惰性涂层化、表面氧化、表面活性化和表面接枝大分子等.     

Status of surface modification techniques for artificial hip implants

Surface modification techniques have been developed significantly in the last couple of decades for enhanced tribological performance of artificial hip implants. Surface modification techniques improve biological, chemical and mechanical properties of implant surfaces. Some of the most effective techniques, namely surface texturing, surface coating, and surface grafting, are applied to reduce the friction and wear of artificial implants. This article reviews the status of the developments of surface modification techniques and their effects on commonly used artificial joint implants. This study focused only on artificial hip joint prostheses research of the last 10 years. A total of 27 articles were critically reviewed and categorized according to surface modification technique. The literature reveals that modified surfaces exhibit reduced friction and enhanced wear resistance of the contact surfaces. However, the wear rates are still noticeable in case of surface texturing and surface coating. The associated vortex flow aids to release entrapped wear debris and thus increase the wear particles generation in case of textured surfaces. The earlier delamination of coating materials due to poor adhesion and graphitization transformation has limited the use of coating techniques. Moreover, the produced wear debris has adverse effects on biological fluid. Conversely, the surface grafting technique provides phospholipid like layer that exhibited lower friction and almost zero wear rates even after a longer period of friction and wear test. The findings suggest that further investigations are required to identify the role of surface grafting on film formation and heat resistance ability under physiological hip joint conditions for improved performance and longevity of hip implants.     

Enhancement of oxidation and wear resistance of Fe-based amorphous coatings by surface modification of feedstock powders

Surface oxidation of the in-flight powders during the preparation of amorphous coatings in high velocity oxygen fuel process causes the formation of oxygen-rich intersplat regions. These regions are brittle in nature and can dramatically deteriorate the mechanical performance of the coatings. To solve this problem, the starting FeCrMoCBY amorphous feedstock powders were modified by electroless plating a thin layer of Ni–W–P amorphous phase. It was found that the covering of the Ni–W–P layer can significantly reduce the oxygen content in the resultant Fe-based amorphous coatings. The wear resistance of the coatings with and without the modification of Ni–W–P thin layer was comparatively studied by ball-on-disk wear tests against Si₃N₄ counterpart in air. It revealed that the wear of two types of coatings follows the same oxidation wear mechanism but the modified coating exhibits much better wear resistance due to the improved oxidation resistance.     

医用钛金属材料表面改性研究

由于具有优良的力学、生物学、安全性等性能，钛及其合金被日益广泛的应用于人体硬组织的修复、替换。然而其表面硬度低、耐磨性差、生物惰性等是作为医用材料不容忽视的问题，为了改善这些性能，需要对钛合金表面进行改性处理。综合评述了多种表面处理技术的优点，指出对多种表面处理技术进行综合应用是今后的研究方向。     

锂离子电池富锂锰正极材料的最新进展

富锂锰正极材料(Li-rich manganese cathode material,LMCM)因高比容量(>250 mAh·g^-1)、低成本等优势,被视为最具前景的下一代锂离子电池正极材料。然而,该正极材料在循环过程中存在不可逆的结构转变等问题,造成首次不可逆容量损失高、倍率性能差、能量衰减和电压衰减等问题。通过体掺杂、表面包覆和结构优化设计等策略可一定程度上改善LMCM存在的以上问题。本文重点介绍LMCM存在的问题及改性研究工作,分析LMCM存在的问题及起因,详细阐述目前主要改性方法的研究现状,并讨论各种改性方法的优缺点及今后的重点研究方向。此外,本文还分析目前LMCM材料产业化进展和面临的主要挑战。由于自身存在的问题和配套材料发展缓慢,目前仅在部分企业实现小批量生产。     

铸铁表面激光熔敷层的抗裂性和耐磨性

采用免预热多道搭接的激光熔敷工艺，在铸铁表面制备出抗裂耐磨的激光熔敷层，研究了激光功率和扫描速度对熔敷层抗裂性的影响。适当的激光功率和扫描速度可以使铁基熔敷层的裂纹率最低．随着Ni含量的增加，熔敷层内奥氏体相体积分数增加；K可促进共晶碳化物团球化，熔敷层抗裂性增强．通过对铸铁表面激光熔敷层裂纹的萌生与扩展的动态观察，揭示了熔敷层开裂的微观机制．裂纹易在粗大渗碳体区或石墨与奥氏体的界面处萌生，奥氏体可明显抑制裂纹的扩展．Ti含量增加使熔敷层中原位自生的TiC的体积分数增大，熔敷层磨损质量损失减少，耐磨性增强．     

Effects of steel fiber reinforcement on surface wear resistance of self-compacting repair mortars

Self-compacting repair mortars (SCRM), as new technology products, are especially preferred for the rehabilitation and repair of reinforced concrete structures. The self-compactability of repair mortars may bring considerable advantages at narrow mould systems. However, due to the high powder content and absence of coarse aggregate, plain SCRMs are susceptible to surface abrasion, especially in case of repair of surfaces under high rates of abrasion (floors, slabs). Steel fiber reinforcement can be an excellent solution for the abrasion resistance problem of SCRMs. However, the optimum amount of fiber reinforcement to sustain self-compactability should be pre-determined. In this study, the optimum superplasticizer dosage and the maximum possible amount of fiber addition, which maintain the self-compactability and stability, was determined for mortars incorporating steel fibers. In addition, the mechanical performance and abrasion resistance of SCRMs prepared by using these fibers were determined. It was concluded that steel fibers can have rheological and mechanical synergistic effects, and that optimised fiber – superplasticizer dosage combinations can better improve the wear resistance while maintaining adequate flow properties for FR-SCRM.     

The effects of functionally graded material structure on wear resistance and toughness of repaired weldments

To perform a long lasting, crack-free repair welding on ultrahigh strength steels, the filler metal must be chosen and applied properly. Avoiding several short-term repairs or replacements, the repaired weldment should reveal comparative characteristics such as wear resistance, toughness and hardness to base metal. In the present study, a novel functionally graded material have been introduced to obtain enhanced wear resistance and hardness at surface as well as improved fracture toughness at fusion line of repaired weldments. A comparative study of wear resistance of repaired weld metals has been carried out by pin-on-disk apparatus at 5 N normal load and 0.14 ms⁻¹ sliding speed. Fracture toughness of weld metal was also evaluated by charpy absorbed fracture energy tests and scanning electron microscopy fractograghs. The results show that by employing functionally graded layers, toughness was enhanced significantly while retaining the surface wear resistance.     

复合改性对聚磷酸铵填充EVA材料抗渗性能的影响

利用高岭土与聚磷酸铵(APP)进行复配,使用二甲基硅油对复配后阻燃填料进行表面改性处理,并利用接触角及红外分析对阻燃剂抗渗性能提高的机理进行分析。结果表明:优化复配比例及改性条件为:高岭土以质量分数30%的复合比例与APP复合、有机改性剂二甲基硅油使用量质量分数最优条件为2.0%,改性温度95℃。改性后阻燃剂抗渗析性得到显著提高,渗析率由1.81%减小至0.61%。     

Effect of surface nanocrystallisation on the microstructure and wear resistance of vacuum carburised alloy

In this work, a nanocrystallisation surface layer with an average grain size of 29?nm was fabricated on the 12Cr2Ni4A steel by the supersonic fine particles bombarding (SFPB). The vacuum carburising process was carried out on the original and the SFPB pre-treatment samples. X-ray diffraction, scanning electron microscopy and hardness tester were employed to study the phase constituents, grain size, hardness and residual stress of the two carburised samples. Experimental results showed that compared to the coarse-grain carburised layer (without SFPB), the carburised layer with SFPB pre-treatment has smaller martensite and carbide, and its thickness, hardness, compressive residual stress and wear resistance have been significantly improved. The dominant wear mechanisms of the two carburised samples were both abrasive wear and fatigue wear.