Mani Gopinath, Ornberg Andreas, Shulfer Robert, Kamberi Marika
Global Biocompatibility and Science & Technology, Abbott, St. Paul, Minnesota, USA.
J Biomed Mater Res B Appl Biomater. 2025 Aug;113(8):e35626. doi: 10.1002/jbm.b.35626.
Chemical passivation is a standard surface finishing treatment applied to commercially pure Titanium (cp-Ti) and Titanium-6Aluminum-4Vanadium (Ti-6Al-4V) when preparing them for use in medical devices. Although this treatment has been widely used for over 50 years, there remains a lack of consensus regarding its precise impact on surface characteristics and subsequent biocompatibility. This article comprehensively reviews the literature on this topic and sheds light on the reasons behind the conflicting research findings even after decades of practice. First, the nitric acid-based passivation protocol, originally developed for stainless steel, is often directly applied to cp-Ti and Ti-6Al-4V without specific optimization studies. Second, the pre-treatment processes, pre-cleaning procedures, and passivation protocols are significantly varied among the studies in the literature to provide vastly different outcomes regarding surface properties and subsequent material performance. Third, the ASTM F86 standard, commonly used in many studies, has several limitations. It provides open-ended recommendations for certain parameters (such as acid treatment time) without specifying maximum limits, lacks clearly defined validation processes, and relies on inadequate inspection methods (like visual examination). These limitations result in significant variations in outcomes and incomplete characterizations. Fourth, the surface characteristics subjected to chemical passivation differ due to the diverse manufacturing processes used in the studies. This results in varying outcomes, even when the same passivation protocol is employed. Considering the various shortcomings in the literature, a set of best practice recommendations is provided to enhance the reliability and consistency of research outcomes in the chemical passivation of cp-Ti and Ti-6Al-4V.
化学钝化是一种标准的表面处理工艺，用于对商业纯钛（cp-Ti）和钛-6铝-4钒（Ti-6Al-4V）进行表面处理，以便将它们用于医疗设备。尽管这种处理方法已经广泛使用了50多年，但对于其对表面特性和后续生物相容性的确切影响，仍然缺乏共识。本文全面回顾了关于这一主题的文献，并阐明了即使经过数十年的实践，研究结果仍相互矛盾的原因。首先，最初为不锈钢开发的基于硝酸的钝化方案，常常未经特定的优化研究就直接应用于cp-Ti和Ti-6Al-4V。其次，文献中的研究在预处理工艺、预清洁程序和钝化方案方面存在显著差异，导致表面性能和后续材料性能的结果差异很大。第三，许多研究中常用的ASTM F86标准有几个局限性。它对某些参数（如酸处理时间）提供了开放式建议，没有规定最大限值，缺乏明确界定的验证过程，并且依赖于不充分的检测方法（如目视检查）。这些局限性导致结果存在显著差异，且表征不完整。第四，由于研究中使用的制造工艺不同，经过化学钝化的表面特性也有所不同。即使采用相同的钝化方案，也会导致不同的结果。考虑到文献中的各种缺点，本文提供了一套最佳实践建议，以提高cp-Ti和Ti-6Al-4V化学钝化研究结果的可靠性和一致性。
