The present study concentrates on the bioactive behavior of HVOF-sprayed HAp/TiO₂ graded coatings on a Ti-6Al-4V alloy. In-vitro bioactivity was evaluated by immersing graded coating samples in Hank’s solution at body temperature up to 28 days. Natural in-vitro bioactivity of the graded coatings was compared with in-vitro electrochemical analysis also performed for 28 days. Potentiodynamic polarization, open circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy measurements in Hank’s solution, at body temperature, were performed to study the interaction of the HVOF-sprayed HAp/TiO₂ graded coating with the simulated body fluid. Electrochemical in-vitro data of graded coatings were compared with those from an uncoated Ti-6Al-4V alloy. Graded coatings presented a rapid interaction with simulated body fluid during the first 4 days of immersion. The interaction between HAp/TiO₂ graded coating and simulated body fluid led to the formation of a bone like-apatite layer on the top surface of the graded coating. This layer was not observed on the surface of the Ti-6Al-4V alloy. The growing kinetics of the apatite layer on the top surface of the graded coatings varied on time and provided useful information for future in-vivo studies focused on studying medical healing times. From a bioactive standpoint, the present study shows the advantages that a HVOF-sprayed HAp-based coating architecture has over an un-coated Ti-6Al-4V alloy, and how it represents a step forward in the development of bioactive coatings for implant technology.

本研究集中在Ti-6Al-4V合金上HVOF喷涂的HAp / TiO ₂梯度涂层的生物活性行为。通过将梯度涂层样品浸入Hank's溶液中达28天的体外生物活性进行评估。将梯度涂层的天然体外生物活性与同样进行了28天的体外电化学分析进行了比较。在人体温度下，在汉克溶液中进行电位动力学极化，开路电势，线性极化电阻和电化学阻抗谱测量，以研究HVOF喷涂的HAp / TiO ₂的相互作用用模拟体液对涂层进行分级。将梯度涂层的电化学体外数据与未涂层的Ti-6Al-4V合金的电化学体外数据进行了比较。浸入的前4天，渐变涂层呈现出与模拟体液的快速相互作用。HAp / TiO ₂之间的相互作用梯度涂层和模拟体液导致在梯度涂层的顶表面上形成骨样磷灰石层。在Ti-6Al-4V合金的表面上未观察到该层。渐变涂层顶表面上磷灰石层的生长动力学随时间变化，并为以后的体内研究（专注于研究医疗愈合时间）提供了有用的信息。从生物活性的角度来看，本研究表明，HVOF喷涂的基于HAp的涂层结构优于未涂层的Ti-6Al-4V合金，以及它如何代表着用于植入技术的生物活性涂层的发展。