Department of Mechanical Engineering, University of Melbourne, VIC 3010, Australia.
J Biomed Mater Res B Appl Biomater. 2010 Apr;93(1):1-8. doi: 10.1002/jbm.b.31537.
The performance of biomedical implants relies on the ability to assess and refine the microstructure of biomaterials. Instrumented nanoindentation was applied to determine the mechanical properties of plasma sprayed hydroxyapatite-coated implants from different commercial vendors. All biomedical devices contained both amorphous and crystalline phases. Nanoindentation of the amorphous phase revealed a hardness of 1.5 + or - 0.3 GPa and an elastic modulus of 48 + or - 6 GPa. The crystalline phase revealed a range in hardness of 3.0-7.7 GPa. The large range is attributed to the presence of porosity, surrounding amorphous areas, and hydroxyapatite (unmolten particle cores and recrystallized hydroxyapatite). A selection of the powder type (spray-dried or sintered) leads to different mechanical properties within the coating. A spray-dried powder provides a lower hardness and elastic modulus when unmolten particle cores are included in the coating. Meanwhile recrystallized areas are intermediate in hardness. The combination of a polished cross-section and nanoindentation offers the ability to determine a range of quality control tests including hardness, elastic modulus, bond strength, fracture toughness, substrate and coating roughness, crystallinity, and coating thickness. Property maps determined from nanoindentation will provide a graphical representation of the mechanical property distribution within the coating and provide a basis for coating property refinements. The assessment of commercial coatings is used a basis for discussion of future developments for hydroxyapatite coatings.
生物医学植入物的性能依赖于评估和改进生物材料微观结构的能力。仪器化纳米压痕法被应用于测定来自不同商业供应商的等离子喷涂羟基磷灰石涂层植入物的机械性能。所有生物医学器件都包含非晶相和晶相。非晶相的纳米压痕显示出硬度为 1.5 ± 0.3 GPa 和弹性模量为 48 ± 6 GPa。晶相的硬度范围为 3.0-7.7 GPa。这种大的范围归因于存在孔隙率、周围的非晶区和羟基磷灰石（未熔化的颗粒核心和再结晶的羟基磷灰石）。粉末类型（喷雾干燥或烧结）的选择导致涂层内具有不同的机械性能。当未熔化的颗粒核心包含在涂层中时，喷雾干燥的粉末提供较低的硬度和弹性模量。同时，再结晶区域的硬度处于中间水平。抛光的横截面和纳米压痕的组合提供了一系列质量控制测试的能力，包括硬度、弹性模量、结合强度、断裂韧性、基底和涂层粗糙度、结晶度和涂层厚度。从纳米压痕确定的属性图将提供涂层内机械性能分布的图形表示，并为涂层性能改进提供基础。对商业涂层的评估用作讨论羟基磷灰石涂层未来发展的基础。
