Cambridge Centre for Medical Materials, Department of Materials Science & Metallurgy, University of Cambridge, UK.
J Mech Behav Biomed Mater. 2012 Feb;6:128-38. doi: 10.1016/j.jmbbm.2011.10.010. Epub 2011 Nov 17.
Bioactive coatings are applied to components of modern orthopædic implants to improve the host tissue response to the implants. Such coatings cannot be applied to polymeric implants by high-temperature techniques, because the use of high temperatures may critically degrade the polymer substrate. Regardless of the coating technique that is used, the coating must be sufficiently well adhered to the underlying substrate to provide any practical benefit. This paper investigates the use of scratch testing to measure the adhesion strength of calcium phosphate (CaP) coatings that were applied to a poly(carbonate urethane) (PCU) substrate by an aqueous process at temperatures of 19, 28, 37, and 50 °C. This work represents the first time that scratch testing analysis has been used to study CaP coatings deposited by an aqueous, low-temperature process on to a polymer substrate. Scratch testing was shown to be a useful technique for obtaining comparative, rather than absolute, values of adhesion strength for hard coatings formed on a compliant substrate. Generally, the coating temperature was not found to influence the CaP-PCU adhesion strength. Although CaP coatings formed at 19 °C exhibited considerably lower adhesion strengths than CaP coatings formed at 28, 37, and 50 °C, this finding was attributable to the inconsistency of CaP coatings formed on the PCU substrates at 19 °C. The coating-substrate adhesion strength was measured for CaP coatings of four different coating ages (0, 1, 2, and 3 years). CaP coatings that were aged for 0, 1, or 2 years exhibited similar coating-substrate adhesion strengths to each other. In contrast, CaP coatings that were aged for 3 years demonstrated considerably lower coating-substrate adhesion strengths. The observed reduction in adhesion strength with age was thought to be attributable to suspected "drying out" of the CaP coatings.
生物活性涂层应用于现代骨科植入物的组件中，以改善宿主组织对植入物的反应。由于高温可能会严重降解聚合物基底，因此不能通过高温技术将此类涂层应用于聚合物植入物。无论使用哪种涂层技术，涂层都必须与底层基底足够牢固地附着，以提供任何实际的益处。本文研究了通过水基工艺在 19、28、37 和 50°C 的温度下将磷酸钙 (CaP) 涂层应用于聚碳酸酯氨酯 (PCU) 基底的划痕测试，以测量其附着力。这项工作代表了首次使用划痕测试分析来研究通过水基低温工艺在聚合物基底上沉积的 CaP 涂层。划痕测试被证明是一种有用的技术，可以获得在顺应性基底上形成的硬涂层的相对而不是绝对的附着力值。通常，发现涂层温度不会影响 CaP-PCU 附着力。尽管在 19°C 形成的 CaP 涂层表现出比在 28、37 和 50°C 形成的 CaP 涂层低得多的附着力，但这一发现归因于在 19°C 下形成的 PCU 基底上的 CaP 涂层不一致。对四种不同涂层龄期（0、1、2 和 3 年）的 CaP 涂层进行了涂层-基底附着力测量。老化 0、1 或 2 年的 CaP 涂层彼此之间表现出相似的涂层-基底附着力。相比之下，老化 3 年的 CaP 涂层表现出明显较低的涂层-基底附着力。观察到的附着力随年龄的降低被认为归因于 CaP 涂层的疑似“干燥”。
