STTR Phase I: Cold Gas Dynamic Spray Processing of Bioactive Nano-hydroxyapatite/Titanium Nanocomposite Coatings

这个第一阶段的小企业技术转移（STTR）项目将测试用水热纳米结构羟基磷灰石（n-HA）和微米级钛制造生物活性涂层的可行性。这两种成分将通过研磨机研磨或机械融合来加工，以制成纳米复合原料。冷气动态喷涂（CGDS）工艺将用于在含有高体积分数n-HA晶体的钛基板上形成多孔钛涂层。例如，预计生物植入物上的这种涂层将促进天然骨的生长，促进植入物与周围骨材料的附着。CGDS工艺是粉末原料制备功能性涂料的新途径。粉末颗粒被加速到超音速（2马赫），达到足够的高动能，在与基材碰撞时形成致密的涂层。CGDS加工与传统喷涂工艺的不同之处在于，它不依赖热能来熔化饲料粉末或促进粘合。瞬间键合仅仅是由于动能在1微秒时间尺度上的耗散。由于处理温度通常为200℃，因此CGDS处理对于维持纳米粒度和温度敏感的晶体化学性质（如n-HA生物材料）是理想的。CGDS工艺将被证明是一种通用的、经济有效的方法来制造利用纳米结构粉末特性的功能表面。由于CGDS涂层面积大，形状复杂，可以应用于各种材料，因此它将在人类医疗和兽医假体植入物中具有广泛的商业影响。

This Phase I Small Business Technology Transfer (STTR) project will test the feasibility of making bioactive coatings from hydrothermal nanostructured hydroxyapatite (n-HA) and micron-size titanium. The two components will be processed by attritor milling or mechanofusion to make a nanocomposite feed stock. Cold Gas Dynamic Spray (CGDS) processing will be used to form a porous titanium coating on titanium substrates that contain a high volume fraction of n-HA crystallites. It is expected that such coatings on bioimplants, for example, would promote the in-growth of natural bone, facilitating attachment of the implant to surrounding bone material. CGDS processing is a new way to form functional coatings from powder feedstocks. Powder particles are accelerated to supersonic speeds (Mach 2) achieving high kinetic energy sufficient to form a dense coating upon impact with a substrate. CGDS processing differs from conventional spray processes in that it does not rely on thermal energy to melt the feed powder or to promote bonding. Instant bonding is due solely to the dissipation of kinetic energy on a time scale of 1 microsecond. Since the processing temperature is typically 200 C, CGDS processing is ideal for maintaining the nanograin-size and temperature sensitive crystal chemistries such as in n-HA biomaterials. The CGDS process will prove to be a versatile, cost-effective way to fabricate functional surfaces that exploit the properties of nanostructured powders. Since CGDS can coat large areas, complex shapes, and can be applied to a variety of materials it will have wide commercial impact applications for human medical and veterinary prosthetic implants.