Cellular titanium by selective electron beam melting
Cellular titanium by selective electron beam melting
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DOI：
10.1002/adem.200700025
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发表时间：
2007-05-01
影响因子：
3.6
通讯作者：
Singer, Robert F.
中科院分区：
文献类型：
--
作者：
Heinl, Peter;Rottmair, Andreas;Singer, Robert F.
钛是一种机械性能突出、密度低、耐化学性高和生物相容性优异的材料。这些特性与多孔结构的结合在航空航天、化学和加工工程行业以及医疗领域开辟了许多潜在的应用。[1]钛在医学上被广泛用作植入材料。[2]然而，人体骨骼和钛种植体的刚度不匹配会导致所谓的应力屏蔽效应，从而导致骨吸收和最终种植体松动。由于可以使植入物的机械性能适应骨骼的生物力学性能，因此细胞结构有望防止应力屏蔽。此外，细胞结构允许骨骼生长到植入物中，从而实现更好的固定。[3]一般来说，由于熔点高（1670°C）以及对氧气、氢气和氮气等大气气体的极端化学亲和力，特别是在高温下，用标准技术制造多孔钛是很困难的。 [1]钛中溶解的气体量极大地影响机械性能。随着气体含量的增加，屈服强度和抗拉强度增加，而延展性却大大降低。[4]此外，液态钛与大多数模具材料发生强烈反应。这就是铸造技术似乎不适合生产多孔钛的原因。目前，多孔钛的制造主要采用粉末冶金方法。[1]然而，如果必须实现分级结构或具有不同密度区域的结构，这些方法就会受到很大的限制。生产多孔钛的有前途的方法是自由形式生成过程，其中复杂形状的部件直接根据 3D CAD 数据逐层生成。这些技术提供了生产具有适当机械性能和功能的复杂结构的技术平台。 [3, 5]
Titanium is a material with outstanding mechanical properties, low density, high chemical resistance and excellent biocompatibility. The combination of these properties with a cellular structure opens many potential applications in the aerospace, chemical and process engineering industry as well as in the medical sector.[1]Titanium is intensively used in medicine as implant material.[2] However, the mismatch in stiffness of the human bone and the titanium implant leads to the so called stress shielding effect responsible for bone resorption and eventual implant loosening. Cellular structures are expected to prevent stress-shielding due to the possibility to adapt the mechanical properties of the implant to the biomechanical properties of the bone. In addition, a cellular structure permits the bone to grow into the implant leading to a better fixation.[3] Generally, the fabrication of cellular titanium with standard techniques is difficult due to the high melting point (1670 C) and the extreme chemical affinity to atmospheric gases like oxygen, hydrogen and nitrogen, especially at elevated temperatures.[1] The amount of gas dissolved in titanium massively influences the mechanical properties. With increasing gas content the yield and tensile strength increase whereas the ductility is strongly reduced.[4] Furthermore, titanium in the liquid state intensely reacts with most mould materials. This is the reason why casting techniques do not seem to be appropriate for the generation of cellular titanium. Currently, the fabrication of cellular titanium is focussed on powder-metallurgy approaches.[1] However, these approaches are strongly limited if graded structures or structures with areas of different density have to be realized. Promising approaches to produce cellular titanium are freeform generative processes where complex shaped components are produced layer by layer directly from 3D CAD data. These techniques provide the technological platform to produce complex structures with adapted mechanical properties and functionality.[3, 5]