忘记胶水，螺丝，热量或其他传统粘合方法。由康奈尔（Cornell）领导的合作开发了一种3D打印技术，该技术通过以超音速速度将粉末颗粒粉碎在一起，从而创建蜂窝金属材料。
This form of technology, known as “cold spray,” results in mechanically robust, porous structures that are 40% stronger than similar materials made with conventional manufacturing processes. The structures’ small size and porosity make them particularly well-suited for building biomedical components, like replacement joints.
该团队的论文“由超音速影响对多孔TI-6AL-4V的固态添加剂制造”，今天11月9日在Applied Materials发表。
The paper’s lead author is Atieh Moridi, assistant professor in the Sibley School of Mechanical and Aerospace Engineering.
“We focused on making cellular structures, which have lots of applications in thermal management, energy absorption and biomedicine,” Moridi said. “Instead of using only heat as the input or the driving force for bonding, we are now using plastic deformation to bond these powder particles together.”
Moridi’s research group specializes in creating high-performance metallic materials through additive manufacturing processes. Rather than carving a geometric shape out of a big block of material, additive manufacturing builds the product layer by layer, a bottom-up approach that gives manufacturers greater flexibility in what they create.
但是，增材制造并非没有自己的挑战。其中最重要的是：金属材料需要在高温超过其熔点的高温下加热，这可能会导致残留的应力积累，失真和不需要的相变。
为了消除这些问题，Moridi和合作者使用压缩气体喷嘴开发了一种方法，以在底物处发射钛合金颗粒。
莫里迪说：“这就像绘画一样，但事情在3D中的发展得多。”
The particles were between 45 and 106 microns in diameter (a micron is one-millionth of a meter) and traveled at roughly 600 meters per second, faster than the speed of sound. To put that into perspective, another mainstream additive process, direct energy deposition, delivers powders through a nozzle at a velocity on the order of 10 meters per second, making Moridi’s method sixty times faster.
颗粒不仅会尽快投掷。研究人员必须仔细校准钛合金的理想速度。通常，在冷喷雾印刷中，粒子在其临界速度之间的最佳位置会加速，即它可以形成浓密的固体的速度 - 及其侵蚀速度，当它崩溃过多以至于无法与任何东西结合。
取而代之的是，Moridi的团队使用计算流体动力学来确定钛合金颗粒的临界速度下的速度。当以稍慢的速度发射时，颗粒会产生更多孔的结构，这是生物医学应用的理想选择，例如膝盖或髋关节的人造关节，以及颅/面部植入物。
莫里迪说：“如果我们用这种多孔结构制作植入物，并且将它们插入体内，则骨骼可以在这些毛孔内生长并产生生物固定。”“这有助于减少植入物松动的可能性。这很重要。患者必须进行许多修订手术，以清除植入物，只是因为它松动并且会引起很多痛苦。”
While the process is technically termed cold spray, it did involve some heat treatment. Once the particles collided and bonded together, the researchers heated the metal so the components would diffuse into each other and settle like a homogeneous material.
莫里迪说：“我们只专注于钛合金和生物医学应用，但是这一过程的适用性可能超出了这一点。”“从本质上讲，任何可以忍受塑性变形的金属材料都可以从此过程中受益。它为大规模的工业应用（例如建筑，运输和能源）打开了很多机会。”
合着者包括博士生Akane Wakai和麻省理工学院，米兰理工大学，伍斯特理工学院，伦敦布鲁内尔大学和赫尔米特·施密特大学的研究人员。
The research was supported, in part, by the MIT-Italy global seed fund and Polimi International Fellowship.
{{comment.datetimestampdisplay}}}
{{comment.comments}}