[Image above] An angle grinder attacks a new ceramic–metal composite—but who will win the battle?信用：GydF4y2BaStefan Szyniszewski， YouTubeGydF4y2Ba
If you are a material, who is your enemy?
当然，确定敌人取决于材料，这也取决于您对敌人的定义或感知，无论是导致您的身体伤害，损害您的声誉还是拒绝认识您的价值。GydF4y2Ba
While I suppose materials might have a plethora of potential enemies, if I was a material, my most hated enemy just might be a rotating cutting tool.
Harnessing the destructive potential of force and rotation, cutting tools like saws, drills, and angle grinders can obliterate the superlative properties that materials work so hard to perfect. And even when materials are designed to work against the power of these tools, the materials still often fail.
因此，如果我们设计了工作材料怎么办GydF4y2Bawith切割工具的力量而不是反对它们？虽然这听起来可能违反直觉，但这正是国际研究人员所做的事情，他们设计的陶瓷 - 金属复合材料都可以抵抗浅层表面切割以外的损害。GydF4y2Ba
来自达勒姆大学，萨里大学和英国斯特林大学的研究人员以及德国汉诺威的弗劳恩霍夫学院和莱布尼兹大学的研究人员开发了一种陶瓷 - 金属复合材料，尽管它仅像钢铁一样致密15％，但几乎是不可支撑的。通过利用振动的力量，该材料将工具的破坏性能量引向自身，然后将工具放下，然后才能对材料造成严重破坏。GydF4y2Ba
The researchers named the material Proteus after scientist and philosopher Francis Bacon’s idea, articulated in his bookSylva sylvarum，这件事永远不会被破坏，而是转变为替代形式。GydF4y2Ba
The strong yet light composite could offer new hope for a more secure material for doors, locks, and much more.
作为核心嵌入式机智灵活的铝h alumina spheres—owes its strength to a hierarchical structure that is inspired by nature. Specifically, it mimics the structure of nacre and many other naturally occurring materials that are stronger as a whole material than as their individual units.
For instance, nacre has a hierarchical structure of stacked crystal calcium carbonate platelets that are mortared together with inorganic materials. Together, this multilevel structural organizationmakes nacre much stronger总体而言，基于其各个材料成分的预测。GydF4y2Ba
因此，利用自然作为灵感，研究人员设计了具有相似系统水平相互作用的陶瓷 - 金属复合材料，从而超过了材料的细胞铝核心单个成分的机械性能和嵌入式氧化铝球的机械性能。GydF4y2Ba
To make the cellular aluminum core, the team mixed aluminum powder with a titanium foaming agent and then cold-compacted and extruded the material into rods. Then, they cut these rods into smaller pieces and stacked them together with 13-mm-diameter alumina spheres in a steel box.
Heating the combination to 760ºC in a furnace melded the individual components together to create Proteus—a cellular aluminum core with 73% porosity, studded with embedded ceramic spheres and bordered by steel alloy faceplates.
Putting this material to the test against potential enemies of an angle grinder (equipped with sapphire-finished cutting discs) and a drill, the researchers showed the composite resists most damage beyond surface cuts, performing better than滚动的同质盔甲GydF4y2Ba。See for yourself in the video below.
尽管它们仅占细胞金属核的14％，但陶瓷球是Proteus强度的关键组成部分。因此，您可能希望研究人员使用他们能找到的最密集，最坚硬的氧化铝球。但是，团队再次采取了一种通常的方法 - 相反，他们使用了具有次优的氧化铝球，这使团队能够用秘密武器在其袖子上设计复合材料。GydF4y2Ba
When a cutting tool slices into Proteus and encounters an alumina sphere, it breaks apart into fine particulate matter—creating a “sandpaper-like, vibrating interface with the cutting disc,” the researchers write in thepaperdescribing their findings. The abrasive action of the alumina particulates quickly wears down cutting surfaces, preventing the tool from penetrating further into the composite. In addition, the small alumina particles better resist penetration “due to the increase of their system level resistance under high strain rates,” the researchers note.
换句话说，材料愿意牺牲一些氧化铝球来保护其整体完整性，从而使其在面对敌人袭击时持续更长的时间。GydF4y2Ba
但是，磨蚀性的表面并不是武器库中的所有复合材料都可以阻止其破坏性攻击者。GydF4y2Ba
材料的固有频率也适用G一个inst cutting tools—as the tool spins, it generates vibrational frequencies that interact with those of the spheres, essentially amplifying vibrations at the interface and further wearing down the tool before it can make significant progress into the material.
Combined, these features give Proteus a one-two-three punch—a highly abrasive interface, heat generated at the interface due to that friction, and vibrations—that work together against the cutting tool, destroying it before it can destroy the material.
此外，研究人员在论文中推测局部加热可以使氧化铝发生相变，从而致密地抗拒切割。GydF4y2Ba
尽管该团队仍在调查Proteus的全部机制和全部潜力，但他们认为“我们的新架构材料的配置可以定制为广泛的应用程序。”GydF4y2Ba
For example, the material could be used for security applications, like doors, safes, barriers, and locks. But the technology could also possibly be used to make cut-resistant clothing and protective gear, such as the soles of shoes or forearm guards, because the composition and configuration of the metal–ceramic composite is adjustable, something the team is only starting to explore for its potential.
“One can tune foam porosity, alter base materials, adjust the size of spheres, and their packing pattern,” they note in the paper. “We can also modify the thickness of the sandwich panels, the diameter of the cylinders, the thickness of faceplates and manufacture curvilinear geometries effectively. The demonstrated components can be welded and bonded with other materials to form larger structural systems.”
You can hear lead authorStefan Szyniszewski，，，，一个ssistant professor at Durham University, talk more about the design approach to Proteushere。GydF4y2Ba
开放式报纸，发表在GydF4y2BaScientific Reports，，，，is “通过局部共振和应变率效应产生的不可察觉的材料GydF4y2Ba” (DOI: 10.1038/s41598-020-65976-0).