Scientists Just Created a Virtually Indestructible Diamond

3 min readHere’s what you’ll learn when you read this story:While diamonds are the hardest naturally-occurring mineral on Earth, they’re also very brittle, and can easily be smashed with a hammer. A new study discovered a method of essentially reinforcing diamonds using multi-walled carbon nanotubes, or MWCNT, that are 1/100,000th the width of a human hair. These carbon-based threads increase a diamond’s toughness by a factor a five, making them potentially useful for aerospace applications.Diamonds really are forever—at least, geologically speaking. As the hardest naturally-occurring mineral on Earth, diamonds resist the slings and arrows of time (and both natural or chemical erosion) thanks to its tight atomic carbon lattice. It’s estimated that it would take longer than the estimated lifetime of the universe for a diamond to naturally degrade into graphite (both forms of a pure carbon) at room temperature.However, this doesn’t mean diamonds are indestructible, because while they’re incredibly hard, they’re also quite brittle. Diamonds form in a cubic, or tetrahedral, lattice shape, and though this arrangement gives the diamond its hardness, there is also weakness along these cubic planes that make the material susceptible to sudden impacts. Strike a diamond with a hammer, for example, and it’ll likely splinter into several pieces.But according to a new study, scientists at the Chinese Academy of Sciences and Beihang University have discovered a way to reinforce diamonds, making them both hard and resilient. With this new creation, the researchers created a material that’s even tougher than tungsten alloys—a material that’s used in the most punishing of conditions, including the fiery furnaces of fusion reactors. The results of the study were published in the journal Nature Synthesis.To create this new “super” diamond, scientists used what are known as “multi-walled carbon nanotubes,” or MWCNTs, which were woven with the diamond grains to create a heterogenous structure in which the MWCNT network essentially sutured any toughness vulnerabilities along the cubic plane. These MWCNT are essentially microscopic “cords” that are roughly 1/10,000th of the width of a human hair, but dozens of times stronger than steel, according to the researchers.Making these fibers wasn’t easy. Scientists needed to blend the diamond powder and subsequently subject the mixture to immense heat and pressure—roughly 2,000 degrees Celsius at 15 gigapascals. This perfect balance of heat and pressure kept the nanotubes from forming into diamonds themselves while degrading into graphite (diamond and graphite are both pure carbon, and only differ in how their atomic lattices are structured). This allowed the carbon nanotubes to keep their shape while fusing with diamonds at the atomic level, according to South China Morning Post. The result is a material with a toughness some five times higher than a single-crystal diamond.“Our findings […] offer profound insights into the toughening mechanism, encompassing crack deflection, stress dispersion, and energy dissipation,” the authors wrote in the paper. “This groundbreaking structural architecture strategy represents a significant milestone in the development of superhard materials and composite ceramics, promising cost reduction lifetime extension, and future technical innovations across various practical applications.”It doesn’t take a vivid imagination to discern what those “practical applications” might be. Diamonds are already an immensely important ingredient in creating robust cutting tools, and a synthetic diamond that also has immense toughness could have expansive manufacturing and aerospace applications. While a diamond’s hardness might be forever, with the help of carbon nanotubes, its toughness could soon come with a similarly impressive warranty.Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.