Slashdot Mirror
Material Tougher Than Diamond Developed
sporkme has handed us a link to a New Scientist article. The piece outlines the development of a new substance reported to be stiffer than diamond. A team of scientists from Washington, Wisconsin, and Germany combined the ceramic barium titanate and white-hot molten tin with an ultrasonic probe. The new material was, in some tests, almost 10x more resistant to bending than diamond. Composite materials researcher Mark Spearing of Southampton University comments on the result: "The material's stiffness results from the properties of the barium titanate pieces, Spearing says. As the material cools, its crystal structure changes, causing its volume to expand. 'Because they are held inside the tin matrix, strain builds up inside the barium titanate,' Spearing explains, 'at a particular temperature that energy is released to oppose a bending force.'"
I love them almost as much as dupes. :) Material Tougher Than Diamond Developed...(in some tests), like say: "The tests were carried out at a variety of temperatures. Between 58C and 59C the samples became stiffer than diamond."
Not to knock the experiment though, it seems interesting, and I'm sure there are all sorts of new exotic materials on the horizon.
http://en.wikipedia.org/wiki/Toughness : Toughness
http://en.wikipedia.org/wiki/Stiffness : Stiffness
Actually the word diamond is derived from the Greek word adamas, so in fact diamond is adamantium.
Toughness is a measure of the amount of energy necessary to break a material. Hardness is a measure of the amount of pressure required to deform it. The two are not the same. In fact, diamond is not a particularly tough material -- which is one reason why folks are discouraged from wearing diamond jewelry when, say, rock climbing. It's easy to fracture a diamond by bashing it against something even moderately hard -- even though no mineral is harder than the diamond, good ol' granite is much tougher.
Don't conflate hardness with strength or stiffness. Hardness is not well quantified. For hardness we refer to the Mohs scale, which will tell you which of two substances is the harder, but doesn't strictly quantify hardness. A claim that substance A is "twice" as hard as substance B probably refers to the Young's Modulus, or stiffness, rather than to hardness.
A common way to measure the Young's modulus is to support a sample of the material on two struts, and then apply pressure from above to the center of the sample. The less it bends, the higher the Young's modulus. The apparatus looks like this.
Strength is a different quantity. Strength is the amount of force needed, per unit cross-sectional area, to cause the material to fail. For tensile strength, this means pulling apart. For compressive strength, it means collapsing. A material with great tensile strength can have a great weight hung from it without snapping, and a material with great compressive strength can act as a pillar to support a great deal of weight.
The article claims nothing about the strength of this material.
TFA says it's stiffer than diamond, that doesn't mean that it's harder than diamond.
Chernobyl 'not a wildlife haven' - BBC News
Just because it's stiffer doesn't mean that it's harder. (god there are so many things wrong with that statement on so many levels)
Note however that we don't need a stonger abrasive material. Grinding works on the basis of extreme velocity on the part of the particles in the abrasive wheel or band to do the cutting work. Aluminum oxide would work for the purposes of grinding this material into print. Given that it's a ceramic within a tin matrix; ALO2 would do beautifully.
As for heavy cutting work, Tungsten Carbide would do just as well. I don't see anything to indicate that the material is HARDER than carbide.
And speak of the applications..........to tell you the truth there really aren't that many widespread uses for a material like this. For now, with the expense of this material that's going to stay as it is for quite a while, there are FEW cases that would warrant using this material.
Of all the Universal Constants, here's one I know: Nice guys finish last
Barium titanate is a structure called a spinel. It has oxygen ions packed in a face-centred cubic structure, with the barium and Titanium ions stuck on the holes between. Above a certain temperature, spinels are cubic. however, at lower temperatures, the structure can reduce its energy by breaking symmetry and squashing a bit down one of the cubic axes, becoming orthorhombic. This compression is not huge, but it is a lot bigger than the typical stretchings you get due to thermal expansion or mechanical stress.
Stick the spinel structure into a tin matrix and cool it. If you are ingenious about your choice of tin matrix, then the stress on the tin can actually get the spinel to change its shape in a way that opposes the bending, rather than going with it as you might expect. Tin is funny stuff - it also has a change in crystal structure on cooling from cubic to hexagonal (though at a much lower temperature) so I guess it is somehow squeezing the spinel in some anisotropic fashion and triggering the phase change.
This is ingenious stuff but it isn't really a high stiffness in the normal sense, any more then the compound pendulums you can somtimes find in grandfather clocks have a very low thermal expansion coefficient. Those have brass and steel rods which all have expansion coefficients, but they are put together in a way that makes the stotal expansion zero. Supposing you had a piezo crystal, with attached electronics that applied a voltage causing it to resist any force put upon it. You could make this infinitely stiff depending on your level of control, or even have it push pack on what is pressing on it.
So, back to your original question. It is heavy, and it only demonstrates the stiffness over a limited range. Bulk material stiffness is not usually important - you can make stiff structures like a cage of tubes by design. However, if you wanted to make some structure appear perfectly stiff, then some active control like the hypothetical piezo stuff I described earlier would probably be lighter and better. I would love to know what this ingenious stuff is for, but I don't think it is for space.
the driver would die.
Your car isn't made of steel any more but foldable, collapsable sections so the car takes damage instead of the people inside. Literally the materials are designed to bend at certain deceleration speeds. This goes back to the passenger compartment, where those sections suddenly become stronger. Ever notice how in a car wreck the only thing in one piece is the passenger compartment? The entire engine will go missing first.
i thought once I was found, but it was only a dream.
... doesn't mean it's tougher than diamond. Any mechanical engineer will remind you that strength, stiffness, and toughness are three different properties. IIRC my materials engineering class 15 years ago, they are approximately:
strength: maximum load before failure
stiffness: resistance to deformation
toughness: tendency to avoid reduction in strength over time in the face of repeated deformation
also:
hardness: ability to resist permanent deformation, particularly vs. small surface insults like scratches and indentations.
Diamond is very strong, very stiff, and very hard but it is definitely not tough: large blocks of the stuff are fairly brittle and tend to crack and chip. In fact extremely stiff materials are often not tough because they are brittle. OP has a very screwed-up title.
From TFA, we have no idea whether or not this new material is either strong or tough or hard: only that it is extremely stiff. (cue tasteless jokes)
I stole this sig from someone cleverer than me.