Civilization's Material Science/Evolution in a nut shell

One of my professors had these slides in his lecture. I thought it was pretty cool. So the next 6 images are plots of available materials graphed as failure strength vs density. Failure can mean a variety of things but these graphs were plotted with failure defined as the onset of plastic (nonelastic) deformation:



1) Note that most of these materials are what archeologists find when ancient cites are excavated. Most people think ceramics are weak but this is because they compare them to dinner plates. Their are many kinds of ceramics and most are actually pretty strong. Many are stiffer than metals such as steel and it is evident from this image that they were strong even in ancient times.



2)By the time the roman empire reach its extents, the bronze and iron age were in full swing. Notice that even with all the metals the ancients found, ceramics were still stronger materials than metals though it is just barely. Even though ceramics are typically stiffer and stronger than metals, ancient civilizations generally preferred metals because ceramics were brittle. They did not fail easily but when they did, the crack propagated through the material very quickly. This defeated their chances of being used for armor but their brittleness made them great for projectile use.



3) The dark ages did not yeild much of anything for civilization. The only notable discovery here is that of cast irons.



4) The industrial revolution led to more metals and finally the emergence of polymers such as rubber which would be used for the tires of automobiles. Also we see that mankind is finding lighter and lighter metals. Aluminium, for instance, has weight and strength that is rivaling that of comparable ceramics depending on what alloy one uses.



5) The second world war brought yet more polymers. Also note that finally metals have been discovered that are lighter than any ceramic such as magnesium which would be used in the ammunition of fighter and b0mber planes as incendiary rounds



6) And finally, our time......marked primarily by the existences of foams for strong and weak applications and the existences of composites (the small group colored as brown above the polymers) which combine 2 or more materials in an process to optimize the properties of the result. All of the other sections have also grown. Ceramics are once again the strongest pure material.


What is interesting about all this is the implications: if you noticed strength generally increased with weight or density. This leaves two notable gaps in our chart. Heavy weak materials (lower right) and strong light materials (upper left). These are gaps that are currently being filled through research to develop hybrids for all kinds of applications. The other implication is the limits of this chart. The materials civilizations find can only get so dense because density is a function of atomic number. So the only way to move further out to the right than the furthest metal is to find a new element.

Cool chart, I've been interested in Materials Science lately, particularly Metals Tech.

You're right, it would be difficult to discover those strong, but light materials - the bonds between the compounds would have to be strong as !!.

I hadn't know much about ceramics, beyond the basics, didn't realize it was the strongest. Its brittleness is its downfall. If diamond was malleable, that would be interesting.

Yea you remember NASA's Columbia? Thats exactly what happened to it. The object that hit one of its heat resistant ceramic tiles caused the tile to crack. That one little crack propagated through the bottom of the shuttle as the flight continued [pic]

Damn, I didn't know that.

yea if you are interested in material science I really recommend two books:

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I read the second one and am reading the first one right now for this class and both are pretty good (though I like the first one better)

I'll try to check them out.

What sort of engineering are you studying?

I am in the Mechanical Department.

Good thread, never considered to look into this.

very dope.......