Thursday, August 8, 2013

Strength - Toughness

Strength and toughness are two properties that, as the terms are used in the non-scientific world.

Something that is strong must also be tough. They mean the same, right?

To a materials scientist, they most certainly do not. As the linked website defines, 'strength measures the resistance of a material to failure, given the applied stress (or load per unit area)' and 'toughness measures the energy required to crack a material; it is important for things which suffer impact.'

The interactive diagram on the linked website graphs the strength vs toughness for a number of materials and finds them grouped with like materials (wood near wood, polymers near polymers, etc). The graph also has some java-based interactivity allowing each group to be further explored.

The site has a number of links at the bottom to similar pages exploring other materials relationships: young's modulus vs cost, strength vs cost, and a dozen more.

PS - Thanks to Todd for finding this site and to Caryn for passing it along.

Mini Materials Camp

Each time there is an MS&T conference, the ASM folks try to be there to run a mini-materials camp. The ASM folks invite local teachers to bring their classes (sometimes even paying for transportation) and see some of the glory that is materials science.

This series of videos shows the process of casting tin using a microwave oven. The process of sand casting is fascinating to watch and still an important industrial process.

The process is broken up into five parts - the remaining four of which are after the jump.

Today's post finishes with another demonstration from the mini-materials camp: the phase change of iron wire.

The mini camps aren't nearly a replacement for the week-long summer camps, but they're great ways to expose your students to materials science if you happen to be lucky enough to be in the area of an MS&T conference - like the Indianapolis folks are this fall (September 2013).

How It's Made Giant Tires

Where's the corny joke at the beginning?

I'm glad to see that some recycled tire rubber is used in this production. It's interesting to hear the mixture ingredients that go into the rubber - sulfur, carbon black, rubber, antioxidants, and apparently the bags that the carbon black and sulfur come in.

All of the by-hand working in the making of the tire makes me understand why it's so expensive. This one's a pretty impressive process. I think I counted about three thousand layers of rubber in the tire.


And the transformation in the end - via steam-filled bladder - is just stunning.

Oh, there's the corny the end this time.

Wednesday, August 7, 2013

World's Roundest Object!

Be careful when discussing this video with your students. This is about the world's roundest sphere...sphere. It's not a ball. It's a sphere.

Just saying.

'Cause I know I've said ball in front of my high school students, and it took me a while to get the boys' attention back.

(In a related aside, my wife is listening in as this video plays. She lost control at 6:22 when the narrator said "Newtons, Joules". To quote her: "heh, heh...Newton's jewels...heh, heh".)

This 'world's roundest object' is more about the basis of our metric (now the systemé international d'unités or SI) than it is about materials science. There are, however, some serious challenges involved in making a material that won't decompose, that won't get dirty, that won't wear away, that won't change over time.

Here they have created - according to the scientist at 7:25 - a single crystal of silicon with 'no voids or dislocations' and containing only one isotope of silicon, making the material just slightly less valuable than absolutely, perfectly, priceless.

Science Lowers Shattering Risk at Home Plate

Image source
From the New York Times...
Welington Castillo smashed a double for the Chicago Cubs late in a game in the 2010 season, his bat exploding on impact with the ball. A long shard of wood flew at a teammate, Tyler Colvin, sprinting home from third base, impaling him a few inches from his heart. Though Colvin scored, his season was over.
That's not Welington Castillo or Tyler Colvin there to the right. That's Hanley Ramirez breaking his bat in a game June 19, 2013. The video of the Tyler Colvin incident can be found on YouTube, though.

I grew up just a few miles from the Hillerich & Bradsby Louisville Slugger factory in Jeffersonville, Indiana, so I can vouch that we've been using wooden baseball bats since at least April, 1975 (and probably longer than that). It would seem like there wouldn't be much room for improvement in wooden bat technology. Sure there are composite bats and aluminum bats and carbon fiber bats, but those aren't for the big leagues. The big leaguers use wooden bats, and wood is wood. It grows, we cut it, we shape it.

In the early 2000's, however, traditional ash bats began to give way to maple bats, favored most famously by Barry Bonds. The maple bats felt harder, stronger, more powerful - perhaps truthfully, perhaps in an example of placebo effect. The important aspect for this article is that maple bats didn't just shatter; they exploded.

Hence the room for materials science, finding a way to make a better maple bat.

Magnetic Mysteries of Earth's Core

Admittedly the BBC article "Magnetic mysteries of Earth's core" might not, at first blush, seem like a materials article. We can't see, touch, or directly interact with the core. We can't make anything out of the core.

But we can test the core and can - as has Professor Kei Hirose of the article - test the core indirectly. Here Hirosa has recreated the temperature and pressure conditions thought to exist in the inner core, using a diamond-tipped vice to exert 3,000,000 atmospheres of pressure on a nickel-iron alloy being simultaneously heated to 4500 C.

At these conditions crystals within the alloy changed and apparently increased to drastic sizes, leading Hirose to propose that the core may include crystals up to 10km in size.

Friday, August 2, 2013

Researchers turn cement into metal

Close-up visualizations of (A) the HOMO and (B) LUMO single-particle electron states in the 64CaO glass. Both states are spin-degenerate, and h1 labels the cavity (cage) occupied by LUMO. Yellow and magenta stand for different signs of the wave-function nodes. (C) Simulation box and the electron spin-density of the 64CaO glass with one oxygen subtracted at h2—that is, with two additional electrons. The two electrons have the same spin and they occupy separate cavities, h1 (boundary, also shown in B) and h2 (center, location of removed oxygen), which are separated by 12 Å from each other. (D) Cage structure around the spin-density of one electron cor- responding to the h2 cavity (close-up from C). Al, gray; Ca, green; O, red. Credit: ANL
I'll readily admit that the science behind this article, summarizing an article from the Proceedings of the National Academy of Sciences, is at the edge of my understanding of materials.

Apparently the scientists turned liquid cement into a semi-conductor analogous to liquid metal and eventually to a metallic-glass material, something that could lead to "positive attributes including better resistance to corrosion than traditional metal, less brittleness than traditional glass, conductivity, low energy loss in magnetic fields, and fluidity for ease of processing and molding."

The process seems to so obvious that I'm disappointed I didn't think of it myself:
The team of scientists studied mayenite, a component of alumina cement made of calcium and aluminum oxides. They melted it at temperatures of 2,000 degrees Celsius using an aerodynamic levitator with carbon dioxide laser beam heating. The material was processed in different atmospheres to control the way that oxygen bonds in the resulting glass. The levitator keeps the hot liquid from touching any container surfaces and forming crystals. This let the liquid cool into glassy state that can trap electrons in the way needed for electronic conduction
Seriously, though, can anybody explain this to me?

I can say that I know what the HOMO and LUMO shown in the diagram are. Those I remember from college chem.

Ice Axes - How it's Made

I was almost a little disappointed that there wasn't a corny joke at the beginning of this video, and then I found out that ice axes are "really designed for peak performance."

I really wonder if as much of this manufacturing process is down by hand as is being shown here.

How It's Made Swords

"...and they go to the hilt to make sure the details are just right."


Ok, if all they're doing is making replica swords, I can see that just cutting it out of a block of metal would be faster, but it can't have nearly the same strength and flexibility that a real sword would.

I'm thinking most of this sword making procedure isn't quite historically accurate, but I will admit that most of my knowledge of sword making comes from Highlander.

Science camp: Living in a materials world

This video is of the Howard University ASM teachers materials camp in the summer of 2012.

The video was filmed and published by Stars & Stripes, a YouTube channel that (in their words) "exists to provide independent news and information to the U.S. military community, comprising active-duty, DoD civilians, contractors, and their families."

It's a fairly standard format: ASM official (Charles Hayes) speaks, labs are shown being done, teacher attendee describes a lab. The only thing missing was a teacher attendee giving a testimonial about the camp.

I particularly loved seeing the borax glass drop (at 0:48) pick up more borax that starts to degas and puff up.

Water and Solutions -- for Dirty Laundry: Crash Course Chemistry #7

Thank you, John Green.

This thirteen-and-a-half-minute-long video covers enough chemistry about water that if my students understood the entire video by the end of my year of chemistry, I would be pretty happy.

Because it's that saturated with knowledge, I don't know that I'd necessarily show it in one sitting in the classroom. It's dense, man, but it does a spectacular job explaining (and showing via animation) a whole lot of ideas about the chemistry of water. I'll list some of them...
  • oxidizing (like bleach and hydrogen peroxide do)
  • solutions (aqueous ones)
    • solute
    • solvent
  • polar molecules
    • polar and nonpolar molecules dissolving each other
  • water dissolving ionic compounds
  • electrolytes
    • strong, weak, and non-
  • moles
  • concentration
    • molarity
    • molality 
    • diluting

Magic Molecule by Christopher Chapman & Hugh O'Connor,

Man, the '60's, huh?

Throw in the fact that these filmmakers are Canadian, and you have an absolutely perfect recipe for weirdness.

This video - available online thanks to the National Film Board of Canada - certainly is weird and dated, but it makes for a pretty impressive overview of what the dreams of a plastic world used to be.

Nowadays the world of plastics tends to be viewed with a far more environmentally-suspicious lens than the one through which our intrepid polymerist gazes at 2:00, but in the 1960's, everything was coming up plastics.

I do believe that at 5:40, we have a composite.

And I just love the opening poem...
It's a fine phenolic, acrylic day.

The cellusoics are in good fettle, and there's a hint of melamine in the air.

Yes, everything is perfectly synthetic, for this is the bright, new world of plastic products.
...and the cool shorts outfit at 1:28...

...and the beautiful world of 7:04...

...and the Legos from 7:20 through 7:40...

...and the boat of 7:50...

Hey, what happened to the old dude at 7:50? Where'd he go?

PS: Thanks to Kristin for the find here. As always, if you find a great materials science video, feel free to send it my way.

Jeep Grand Cherokee Manifesto Commercial

First off, the song is "God's Gonna Cut You Down" as performed by Johnny Cash. The video starring just about everybody but Cash is over here if you want to hear the whole song.

I knew you wanted to know.

The video - one-minute long - is officially an advertisement for a Jeep, but it uses patriotism and transfer about the great manufacturing history of America to make you think that if we made great things here once, the Jeep must be one of those things.

Which it might be, but that's not our point.

For me, the video is a nice, emotional call-out to return to manufacturing greatness, something that materials science just might help us do.