How Japanese Masters Turn Sand Into Swords

This isn't a replacement for the Nova episode "Secrets of the Samurai Sword". 

...but the Nova episode tends to appear and disappear from YouTube and DailyMotion with fair frequency, so you might need another video that goes through the ancient art of creating samurai swords from the initial collecting and smelting of iron-rich sand through to the slicing of tatami mats to demonstrate the sword's quality and the sword wielder's technique.

This video's contents...

• 2:00 - why bronze was used for sword and was eventually replaced
• 3:00 - cyanobacteria creating oxygen that precipitated iron from ancient oceans
• 6:30 - carbon + iron = steel, initial interstitial positions shown...why alloys are harder than pure metals
• 10:30 - slag formation and removal from the 'ancient' forge
• 13:30 - forging the steel by master swordsmiths
• 14:30 - folding the steel - how and why
• 16:15 - how carbon atoms migrate to different positions and form ferrite, cementite, perlite, and martensite
• 18:30 - differential cooling rates via clay thickness creating different steel types and the distinct blade shape

Another great video from Veritasium and one that shows that he's got a team of folks making videos with/for him at this point...and it's short enough at about half an hour - to get through in a single class period, unlike the Nova episode.

Four videos about one really bad event that could have been much worse

We'll start with the video debrief of the driver with the armored vehicle manufacturer after the fact so we're all aware that things worked out fine for the people you'll see in the next two videos which are the original footage - first one inside the vehicle, second one a dashcam pointed out of the video.

We've had impressive videos of bulletproof, composite glass before, but this is a really impressive application of that material in its designed use. And, of course, the host sits in the car at the very end while one of his coworkers fires another two shots at him. Nuts, man...

And the final video is from an American morning show providing some context on the interior video that was making its rounds on social media at the time.

Heck of a first day on the job for the guy in the passenger seat.

littering war zone halos named for fallen heroes

Stick with me, folks.

I wouldn't normally turn to Fox News for my science reporting, but their story does the best job - of the ones I quickly searched on YouTube - of explaining the Kopp-Etchells effect in which the edges of helicopter rotor blades get abraded via airborn grains of sand, sending showers of pyrophoric tittanium-nickel alloys into the air and making for a lovely light show - that admittedly shortens the lifespan of the blades and advertises the presence of the helicopters at night.

Effectively, it turns the edges of the blades into sparklers.

It makes for some really pretty pictures, though...

Source - reddit

Source - wikipedia

Here's another video with a little more science presented in meme-ified format.

Why on Earth is Depleted Uranium Used for Military Ammunition?

Depleted uranium just sounds terrifying. Sure, you can pick up some uranium ore and yellowcake from United Nuclear, but trying to buy depleted uranium is going to likely be a little dodgier.

With that being said, the US military has used depleted uranium (DU) as a source of armor penetrating ammunition over the years. I thought - wrongly from the video above - that the DU was simply used because of its high density and nature otherwise as nuclear waste. Today's video posits that there are quite a few other advantages of DU in high-caliber munitions applications.

There are also some seemingly obvious health risks involved in living in an area where spent DU shells are peppering the ground or having been in a tank where DU rounds entered and as least slightly vaporized. The video also goes through those health risks and says that they have largely been disproven, though I would be skeptical and appreciate that many military branches are "not considering depleted uranium anymore because of the environmental problems associated with it, be [they] real or perceived."

I think I'll stick to good ol' tungsten for my armor piercing needs.

process of making Damascus knife. Korea's top handmade knife master.

There simply are no words.

I mean throughout this twenty minute video there literally are no words spoken.

Instead, we just watch a knifemaker craft a single, beautiful knife from initially forge welding stacks of steel together to testing the finished knife.

It's mesmerizing.

Making a BULLETPROOF John Wick Suit in Real Life!

I love the John Wick series. It's ridiculous and phenomenally unreal that the main character would survive even the remotest bit of the damage done to him throughout the series of films.

With that being said, I guess a bulletproof dress suit similar to John Wick's is possible. I say that because this video is about the process of making just such a suit.

There is a lot of firing of guns - all on a controlled, safety-checked gun range, at least - in the video. The high quality stuff to me is the initial exploration of how they should do the testing to see which materials are bulletproof and the minimum of those materials that they can use. The try to cheap out on the testing methods initially but come to realize that the testing standards are written because the standards describe the ways that actually work. I appreciate that.

I also appreciate the discussion of composite materials even though the sheer-thickening fluids from my previous post didn't seem to provide any advantages, which is a little disappointing.

What is the Castillo de San Marcos made of?

Coquina.

That's it. That's the answer. 

It's a composite stone made of compressed seashells with carbonic acid leaching out calcium out of the shells to fuse them together into stone.

The above video, from the US National Park Service, explains the material of the walls of Castillo de San Marcos and how its porosity was both a weakness (it needs to be plastered to waterproof it) and a strength (the walls could 'absorb' cannon balls fired at it in an attack.)

The second video - below - explores the preservation efforts necessary to maintain the coquina walls.

MAKING A BOWIE KNIFE WITH REAL ENGINEERING!!! PART 1

I get that much of your personal taste in enjoying YouTube videos (or not) comes down to the personality of the presenter. That's why I'm going to refrain from commenting on Alec Steele's videos.

I won't mention the overly-enthusiastic schtick.

Honestly, I won't.

I'm a little disappointed that this isn't the video I was really looking for. I was looking for the video showing the testing of the various heat treatments of the steel.

I guess that's on part 2. Arrgghh...I guess that's next week then.

Heat Treatment -The Science of Forging (feat. Alec Steele)

There is something weird happening with the Real Engineering guy's accent. I'm struggling to place it exactly. There's a sing-song lilt to it that's screaming, "Irish" to me. Then, at 1:50, there's a weird ll-th thing going on with the 'through the heat treatment process' phrase that makes me think he's almost got Welsh in there. His patreon page says Galway, Ireland, but I've not heard that ll-th thing anywhere but from Wales.

Can anybody definitely say where he's from?

I'm going to have to check out the testing video from Alec Steele (an aptronym). Maybe that'll be next week's post.

So much great metallurgical explanation here...BCC, FCC, ferrite vs austenite vs pearlite, phase diagrams, quenching vs tempering vs annealing (normalising - British spelling, natch).

What quenching and tempering does to SWORDS

Trigger warning: Aussie accent...keep hacky comedians and actors away lest they start doing the Philosophers song.

There's a whole bunch of high-quality explanation in this one...

• 1:19 - percentage breakdown of carbon in various steels (low carbon, medium carbon, high carbon)
• 1:49 - "When the iron is hot...reaches the austenite phase...lost magnetic interaction...body centered cubic or face centered..." Honestly, he screws up the crystals verbally (though the graphics are correct) but does nicely say that "there's more room in between the iron atoms when it's this hot which means carbon atoms can all fit around evenly wherever they want" and that "when iron is cool...they try and squeeze out the carbon in between these iron atoms" and shows ferrite in the graphic
• 2:56 - micrograph of ferrite and cementite as the carbon in squeezed out from between the iron atoms, making pearlite
• 4:16 - Say "crystals" not "structure", man...c'mon
• 4:44 - discussion of work hardening and how that's lost once the metal is reheated, "it loosens the insides. It basically gives the opportunity for the stresses to be released and moved around and become uniform...as soon as you heat it up, you're losing whatever benefits - but also detriments - you might've put into the steel"
• 8:16 - "When heated up to where austenite is formed in the steel, the carbon is not forced into these veins/pocket/lines...and if you were to cool it down rapidly, you can actually give those iron atoms not enough time to force [carbon] out into these more condensed pockets...and a different, amazing crystalline structure is formed within the steel called martensite"
• 9:40 - "[Martensite] can be very useful to swords because you want swords to have a very hard edge, but you don't want them to be too brittle"...Goldilocks of metals, eh
• 10:05 - how the Japanese solved the problem, great diagram of the anatomy of a samurai sword (ion core, pearlite jacket, martensite edge) created via clay control of cooling rate
• 11:50 - tempering makes its appearance...we've been waiting, Shad
• 12:30 - showing quench of a katana with differential cooling causing bending in both directions (flubbed vocals but corrected captions)
• 13:10 - "[tempering] releases stress between these dislocations creating a much greater level of ductility and flex in between the crystal structure that's being formed within it" - nice micrographs of martensite and tempered martensite
• 15:00 onward...what makes for a good sword, particularly its sharpness...not so much material science 

The Physics of Slingshots 2 | Smarter Every Day 57

I keep wanting to tell Destin that he's gonna shoot his eye out.

But it looks like he still has his predator vision at the end of this video, so that's his business as to whether he wears goggles or not.

At 2:13, Destin shows a graph of the potential and kinetic energy of the ball/band system as the band stretches and releases.

At 4:39, he then uses actual data/video to show that a tapered slingshot band accelerates the bullet faster than does an un-tapered band.

Then, at 5:00, our favorite - the stress-strain curve - shows up.

Sadly, some of the links in the video description to learn more about hysteresis, for example, are dead.

Destin got two videos out of his visit with Jorg (check the slingshot channel for even more). The other video doesn't have as much material science content, but it's still fun, and it shows some momentum and energy calculation with a gigantic slingshot.

Brad Makes a Knife with Bob Kramer | It's Alive | Bon Appétit

I'm a fan of goofy Brad, the host of the video series, It's Alive. Mostly the show is about cooking in the realm of fermented foods (kombucha, beer, garlic honey, cultured butter, sauerkraut, etc), but this time Brad goes to a small-scale knife shop because, as he says at about 13:10, "this ain't necessarily alive, but it's got energy...watching [the knife-making process] from start to finish, if it don't make you feel alive, I can't help you.

There are a bunch of metal topics covered here...

• 0:45 - "make some steel from scratch"...they make their steel from powdered ingredients (carbon, iron, manganese) and then melt them together
• 1:30 - induction heat melting of the steel ingredients
• 2:20 (and again at 3:00) - forging...the take the fresh, steel 'biscuit', reheat it 
• 2:45 - heating the steel back up to the plastic state...they don't mention the phase transition from BCC to FCC, but they do explain that hot steel can change it shape more easily...and that they have to reheat the 'biscuit' because it's getting cold
• 3:30 - rolling mill...a small mill but still far larger than what we show in the summer workshop
• 4:15 - forge welding different steels together...they only refer to the steels as steel A and steel B...no mention of high- or low-carbon steels
• 4:40 - iron oxide...the captions explain that, "[t]hose dark flakes are iron oxide. High temperatures accelerate the oxidation process."
• 6:20 - "quench tank there, Vinnie"...Vinnie is the camera man for all the Bon Appétit videos...no explanation yet as to why you would quench something
• 6:58 - hardening the knife...molten salt bath for an oxygen-free atmosphere for heating..."dissolving the carbon into the iron" then capturing it during the quench...followed by a tempering bath to, "bring the knife to a working hardness, so it's not too hard...not too brittle"..."when it's hardened, it's under a lot of STRESS...we go in there (the tempering bath) and it just adds some heat, kind of massages it...makes the knife 'happy'...yeah, this is the 'martini' for the knife"...there's a decent graphic summary of this at 7:50
• 8:40 - acid etching the knife..."the acid eats these layers at a different rate...because we mixed in different things in the steel"
• 11:20 - nothing curricular, but watching Bob Kramer put a blade on the knife just by eye as stunning...I assume it took a few more passes than what the video shows, but he makes it look so casual and awesome...I'm amazed

Warnings

• 7:35 - mention of making the steel happy via a 'martini'
• 10:20 - there's a bleeped, "I always f*#^ that up"

Brad's a goof, but it's loads of fun to watch him make a knife.

Forged in Fire: Bladesmithing 101: The Quench | History

"Fighting the Dragon"?

In our summer materials camp, we heat treat steel (bobby pins and paper clips) including quenching them in water. For the work we're doing, quenching in water works just fine. The mass of the materials is tiny. We're not looking for precise, perfectly repeatable work and products. Water's all good...

But there are a lot of other options for quenching materials. There's air quenching, noble gas quenching, salt quenching, oil quenching, quenching your thirst, quenching your curiosity, quenching in quince.

Wait, those last few aren't really anything with material science.

King Tutankhamun's Dagger Was Literally Out Of This World

"That’s right: King Tut had a space dagger."

How cool is that?

An article published in May in the journal Meteoritics and Space Science is titled "The meteoritic origin of Tutankhamun's iron dagger blade".

In the article (sadly behind a paywall but detailed at IFLScience) scientists recount the process of using x-ray fluoroscopy to determine the precise elemental composition of the dagger's blade without any harm to the blade itself.

The scientists were even able to determine the exact meteorite from which the dagger was forged nearly 700 years ago.

Science is stunning.