Warning: NSFW words (mostly starting with f's) at 0:45...and at 3:43...and at 4:39...and at 4:57...and at 5:33...and at 7:26 and 7:31...and at 7:44...and at 8:42...and at 9:10...and at 10:45...and at a14:10
Ok, so maybe this shouldn't be shown in class.
I've long wondered how single crystal turbine blades are grown to be single crystals. We mimic this is far less complicated ways with our copper (II) sulfate crystal growth lab in our matsci class at Princeton (and in many other ASM-born matsci classes).
...but I knew that simplistic method clearly wasn't going to work for the cast metal structures for metallic crystals.
Thankfully this video's foul-mouthed Yorkie host explains how we go from molten metal to single crystal, grain-boundary-less macrostructures. It's not a very thrilling video as it's just a knowledgeable guy explaining things in his garage with a white board to show what he's talking about. I respect the knowledge and appreciate his explanation about something I've wanted to know for a while now.
Maybe just watch it and explain things to your students rather than showing the video itself.
...because the video itself is absolutely fandabidozi.
Admittedly, the fact that their first launch wasn't fully successful isn't anything to look at as a failure in my eyes. The fact that the first launch failed is sort of the benefit of the 3d printing process. One of their supposed benefits is the fact that the engineering cycle will be sped up, allowing iterations to happen in far more rapid succession than was previously possible.
So, good on ya, Relativity. I look forward to seeing your 3d-printed metal rockets in space someday soon...just not yesterday.
I've been looking for an amorphous metal demonstrator off and on for a few years but with no success.
There are some samples of amorphous metals available on ebay, but I really don't have any idea of what those metals actually are, whether they're really the zirconium-beryllium-titanium-copper-nickel alloy that Steve describes at 7:10 in this above video.
This video sees Steve explore how to optimize the bounces - which material should the ball bearing be made from, how big should the ball bearing be, how can you measure the number of bounces most easily - which is cute, but the big payoff in the video comes after around 10:00 when Steve explains how materials plastically deform and why amorphous metals don't easily deform plastically.
That's absolutely fascinating, and I even more desperately want one of these atomic trampoline demonstrators.
Feel free to hunt one down and buy me one for Christmas. I'll happily give you my address if you do get ahold of one.
Now I'm curious how an amorphous metal would respond to a hardness test. Would it be much tougher to create a traditional 'dent' from a hardness tester?
(In hunting down more info on amorphous metals, I might've found a preliminary answer to that one on the LiquidMetal website, scroll down partway to find hardness data.)
Here's more info about amorphous metals and a video from Grand Illusions, from whom Steve borrowed his atomic trampoline demonstrator.
I'm not teaching material science this year (2022-23), but my neighboring chemistry teacher is.
He taught the class a decade or so ago when it was just a semester, and he's never taught it as a year-long course before.
As such, he's been coming to me quite often for help in understanding the concepts, explaining them, and practicing the labs and demonstrations. It's been kind of rewarding to help him understand things better - and in a few cases it's forced me to understand the material science concepts better so I can explain them to him, something I'm used to in teaching students but that isn't as familiar to me in teaching my fellow teachers in a longer form than our week-long summer camps.
Recently, my neighbor came to me asking about slip planes, so I went looking for a video that would directly and clearly label the slip planes in face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close packed (HCP) crystal structures. I wanted a shortish video that would use computer animation to highlight the slip planes and give me a concise, clear marking of where the slip planes are in each type of crystal.
Much to my chagrin, such a video doesn't seem to exist - at least not that I could find with a few days of searching on YouTube.
What I did find, however, was a much deeper understanding of what slip planes and - possibly more appropriately - slip systems are.
In this first video, I found a very helpful quote as written in the notes...
"Slip plane will be most densely packed highest planar density"
So the slip plane is the plane with the highest packing. For FCC that's the diagonal labeled as (1,1,1) because it connects the vertices of the crystal structure and is the 'triangular' plane that we show with our tennis balls in class. For HCP it's any of the 'horizontal' layers that we show with our tennis balls. For BCC, it's the diagonal from edge to edge in the crystal - but it's not very closely packed, making it a crappy slip plane.
"Slip direction is the one most closely packed with atoms (linear density)"
That means FCC structures have three slip directions for every one of their four slip planes. That give them twelve (4x3) slip systems.
But HCP crystals have only three slip systems - one slip plane times three slip directions.
...however, unlike fcc, there are no truly close-packed planes in the bcc crystal structure. Thus, a slip system in bcc requires heat to activate.
I still want a nice, succinct video that shows all that, but I'll take this combination that has helped me understand slip planes way better than I did before my neighbor asked me to explain them to him.
The first 7:53 of this video is all about orbital mechanics - which is interesting, I'll grantcha, but isn't the focus of this blog.
If orbital mechanics is your jam, go play some Kerbel and get back when you reach an expolanet.
We're here to learn about material science, and that's where the video takes a big turn at about 7:55, first exploring the carbon foam composite of the solar shield, itself, and the ceramic, reflective paint on its sun-side.
Then - at 9:15 - we get into the solar probe cup and its measurements of the solar wind. The big issue there is that the cup can't hide behind that carbon-carbon composite shield. It has to survive nakedly in the solar wind at 1400 degrees C which sort of limits the acceptable materials. The conductive mesh is made of acid-etched tungsten, and the wires leading to and from the mesh are a niobium alloy called niobium C-103 (89% Nb, 10% Hf, and 1% Ti) with sapphire bead insulation...you know, as is tradition.
Space is frickin' wild, man.
And that doesn't even get into how we tested those materials - a whole other journey that's covered after 13:55 in the video.
Every ASM teachers summer camp (schedule and curriculum here) includes a field trip to some local materials science place. It might be a heavy industry tour like the one I got to take of a Nucor steel mill in Alabama; a lighter industry tour like the one at REC Silicon refining in Montana; a testing lab like Element here in the Cincinnati, OH area; or an artsy tour like the one I was thrilled to take to the Indianapolis Art Museum a few years back.
The campers got to tour their conservation lab and got a great, materials-focused tour from Gregory Smith. You can hear from Gregory in a video way down after the jump.
I was initially skeptical of the Indianapolis Art Museum tour, wondering just how much science we were going to get from even their conservation lab, but I was pleasantly surprised at how much chemistry, materials science, and even biology there was at work in the lab and at how great Gregory was in explaining it all to us.
