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.
This might be my prize material science possession. It's three pieces of silicon.
The Lego figure is just there to show some scale. I figure everybody knows how big a Lego minifigure is, especially Margaret Hamilton.
These were sitting in the back room of the original Princeton High School building before it was torn down. During the last year in the building - as we transitioned across the street - we were doing a lot of paring down, preparing to move what we needed and leave the rest behind for a public auction. This was on the shelf of another science teacher's storage room and was clearly bound for the auction. They didn't know what it was, didn't want it, didn't think it had much value.
And I grabbed it with great gusto.
I wasn't letting this one go because I know I'll likely never get another chance at it.
You can see the process of producing mono-crystalline silicon in videos I've posted before. The silicon has to be refined before this (something I got to see done outside of Butte, Montana - but where they didn't allow any photos, sadly). That results in something like the rough chunk in the front, left of the photo. This chunk is roughly small-fist sized.
That chunk - and a bunch more like it - is melted and a single silicon crystal is lowered into the rotating vat of molten silicon. The single crystal is slowly raised from the surface of the molten silicon, rotating in one direction while the vat is rotated in the opposite direction. If the conditions are just right, an single crystal of silicon is raised from the vat. That's what the tower is in the photo above. The final product was likely taller and didn't end in a flat bottom layer but rather a second tapered end.
Check out the process from about 1:00 - 3:00 in the below video.
The tower (technically a pull of silicon) would then be sliced into flat wafers that would then be etched into computer chips.
As to how Princeton High School got the silicon tower and chunks...I'm not entirely sure.
I've heard from a couple of non-PHS teachers that Cincinnati had a silicon wafer production facility that shut down and donated silicon samples to local schools, but I haven't been able to track down any information about that donation. I did find information about two silicon wafer production facilities in the Cincinnati area. One was near Maineville, but that one closed down in 2010. That's too late to fit into our timeline. The other, now known as Milacron, produced silicon wafers in the 1970s-1990s ("by 1984, the Mill had become the world's largest supplier of this type of wafer.) While I don't have any proof, that fits the timeline of a possible donation to Princeton much better. So I'm assuming we have Milacron to thank for this donation.
Yes, there is are a couple of hour-long videos about Naica cave, but sometimes we just don't have an hour to devote to that world's largest monocrystaline growths.
That's kind of why a video like this one - just under 3 minutes long - can be nice. It's a quick exploration of the Naica crystal cave, drained and being explored as of the time of these photos (no video, just stills).
I'd been hearing for a while that the caves 'were going to be refilled', but I just found - in a quick research bit - that the BBC reported in 2014...
In her discussion with reporters [Dr Penelope Boston] lamented the fact that the crystal complex had become flooded following the recent cessation of mining activities, preventing any further access.
"It is tear inducingly beautiful down there. I wrote several poems about it actually.
The original source is here, but I went ahead and reposted it here.
I'd always heard that in Canada there was a contest for high school students to grow the best/largest single crystals (thank you, Chem13, for introducing me to that one). Admittedly - and offensively, I'm sorry - I would typically follow that up with some repetition of Jim Carrey's "Canada" routine (thanks, Becky Heckman, for introducing me to that one).
Since I've gotten into the material science course and the CuSO4 crystal-growing world myself, however, I've been kind of interested in playing along.
Anybody wanna get something like this started in these here United States of America?
The above, silent video shows a monocrystal of silicon being drawn from a molten silicon bath by one, pencil-thin silicon crystal. There is no narration or explanation given. For that, might I suggest...
The show How Do They Do It seems to be a British take on the more American How It's Made series. Here they visit Texas to see how silicon microchips are made. The above process shows up at 2:00 and shows the four-fold symmetry of the silicon crystal, a 200kg, 200mm across (that's like 440 pounds and not quite 8 inches across, for us Americans.)
From there it's to the silicon sausage slicing machine, buffing, and creating the teeny, weeny, tiny microchips from the 2/3 mm thick sheet.
From worthless pile of sand to a product that sells for $1000 per gram? Outstanding return on investment...
