Materials Day 2009 at MIT

Today I skipped a music class and XC practice to go to a day long Materials Day symposium at MIT. It consisted of the following presentations:

1: "New materials for PV modules: Cost, Performance and Reliability" - Let my preface my reaction to this talk by saying that I believe that I do not have a future in photovoltaics. I find it not very interesting, and not related to materials science in ways I find interesting. Thus, I didn't find this talk very exciting, and, being the first of the day, it may have been all I could do to stay awake.

2: "Nanostructured Heat Transfer and Energy Conversion Materials" -This presentation was probably my favorite. I was wide awake for all of this. It described a certain system consisting of a p-type semiconductor and an n-type semiconductor, each attached to two different plates. Then, if you create a temperature gradient between the plates, it creates an electrical current. Conversely, if you put a current through the semiconductors, you can create a temperature gradient! So this talk was all about this technology and the search for a material with high electrical conductivity and low thermal conductivity, and various methods for achieving and optimizing this.

3: "Progress and Challegnes in Solid-State Lighting" - All about LEDs. Not very interesting. A lot more semiconductor and electricity stuff.

4: "What's Exciting about Excitonics?" - This one seemed pretty cool, although I understand any of it really. It was about these things called excitons, which I guess are energy carriers of some sort? 

5: "Nano-structured Materials for Next Generation Fuel Cells" - This one wasn't terribly interesting, but I liked the speaker. However, he mostly just talked about how his group tried this and they got some unexpected results and it was cool and all but not useful so they tried this instead but then they got these unexpected results which were also cool but not useful. 

6: "The "Materials Genome" Project at MIT: Accelerated and Large-Scale Materials Discovery in the Energy Field" - This talk was fantastic. This guy is heading a group at MIT that is trying to computationally characterize and predict the properties for as many materials as they can (generally single-crystal crystalline materials of various compositions). The things they can do and have found are amazing. I think that this sort of sorting and computational prediction of the structure and properties of materials will become a lot bigger in the future, especially when computational power increases. 

7: "A123systems Li-ion batteries: from Nanotech to Reality" - This talk was pretty good, all about how this MIT spin-off company, A123 Systems, grew and became successful. They make lithium ion batteries. I find I liked the part of the presentation about the company and the entrepreneurship better than the information about batteries, as again, it's a lot of electronics related materials science.

8: "Creating and Funding Startups: A Venture Capital Perspective" - This talk was given by a venture capitalist all about what venture capitalism is, how it works, what they look for, etc. Very interesting.

After the talks was a poster session and a dinner, both of which I did not attend as I needed to get home and get a lot of work done. The talks that were interesting, I really enjoyed, and I'm very glad I went. 

Flamecutting and Grinding!

I learned two exciting new skills in my welding class yesterday, flamecutting and grinding. 

Flamecutting is certainly interesting. At times a bit more scary than fun. Basically, you have a nozzle with 9 holes, eight on the outside and one in the center. The outer 8 are for preheating, and the center one is for the actually cutting. The center hole is only used when you depress a lever on the side of the nozzle which I believe completely opens up the path for oxygen, which saturates the flame with oxygen making it very hot but also making it such that it will oxidize the steel. With flamecutting, however, this is not a worry because you are removing all of the steel that contacts the oxidizing flame.

The removing part is where it gets exciting. After preheating the steel up to about a yellow hot, you depress the lever and the flamecutting flame comes out and it is hot enough to instantly melt the steel, and the pressure from the gas from the nozzle shoots the melted metal away in a shower of sparks. Where do these sparks go? Why, directly away from the nozzle, of course. It's because of this I've learned to always try to flamecut away from yourself. Also I've learned to always have your pants over your boots, to avoid having hot pieces of metal fall into your boots and sit their for a while burning you.

It gets better, though.  Sometimes you have what's called a blowback, where instead of going away from you, pushed by the gases of the nozzle, the melted metal explodes outwards in all directions, and often makes an extremely loud and sudden popping noise. My guess is that this is caused by a pocket of air in the metal that, when heated up to quickly, explodes, causing the metal to behave much like several thousand degree hot liquid popcorn. This happens most of the time if you try to flamecut over an area that has already been cut. This is a tempting thing to do, as occasionally, if the part of the metal that was just cut stays too hot, the steel will fuse back together. 

And, just to add to all this, it's really hard to keep yourself steady if, like me, you're naturally a shaky or trembling person. This causes all your cuts to turn up looking like tiny zig-zags.

But, thankfully, this is why we have grinding tools. After having done a good bit of flamecutting, we were introduced to the 4 and a half inch grinders. These are somewhat crazy power tools that you plug into the wall, and when you turn it on, it will spin a 4.5 in. diameter disk really fast, fast enough to create a nice breeze, which you then put up against steel. What happens then is that some amount of steel is converted into a 15-foot jet of sparks. Yes, 15 feet, and, Yes, a jet. And these aren't all harmless little sparks, several of the things that shoot off the grinder are decent sized particles of hot steel. Luckily, most of the time, this just is facing away from you, though, depending on the side of the grinder you use, it can be facing you, and there are always little bits that get whipped around and towards you. The little devils get everywhere too. They've been known to light clothing on fire, light paper nearby on fire, and even bounce their way under your safety glasses and into your eye. Again, I try to avoid sending the stream in my direction.

This grinding, however, is extremely useful. When flamecutting, you'll often accumulate little beads of melted metal that are blown onto the sides of the steel. These little beads are no longer steel but are rather, because of the oxidizing flame I mentioned earlier, slag. The grinder is great for getting them off. The grinder also can smooth down the rough edges that all your trembling makes while flamecutting. Even more, the grinder can polish the metal and expose bright shiny bits under the black oxide coating, making the steel look a lot nicer. 

I think I can look forward to a lot of grinding in my future. 

Visit to the SEM

Last Thursday my boss took me on a trip to a scanning electron microscope nearby that we had rented some time with. He wanted to check some carbon residue for carbon nanotubes, and to examine the epitaxy of a certain grown sample.

First, we looked at the carbon residue. It looked like soot, and under the SEM it looked very disorganized and splotchy. However, we did see some carbon nanotubes. They looked like white strings in the SEM. There were not as many of them as my boss had hoped, but it was still cool for me to see what a carbon nanotube looks like under and SEM.

The next sample was ever cooler. First we got a look at some crystals. We wanted to see whether they were arranged epitaxially, which, unfortunately, they were not. It was still cool to see the crystals up close. When we zoomed in further though, past the large crystals and into about a 100 nm scale, we saw odd shapes that looked almost like olives. This was really cool because we have no idea what they are, but we believe they may be some odd arrangement of carbon. Hopefully we will figure out soon what it was we saw, it could be some exciting discovery!