WM_Su2014_01

That's not enough, let me know. Okay, so in Fontana, uh, if you look at the beginning of Fontana, the, in the index, um, are the table of contents. Actually chapter three is on the eight forms of cor— I guess I didn't copy the index, but he talks about the eight forms of corrosion, and he's one of the first people back in the 1940s when we put everything together to talk about these eight forms. Are there only eight forms of corrosion? Of course not. Um, it's just a way of putting things together.

But uh then there's a guy CP Dylan [Dillon], who, I think Dylan [Dillon] is probably still alive, he's probably his 80s or 90s, he's out of West Virginia, and he wrote a book for the National Association of Corrosion Engineers, NACE, called The Forms of Corrosion: Recognition and Prevention, volume one. I don't know if there is a volume two, but his eight forms of corrosion are not necessarily the same as Fontana's. Okay, so here's a handout from that book, and here is my review of comparing their forms of corrosion. Okay, so there are lots of different forms of corrosion. You can slice this thing in any way you want as far as that goes.

But um, why does corrosion occur? Anybody have an idea? There are only three metals that exist in nature as metals in a native state. You might have an idea what they are. Gold. Copper. Uh, platinum. Iron's always oxid—, most things are an oxide, sulfide, um, and platinum is often combined with other things like sulfur and stuff. But uh, even silver, with which silver oxide is not stable at room temperature, but silver sulfide is very stable, that's why silver tarnishes. It's the sulfur in the air that causes silver to tarnish, okay. So silver is always found as a sulfide, iron is usually an oxide, sometimes a sulfide. But in fact most of these metals require a tremendous amount of energy.

This comes out of a book called Ashby, or Ashby's book. Ashby — I brought Ashby's book, let me put— matter, um, I've got, or not. Um, Mike Ashby, um, was a professor at Harvard, then he went back to Cambridge, and he's retired for about ten years now. But he came up with a program for selection of materials, and he's a materials mechanical engineer. And um, he's actually one of the great materials engineers in the world right now so far as that goes, in terms of the way he looks about, looks at things. But he has some books that go through and talk about, uh, in general, the energy content of different materials.

Aluminum is 300 gigajoules per ton. That means it takes 300 gigajoules of energy to take aluminum oxide, which is what we find in nature, and turn it into aluminum metal. It's a very high energy cost, okay. Eighty, ninety percent of the cost of aluminum is the energy cost to turn it into aluminum from its native state as the oxide, okay. And um, plastics, they have about 100 gigajoules — just if you burn them, they come from oil, and if you use it as a fuel, it's about 100 gigajoules per ton. Copper is 100 gigajoules rising to 500, and the reason is, we used to have ores that were two to six percent copper in the world. We mined them out, and now we're mining ores that are less than half a percent copper. And so now you're talking a half percent copper, you're talking about getting um, ten pounds out of a ton, okay. You got to mine a ton of material to get ten pounds of copper, and you have to, you refine it electrolytically usually through that anyway. Steel is only 50, so it turns out.

People talk about, the Navy wants to build aluminum ships, right? Guess what, they're going to be more expensive, even though aluminum's lighter, okay. And people talk about all-aluminum automobiles. I used to give a talk back in um, the early 1990s and saying that, and people were talking about all-aluminum vehicles. I said, what's the big deal about an all-aluminum vehicle? Um, what's his name, Mellon — can't remember Mellon's first name, but of Mellon Bank, he helped fund Alcoa. And so the two of them in Pittsburgh kind of rose the great wealth, okay. In fact it's Carnegie Mellon University, okay. Well, Mellon had an all-aluminum Pierce Arrow in the 1930s because he sort of funded the whole aluminum industry at the time. So why not drive an aluminum car? Um, we had all-aluminum Duesenbergs in the 1930s. It's not new technology to make an all-aluminum car.

But they were trying to make a Ford Taurus that would compete with a Toyota Camry made out of steel. And I used to give this talk that you'll never see that in the next 25 years. And at the time Alcoa was working very closely with Audi to make the first all-aluminum Audi. And it turns out the senior Executive Vice President of Alcoa, Peter Bridenbaugh, graduate of this department, and I gave talks at various times and he'd get up and talk about how they're building all-aluminum Audi. Well, anybody can build an all-aluminum car if it's cost $90,000. But if you're going to buy a $20-25,000 Ford Taurus, I don't think it's going to be all aluminum, okay. And I kept saying that for about 5 or 10 years. Peter actually and I talked about the price of gas, and we can talk about that as far as that goes. But it gets down to, you know, all-aluminum cars in 1990 made no sense unless you were talking about gas at $4 a gallon. And at that time gas was about a buck 50 a gallon. And so actually I used to be conservative, I said well you're not going to have all-aluminum cars until the gas is $3 a gallon. And Peter came up to me at the end one conference, no, it's $4 a gallon, okay, 'cause Alcoa knew it, okay. It's the energy cost of the aluminum.

In fact, right after the former Soviet Union broke up and peace was breaking out in the early 1990s, the Soviets had big aluminum plants out in Siberia. And uh, they were also looking for foreign exchange, and what did they do? They couldn't get, they hadn't built pipelines yet to get the oil or the gas from the area, they had to ship the aluminum. And people for decades have been calling aluminum canned electricity, because you refine aluminum by using electrons. And they build aluminum plants right next to big hydroelectric plants, the Grand Coulee Dam and you know, things, wherever they have big hydroelectric plants they build aluminum smelting plants. Um, Iceland — I mean, Alcoa's got a huge production facility in Iceland because they got lots of hydroelectric power and you can't transport the electricity off the island, okay, unless you do it as aluminum.

So anyway, um, we'll talk tomorrow about how much of these things we use. But the highest tonnage of material that we ever use is gravel, and part of that because it's cheap, okay, in terms of energy cost. So in any case, um, everything, all the metals — and why do we want to use metals rather than ceramics or plastics? If we're trying to use the material, why don't we make plastic ships? Well, we do. We make these little things, kids use them in the bathtub, right, plastic ships. Actually you make bigger plastic ships, you make minesweepers of fiberglass, which is a plastic ship. They made the Visby — anybody know what the Visby is? The Swedes built a combat ship, sort of a corvette or something, called the Visby back in the mid-90s, all fiberglass basically. It was very famous at the time. Oh, the Swedes have leapfrogged this. Well, good thing they're our friends — they're actually neutral to everybody all the time.

Um, but it turns out, what I've learned from some of people in your class over the years, is the Visby is not quite so great because it tends to flex a lot, okay. There's a certain advantage of having the stiffness of steel when you're building a big ship, okay. And one of the problems with aluminum, it's got one-third the stiffness of steel, okay. And there's nothing you can do about that. That's, well, you can do something by using bigger sections, but that, you lose a lot of your weight advantage when you do that. In any case, um, there's a lot of energy content to these things. Most materials, go to another page of Ashby — um, he has a lot of, this is a plot showing the energy content. If it's negative energy you have to put energy in to make the material. Beryllium takes — beryllium and aluminum, see, there's aluminum, one of the highest energy contents along with cerium, uranium, titanium. Lots of energy to get them out of their oxide state into a metallic state. Silicon up here. Steel is going to be where, is see steel on here? Anyway, steel would be down in here. Oh, here's iron, it's almost like steel.

Um, so there's iron. The things that are stable that you find in nature are salts. We have salt domes, okay, big mines, salt mines. That's a— these are stable compounds, um, more stable than oxides and sulfides, and they, um, you actually can get energy out. Well, let me just— you find them as chlorides. Um, but this is actually moles of oxygen, I guess that's why it's positive. Gold is slightly positive, that's why you find it as, regular, it's native state. Silver is sort of neutral, but sulfide is bad. And here's platinum and here's copper.

Um, why does, why — you can find copper. Anybody been to the Smithsonian and seen the big copper nugget? It's about the size of a coffee table and weighs tons, they got in the Smithsonian. There's a bigger one up in Whitehorse in the UK, on, they have big stands about six feet tall. This copper nugget — used to be able to walk on the ground in Michigan and pick up native copper, okay, chunks of it the size of your hand, okay. Can't do that anymore, price of copper, people have been scouring the countryside to pick up the copper as far as that goes. But copper is found in its native state because it forms a tarnish that's protective. It's not just straight copper oxide, it's a copper oxide sulfide and other things. They call it a patina, okay.

And this is very artsy, wealthy people will make their gutters of their wealthy homes — actually the homes aren't wealthy, but they will spend some of their wealth on their homes, and they will use copper gutters and downspouts. And then the thieves will come around at night and steal the copper from, okay. You know, people are going into old homes and ripping out the copper plumbing. Some people ripping out their own copper plumbing and putting in the plastic tubing and then selling the copper, okay. We don't have copper pennies anymore 'cause the price of copper went up. And now they're running the problem, should we get rid of pennies because it costs more than a penny to make a penny, because the zinc price is going up, okay, with inflation.

Anyway, so there's an inherent desire of materials to go back to their native state, okay, and they corrode. And in fact, the corrosion folks, they didn't like the term corrosion. I mean, who wants corrosion? I mean, who wants to admit that they're— if you're in hot corrosion, Professor Sway [Soiffer? Saway?] and I used to call it hot rot, okay. Um, so — and to show you some hot corrosion, these are some turbine blades, they came off a functioning Mexicali airline jet maintained by United Airlines. So um, this is one that didn't corrode, this is one that did corrode, it was still in the— and if you look at it carefully, see this one sort of warped, you know, not quite straight anymore. This is sulfidation, okay. We'll talk about that a little bit later.

But about 20 years ago they decided they needed a better handle than to call it corrosion. So they now call it environmental degradation of materials. That sounds a lot better, doesn't it, okay? To know that I don't work on corrosion, I work on environmental degradation of materials. And so I'm an environmentalist of some— I don't know what it is. I don't work in corrosion, but that's what they call it. So why don't we take a break for 5 to 10 minutes. You can eat some more donuts and coffee, go to the restroom. Ladies' room is this way, men's room is actually right under on the basement, you go around the corner to the main corner. We'll start up again about—