WM_Su2015_14

[Tom passes around a sample.] Passed around, this is crystal bar titanium. I don't have a piece of crystal bar zirconium, but this is — I'll show you a larger picture of it. They're both made the same way. You start with zirconium oxide or titanium dioxide. They're both relatively abundant in the Earth's crust, but then you have to convert them to zirconium tetrachloride or titanium tetrachloride. And titanium tetra— for [DuPont] probably makes several million tons a year, because we then take that tetrachloride and we oxidize them to very fine — a lot of titanium dioxide. All the paintings, all these rooms is titanium dioxide because it has a very high specular reflection. Actually zirconium oxide has a higher specular reflection than diamonds. That's why the lights are —

Okay, and so, you know, if your fiancée doesn't like cubic zirconia, it's because she doesn't want something that sparkles more than diamonds. So that's crystal bar titanium. That's the raw product. They basically start with a hot wire inside a vacuum system, introduce the titanium tetrachloride, the chloride goes off, decomposes, and at least one hundreds of crystals very pure titanium — this is actually — people, the pieces are going to be just like — you said, centimeter diameter cool pellets go in there, about thirty bucks a foot or a hundred dollars a meter. A hundred thousand meters, as you said typically — so that's ten million dollars. That's up just plant, and hold the fuel. Navy reactors are smaller with zirconium, still uses zirconium because I think the point eight one barns is the lowest of anything on the periodic table. I want to — softer our table that had two barns early element and I think they're coming — Lewis and more I is, you know, not typical metals. Around three or even iron and something info when they were 3 divided rather than point 18. Yeah, I think boron is like 20 or something, okay. That's why we use boron in water to control the neutron flux. Boron has a very high barn cross-section. Going to ask you — of a barn —

Processes, we talked a little bit about tipping yesterday, and this is something I had filed. This is the titanium alloys notebook. And it shows the key strength rock, which makes these needs — forged titanium, which is pretty pricey, cast plus kind of static pressure or cast. Now they overlap quite a bit, but nonetheless the hot isostatic pressing can get rid of these two boys — voids — that are in the material and squeeze them out without changing the shape of the product. So think of it as forging without shape change. Repair them back —

The Air Force little — multiple ten-million-dollar system out in Oklahoma City. The Air Force says they own a pair of, you know, jet engines, and this is a turbine blade that — tips and worn off and they built up by welding 25 [to] 10 passes. That's one millimeter. So they built up about less than a centimeter, following seven-tenths of — or so, and they got a machine that, okay. But they're refurbishing this blade and they're showing the different microstructures. Yes, stuff that — there's like 25, 12 passes, one on this side and one — is lots of little bitty weld passes to build that back up. Why? Because this type of thing is not hollow, it's not single crystal, but it's still probably costs you about 500,000 bucks and it's worth repairing this. Again, that's as far as that goes. So any questions coming?

That is just kind of catch up on something. Here is something that basically shows you — I'm going to talk about lightweight materials, just came out of a book on lightweight materials okay. And so we got steel, titanium, aluminum, magnesium alloys. Steel can have tremendous strength, and this is megapascal, so we're talking 250 ksi. These are the types of things like 300 down before we go into air. Titanium landing gears for aircraft — we went to — we used to have 250 or 300 ksi steels which are very susceptible — require a tremendous amount of remain— maintenance to make sure you don't have any hydrogen embrittlement or corrosion on those things.

The interesting thing — I remember I was told, the first thing you design when you're going to build a new aircraft is the landing gear, but everything else depends on the landing — way to the landing gear and how much force the landing gear can take when it takes it — around the impact. So you design the landing gear and then you build everything up, the structure up from that, because it has to absorb that landing force. The rest of the structure has to be able to absorb that — dissipative food restaurant inspector. So you design the landing gear, you have some ballpark of what weight you watch for the overall aircraft weight, and then you design the landing gear and then you build all the structures out from there. The wings — fuselage hangs on the wings. In fact a 747 supposedly the fuselage is held onto the wings with four bolts, very penetrating nickel alloy super alloy bolts in this kind of strength range, which are not susceptible to hydrogen damage problem. Okay, for example is — so this shows you —

Dorf episode — so we've been talking on time too — high-strength steel is very susceptible. So why are they other obstacles? These are steels okay, but the types of steels you guys are going to use, HY 100 here, because you've got worried about — staffing weldable, and you have let it grow some, or allow for the fact that micro— like they forgot to put the same song that was interesting with that, the Coast Guard. And you're approving the ghost next, you had to scrap the couple's 103-foot, you know, both. You guys at acting system? Yeah. Guess not. [Pause.] It's a impressed current, but —

Eight nights in any case, titanium alloys, yeah, then get to 200 ksi, but for now [Ti-]6Al-4V is the workhorse alloy. We'll get to that later. But the Navy has a Ti-100 they developed back in the 60s, but again it's a hundred ksi, I buy this — a lot lighter, so the greater capability for submersibles. Get to the aluminum alloys, and it turns out — I didn't bring it down, I guess I was wrong — the highest strength aluminum alloys are found in baseball bats. We'll talk about why. But up to a hundred ksi or just over a hundred ksi. The typical alloys are up in the 80 to 90 for aircraft wings and things like that. 2014 is a little popper alloy, has been around — there the 19 since the 1920s. In fact the Wright brothers engine block for their — they're white which goes back over 100 years was — 6061 is the workhorse, 50 ksi strength. Magnesium alloys — not a lot of them, we'll talk about why. Magnesium has two Achilles heels. It's one wonderful property and that's that it's lightweight, but the two Achilles heels — it can be welded, and it is very pretty — very corrosion-prone, oxidizes — don't look at it overly.

Okay, to give you an idea of some of these densities — [Tom holds up samples.] here is a piece of zinc which is just about ten percent less than the density of steel. So think of this, that's roughly steel. There's magnesium — you can tell, you can feel the density. Here's aluminum, I don't have anyone — throw up here's a piece of titanium. Okay, you know, comparable size pieces, and you can look at that. If you now divide by the density of each one of these, you find — titanium at the highest strength, and all the alloys — all of those are about the same when corrected for density. Why do you correct for density? Well if something doesn't move, we don't care about this. You put it on the ground, the earth doesn't move, it doesn't move, there's no problem. But if anything moves we want to be lightweight, and the faster it moves the more you value lightweight. And in my material selection lecture I go through this in some detail. But in any case we want lightweight alloys. Everybody wants lightweight thing, and that's why they look at cell phones. Open gentlemen aerogels and it gets all excited because it's so light, it has no mechanical properties, but it's light. That's sort of what the trade-off is, some of these properties.

And the aluminum alloys — let's start with the aluminum alloys. There are a whole series of aluminum alloys, and the aluminum alloys go by four-digit number just like the American Iron and Steel Institute 1018 steel okay. There's not a 1018 aluminum, but there's a thousand series of aluminum, 2000 series, 3000, 4000, five, six, seven, and even an 8000 — this book didn't go out that far. But the thousand is not heat treatable. It's basically nearly pure aluminum. Examples 1100 — 99 percent aluminum and rest is just impurities. There are heat-treatable alloys — the 2000 series, aluminum copper alloys. Virtually all the aluminum alloy elements like to form a phase diagram. We're going to see over and over here and talk about that — it's a look like this is heptectic.

This is percent — call it copper, right? Now increasing, this is one hundred percent aluminum, and this is five percent. So 660 centigrade is melting point here, 540 or so here, 120 degree centigrade temperature differential. Kind of something only melts at 660, so aluminum doesn't have really good high-temperature properties. In fact we're going to see that some of them — that you, people, alloys are not very good at all at temperatures above even 200 degrees Fahrenheit, okay. Boil water and wipe them out. So these are heat-treated alloys, and this essentially 2219 is a modern alloy. That's what they used to build the Space Shuttle main tank. I love now — these are lightweight. Now they don't blow this at all, but 2219 was — basically over them near four and a half percent copper alloy that was more weldable than some of the others. The Wright brothers — if you try to weld the gas tungsten arc — not, you know what that is after yesterday — on the Wright brothers crankcase or the cylinder housing for their — this engine, you would crack it. You'd melt it and you'd have nice cracks for the appropriate carline, pull that rope, melted metal right out. That's all the practice underneath this with the same type of problem as you have on the Monel and things — you get cracking, equation melting in the heat affected zone in the copper interiors.

The non-heat-treatable 3000 series — here's your beer can stock okay, largest use. Largest used aluminum, widely used in tonnage alloys, and at one time forty percent of all the aluminum in the world went into beer cans okay. It's a major part of the aluminum industry — thankful — billion-dollar plants, and that's all they do is turn out cheap stock to go to the beverage manufacturers. And as you wish, non heat treatable, spent like one or two percent manganese indicates higher strength of this. But it's mostly there, performing though. The heat treatable, not heat treatable. 4000 series have silicon enough — basically is welding wire. The most common welding wires are pure aluminum — number 43, 4043, 4042. Well most of the other non-heat-treatable. The 5000 series, the Navy uses these for building hulls and has for 50 years. They're basing a little bit magnesium alloys.

There are two big uses of magnesium in the world. The biggest use is alloying with aluminum, okay. As it's like the biggest use of manganese in the world is alloying with steel okay. But manganese — ninety percent of manganese the world goes into steel. In the case of magnesium and things, only about fifty percent of all the magnesium — about thirty or forty percent of all magnesium goes into sacrificial anodes for corrosion and things like top water tanks and things like that. So it's just a sacrificial anode because its best property of all is it corrodes really well, okay. In fact the Navy loves it — Portfolio Me is where divers and the Navy do things, and they have a little test lab, research lab. A number of years ago they developed magnesium-carbon — carbon outlets — and they take carbon powders and magnesium powders and press them together, and you can stick this in seawater and it actually — you can try to polish it in the laboratory, and if you use a water-based polish slurry, it would grow the faster the new propulsion okay. So they use oil-based polishing. But if you stick it in seawater, one of the things that they found use for was salvage. You put in a little plastic bag, the diver takes it down beneath the surface, it gets a big plastic part that he puts over and connects it to whatever he wants, he puts this little plastic-coated piece of magnesium-carbon alloy in underneath that tarp, breaks of seawater comes in, and he generates a hydrogen bubble that floats the thing to the surface okay. That's how fast 64 hose — that you can generate your own hydrogen underwater okay. So it was a pretty cool — you don't have to carry big wraparound tanks of gas that are lighter than water, you can carry on the ground a little thing in the water will produce your own gas. Hi okay, very good.

Anyway, the other thing they did — it grows so fast that in cold environments they can strap it to the diver's belt, and then you take his life, and he can punch in the bag and it will create enough heat to keep them warm. So those are two — happy just to give you an idea how fast magnesium oxidizes over okay. It really curl — it's great okay, that's why we don't use it much okay. But the Department of Energy has been spending tens, if not hundreds, of millions of dollars every year for the last 50 years because oh if we can use magnesium in automobiles we can take out a thousand pounds out of every automobile and you know it will be great for sales. You're going to be really replacing those cars every six months.

And in fact they use magnesium under the dashboard where you can't see the corrosion okay, and where what's protected from the elements — updates the passenger compartment right. So under the dash, some of the dashboard structure, sub-structure, will be a cast magnesium panel okay. You think I'm recent activity — they use it in helicopters and other aircraft because you know helicopters get two hours of maintenance for every hour of flight, and if you're going to check things that often you know on your maintenance, you can use it for aerospace when you need lightweight great materials okay, just as a few maintenance issues.

Aircraft — the brakes on aircraft, big aircraft, are actually carbon-carbon composite okay. Very expensive. And in fact — well they're very expensive — it's possible that they might use some magnesium in some of the calipers and stuff, a structure that holds the brake pads, but the brake pads can get so hot when you're trying to stop 450 tons rolling down the highway 100 miles an hour, right ones okay. You need to dissipate a lot of energy. In fact I watched a program years ago on the certification process of the 777, Boeing 777, and they basically had to land the aircraft and stop it in such-and-such a distance, and then the brakes could catch fire. But they had to have at least three minutes before the fire crew can put it out, because, you know, in real-world situation the fire department's not standing right there with plenty dumps of rest at the end of the runway. So they had to give three minutes to get there. But you have to basically pass some tests where you don't destroy the rest of the engines or hydraulic leaks and things like that for three minutes. You can have a big flaming fire and your carbon-carbon composite brakes starting to go on, you know, burn. Remember carbon-carbon composite — so what we use for cruise missile engines and things like that, take high temperatures, but they don't last very long. But thanks so much — very much, okay.

I know how they commercially handle brake wear in the commercial airlines. It's prop landing. But United or American or whatever, they don't own the brakes. Honeywell, who makes the brakes, leases the brakes to the airline, and if they wear out quickly, Honeywell — well, they got a contract, they have to have brakes. You know, if you're the mechanic working for United or American, you look at it, needs to replace the brakes, the caution anything except the time of the labor to replace the brakes. But Honeywell has three — pays for all rights. So Honeywell has an incentive to develop brakes that will have long lifetime, and the aircraft — the airlines know exactly how much it's spending on brakes for every landing because they're paying by the landing okay.

They do the same thing now with engines. Either Pratt Whitney or General Electric — they want to tear investment, or it could be a brokerage firm or something, that basically releases the engine to the airline. And the airline pays so much — it costs powered by the hour okay. They pay so much for every hour the engine operates, and so the owner of the engine has every incentive to make engines last for a long time and not have to go back for maintenance overhauls because they're getting the profit out of the long-lasting engine. They have a lot of maintenance problems with the engines — again the mechanic has no incentive to not replace the engine that PC something wrong, doesn't cost anything new widget. Hey, you know, the brokerage company or Pratt Whitney they got them in their cubs, you know, they come in these circular shipping casts, they got on there, and just the labor and the time to bolt on.

But that's the way they're doing it. And even people are getting to the point where they're — the commercial airlines — they don't even want to own the aircraft, okay. I haven't quite gotten to aircraft by the hours I know of, which they're kind of heading in that direction okay. Start out with brakes, and then by the end then the engines, and it does provide a lot of right incentives for the mechanics okay, replace it if you need. Now there is a balance of it — the airline still has painful labor to replace it, but the cost of the parts are paid for by someone who's getting a fee for every landing.

Where we operate, we have the 5000 series of non-heat-treatable, we can get bolster — 100 percent strength of the weld, one hundred percent joint efficiency. We're course always — 5152 maybe is 54 used to — who, they come up with a couple new ones now. Heat-treatable magnesium-silicon alloys, where you have to heat the alloy them up, quench it in water, and then bring it up temperature high strength. You can get double the strength than the six thousand — five thousand — but when you weld it, you've been weld 6061, you may only get fifty percent or sixty percent joint efficiency. You cannot get a hundred percent joint. They have twice the strength, but once you weld it, everything becomes a casting again, and castings are not heat-treated. Oh, you guys — you could weld it and then reheat-treat the weldment okay, and you can get the strength up there, but that gets really expensive, amusing weldness of complex shape of the sort.

There's the 7000 hours — these are highest strength, and these are things like the wings on the aircraft and stuff. And then off to the end, where we don't have anything on this one, we have 8000 series, which is a catch-all, and now who's aluminum-lithium alloys, which have — it says this low ranking — other elements is 8000 series and 9000 and still in use. Those are the standard designation cowboys.

Yep — Student: The other day you showed us that stainless steel pot, it was cracking that they punched it out into the bottles aluminum?

Yeah, look at that, none of that really is — why do you look at the base there — because then good thermal conductivity. Let's say your steel pots okay, you're saying that you're boiling water sometimes been damaged it if it's longer, now it has copper things — that thing on the bottom. Pure aluminum has excellent water-produce resistance — the right aluminum alloys have excellent fresh water corrosion resistance. We build sewage treatment plants out of aluminum. They don't rust okay, if you pick the right alloys that don't have pitting or stress corrosion cracking problems, and there are plenty of aluminum alloys that don't have that. They tend to be lower strength, but you go down here to Deer Island treatment facility, where is what they do, clean up across the harbor water, it's all lower strength, you know, like its piping carrying water, dirty water but no — just work. So aluminum actually has excellent corrosion. So they will go fry pans okay. But friends is aluminum foil. A regular fire — maybe just above the melting temperature of aluminum, but you don't darn melt the aluminum cooking purposes — there's steam, cool — you're cooking something that's water — convicted, hey, you've been a Boy Scout, you ever had a foil dinner and wrap it in aluminum foil. If you put — if you put a steel bolt in there and put it in the fire, you'll probably melt your aluminum foil, because there's no steam to cool the aluminum foil okay. But you can melt the foil and go to hot fire okay, but you don't use you to it because just a little bit of moisture and it comes with what you're cooking.

Okay, so if we just — giving you trouble — actually one — we take a break, and we're going to take — one day you need a 10 minute break, are you let the stood right there.