Welcome to Tech Stuff, a production from iHeartRadio. Hate there and Welcome to tech Stuff. I'm your host, Jonathan Strickland. I'm an executive producer with iHeartRadio. And how the tech are you. I'm back after my vacation and then the holiday, and we're ready to tackle some new episodes. And there have been a few really big events in the news over the last few weeks that have a tech angle to them. There's the ongoing war in Ukraine, which was punctuated by a brief but notable coup attempt in Russia. There's the ongoing chaos over at Reddit, which has had effects far beyond Reddit itself because companies like Google have struggled to deliver satisfying search results, while hundreds of popular subreddits either remain dark or cluttered with memes, or some of them are set to not safe for work status and so they're not showing up properly. And then there's the Titan submersible, the vehicle where five people perished when the submersible suffered a catastrophic failure. I thought today I would talk about something relating to that last story. Now I'm not going to do a full story about the systems aboard the Titan submersible, because a lot of other people have already done that to varying degrees. I've seen some treatments that were very high level. I've seen one really decent video that talked about the various systems. If you do want a deeper conversation about the Titan submersible, I will go into it. But I figure that because there's already all this coverage out there, and even by the time this episode goes out, you know, with news going as fast as it does, a lot of people would already say it's old news. So chances are you might already know everything there is to know already. But if you would like me to do an episode about the Titan submersible and its various systems and how it worked, let me know and I will be sure to tackle that. So instead, for this episode, I thought I would focus on one of the primary materials, not the only one, but one of the big ones used in the construction of the Titan submersible, which is carbon fiber. I figure we can learn about the history of this material and what makes it special, and a little bit about how it's produced and what applications benefit from it versus ones that perhaps are not ideal applications of carbon fiber, because, as it turns out, carbon fiber has a lot of really good legit uses and applications, but not all of them make sense necessarily. But let's start by talking about carbon itself, because, as the name implies, carbon fiber is made up of carbon. It is the sixth most plentiful element in the universe by the number of atoms out there, according to Encyclopedia Britannica. That is, it trails behind hydrogen, helium, oxygen, neon, and nitrogen. On Earth, carbon doesn't really rank that high as far as elements found in the Earth's crust. In fact, it makes up about point zero two five percent of the Earth's crust. Now, despite this tiny little pathetic showing on the Earth's crust, carbon is actually part of more compounds than any other element. It can make more compounds than any element you can think of. In fact, it forms more compounds than all the other elements put together. Not put together in a compound, but I mean, like all their various combinations that we have discovered. Now you've likely heard the fray, the carbon based life form. At least you have. If you've watched any science fiction, you've probably heard the phrase organic compounds. Well, an organic compound is one that contains carbon, and any compound that does not contain carbon is an inorganic compound. So why do scientists associate the words life and organic with carbon. Well, it's because of carbon's tendency to form multitudes of compounds at a range of temperatures that we find here on Earth. Right, not all elements will form specific compounds under Earth temperatures. You might have to go to extremes to create certain compounds, but carbon readily forms countless compounds here on Earth just in regular Earth conditions. Many of those compounds are polymers. Polymers are large molecules that are made up of repeated units that are chained together, and all living stuff on Earth has carbon in it. So the thinking goes that carbon is just so well suited for making all these different compounds at temperatures that we associate as being livable temperatures that, at least here on Earth, it makes sense that it's a foundational element for life. Now, whether that is true elsewhere in the universe is hard for us to say. We have a sample size of one planet that we know to have life on it, and we live on it. That's it. We don't know of any other planets. It's quite possible there are maybe countless planets that have life on them. We don't know about them. Carbon's utility and tendency to bind in molecular compounds seems to give it an edge over others. But science fiction is filled with examples of, say, alien civilizations that turn out to be life forms that are based on other elements like silicon. It's just that carbon. Because it's such an interesting element, and it does form all these compounds so readily under earthlike conditions, we figure this is probably a cornerstone for life, at least life as we understand it. Carbon is non metallic. You know, if you burn wood down into charcoal, that's carbon. That's the charcoal is carbon. If you squeeze it hard and hot and long enough, which sounds a bit racy, but if you do that, then obviously you get a diamond. Carbon's really neat. Depending upon its molecular arrangement, it can be soft enough to use as pencil lead that would be graphite, right, Like, that's soft enough where if you drag the lead across vapor. It leaves some of it behind, right, it's just the pressure of your hand pushing the pencil against paper is enough to rub some of the carbon off. That's graphite, But it could also be made into a diamond, which is hard enough to cut most other materials. Again, it's all in that molecular structure. How are those carbon atoms arranged, and that's what really matters. How do those carbon atoms form crystaline structures. That determines the features of the material that you end up with in aggregate, whether that's coal or charcoal or diamond or anything like that. So that's carbon in a nutshell. Well, obviously you could spend multiple university level chemistry classes talking about it. I mean, the whole branch of organic chemistry focuses on it. But for our purposes we're gonna leave off from there because really there's not much more to say about it when we're talking about carbon fiber. So let's turn our attention there. And by the way, first of all, if you're in America, you're probably spelling fiber fiber, and if you're a brit you're probably spelling it fiber bray I bre Now I've already mentioned that carbon can form polymers, these long chain molecules that have repeating structures in them. A carbon fiber is essentially a really really long one of these, or rather a tube made up of these carbon nanotubes, by the way, kind of takes the same concept, but down to the nano level. Anyway, carbon fiber material ends up being lightweight and strong. It can be electrically conductive. It can also be thermally conductive, depending upon the carbon fiber used in the process you use to produce it. We'll talk more about the qualities of carbon fiber in a bit, but before we get to that, let's talk about its actual history. The story of carbon fiber is fascinating and it involves the inventor of the incandescent light bulb. And some of y'all clever smarty pants out there already know I'm being coy because I am not talking about Thomas Edison. Thomas Edison did not invent the incandescent light bulb. Now here in America. One of Edison's many nicknames is the Inventor of the light bulb. But the truth is that Joseph Wilson swan over in the UK, beat Edison to the punch by a couple of decades, and he did it using carbon fiber as a filament, or at least eventually he did use carbon fiber. So we're talking around eighteen sixty here, and before figuring out how to make carbon fiber, Swan had started off with carbonized paper as the filament. So this is the stuff folks would use to produce copies from one document. You would have your primary document and that would be on the top of a stack. Right below your primary document would be a sheet of carbonized paper that is paper coated with carbon on one side the site that's face downward from the top page. And then the next layer would be a blank sheet of paper that would be your copy that you'd be creating. So if you wrote on the top document, it would put enough pressure on this carbonized paper to leave an imprint on the blank sheet below that, and boom, you get two documents for the effort of making one. Now, you could actually do more layers of carbonized paper than blank sheets, but as you go down the layers, the pressure that is being put on the paper is decreasing, so unless you're being super heavy handed with your writing, the bottom copies will be much more faint than the upper ones would be, so you have a limit to how many copies you can produce through this method. Anyway, Swan was using carbonized paper as his filament, so he was connecting pieces of carbonized paper to a pair of electrodes, and he encased the whole thing in glass and attempted to create a vacuum inside the glass and then zap the heck out of the paper using the electrodes. The paper would heat up to the point of glowing, but the lack of oxidizers in the glass meant it wouldn't catch fire, except the Swan couldn't get a perfect vacuum seal in. The carbon paper didn't last very long, nor did it give off much light, so it wasn't really a practical filament for an incandescent bulb. It worked in the sense that it would glow, but it wasn't bright enough and it didn't last long enough for it to have any practical use. So Swan wanted to find something else to serve as the filament in his incandescent bulb. He was also experimenting with some other stuff like nitro cellulose. This stuff is highly flammable, so flammable that at one time it was being used as propellant for firearms, and it was called gun cotton back in those days. Well, Swan figured out that he could push nitro cellulus through like a mesh with very small holes in it, and the nitro cellulus would form fibers as a result, kinda like one of those playto playsets where you push down on a lever and it squeezes your play doo through a grid of holes, so you can make I don't know, dayglo, pink spaghetti or what. Well what Swan did the nitro cellulose, he also tried with carbon. He took carbon and in the form of cotton fibers. In this case, he treated the cotton fibers with sulfuric acid and then he pressed this solution through a screen with tiny holes in it, and on the other side of the screen he ended up with carbon fibers, and he could curl those fibers up to make tight spirals, which would increase the amount of material that he could fit between a pair of electrodes. And the carbon fibers, when used as a filament, produced better light than the carbon paper version he had been relying on and his process for making carbon fiber would become a standard. There are chemists and labs today who essentially use the exact same approach, though things get way more complicated when you're talking about mass engineering. For you, big industrial uses of carbon fiber. Now we're going to take a quick break. When we come back, we'll talk more about what makes carbon fiber special, but first let's hear from our sponsors. Okay. As smart as smarty pants Swan was, he wasn't able to see the potential mechanical applications of carbon fiber. He was just using it as an incandescent bulb filament. But he had no way to know that his material, if woven properly and combined with other stuff, could be strong, lightweight, and perfect for futuristic applications like the aerospace industry. Silly Swan not to anticipate all those uses back in the mid nineteenth century. Now. In fact, carbon fiber would kind of go into hibernation for many decades because there just weren't any practical uses for it or any real way to produce it at scale. It re emerged in nineteen fifty eight when a physicist named Roger Bacon produced carbon fiber and discovered that if constructed properly, it would be a really stiff, really strong, and extremely lightweight material. But it was super expensive to produce due to the time and effort involved, and the small amount of output you would get meant that there wasn't much you could do with it, so there was no commercial use for it just yet. But he was showing that this material had promise and that people would likewise start to pour money into improving manufacturing processes to make it practical. The evolution of those processes happened mainly in the nineteen seventies. Scientists in different parts of the world found new ways to produce carbon fibers. Some of those would be suitable for high heat applications, such as in the aerospace industry, where you might need to radiate heat outward from an engine before you get to a point where that's no longer your concern. Others would be suitable for more terrestrial uses. The eighties and nineties proved to be a boom era for carbon fiber research and development, as engineers recognized the material as being a good candidate for various applications, particularly in the space industry. Where there is a real need to create materials that are very strong, but you also want to cut way back on weight as much as you can in order to reduce the amount of energy you need to launch the stuff off this rock in the first place. So carbon fiber would become a really strong candidate for lots of space based applications. Now, as I mentioned earlier, carbon fiber has some really cool properties. It is really strong and really light. In fact, it's five to ten times stronger than steel, depending upon which source you're reading and the method of production for carbon fibers, and the specific type of steel you're talking about, and what you're actually looking at. So saying it's stronger than steel has really a simple answer to a complex situation, and it does mean that we need to spend a little bit more time to talk about material strength and what that actually means. So essentially, we quantify a material strength by examining how much stress or strain it can withstand before the structure we're looking at deforms to a point that when we remove the stress, it will not go back to its original shape. So, in other words, if you were to bend a bar and then you stop applying force, to the bar and the bar stays bent, you have exceeded the material strength of that bar. And if it pops back into its regular bar shape, then you did not exceed the material strength of that bar. There are different kinds of stresses that you can apply to materials, So when we say something is strong, we actually have to think about in what context. So again, let's talk about it having a short pipe. Now it's made out of whatever, it doesn't matter. We're just talking about the types of stresses you could put on this pipe. So let's say that you were to grip either end of that pipe and you were to pull in opposite directions, trying to allow lung gate the pipe. You're putting tension on it. This is the test for tensile strength of the pipe. How well does it hold up to stresses that attempt to elongate the material. And once you reach the point where you have exceeded that material strength, that tensile strength of that material, does it rip apart? Does it shatter? What happens? Now? What if instead of pulling on either end, you were pushing inward on either end of the pipe. You're trying to compress the pipe, You're squeezing the material. In other words, typically most materials have a high compressive strength compared to tensile strength, like a higher one. There are some elements at play here that can lead to other complications, Like, yes, it may be that it can withstand compression and it doesn't really compress beyond a certain point, but it might buckle, right, So there are other elements you have to look at when you're testing compressive strength. Then you've got sheer strength. Now, not sheer as an sh ee r strength. I'm talking about sh ea r strength like a pair of shears, because scissors effectively put this kind of stress on a material. So a shear stress is one in which the stress on either end of the material is parallel to each other, but they're in opposite direction. So if you think of scissors, like when the blades of scissors are coming together, one blade moving down, the other blade moving up, it is putting that kind of pressure on the material that you're cutting. Right, the one blade is moving up, one blade is moving down, so they are parallel to each other, but they're moving in opposite directions. And if you apply that kind of stress to a material, you can find out how resistant it is to shear stresses. So this is also called torsional loading. Right, You're at a torsional load to the material. Now, comparing materials against each other isn't always as simple as saying one is stronger than the other. One material might have greater tensile strength, meaning it could withstand elongation better than another material could in the same sort of situation. But maybe that first material can't hold up to the same sheer stresses that material two can withstand. You know, like some Facebook relationship status is it's complicated? Just does Facebook actually still have its complicated as a relationship status? Is anyone still on Facebook? Can I get a check on that? Anyway? Let's get back to carbon fiber. I think one way we can look at this is to think of strength in comparison to some other component and then compare two different materials. So in this case, we'll say strength to weight ratio. How strong is something compared to how much which it weighs. If we do that, if we look at it as strength to weight, carbon fiber is way stronger than steel. If you have a pound of carbon fiber and a pound of steel and they both have been made into some sort of you know, structure, the carbon fiber is going to be technically stronger than the steel is, and that's because steel is a really super dense material. So depending upon the application, a lightweight carbon fiber structure might be the way to go. For example, if you wanted to create a resilient helmet for football players I'm talking about American football here, well you would probably want to go with carbon fiber, not with steel, because I'm pretty sure no football player wants to wear a big steel helmet out on the field. But a lightweight helmet made with carbon fiber, that's a different story. However, if we were to instead look at strength compared to volume, the story is different. I watched a video from Crazy Hydraulic Press that compared stuff like acrylic fiberglass, aluminum, or aluminium if you prefer brass, titanium, steel, and carbon fiber to a hydraulic press test. The video has all of these materials made in the same simple shape a rectangular rod, so you know, it's like a rod, but it's squared off, it's not a circular rod, and it's the exact same dimensions for every single material, same length, same with you know, So that way you've got different substances, but they all are making rods of the exact same size from each substance. And that means that when you put the rods next to each other, the carbon fiber rod is going to weigh a lot less than the steel rod will, right, because steel is way more dense, it's heavier, it's gonna have more mass, even though the physical dimension of the two rods will otherwise be identical. Right, And if you put these two different rods to the test, the steel one's likely to hold up better because by volume, steel is the stronger material. If you look at weight, carbon fibers the stronger material. Like I said, it's complicated. And for the record, in the video I watched, the carbon fiber rod had a mass of fifteen point two grams and the steel rod had a mass of seventy six point eight grams. If we were to convert that to weight, and let's say we just go with pounds just to make it silly, then the carbon fiber weigh just point zero three pounds. The steel rod weighed point one seven, so way way more than the carbon fiber rod. And in the video they set the rods lengthwise across two prongs, metal prongs, and they use a hydraulic press to apply stress down across the length of the rod, like to push down right in the middle. So it's sort of like if you were to take a branch and try to break it in half across your leg. The carbon fiber rod broke when the press hit seven hundred and forty kilograms of weight at that point of the rod, and the steel held out till three thousand, eight hundred seventy kilograms. So again, carbon fiber seven hundred and forty, steel threey, eight hundred and seventy. But the story would be totally different if instead of volume, we were going by weight. If you had fifteen point two grams of carbon fiber and fifteen point two grams of steel, you would see that the carbon fiber would hold up way better because that would be a very small steel rod, very thin, and it would deform much faster than the carbon fiber would. And I'm going to talk more about carbon fiber, but we do need to take another quick break to thank our sponsors. We'll be right back to talk a bit more about what carbon fiber is used for and how it's used. Because it's not as simple as just making a frame out of carbon fiber. But we'll talk about that in just a moment. Okay, before the break, I talked about how carbon fiber is not just used as pure carbon fiber and stuff. In fact, we're usually talking about carbon fiber that is bonded to some other material, and carbon fiber access kind of like a reinforcing layer. So I like to think of it as similar to iron rebar that's inside a concrete structure, because the carbon fiber is providing strength and resilience, but it doesn't make up the totality of say the football helmet, for example, you have a binding agent in there. Typically you're using something like plastic and you're reinforcing it with carb fiber. So, to put it in another way, steel is really hard stuff. It's also really heavy, and it's challenging to mold steel into complicated shapes. We can do simple shapes pretty easily, but if you want to do something like a really a complex curve, maybe multiple curves in a single panel, it's hard to get steel to take that shape and not have it be an exorbitantly expensive process. But using a technology like injection molding and a material like plastic, you can create all sorts of wild shapes, and plastic is way lighter than steel, but of course it's nowhere near as strong. So combining plastic with carbon fiber can provide the strength you want, the weight you want, and the shape you want. Now, let's talk about what happens when carbon fiber fails. That is, when you apply a stress that exceeds the material strength of carbon fiber, and you're doing this to a structure made out of carbon fiber. Unlike some other materials, carbon fiber will not remain permanently deformed if a stress exceeds its material strength. Right, Like we were talking about the classic iron bars example of bending an iron bar, Well, you can bend an iron bar and it will stay bent, but that doesn't happen with carbon fiber. Instead, as dragon plate carbon fiber composites puts it quote, it will fail suddenly and catastrophically end quote. So in other words, once you go past the stress limit for carbon fiber, it's all over. You don't end up with a dent that can be hammered out later. You end up with shattered material or splintered material. To this day, carbon fiber fabrication is really expensive and it's complicated. When you look at a carbon fiber frame bicycle, for example, you're not looking at something that's made out of pure carbon fiber. You're really looking at a compound or a composite rather made out of material like plastic that has carbon fiber sandwiched inside of it to provide rigidity and strength. It wouldn't make any sense from an economic standpoint to go with a pure carbon fiber frame to replace, like I don't know, the chassis of an automobile, for example. You could go with a compound or composite that uses carbon fiber, and you would end up with a chassis that could be as strong as a steel chassis, but much much lighter, which ends up going to it's going to have a big effect on things like fuel economy, right because the engine's not going to have to move a vehicle that's nearly as heavy if the components are made from carbon fiber as opposed to steal. If you did go full carbon fiber, you would run into lots of problems. One would be the price tag because it would just be exorbitantly expensive. But also carbon fiber is not the perfect solution to all challenges. It's just a solution for certain engineering needs. Like there are components within vehicles that undergo a lot of different stress, right, not just tensile or compression, but also you know rotational that tortionial force can be a part of it. And in some of those applications a carbon fiber composite might shatter, whereas in other applications it's the carbon fiber composite is a perfect solution. So yeah, you have to pick and choose. You don't have just one material that's good for everything. Now, this brings us up to the tragedy of the Titan submersible. As we all know now, the Titan had a catastrophic failure that resulted in the implosion of the vehicle deep in the Atlantic Ocean. Authorities have now salvaged some of the wreckage and we can expect a full investigation to determine what was the point of failure, if it is in fact possible to determine that. Now, there's a chance that the culprit here is the carbon fiber hull, which wasn't totally carbon fiber. The end caps were made out of titanium, but the body of the submersible was carbon fiber or a carbon fiber composite. It's possible that the carbon fiber composite failed to hold up under the massive pressure that was exerted upon it by the sea. You know, as you get into those depths, that's a lot of weight that's pushing down on you. That pressure is incredible. It could also turn out that a totally different part of the submersible was to blame. One potential culprit could be the epoxy that actually bound the carbon fibers together. Remember, carbon fiber typically ends up being part of something else, like sandwiched in with other materials, and the epoxy was what kept the carbon fibers in their shape in the proper alignment. So maybe that epoxy, after multiple and prolonged exposure to sea water, degraded. We don't know yet. Still, the use of carbon fiber at all as a submersible material made it a little confusing for me. As we have covered, a big advantage of carbon fiber is its strength to weight ratio, and so it's really really good for applications where you want to limit weight as much as you can while not giving ground on strength. Right, you want something to be strong but light weight every pound counts. So again, when we look at the space industry, it makes perfect sense. You want materials that are as strong as they can be while still being light weight. Steel is strong, but steel's really heavy. So if you can make it out of something else that's resilient and tough like steel is, but is much lighter, that can make a lot of sense. But when it comes to submersibles, weight is not necessarily your primary concern. I mean, you don't want it to be so heavy that there's no way for you to lift it back out again. But you want really whole integrity. That's your main concern, not how heavy the submersible is. Most deep sea vehicles make use of steel, titanium, and aluminum rather than carbon fiber when it comes to what their pressure holes are made out of. Also, you know, there hasn't been that much research into how carbon fiber holds up under deep sea pressure, which means we don't know what we don't know. We have a big gap in our knowledge. And that was one of the big criticisms directed at ocean Gate, the company behind the Titan submersible, that the company had rushed through the process of making a submersible with a carbon fiber hull without first going through really rigorous testing to make certain that the carbon fiber hull was appropriate for the use that they had in mind for the titan mainly to go down and view the wreckage of the Titanic. Now, we do know that titan had already made trips down to the Titanic in the past. This was not the Titans made in voyage where the catastrophe happened. It had gone down there before, so the submersible had proven to be deep sea worthy on previous trips, which means we really do need to get a more definitive answer after authorities have investigated the wreckage to try and figure out what actually happened. Where was the failure, because right now it's all still a big question mark. Was it the carbon fiber hull, Maybe, but maybe not. As for carbon fiber itself, that's going to continue to be a really important material in engineering, particularly for things like aircraft, you know, the aerospace industry, things like automotive industry, bicycles, anywhere where you want a lot of strength but you want to cut down on weight. That's where it's going to make sense, not in every application, because again carbon fiber doesn't work under every situation at the same level of reliability as steel or other materials like aluminum, So it's all dependent upon the specific application. This is not like one material solves all problems. And the reason why I keep hammering on that, I know I sound like a broken record, but the reason I keep doing it is because I find that a lot of science reporting oversimplifies and just says carbon fiber is lighter and stronger than steel. And while that might be true in some particular instances, it doesn't mean that carbon fiber should replace steel in everything that we rely upon for you know, from steel. So that's why I go on and on about this, because I think you have to look at it as a more complicated subject than that. Otherwise you're over simplifying to a point where you just start to make bad decisions. Now I'm not saying that's what ocean Gate did in this case, but based upon a lot of the criticisms I've seen, it sounds as if Stockton Rush, the founder of ocean Gate, he was aboard the Titan submersible when it imploded, that perhaps he was a little too gung ho in forging a path forward to go through the rigorous steps that are really necessary to do things like make certain that the approach you're using is safe and reliable. Could this have tragedy have been prevented. It's hard to say because the investigation hasn't been complete yet. Maybe there was some wild thing that happened that we didn't anticipate, that couldn't have been anticipated, and it turns out that nothing we would do or have done would have changed it. Or maybe it turns out that this was something that was avoidable. We just don't know yet. So carbon fiber is still really interesting material, still really useful for specific applications, and this could also lead into a deeper discussion of things like carbon nanotubes, which in itself that's a fascinating technology too. When you start getting down to the nanoscale, you really see some very interesting features of materials, including carbon and carbon nanotubes being a super cool area of technology, but one we've been talking about for a long time, and for some people it may just seem like it was one of those technologies that seemed like it had a lot of promise but never went anywhere. That's not the case. It has gone places. It's just that it's not as sudden as we would all like, because we as we know, the real way toward the future is marking the passage of time and that doesn't change. That just keeps on creeping on, creeping on. All right, that's it for this episode about carbon fiber, a kind of overview of carbon fiber. And I hope all of you are well. I hope those of you in the United States had a fun and safe Fourth of July. I hope everyone to have a fun and safe Fourth of July. You just don't have a real reason to celebrate Fourth of July if you're not American, because it's related to our history. So hope you're all well, and I'll talk to you again really soon. Tech Stuff is an iHeartRadio production. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.

Welcome to Tech Stuff, a production from iHeartRadio. Hate there and Welcome to tech Stuff. I'm your host, Jonathan Strickland. I'm an executive producer with iHeartRadio. And how the tech are you. I'm back after my vacation and then the holiday, and we're ready to tackle some new episodes. And there have been a few really big events in the news over the last few weeks that have a tech angle to them. There's the ongoing war in Ukraine, which was punctuated by a brief but notable coup attempt in Russia. There's the ongoing chaos over at Reddit, which has had effects far beyond Reddit itself because companies like Google have struggled to deliver satisfying search results, while hundreds of popular subreddits either remain dark or cluttered with memes, or some of them are set to not safe for work status and so they're not showing up properly. And then there's the Titan submersible, the vehicle where five people perished when the submersible suffered a catastrophic failure. I thought today I would talk about something relating to that last story. Now I'm not going to do a full story about the systems aboard the Titan submersible, because a lot of other people have already done that to varying degrees. I've seen some treatments that were very high level. I've seen one really decent video that talked about the various systems. If you do want a deeper conversation about the Titan submersible, I will go into it. But I figure that because there's already all this coverage out there, and even by the time this episode goes out, you know, with news going as fast as it does, a lot of people would already say it's old news. So chances are you might already know everything there is to know already. But if you would like me to do an episode about the Titan submersible and its various systems and how it worked, let me know and I will be sure to tackle that. So instead, for this episode, I thought I would focus on one of the primary materials, not the only one, but one of the big ones used in the construction of the Titan submersible, which is carbon fiber. I figure we can learn about the history of this material and what makes it special, and a little bit about how it's produced and what applications benefit from it versus ones that perhaps are not ideal applications of carbon fiber, because, as it turns out, carbon fiber has a lot of really good legit uses and applications, but not all of them make sense necessarily. But let's start by talking about carbon itself, because, as the name implies, carbon fiber is made up of carbon. It is the sixth most plentiful element in the universe by the number of atoms out there, according to Encyclopedia Britannica. That is, it trails behind hydrogen, helium, oxygen, neon, and nitrogen. On Earth, carbon doesn't really rank that high as far as elements found in the Earth's crust. In fact, it makes up about point zero two five percent of the Earth's crust. Now, despite this tiny little pathetic showing on the Earth's crust, carbon is actually part of more compounds than any other element. It can make more compounds than any element you can think of. In fact, it forms more compounds than all the other elements put together. Not put together in a compound, but I mean, like all their various combinations that we have discovered. Now you've likely heard the fray, the carbon based life form. At least you have. If you've watched any science fiction, you've probably heard the phrase organic compounds. Well, an organic compound is one that contains carbon, and any compound that does not contain carbon is an inorganic compound. So why do scientists associate the words life and organic with carbon. Well, it's because of carbon's tendency to form multitudes of compounds at a range of temperatures that we find here on Earth. Right, not all elements will form specific compounds under Earth temperatures. You might have to go to extremes to create certain compounds, but carbon readily forms countless compounds here on Earth just in regular Earth conditions. Many of those compounds are polymers. Polymers are large molecules that are made up of repeated units that are chained together, and all living stuff on Earth has carbon in it. So the thinking goes that carbon is just so well suited for making all these different compounds at temperatures that we associate as being livable temperatures that, at least here on Earth, it makes sense that it's a foundational element for life. Now, whether that is true elsewhere in the universe is hard for us to say. We have a sample size of one planet that we know to have life on it, and we live on it. That's it. We don't know of any other planets. It's quite possible there are maybe countless planets that have life on them. We don't know about them. Carbon's utility and tendency to bind in molecular compounds seems to give it an edge over others. But science fiction is filled with examples of, say, alien civilizations that turn out to be life forms that are based on other elements like silicon. It's just that carbon. Because it's such an interesting element, and it does form all these compounds so readily under earthlike conditions, we figure this is probably a cornerstone for life, at least life as we understand it. Carbon is non metallic. You know, if you burn wood down into charcoal, that's carbon. That's the charcoal is carbon. If you squeeze it hard and hot and long enough, which sounds a bit racy, but if you do that, then obviously you get a diamond. Carbon's really neat. Depending upon its molecular arrangement, it can be soft enough to use as pencil lead that would be graphite, right, Like, that's soft enough where if you drag the lead across vapor. It leaves some of it behind, right, it's just the pressure of your hand pushing the pencil against paper is enough to rub some of the carbon off. That's graphite, But it could also be made into a diamond, which is hard enough to cut most other materials. Again, it's all in that molecular structure. How are those carbon atoms arranged, and that's what really matters. How do those carbon atoms form crystaline structures. That determines the features of the material that you end up with in aggregate, whether that's coal or charcoal or diamond or anything like that. So that's carbon in a nutshell. Well, obviously you could spend multiple university level chemistry classes talking about it. I mean, the whole branch of organic chemistry focuses on it. But for our purposes we're gonna leave off from there because really there's not much more to say about it when we're talking about carbon fiber. So let's turn our attention there. And by the way, first of all, if you're in America, you're probably spelling fiber fiber, and if you're a brit you're probably spelling it fiber bray I bre Now I've already mentioned that carbon can form polymers, these long chain molecules that have repeating structures in them. A carbon fiber is essentially a really really long one of these, or rather a tube made up of these carbon nanotubes, by the way, kind of takes the same concept, but down to the nano level. Anyway, carbon fiber material ends up being lightweight and strong. It can be electrically conductive. It can also be thermally conductive, depending upon the carbon fiber used in the process you use to produce it. We'll talk more about the qualities of carbon fiber in a bit, but before we get to that, let's talk about its actual history. The story of carbon fiber is fascinating and it involves the inventor of the incandescent light bulb. And some of y'all clever smarty pants out there already know I'm being coy because I am not talking about Thomas Edison. Thomas Edison did not invent the incandescent light bulb. Now here in America. One of Edison's many nicknames is the Inventor of the light bulb. But the truth is that Joseph Wilson swan over in the UK, beat Edison to the punch by a couple of decades, and he did it using carbon fiber as a filament, or at least eventually he did use carbon fiber. So we're talking around eighteen sixty here, and before figuring out how to make carbon fiber, Swan had started off with carbonized paper as the filament. So this is the stuff folks would use to produce copies from one document. You would have your primary document and that would be on the top of a stack. Right below your primary document would be a sheet of carbonized paper that is paper coated with carbon on one side the site that's face downward from the top page. And then the next layer would be a blank sheet of paper that would be your copy that you'd be creating. So if you wrote on the top document, it would put enough pressure on this carbonized paper to leave an imprint on the blank sheet below that, and boom, you get two documents for the effort of making one. Now, you could actually do more layers of carbonized paper than blank sheets, but as you go down the layers, the pressure that is being put on the paper is decreasing, so unless you're being super heavy handed with your writing, the bottom copies will be much more faint than the upper ones would be, so you have a limit to how many copies you can produce through this method. Anyway, Swan was using carbonized paper as his filament, so he was connecting pieces of carbonized paper to a pair of electrodes, and he encased the whole thing in glass and attempted to create a vacuum inside the glass and then zap the heck out of the paper using the electrodes. The paper would heat up to the point of glowing, but the lack of oxidizers in the glass meant it wouldn't catch fire, except the Swan couldn't get a perfect vacuum seal in. The carbon paper didn't last very long, nor did it give off much light, so it wasn't really a practical filament for an incandescent bulb. It worked in the sense that it would glow, but it wasn't bright enough and it didn't last long enough for it to have any practical use. So Swan wanted to find something else to serve as the filament in his incandescent bulb. He was also experimenting with some other stuff like nitro cellulose. This stuff is highly flammable, so flammable that at one time it was being used as propellant for firearms, and it was called gun cotton back in those days. Well, Swan figured out that he could push nitro cellulus through like a mesh with very small holes in it, and the nitro cellulus would form fibers as a result, kinda like one of those playto playsets where you push down on a lever and it squeezes your play doo through a grid of holes, so you can make I don't know, dayglo, pink spaghetti or what. Well what Swan did the nitro cellulose, he also tried with carbon. He took carbon and in the form of cotton fibers. In this case, he treated the cotton fibers with sulfuric acid and then he pressed this solution through a screen with tiny holes in it, and on the other side of the screen he ended up with carbon fibers, and he could curl those fibers up to make tight spirals, which would increase the amount of material that he could fit between a pair of electrodes. And the carbon fibers, when used as a filament, produced better light than the carbon paper version he had been relying on and his process for making carbon fiber would become a standard. There are chemists and labs today who essentially use the exact same approach, though things get way more complicated when you're talking about mass engineering. For you, big industrial uses of carbon fiber. Now we're going to take a quick break. When we come back, we'll talk more about what makes carbon fiber special, but first let's hear from our sponsors. Okay. As smart as smarty pants Swan was, he wasn't able to see the potential mechanical applications of carbon fiber. He was just using it as an incandescent bulb filament. But he had no way to know that his material, if woven properly and combined with other stuff, could be strong, lightweight, and perfect for futuristic applications like the aerospace industry. Silly Swan not to anticipate all those uses back in the mid nineteenth century. Now. In fact, carbon fiber would kind of go into hibernation for many decades because there just weren't any practical uses for it or any real way to produce it at scale. It re emerged in nineteen fifty eight when a physicist named Roger Bacon produced carbon fiber and discovered that if constructed properly, it would be a really stiff, really strong, and extremely lightweight material. But it was super expensive to produce due to the time and effort involved, and the small amount of output you would get meant that there wasn't much you could do with it, so there was no commercial use for it just yet. But he was showing that this material had promise and that people would likewise start to pour money into improving manufacturing processes to make it practical. The evolution of those processes happened mainly in the nineteen seventies. Scientists in different parts of the world found new ways to produce carbon fibers. Some of those would be suitable for high heat applications, such as in the aerospace industry, where you might need to radiate heat outward from an engine before you get to a point where that's no longer your concern. Others would be suitable for more terrestrial uses. The eighties and nineties proved to be a boom era for carbon fiber research and development, as engineers recognized the material as being a good candidate for various applications, particularly in the space industry. Where there is a real need to create materials that are very strong, but you also want to cut way back on weight as much as you can in order to reduce the amount of energy you need to launch the stuff off this rock in the first place. So carbon fiber would become a really strong candidate for lots of space based applications. Now, as I mentioned earlier, carbon fiber has some really cool properties. It is really strong and really light. In fact, it's five to ten times stronger than steel, depending upon which source you're reading and the method of production for carbon fibers, and the specific type of steel you're talking about, and what you're actually looking at. So saying it's stronger than steel has really a simple answer to a complex situation, and it does mean that we need to spend a little bit more time to talk about material strength and what that actually means. So essentially, we quantify a material strength by examining how much stress or strain it can withstand before the structure we're looking at deforms to a point that when we remove the stress, it will not go back to its original shape. So, in other words, if you were to bend a bar and then you stop applying force, to the bar and the bar stays bent, you have exceeded the material strength of that bar. And if it pops back into its regular bar shape, then you did not exceed the material strength of that bar. There are different kinds of stresses that you can apply to materials, So when we say something is strong, we actually have to think about in what context. So again, let's talk about it having a short pipe. Now it's made out of whatever, it doesn't matter. We're just talking about the types of stresses you could put on this pipe. So let's say that you were to grip either end of that pipe and you were to pull in opposite directions, trying to allow lung gate the pipe. You're putting tension on it. This is the test for tensile strength of the pipe. How well does it hold up to stresses that attempt to elongate the material. And once you reach the point where you have exceeded that material strength, that tensile strength of that material, does it rip apart? Does it shatter? What happens? Now? What if instead of pulling on either end, you were pushing inward on either end of the pipe. You're trying to compress the pipe, You're squeezing the material. In other words, typically most materials have a high compressive strength compared to tensile strength, like a higher one. There are some elements at play here that can lead to other complications, Like, yes, it may be that it can withstand compression and it doesn't really compress beyond a certain point, but it might buckle, right, So there are other elements you have to look at when you're testing compressive strength. Then you've got sheer strength. Now, not sheer as an sh ee r strength. I'm talking about sh ea r strength like a pair of shears, because scissors effectively put this kind of stress on a material. So a shear stress is one in which the stress on either end of the material is parallel to each other, but they're in opposite direction. So if you think of scissors, like when the blades of scissors are coming together, one blade moving down, the other blade moving up, it is putting that kind of pressure on the material that you're cutting. Right, the one blade is moving up, one blade is moving down, so they are parallel to each other, but they're moving in opposite directions. And if you apply that kind of stress to a material, you can find out how resistant it is to shear stresses. So this is also called torsional loading. Right, You're at a torsional load to the material. Now, comparing materials against each other isn't always as simple as saying one is stronger than the other. One material might have greater tensile strength, meaning it could withstand elongation better than another material could in the same sort of situation. But maybe that first material can't hold up to the same sheer stresses that material two can withstand. You know, like some Facebook relationship status is it's complicated? Just does Facebook actually still have its complicated as a relationship status? Is anyone still on Facebook? Can I get a check on that? Anyway? Let's get back to carbon fiber. I think one way we can look at this is to think of strength in comparison to some other component and then compare two different materials. So in this case, we'll say strength to weight ratio. How strong is something compared to how much which it weighs. If we do that, if we look at it as strength to weight, carbon fiber is way stronger than steel. If you have a pound of carbon fiber and a pound of steel and they both have been made into some sort of you know, structure, the carbon fiber is going to be technically stronger than the steel is, and that's because steel is a really super dense material. So depending upon the application, a lightweight carbon fiber structure might be the way to go. For example, if you wanted to create a resilient helmet for football players I'm talking about American football here, well you would probably want to go with carbon fiber, not with steel, because I'm pretty sure no football player wants to wear a big steel helmet out on the field. But a lightweight helmet made with carbon fiber, that's a different story. However, if we were to instead look at strength compared to volume, the story is different. I watched a video from Crazy Hydraulic Press that compared stuff like acrylic fiberglass, aluminum, or aluminium if you prefer brass, titanium, steel, and carbon fiber to a hydraulic press test. The video has all of these materials made in the same simple shape a rectangular rod, so you know, it's like a rod, but it's squared off, it's not a circular rod, and it's the exact same dimensions for every single material, same length, same with you know, So that way you've got different substances, but they all are making rods of the exact same size from each substance. And that means that when you put the rods next to each other, the carbon fiber rod is going to weigh a lot less than the steel rod will, right, because steel is way more dense, it's heavier, it's gonna have more mass, even though the physical dimension of the two rods will otherwise be identical. Right, And if you put these two different rods to the test, the steel one's likely to hold up better because by volume, steel is the stronger material. If you look at weight, carbon fibers the stronger material. Like I said, it's complicated. And for the record, in the video I watched, the carbon fiber rod had a mass of fifteen point two grams and the steel rod had a mass of seventy six point eight grams. If we were to convert that to weight, and let's say we just go with pounds just to make it silly, then the carbon fiber weigh just point zero three pounds. The steel rod weighed point one seven, so way way more than the carbon fiber rod. And in the video they set the rods lengthwise across two prongs, metal prongs, and they use a hydraulic press to apply stress down across the length of the rod, like to push down right in the middle. So it's sort of like if you were to take a branch and try to break it in half across your leg. The carbon fiber rod broke when the press hit seven hundred and forty kilograms of weight at that point of the rod, and the steel held out till three thousand, eight hundred seventy kilograms. So again, carbon fiber seven hundred and forty, steel threey, eight hundred and seventy. But the story would be totally different if instead of volume, we were going by weight. If you had fifteen point two grams of carbon fiber and fifteen point two grams of steel, you would see that the carbon fiber would hold up way better because that would be a very small steel rod, very thin, and it would deform much faster than the carbon fiber would. And I'm going to talk more about carbon fiber, but we do need to take another quick break to thank our sponsors. We'll be right back to talk a bit more about what carbon fiber is used for and how it's used. Because it's not as simple as just making a frame out of carbon fiber. But we'll talk about that in just a moment. Okay, before the break, I talked about how carbon fiber is not just used as pure carbon fiber and stuff. In fact, we're usually talking about carbon fiber that is bonded to some other material, and carbon fiber access kind of like a reinforcing layer. So I like to think of it as similar to iron rebar that's inside a concrete structure, because the carbon fiber is providing strength and resilience, but it doesn't make up the totality of say the football helmet, for example, you have a binding agent in there. Typically you're using something like plastic and you're reinforcing it with carb fiber. So, to put it in another way, steel is really hard stuff. It's also really heavy, and it's challenging to mold steel into complicated shapes. We can do simple shapes pretty easily, but if you want to do something like a really a complex curve, maybe multiple curves in a single panel, it's hard to get steel to take that shape and not have it be an exorbitantly expensive process. But using a technology like injection molding and a material like plastic, you can create all sorts of wild shapes, and plastic is way lighter than steel, but of course it's nowhere near as strong. So combining plastic with carbon fiber can provide the strength you want, the weight you want, and the shape you want. Now, let's talk about what happens when carbon fiber fails. That is, when you apply a stress that exceeds the material strength of carbon fiber, and you're doing this to a structure made out of carbon fiber. Unlike some other materials, carbon fiber will not remain permanently deformed if a stress exceeds its material strength. Right, Like we were talking about the classic iron bars example of bending an iron bar, Well, you can bend an iron bar and it will stay bent, but that doesn't happen with carbon fiber. Instead, as dragon plate carbon fiber composites puts it quote, it will fail suddenly and catastrophically end quote. So in other words, once you go past the stress limit for carbon fiber, it's all over. You don't end up with a dent that can be hammered out later. You end up with shattered material or splintered material. To this day, carbon fiber fabrication is really expensive and it's complicated. When you look at a carbon fiber frame bicycle, for example, you're not looking at something that's made out of pure carbon fiber. You're really looking at a compound or a composite rather made out of material like plastic that has carbon fiber sandwiched inside of it to provide rigidity and strength. It wouldn't make any sense from an economic standpoint to go with a pure carbon fiber frame to replace, like I don't know, the chassis of an automobile, for example. You could go with a compound or composite that uses carbon fiber, and you would end up with a chassis that could be as strong as a steel chassis, but much much lighter, which ends up going to it's going to have a big effect on things like fuel economy, right because the engine's not going to have to move a vehicle that's nearly as heavy if the components are made from carbon fiber as opposed to steal. If you did go full carbon fiber, you would run into lots of problems. One would be the price tag because it would just be exorbitantly expensive. But also carbon fiber is not the perfect solution to all challenges. It's just a solution for certain engineering needs. Like there are components within vehicles that undergo a lot of different stress, right, not just tensile or compression, but also you know rotational that tortionial force can be a part of it. And in some of those applications a carbon fiber composite might shatter, whereas in other applications it's the carbon fiber composite is a perfect solution. So yeah, you have to pick and choose. You don't have just one material that's good for everything. Now, this brings us up to the tragedy of the Titan submersible. As we all know now, the Titan had a catastrophic failure that resulted in the implosion of the vehicle deep in the Atlantic Ocean. Authorities have now salvaged some of the wreckage and we can expect a full investigation to determine what was the point of failure, if it is in fact possible to determine that. Now, there's a chance that the culprit here is the carbon fiber hull, which wasn't totally carbon fiber. The end caps were made out of titanium, but the body of the submersible was carbon fiber or a carbon fiber composite. It's possible that the carbon fiber composite failed to hold up under the massive pressure that was exerted upon it by the sea. You know, as you get into those depths, that's a lot of weight that's pushing down on you. That pressure is incredible. It could also turn out that a totally different part of the submersible was to blame. One potential culprit could be the epoxy that actually bound the carbon fibers together. Remember, carbon fiber typically ends up being part of something else, like sandwiched in with other materials, and the epoxy was what kept the carbon fibers in their shape in the proper alignment. So maybe that epoxy, after multiple and prolonged exposure to sea water, degraded. We don't know yet. Still, the use of carbon fiber at all as a submersible material made it a little confusing for me. As we have covered, a big advantage of carbon fiber is its strength to weight ratio, and so it's really really good for applications where you want to limit weight as much as you can while not giving ground on strength. Right, you want something to be strong but light weight every pound counts. So again, when we look at the space industry, it makes perfect sense. You want materials that are as strong as they can be while still being light weight. Steel is strong, but steel's really heavy. So if you can make it out of something else that's resilient and tough like steel is, but is much lighter, that can make a lot of sense. But when it comes to submersibles, weight is not necessarily your primary concern. I mean, you don't want it to be so heavy that there's no way for you to lift it back out again. But you want really whole integrity. That's your main concern, not how heavy the submersible is. Most deep sea vehicles make use of steel, titanium, and aluminum rather than carbon fiber when it comes to what their pressure holes are made out of. Also, you know, there hasn't been that much research into how carbon fiber holds up under deep sea pressure, which means we don't know what we don't know. We have a big gap in our knowledge. And that was one of the big criticisms directed at ocean Gate, the company behind the Titan submersible, that the company had rushed through the process of making a submersible with a carbon fiber hull without first going through really rigorous testing to make certain that the carbon fiber hull was appropriate for the use that they had in mind for the titan mainly to go down and view the wreckage of the Titanic. Now, we do know that titan had already made trips down to the Titanic in the past. This was not the Titans made in voyage where the catastrophe happened. It had gone down there before, so the submersible had proven to be deep sea worthy on previous trips, which means we really do need to get a more definitive answer after authorities have investigated the wreckage to try and figure out what actually happened. Where was the failure, because right now it's all still a big question mark. Was it the carbon fiber hull, Maybe, but maybe not. As for carbon fiber itself, that's going to continue to be a really important material in engineering, particularly for things like aircraft, you know, the aerospace industry, things like automotive industry, bicycles, anywhere where you want a lot of strength but you want to cut down on weight. That's where it's going to make sense, not in every application, because again carbon fiber doesn't work under every situation at the same level of reliability as steel or other materials like aluminum, So it's all dependent upon the specific application. This is not like one material solves all problems. And the reason why I keep hammering on that, I know I sound like a broken record, but the reason I keep doing it is because I find that a lot of science reporting oversimplifies and just says carbon fiber is lighter and stronger than steel. And while that might be true in some particular instances, it doesn't mean that carbon fiber should replace steel in everything that we rely upon for you know, from steel. So that's why I go on and on about this, because I think you have to look at it as a more complicated subject than that. Otherwise you're over simplifying to a point where you just start to make bad decisions. Now I'm not saying that's what ocean Gate did in this case, but based upon a lot of the criticisms I've seen, it sounds as if Stockton Rush, the founder of ocean Gate, he was aboard the Titan submersible when it imploded, that perhaps he was a little too gung ho in forging a path forward to go through the rigorous steps that are really necessary to do things like make certain that the approach you're using is safe and reliable. Could this have tragedy have been prevented. It's hard to say because the investigation hasn't been complete yet. Maybe there was some wild thing that happened that we didn't anticipate, that couldn't have been anticipated, and it turns out that nothing we would do or have done would have changed it. Or maybe it turns out that this was something that was avoidable. We just don't know yet. So carbon fiber is still really interesting material, still really useful for specific applications, and this could also lead into a deeper discussion of things like carbon nanotubes, which in itself that's a fascinating technology too. When you start getting down to the nanoscale, you really see some very interesting features of materials, including carbon and carbon nanotubes being a super cool area of technology, but one we've been talking about for a long time, and for some people it may just seem like it was one of those technologies that seemed like it had a lot of promise but never went anywhere. That's not the case. It has gone places. It's just that it's not as sudden as we would all like, because we as we know, the real way toward the future is marking the passage of time and that doesn't change. That just keeps on creeping on, creeping on. All right, that's it for this episode about carbon fiber, a kind of overview of carbon fiber. And I hope all of you are well. I hope those of you in the United States had a fun and safe Fourth of July. I hope everyone to have a fun and safe Fourth of July. You just don't have a real reason to celebrate Fourth of July if you're not American, because it's related to our history. So hope you're all well, and I'll talk to you again really soon. Tech Stuff is an iHeartRadio production. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.