I'm far from an expert when it comes to firing ceramics. I've been using the same programs on the same kilns in my classroom at Princeton HS for almost twenty years now, and as I've learned from the actual ceramics teacher in my school, that likely means my elements and thermocouples aren't anywhere near optimal working condition anymore. She offered to replace the elements for me, and I think I'm going to take her up on that this year.
I've also learned that I should probably be using some pyrometric cones to confirm some of the temperatures that I think we're getting to according to the thermocouples and the digital controllers on the various kilns.
A little while ago, I went looking for a video to explain the oxidation/reduction aspects of raku so I could assign it for my students to watch while I was out of the classroom for a day.
Sadly I didn't find one, but I did come across this video from the inaugural ASM teacher camp in Butte, Montana. It doesn't explain the redox aspects of raku - though the title suggests that it might - but it does include your friendly, neighborhood blogger in his orange polo shirt (ASM-branded, natch), and jeans.
Because the video doesn't explain the science, I'll give a quick version...
We use a clear glaze into which we mix oxidized metals (cobalt oxide, iron oxide, copper carbonate, nickel oxide, etc). Each glaze gets just one of those oxidized metals.
The pottery is taken out of the kiln while it's hot - somewhere around 1050 oC. At that point the glaze is molten, allowing oxygen to leave the glaze.
The hot pottery is placed into a metal can with something flammable. In this situation we're using torn up newspaper.
The torn up newspaper catches fire and starts to consume the oxygen in the now-sealed can.
The carbon and hydrogen from the paper continues to 'search' for more oxygen, so it reduces the metal in the glaze and takes the oxygen from the oxidized metals. (This only works if the pot is hot enough for the glaze to stay molten in the reduction environment.)
The glaze cools, sealing in the now-reduced metal within it, leaving - hopefully, if everything works right - reduced, shiny metal in the glaze.
The pottery is quenched in water to lock in the final version of the metal within the glaze - either reduced or oxidized metal.
You can see lots of versions of raku pottery on other blog posts.
I need to remember to take my umbrella the next time I got to Chicago in case a 350-pound Carrara marble slab comes tumbling down from a building.
The building in question - now known as the Aon Center - was originally clad in the aforementioned Carrara marble, using panels that were 1.25 inches thick.
Apparently marble isn't terribly durable when going through extreme freeze-thaw-hot-summer cycles with each temperature shift leading to tiny cracks developing which allowed water to get into the cracks and freeze - like pot holes forming on the side of the (initially) world's 4th tallest building.
Eventually, all the marble panels were replaced with granite which seems to weather the Chicago winters far better and is less prone to hurling itself off the building's facade and onto the tourists looking up with their mouths agape.
A few years back I took a workshop from the American Ceramic Society and got a free Materials Science Classroom Kit.
The workshop was a bit of a bust because of a minor snowstorm that kind of cancelled the workshop even though half the participants still showed up, and the presenters did a game job of presenting the workshop as best they could with their limited staff and attendees.
In case you'd thought about getting this kit or taking the workshop, I thought I'd run through what you get for $249 (seriously, that's the price as of my posting of this info.)
The box contains...
package of 60 bobby pins
propane torch top
5 small C clamps (maybe 2")
20' rolls of nichrome and copper wire
alligator clips with wires
string
small electronic balance
6" of nitinol wire
6" of steel wire
100mL beaker
plastic cups
hole punch
rubber-coated beaker tongs
dust mask
plastic measuring spoons
disposable pipets
four LEDs
two piezoelectric discs
two piezoelectric polymer films
3 each glass rods (soda lime, borosilicate, and fused silca)
hot or not (putting a torch to the refractory brick and showing the it doesn't transmit heat well)
candy fiber pull (melting jolly ranchers in the beaker and pulling it to make 'glass' fibers)
piezoelectric materials (lighting the LEDs by bending or tapping the piezoelectric materials)
shape memory alloys (demonstrating steel wire and nitinol wire both going into hot water)
thermal shock (heating the three types of glass rods and plunging them into cold water)
glass bead on a wire (making borax glass on copper and nichrome wires with a torch)
engineered concrete (cement pucks in styrofoam bowls with student-chosen reinforcements)
thermal processing of bobby pins (heat treating bobby pins)
How strong is your chocolate (doing 3-point bend tests by hanging plastic cups with weights [pennies are suggested] from various chocolate candy bars)
A textbook The Magic of Ceramics (currently $60 at Amazon)
The labs are solid labs, though I will say that many of them will seem very familiar to anyone who has attended our ASM summer workshops. (Note that I'm not claiming any sort of copying but rather than both programs have some similar DNA to them, likely coming from labs that some teachers have done in classrooms for years. Heck, the kit is endorsed by a quote from our very own Andy Nydam:
"The lessons are some of the most well-written lessons I’ve seen in the industry. They are truly great and valuable for all science teachers!"
I'll admit that I'm not sure the materials included are worth $249, particularly because teachers would have to provide a fair bit of - admittedly inexpensive - materials to perform each of the labs. The teacher manual is available online and most of the materials are easy enough to source (the nitinol, nichrome, piezoelectric film and discs, borosilicate and silica glass, and space shuttle tile would be the only ones that aren't available from Walmart or a big box hardware store). As to whether those materials are rare enough to you for the $249 price tag is up to you.
The lab manual is available online (link up above), and the textbook would be easy enough to find at a decent library. The consumable materials are also available in their replacement materials kit for just $80 and includes most of the tougher-to-source materials (other than the refractory brick).
There is also an option to request a kit grant, but that looks to be more about running a program where you need multiples of either this kit or the mini materials kit or their glass science kit - neither of which I can speak to as I have no experience with either.
I was at Indian Lake in northern Ohio recently and saw a vehicle/machine driving back and forth in the water about twenty feet out from Oldfield Beach. When I asked what the machine was doing, I was told that it was chopping up and supposedly harvesting invasive pondweed (details of the plan here) that was plaguing the lake because of its shallowness and prevalence of fertilizer run-off from nearby farms leading to blue-green algae blooms and near dead zones.
I don't have any idea what they're doing with the pondweed that they harvest from Indian Lake, but I feel like I might was to put those folks in touch with the subject of today's video as he seems to have found something to do with unwanted aquatic plant growth.
I'll admit that I do wish today's video would do a little better job of telling what porcelain is rather than just telling why it's so labor intensive to make.
So I went looking around the intertubes to find some definitions of what porcelain is.
Porcelain is a ceramic material made by heating raw materials, generally including kaolinite, in a kiln to temperatures between 1,200 and 1,400 °C (2,200 and 2,600 °F). The greater strength and translucence of porcelain, relative to other types of pottery, arise mainly from vitrification and the formation of the mineral mullite within the body at these high temperatures.
Porcelain, vitrified pottery with a white, fine-grained body that is usually translucent, as distinguished from earthenware, which is porous, opaque, and coarser. The distinction between porcelain and stoneware, the other class of vitrified pottery material, is less clear. In China, porcelain is defined as pottery that is resonant when struck. In the West, it is a material that is translucent when held to the light.
a hard, fine-grained, sonorous, nonporous, and usually translucent and white ceramic ware that consists essentially of kaolin, quartz, and a feldspathic rock and is fired at a high temperature
Ceramic is a broad term for various materials that are made by firing clay or other mixtures at extremely high temperatures. Generally, it includes products such as pottery, tiles, and cookware. The surfaces of ceramic can be painted or glazed to create different finishes and styles.
Ceramics are usually broken down into three categories: porcelain, stoneware, and earthenware.
Porcelain is denser than stoneware and earthenware, which makes it the strongest type of ceramic. In addition to its strength and durability, porcelain also has an extremely smooth surface that lends itself well to decorative treatments such as hand painting or airbrushing. Porcelain is also the least porous type of ceramic material, which makes it ideal for use in bathrooms or kitchens where watertightness is important.
Earthenware is the softest type of ceramic material and can be very delicate in nature. It also has a tendency to absorb moisture easily.
Earthenware pieces tend to be thicker than their porcelain counterparts due to their lack of strength and durability. As a result, they are often produced in simpler shapes with fewer decorative details since any intricate detail may be too delicate to survive regular use or exposure over time.
Stoneware falls somewhere between porcelain and earthenware in terms of strength and durability making it a popular choice for everyday items like plates or mugs since it can withstand some wear-and-tear but isn’t overly fragile like earthenware pieces tend to be. Stoneware has been used throughout history for many types of items including storage jars, jugs, figurines and table services sets due its versatility in design options depending on the levels at which it’s fired during production processes.
...
Porcelain is a fine-grain ceramic material made from kaolin, a white clay mined in various parts of the world. It is used for tableware, tiles, and other applications where strength, hardness and stain resistance are desired.
Porcelain has an extremely low porosity—it is nearly waterproof—and it is considered to be thermal shock resistant. It can withstand temperatures up to 1800 degrees Fahrenheit and it does not react with chemicals in the same way as other ceramics. Porcelain can accept a wide variety of decorative glazes and finishes, which makes it ideal for many applications.
When comparing porcelain to its relative ceramic, there are some key differences to consider:
Porcelain has a finer grain than ceramic and its ingredients go through more processing before they can be used as a material choice.
Due to its high degree of density, porcelain is more durable than ceramics but it also costs more because of the processing involved in producing the material.
Every time I see things like this I am reminded of how fortunate a life I am living.
I don't think it's too radical an idea that we might need to cover some sustainability in our materials science courses. When the limestone from this quarry is being used to make cement and paper and tiles and much more, we might want to rethink whether we actually need to use that much limestone - and if we do, how we might want to pay a little more so that the people who are manning those quarries can actually survive the process.
I stumbled upon the above video in searching for totally different ceramic stuff on YouTube, but I was immediately taken by the magnetic stalactites that the artist is creating in the video still.
He mentions in the video that he creates them by using a magnetic clay of his own devising between two super-strong magnets.
Then the video goes through him using his ceramic as an electrode - which inherently doesn't make sense to me since ceramics are naturally non-conductive - in what appears to be a copper (II) sulfate solution and using a current to grow copper crystals on the ceramics.
Then the gold, pocked inner surface of other ceramic bowls showed up, and I was blown away with the beauty.
So I went searching the guy out to see just how much one of his pieces would cost me - assuming fully that I wasn't going to be able to afford it.
The first 7:53 of this video is all about orbital mechanics - which is interesting, I'll grantcha, but isn't the focus of this blog.
If orbital mechanics is your jam, go play some Kerbel and get back when you reach an expolanet.
We're here to learn about material science, and that's where the video takes a big turn at about 7:55, first exploring the carbon foam composite of the solar shield, itself, and the ceramic, reflective paint on its sun-side.
Then - at 9:15 - we get into the solar probe cup and its measurements of the solar wind. The big issue there is that the cup can't hide behind that carbon-carbon composite shield. It has to survive nakedly in the solar wind at 1400 degrees C which sort of limits the acceptable materials. The conductive mesh is made of acid-etched tungsten, and the wires leading to and from the mesh are a niobium alloy called niobium C-103 (89% Nb, 10% Hf, and 1% Ti) with sapphire bead insulation...you know, as is tradition.
Space is frickin' wild, man.
And that doesn't even get into how we tested those materials - a whole other journey that's covered after 13:55 in the video.
In fact, there aren't even any words in the video - either recorded diegetic or narrated after the fact.
Instead, we just get some stunningly gorgeous raku pottery from an outdoor kiln.
We can see the fully oxidized, green of the copper glaze and the stunning, reduced copper after the quench.
The Clay Collective published three videos. I've put the prettiest one up above, but the other two are worth seeing, as well. 'Round 3' shows them setting up the kiln initially, and 'Round 2' shows pieces that didn't get nearly the reduction that they got in the video above (assumedly, 'Round 1').
I find myself digging the shift that has taken place on the Real Engineering channel.
Brian McManus - the host of Real Engineering - has been putting in a ton of work to step up the video's quality and the content's depth. I find myself learning a whole bunch of new stuff in every video that he's posting.
In this one, McManus details the reasons that the solar energy striking most photovoltaic solar cells is only turned into electricity at a lab-tested 20% efficiency - and even lower 18% real-world efficiency.
This is due to light being reflected, the threshold energy necessary for silicon to release electrons, heat build up, adding metal contacts which block light hitting the cell itself, oxygen defects in the silicon wafers itself.
...and there's some awesome explanation (along with animation) of how p-type and n-type semiconductors are used to produce voltages in solar cells.
The Real Engineering videos do tend toward higher level concepts nowadays, but they're brilliantly cited and clearly explained.
I know, feel free to applaud for taking such a bold, controversial stand.
They're bad for pests, for us, and generally for the environment.
But there are a few pesticides that aren't terribly bad for us or the environment while still maintaining the 'really bad' nature for pests. There's diatomaceous earth, for example, which works by grinding away at insect exoskeletons but is relatively harmless to anything with skin and an endoskeleton.
In the linked article from phys.org, experimenters applied a spray of perlite, a volcanic glass, and water and measured its effectiveness in killing mosquitoes - primarily malaria-infected ones.
Their results suggest that perlite is highly effective - as high as 78% mortality rate six months after application, and the perlite seems to be safe for people in the huts. According to the article, the mechanism of mortality is that the perlite particles simply dehydrate the mosquito after they're picked up. The mosquitos also didn't show any indication of learning to avoid the perlite-sprayed walls or building up a tolerance to the perlite.
The article might say that perlite isn't a silver bullet, but early indications looks to me like it might be.
First off, thanks to Eric Moorman who sent me this video. Mad love for Eric.
Let's go through the material science awesomeness in this video about how to get the most durable, prettiest finish on your car.
The first four minutes or so are all about the causes of the tiny scratches on car surfaces and how to clean the car before applying a finish coating of either wax or ceramic.
At 4:10 we get a discussion of wax, and the host even uses the word hydrophobic, explaining how the water beads up because of the hydrophobic nature of the wax.
At 5:10, we finally get to the ceramics, "a non-metallic solid material making up an inorganic compound of metal and nonmetal (or metalloid) atoms primarily held in ionic and covalent (?) bonds." The host explains that those atoms can be crystalline (in various ways) or even vitrified.
There's an explanation of the Moh's hardness scale, and a mention that there are other ways to measure hardness like via measuring scratch resistance.
Heck, he even shows a very simplified version of covalent bonding with shared pairs of electrons.
We get into using nanotextures to increase the hydrophobic character of a surface, increasing the contact angle between a drop and the surface - with a nice diagram, too - explaining super hydrophobic coatings.
Admittedly, I had no idea such coatings existed for cars.
0:15 - dutch angles shifting back and forth (repeats at 0:31...and 0:53...and so many times) just to make things 'exciting'
0:25 - flickering font on screen
0:37 - jumping footage, eliminating some frames to make the motion 'edgier'
0:40 - the good doctor's duster coat
0:46 - repeated, slightly closer footage of the same hammer hitting a window
0:49 - animation repeating quickly again and again
1:24 - science lab lit with green, orange, and purple lights
1:53 - slow motion glass jar drop
2:24 - unnecessary sound effect
2:50 - glass falling footage repeated from earlier
2:53 - racing footage stretched and tilted as it plays
3:09 - washed-out airplane footage tilting back and forth to a rock score
Ok, I quit...the cliches are just too numerous for me to note for the full fifteen minute run time of the video.
It's like the Bill Nye Show has come alive all over again.
I will recap the content, however...
hardening tempered glass
space shuttle tiles
ceramic engineering lab footage
basic ceramic properties
possibilities of ceramic engines in cars
catalytic converters
superconductivity
piezoelectric crystals
liquid crystal window coatings
fiber optics
bioceramics
The animation at 2:03 - showing ion exchange to harden the surface a glass (similar to the production of Gorilla Glass) isn't necessarily a 90's cliche, but it is really well explained.
In case you're curious, Alfred University still hosts the New York State College of Ceramics. Looks like it might be fun to visit. Plus it looks like Alix (now Alexis) Clare is still there.
Wait, if the material is actually a mixture of aluminum, oxygen, and nitrogen - "also known as Alon" (about which I've posted before)- then it's really a ceramic not a metal at all.
I feel a little mislead by this obvious click-bait title.
Clearly piezoelectricity is way more common than I knew.
Sugar crystals? DNA? Bones? All are piezoelectric?
And if piezoelectric crystals lack a center of symmetry (2:20), how the heck is quartz piezoelectric? It looks awfully symmetrical to me.
Apparently, though, the quartz crystal is absolutely piezoelectric, as shown by Bill Hammack, the Engineer Guy...
Theoretically, it's possible to make and test your own piezoelectric crystal at home...(though sadly he uses a commercial piezoelectric crystal to make his guitar pickup)
CarbonCure works with existing concrete factories to simply add CO2 without changing the concrete recipe or machines. CO2 is collected from smokestacks of large polluters like coal power or cement plants and brought to the concrete factory for recycling. Our proprietary technology injects the CO2 gas into the concrete where it is converted into more stone within the concrete...
The best part is that it costs about the same and it keeps the same good looks and durability that you're used to with regular concrete.
It's green concrete without the trade-offs.
...I find myself skeptical as to just how we get benefits without any downsides at all.
Ok, I don't get it. My understanding is that cement is produced by heating calcium carbonate to decompose it into calcium oxide and carbon dioxide. Why, then, can we just add the carbon dioxide back into the concrete to produce calcium carbonate later in the process? And if that's the case, why did we both to take the carbon dioxide out of the calcium carbonate in the first place?
CarbonCure's system takes captured CO2 and injects it into concrete as it's being mixed. Once the concrete hardens, that carbon is sequestered forever. Even if the building is torn down, the carbon stays put. That's because it reacts with the concrete and becomes a mineral.
...
"The best thing about it is the mineral itself improves the compressive strength of the concrete," Christie Gamble, the director of sustainability at CarbonCure, told CNNMoney."
Again with the extraordinary claims. I'm going to need a little more detail.
From the CarbonCure website...
The technology may be used to increase the compressive strength
performance of a concrete mix. The strength improvement can then be
leveraged in the optimization of the mix design for a specific end goal[.] (source)
...
Once injected into the wet concrete mix, the CO2 reacts with calcium ions from cement to form a nano-sized calcium carbonate mineral that becomes permanently embedded in the concrete. (source)
I hope that this technology is as perfect as is suggested, but I'm not holding my breath.
I teach, admittedly, a simplified version of material science. That's partially because my students aren't quite ready for more advanced versions but also because I'm not always aware of just how much more there is to material science.
For example, when we study ceramics and glasses, one of the things I explain is that glass is amorphous, and one indicator of that is the fact that it's transparent to visible light. Ceramics, on the other hand, are generally crystalline, and that's why they're opaque.
It turns out things are much more subtle than that. Check out Surmet's ALON (aluminum oxynitride.) From the wikipedia article...
AlON is optically transparent (≥80%) in the near-ultraviolet, visible and midwave-infrared regions of the electromagnetic spectrum. It is 4 times harder than fused silica glass, 85% as hard as sapphire, and nearly 15% harder than magnesium aluminate spinel. Since it has a cubic spinel structure, it can be fabricated to transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. AlON is the hardest polycrystalline transparent ceramic available commercially. Combination of optical and mechanical properties makes this material a leading candidate for lightweight high-performance transparent armor applications such as bulletproof and blast-resistant windows and for many military infrared optics. AlON-based armor has been shown to stop multiple armor-piercing projectiles of up to 50 cal. It is commercially available in sizes as big as 18x35-inch monolithic windows.
There is so much to learn...for my students and for me, too.
The titanium, then, can be oxidized to produce gorgeous colors. The process of creating an oxide coating on a metal via application of electrical current is called anodizing.
One of these years I'll get around to trying to do some anodizing myself, but I'm going to have to get a steady supply of titanium before I can use it as a class lab. Titanium's kinda expensive and really, really hard to cut - something that I need to consider, too.
When I do get around to it, though, I'll check back on these instruction pages.
As a warning, there isn't really any color to the oxide layer. It's caused by light wave interference. Check the scienceout if you really want to know.
If you were thinking of a gift for your favorite material science blogger, I'll need to measure my ring size first, but this one's the current choice.
I appreciate the intricacies of 3d printed parts. There are forms that can't be made by casting, carving, forging, or any method other than via 3d printing.
I've seen 3d-printed materials in various polymers, chocolate, sugar, and lots of metals, but 3d-printed ceramics are new to me.
