Failing At Making Ferrofluid

October 26, 2018 by Al Williams 17 Comments

[NileRed] admits that while ferrofluid has practical uses, he simply wanted to play with it and didn’t want to pay the high prices he found in Canada. A lot of the instructions he found were not for making a true ferrofluid. He set out to create the real thing, but he wasn’t entirely successful. You can see the results — which aren’t bad at all — in the video below.

We’ve always said you learn more from failure than success. The process of creating ferrofluid involves two key steps: creating coated nanoparticles of magnetite and removing particles that are too large or improperly coated. After the first not entirely satisfactory attempt, [NileRed] tried to purify the material using solvents and magnets to create better-quality particles. Even the “bad” material, though, looked fun to play with along with a powerful magnet.

You’ll see that the material is clearly magnetic, it just doesn’t spike like normal ferrofluid. [NileRed] had commercial ferrofluid for testing and found that if he diluted it enough, it behaved like his homemade fluid. So while not conclusive, it seems like he diluted the batch too much.

We hope to see a better batch from him soon. The base material he used for the first patch was homemade — he covers that in a different video. However, for the second batch, he is going to start with commercial ferric chloride — what we know as PCB etchant.

Even though the experiment was not entirely successful, we enjoyed seeing the process and watching the performance of both the homemade batch and the commercial ferrofluid. He’s getting a lot of advice and speculation in the video comments, and it is very possible a Hackaday reader might be able to help, too.

We’ve seen other reports of unsuccessful ferrofluid production. If you need a practical reason to make or buy some, how about a clock?

Retrotechtacular: Disposing Of Sodium, 1947-Style

October 3, 2018 by Dan Maloney 55 Comments

A high school friend once related the story about how his father, a chemist for an environmental waste concern, disposed of a problematic quantity of metallic sodium by dumping it into one of the more polluted rivers in southern New England. Despite the fact that the local residents were used to seeing all manner of noxious hijinx in the river, the resulting explosion was supposedly enough to warrant a call to the police and an expeditious retreat back to the labs. It was a good story, but not especially believable back in the day.

After seeing this video of how the War Department dealt with surplus sodium in 1947, I’m not so sure. I had always known how reactive sodium is, ever since demonstrations in chemistry class where a flake of the soft gray metal would dance about in a petri dish full of water and eventually light up for a few exciting seconds. The way the US government decided to dispose of 20 tons of sodium was another thing altogether. The metal was surplus war production, probably used in incendiary bombs and in the production of aluminum for airplanes. No longer willing to stockpile it, the government tried to interest industry in the metal, but to no avail due to the hazard and expense of shipping the stuff. Sadly (and as was often the case in those days), they just decided to dump it.

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Testing Lithium Ceramic Batteries (LCBs)

September 15, 2018 by Steven Dufresne 29 Comments

Affordable solid-state batteries large enough for cell phones and drones have been promised for a long time but seem to always be a few years away from production. In this case, Taiwan based Prologium sent [GreatScott] samples of their Lithium Ceramic batteries (LCBs) to test, and even though they’re not yet commercial products, who are we to refuse a peek at what they’ve been up to? They sent him two types, flexible ones (FLCBs) and higher capacity stiff ones (PLCBs).

The FLCBs were rated at 100 mAh and just 2 C, both small values but still useful for wearables, especially given their flexibility. Doing some destructive testing, he managed to keep an LED lit while flexing the battery and cutting away at it with tin snips.

Switching to the thicker 7.31 Wh PLCB, he measured and weighed it to get an energy density of 258 Wh/L and a specific energy of 118 Wh/kg, only about 2/3rds and 1/2 that of his LiPo and lithium-ion batteries. Repeating the destructive tests with these ones, the LED turned off and smoke appeared while cutting and hammering a nail through, likely due to the shorts caused by the electrically conductive tin snips and nail. But once the snips and nail were moved away, the smoke stopped and the LED lit up again. Overcharging and short-circuiting the batteries both caused the solder connecting the wires to them to melt but nothing else happened. Rapidly discharging through a resistor only resulted in a gradual voltage drop. Clearly, these batteries are much safer than their LiPo and lithium ion counterparts. That safety and their flexibility seem to be their current main selling points should they become available for us hackers. Check out his tests in the video below.

Meanwhile, we’ll have to be content with the occasional tantalizing report from the labs such as this one from MIT of a long battery life and another from one of the co-inventors of the lithium-ion battery which uses a glass electrolyte.

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Chemistry And Lasers Turn Any Plastic Surface Into A PCB

September 4, 2018 by Dan Maloney 30 Comments

On the face of it, PCB production seems to pretty much have been reduced to practice. Hobbyists have been etching their own boards forever, and the custom PCB fabrication market is rich with vendors whose capabilities span the gamut from dead simple one-side through-hole boards to the finest pitch multilayer SMD boards imaginable.

So why on Earth would we need yet another way to make PCBs? Because as [Ben Krasnow] points out, the ability to turn almost any plastic surface into a PCB can be really handy, and is not necessarily something the fab houses handle right now. The video below shows how [Ben] came up with his method, which went down a non-obvious path that was part chemistry experiment, part materials science. The basic idea is to use electroless copper plating, a method of depositing copper onto a substrate without using electrolysis.

This allows non-conductive substrates — [Ben] used small parts printed with a Formlabs SLA printer — to be plated with enough copper to form solderable traces. The chemistry involved in this is not trivial; there are catalysts and surfactants and saturated solutions of copper sulfate to manage. And even once he dialed that in, he had to figure out how to make traces and vias with a laser cutter. It was eventually successful, but it took a lot of work. Check out the video below to see how he got there, and where he plans to go next.

You’ve got to hand it to [Ben]; when he decides to explore something, he goes all in. We appreciate his dedication, whether he’s using candles to explore magnetohydrodynamics or making plasma with a high-speed jet of water.

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Non-Newtonian Batteries

September 2, 2018 by Brian McEvoy 43 Comments

Batteries placed in harm’s way need to be protected. A battery placed where a breakdown could endanger a life needs to be protected. Lithium-ion batteries on the bottoms of electric cars are subject to accidental damage and they are bathed in flame-retardant epoxy inside a metal sled. Phone batteries are hidden behind something that will shatter or snap before the battery suffers and warrant inspection. Hoverboard batteries are placed behind cheap plastic, and we have all seen how well that works. Batteries contain chemicals with a high density of energy, so the less exploding they do, the better.

Researchers at Oak Ridge National Laboratory have added a new ingredient to batteries that makes them armored but from the inside. The ingredient is silica spheres so fine it is safe to call it powder. The effect of this dust is that the electrolyte in every battery will harden like cornstarch/water then go right back to being a liquid. This non-Newtonian fluid works on the ~~principal~~ principle of shear-thickening which, in this case, says that the suspension will become harder as shear force is applied. So, batteries get rock hard when struck, then go back to being batteries when it is safe.

Non-Newtonian fluids are much fun, but we’re also happy to see them put to use. The same principle works in special speed bumps to allow safe drivers to continue driving but jolts speeders. Micromachines can swim in non-Newtonian fluids better than water in some cases.

See The Fabulous Workmanship In This Smart Pressure Regulator

August 28, 2018 by Donald Papp 8 Comments

For many projects that require control of air pressure, the usual option is to hook up a pump, maybe with a motor controller to turn it on and off, and work with that. If one’s requirements can’t be filled by that level of equipment and control, then it’s time to look at commercial regulators. [Craig Watson] did exactly that, but found the results as disappointing as they were expensive. He found that commercial offerings — especially at low pressures — tended to leak air, occasionally reported incorrect pressures, and in general just weren’t very precise. Out of a sense of necessity he set out to design his own electronically controlled, closed-loop pressure regulator. The metal block is a custom manifold with valve hardware mounted onto it, and the PCB mounted on top holds the control system. The project logs have some great pictures and details of the prototyping and fabrication process.

This project was the result of [Craig]’s work on a microfluidics control system, conceived because he discovered that much of the equipment involved in these useful systems is prohibitively expensive for small labs or individuals. In the course of developing the electronic pressure regulator, he realized it could have applications beyond microfluidics control, and created it as a modular device that can easily be integrated into other systems and handle either positive or negative pressure. It’s especially well-suited for anything with low air requirements and a limited supply, but with a need for precise control.

[Cody] Builds A Chlorine Machine

August 19, 2018 by Dan Maloney 51 Comments

In his continuing bid to have his YouTube channel demonetized, [Cody] has decided to share how he makes chlorine gas in his lab. Because nothing could go wrong with something that uses five pounds of liquid mercury and electricity to make chlorine, hydrogen, and lye.

We’ll be the first to admit that we don’t fully understand how the Chlorine Machine works. The electrochemistry end of it is pretty straightforward – it uses electrolysis to liberate the chlorine from a brine solution. One side of the electrochemical cell generates chlorine, and one side gives off hydrogen as a byproduct. We even get the purpose of the mercury cathode, which captures the sodium metal as an amalgam. What baffles us is how [Cody] is pumping the five pounds of mercury between the two halves of the cell. Moving such a dense liquid would seem challenging, and after toying with more traditional approaches like a peristaltic pump, [Cody] leveraged the conductivity of mercury to pump it using a couple of neodymium magnets. He doesn’t really explain the idea other than describing it as a “rail-gun for mercury,” but it appears to work well enough to gently circulate the mercury. Check out the video below for the build, which was able to produce enough chlorine to dissolve gold and to bleach cloth.

We need to offer the usual warnings about how playing with corrosive, reactive, and toxic materials is probably not for everyone. His past videos, from turning urine into gunpowder to mining platinum from the side of the road, show that [Cody] is clearly very knowledgeable in the ways of chemistry and that he takes to proper precautions. So if you’ve got a jug of mercury and you want to try this out, just be careful.

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