Graphite and Its Awesome Properties

I discovered how useful graphite is!

I think carbon atom is one of the most useful atoms in the universe! For one, it made life on earth possible and yet has much more to offer.

It naturally exists in wood, diamond and graphite, and more recently rediscovered as graphene, nanotubes and buckyball, etc…

For now I just discovered graphite. It is a naturally occurring crystal form of carbon which is in many layers as shown in the picture below. If you can extract a single layer of graphite, that’s what’s called graphene with another set of interesting properties. I’ve heard it is simple to make. And when you role that layer in a cylinder, you get nanotube.

Graphite Crystal

Graphite is highly conductive unlike diamond or wood. But it is conductive along the layers, not perpendicular to them. It has many different applications. Generally it is crushed into powder that can be used to make other components like battery rods, deposited traces on electronics and such.

But pencils are the most basic use of them. If you draw a thick line using pencil on paper and measure the resistance across it, you will see your line is conductive, and if you bring your probes closer on the paper over the line, the resistance gets lower, like a potentiometer. Making a potentiometer is one of the applications of graphite. As seen in picture below, usually a resistance element is made out of graphite. Moving the slider around will select a different length of resistive element. So a potentiometer can be used as a variable resistor, or a variable voltage output circuit depending on how it is connected.

Structure of Potentiometer

As you saw in the video, graphite can withstand huge amounts of heat that can easily be used to generate thermal energy to melt most material from copper to steel to glass. But at the same time, it means that it will not easily deteriorate in harsh hot environments. Brushed DC motor is one of such applications shown below. Such DC motor is likely the most common type of motor used. Brushes are used to connect to the commutator to transfer electricity through rotor windings. It is a pretty bad environment for any contact, because it heats up under heavy loads, it is constantly in mechanical friction and there are high power arcs between commutator and the brush. And yet graphite can withstand this environment for a long time. Carbon is a natural lubricant, so the graphite brush is self-lubricating the contact area. Although the brushes eventually wear out under friction, they still put out many years of service before they are done. In applications where the brushes wear out before the lifetime of the product, they make the brushes replaceable.

DC Brushed Motor

In another application graphite is made into electrodes that can greatly heat up by passing electricity through it like I used in the video.. The extreme heat is use to melt material for molding or other needs.

Graphite is also use in electronic printed circuit boards, although not as often. In a lot of cases, graphite traces can be directly deposited on top of the usually green solder mask to add another connection layer on top of copper traces. Like shown below, I have mostly seen them used as switch footprints in the phone dial pads or remote controls. They are not as low resistance as copper, but they still provide a good electrical connection.

Carbon PCB Traces

And of course battery rods are another important application of graphite. Graphite is made into powder and compacted into a rod mixed with other material for better conductivity, and then commonly used in carbon-zinc batteries. Carbon-zinc batteries are used less and less as the alkaline is taking over the consumer market. I had a hard time finding carbon-zinc batteries. If you buy a flash light that comes with batteries, it is very likely a carbon-zinc battery. I ended up finding a few from a loony store down the street.

Zinc Carbon Battery Rod

I like to thanks SEEK Thermal for providing cameras for my videos and my patrons at 

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