Let’s Talk Automotive – How Things Work: Carbon Ceramic Brakes

Do you think R200 000.00 is worth it for a set of brakes? In this segment, Peter talks about carbon-carbide brakes in more depth and explains how they are manufactured and what some of the benefits are.  Once you know more you can make up your own mind on whether they really are worth it or not.

Estimated reading time: 5 minutes, 14 seconds.

If you can’t watch the video, you can read the video transcription below:

Edited for clarity and readability

Welcome to this week's episode of Let's Talk Automotive. And in this segment on How Things Work, we are going to be taking you through carbon-ceramic brakes. Now you might've heard of some of the other types of brakes that we get such as ceramic brakes or silicon carbide or tungsten carbide, and indeed carbon-ceramic brakes themselves. What do all these mean and are any of them the same thing? Now, the answer is always a bit of yes and no. And in future episodes, we are going to deal with the various exotic braking systems in the future, but in today's segment on How Things Work, we'll be having a closer look at carbon-ceramic brakes. 

Now you would have heard about carbon-ceramic brakes because they seem to be becoming a bit more popular in terms of high performance and exotic vehicles. Why do we need carbon-ceramic brakes you ask, especially when they can easily cost over R200,000.00 a set, which is the price of a small entry-level vehicle? And the answer lies simply in the fact that we get repeated brake performance out of carbon-ceramic brakes. 

So let's take a step back and figure a few things out. So firstly, what is carbon? Well, carbon is a chemical element like hydrogen or oxygen or any of the other elements in the periodic table, but carbon is a very abundant element and it can exist in either a pure form, or a nearly pure form such as diamonds and graphite, but can also combine with other elements to form molecules. These carbon-based molecules are the basic building blocks of life for humans and animals and plants and trees and soils. Some greenhouse gases, such as CO2 and methane, also consist of carbon-based molecules as do fossil fuels, which are largely made up of hydrocarbons, which we've spoken about in previous episodes, and those are molecules consisting of hydrogen and carbon and that is why we talk about a carbon footprint when it comes to emissions.

The hardest pure element just so happens to be carbon in the form of a diamond, which is made from extreme temperature and pressure, an important aspect to remember when we explain how carbon-ceramic brakes are made. So when we want to make a brake surface that can handle very high temperatures and high pressures for that matter, diamonds would be ideal except for the fact that they are hellishly expensive. 

So as usual, the brilliant scientists out there developed a compound that is nearly as hard as the diamond but costs a fraction to produce. And this is in the form of silicon carbide. Now silicone carbide is a ceramic compound. So you may have noticed earlier when we spoke about the different types of brakes we get, that we have carbon-ceramic or silicon carbide brakes, which are exactly the same thing. 

Silicon carbide has a hardness of nine on the Mohs scale with diamonds coming in at 10. Now to give that a bit of perspective, cast iron, which we use on normal brake discs comes in at five. So you'll appreciate that carbon-ceramic brakes are seriously hard. In fact, carbon-ceramic brakes can last as much as 60 times longer than steel brakes. And there are other great properties we get from them. But I first want to have a quick look at how we manufacture carbon-ceramic discs.

The actual process is lengthy and complex, but in basic terms, we initially take two materials, that being carbon fibre and a resin and mix them together. After pressing the mix at over 20 tonnes and at a temperature of over 400 degrees Celsius, the basic shape of the carbon disc is formed. This rough disc is machined to a smoother form and the disc is then again placed in an oven, but this time for two days and up to 980 degrees Celsius. When it comes out, the disc is still only carbon. So now the boffins add ceramic powder made from silicone and place the disc in its container back into an oven to an even higher temperature of over 1,600 degrees Celsius. And this final process melts the silicone and fuses it with the carbon to finally create silicon carbide. The final product is then coated with special paint and cured in an oven to protect the carbon from oxygen because at high temperatures oxygen actually burns the carbon, but now we have a fully-fledged carbon-ceramic disc. So let's go back to some of the great benefits we get from carbon-ceramic brakes.

Because they handle very high heat we don't suffer from brake fade under severe braking. This means that we can expect the same brake performance with little or no loss in performance, time and time again. Now, this is compared to a steel disc which will quickly lose brake performance and we've spoken about that, in the form of brake fade. Also, carbon-ceramic discs don't ever suffer from brake shudder.

Then carbon-ceramic brakes are significantly lighter than steel brakes. This means we can accelerate the vehicle quicker, the car's overall weight is lower and the all-important unsprung weight at the wheel is lower, which improves handling dramatically. 

So, the ultimate question is, are they worth it at over R200,000.00 a set? Well, obviously, if you're using your car just for commuting to work and back, absolutely not. But if you have a high-performance car and you use it at track events, the mere fact that you get 60 times more life out of the brakes combined with the improved safety of the brake performance, for me, makes it a no-brainer. 

So we hope that the little section on how carbon-ceramic brakes work was informative, and we look forward to seeing you on future episodes on How Things Work.

To watch the full episode, visit: https://fb.watch/6Wak9eIfcU/

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