Peter Whyman, sales director at Zircotec Ltd, talks to AZoM about about plasma spraying ceramic coatings for thermal protection of motorsport components.
To start off, could you provide a brief introduction to the industry that Zircotec works within and talk a little about the key drivers as well?
Well we are a specialist plasma spraying company, and our core markets are automotive and motor sport and we’ve been in those markets since the early 1990’s.
We do accept orders and have involvement in other areas but, we tend to look at those on their individual merits, with a greater focus on automotive and motor sport.
It’s Plasma spraying primarily of ceramic thermal barrier coatings, to effectively manage heat across a range of components but mainly exhausts systems. We can coat any part of an exhaust system from manifold right through the tailpipe, wherever there is a heat issue we can help manage that.
The growing part of our business is coating onto carbon composite materials. This allows carbon composite materials, high temperature plastics, etc. to be used in very high temperature areas where they wouldn’t normally be able to. For example brake shrouds, glass shields and heat shields, primarily in high end motor sports such as Formula One or Le Mans series,but we have just completed our first road car composite coating project with Aston Martin.
Lou Cox performing a Zircotec masking process
Ok, great, we’ll get onto that in a bit more detail later. But just briefly, do you mind explaining how the ceramic coatings are created and applied using the plasma spray technology?
Yes, plasma spraying but it’s a very, very high temperature process. I always liken it to a gas welding torch with a flame running at between 10-15 thousand degree centigrade.
It depends upon the coating we’re putting down and the substrate we are coating onto. So we start with a very, very high temperature flame, we then feed powder into the flame - the powder being the coating we are putting down.
So we have minute grains of, for example ceramic, which are fed to the flame, which then become molten and are blasted at the substrate at twice the speed of sound. So, when they hit the substrate it’s almost like welding them to the substrate, these little grains will hit the substrate, they’ll flatten out and cool and solidify into what’s called a splat.
It’s a silly word, but it’s actually a technical term and we build up layers of splats to give us the coating properties we require.
So, from a thermal barrier perspective it’s the combination of the ceramic we are using which is a proprietary mix of zirconias and the air we are trapping between the ceramic that deliver the thermal barrier properties. This provides a compelling mix of thermal barrier protection together with lightweight and minimal package space.
I was wondering if you could tell me a little bit about the different performance ranges you offer - the Performance White, the Performance Colours, and the Primary range of coatings. Could explain how these are different and what the different applications of these are?
If we’re looking at an exhaust coating for example, we first of all apply a proprietary bond coat around 250-100microns thick, then on top of that we would put down a ceramic and this is where those coatings differ.
The Performance White is a proprietary mix of zirconias. The Primary range is a different mix of zirconias, giving lower thermal barrier properties but at a keener price point.
The Primary range will reduce your surface temperatures and range temperatures by about 25%, whereas the Performance White will reduce surface temperatures and range temperatures by about 33%. So it is a higher performing coating that is suitable for harsher environments.
Now, the natural color of the Performance White is a white cream. This is not to everyone’s liking -Motorsports teams tend to like that colour because that’s the layer that does all the work and to some extent they don’t care what it looks like.
However, when we start looking at road cars, aesthetics become very important as well.
So the Performance Colours range is based on the Performance White ceramic, but has an additional process to apply a further colour finish.
This enables the coating to stay clean when in service. There’s an element of porosity about all of our coatings performance white has about 10-12% porosity in it.
The Performance Colour range will seal the surface slightly to help keep them clean, but not affect thermal performance. So thermally, the colors range provides the same thermal protection as Performance White, the only difference is the aesthetics and ease of cleaning because of the surface colour finish.
The primary range is also are entry level. It’s more cost effective with lower cost material and hence a lower cost product, so for people who have budget constraints, it would be the best option to choose.
An example of the primary finish being used in a exhuast component.
So focusing more on the performance white, how are these coatings generally used in motor sports at the moment?
It is used in two main areas on a car but this number of uses is growing – Primarily it is used on the exhaust system itself. They use it on the exhaust to lower under-bonnet temperatures, to improve the flow of the exhaust gases and to protect heat sensitive components around the exhaust.
So it provides thermal management for protection and performance enhancement. In addition, by lowering your under- bonnet temperatures you’re also reducing the flow of heat into the foot well, so keeping the cabin temperatures down, allowing the drivers to maintain concentration and protecting their feet from the heat.
Also as I mentioned earlier, it allows carbon composites to be used in very high temperature areas. Typically carbon composite will start to delaminate at 200-300oC.
But if you look at a Formula One exhaust, you’ve probably got an exhaust gas temperature in excess of 700oC. If you had exhaust gas blowing directly onto a composite material you’d destroy it, but by putting the coating down this protects those composites from those exhaust gases.
You can use it on blast shields and also brakes and formula one break may get into excess of a thousand degree centigrade during use, not for a very long time but, very, very high. Again if you put carbon composite close to a break you would have resin melted delamination of the component.
Sure, and in terms of how lightweight the coating is, does that make a difference in the outcome of the race? Is there a move towards more light weight coatings to improve performance in the races?
Obviously within Formula One weight is very critical, and they’re trying to use more lightweight materials. The coating does add weight, but we minimize the thickness of the coat to just give the thermal protection required on the products.
So we would engineer the coating to suit the clients particular needs and we would also only coat were the coat was specifically needed so we would mask up large areas of the component were it didn’t need it and only coat specific areas trying to keep the weight to a minimum.
How do the coatings help with closer packing of components in high temperature environments?
Well the coating itself only takes up 300-350microns so we can get into very tight areas, we don’t need large spaces like some of these heat shield materials require or bandages require.
We fit in very, very tightly, and because we are keeping much more of the heat within the exhaust gases themselves, we can pack these components much closer to the exhaust because they are protected from the heat by the ceramic coating itself.
There was recently a press release regarding the F1 stock car driver Tom Harris and how he is using Zircotec ZircoFlex®. I was just wondering if you could explain a little bit more about that story and why he’s using the ZircoFlex® in competitive racing?
Tom is one of the leading drivers in that series, he’s a European champion and a national champion in 2012 and as well as racing he also builds cars for himself and other competitors.
He was finding that heat was a major issue for reliability. One example is that cars race on oval tracks and because they only ever race on ovals they only ever turn left so the suspension on the left hand side is very close to the brake disc, and there is a lot of heat transfer.
What he has been trialling is to wrap the damper with ZircoFlex®to stop the oil inside from getting too hot because that causes the dampener to fail and this is about improving reliability and lowering cost.
Inside the car he has been using ZircoFlex®to keep heat away from the cockpit because they are a single seater the driver will straddle the transmission peddle so it’s a very uncomfortable heat environment and he’s using that to make it more comfortable.
So that’s been his current experience with ZircoFlex®, but now he’s also going to try a set of ceramic coated exhausts.
How do you feel the Zircotec coatings are unique in the ceramic coatings field?
Well the coatings themselves are unique because they are a unique proprietary mix of the zirconias.
The process of plasma spraying has been around for many years, but we have turned it to suit are particular needs, so the process itself is unique to us. And we have patents filed on a number of our coatings, particularly for composite substrates.
Lastly, I want to get your thoughts on the future of ceramic coatings. What are the future applications that you see for ceramic coatings?
I think for the moment we still only provide specialty services and there are still a very large number of motor sport teams and car manufacturers that could benefit from the coatings.
We were on 11 of the 12 Formula One teams last year and a similar number this year and we would like to continue with that. The will be changes in regulations for Formula One next year and they’re bringing in the smaller turbocharged engines, so there will be more use on the exhaust systems there.
An example of an F1 composite coating.
We’ve been undertaking more and more OEM projects, notably for carbon composite applications. Whereas historically, carbon composite has always been a motor sport application for us. For example, we’ve recently announced that we are working on the Aston Martin One-77 supercar.
We are being asked for more in different industries, such as oil and gas and mining for example were heat is a major issue.
Something we haven’t really touched upon, is that we are also involved with some hybrid car development projects, and so even though we are moving away from major internal combustion engines. Hybrid and electric cars can still suffer with heat.
Actually they generate a huge amount of heat if not managed properly, so even in the new generation cars there will still be a requirement for thermal management of some type. And the coatings being very thin, very light weight, they are ideal for use on such vehicles. We expect to see more activity in this field.
About Peter Whyman
Peter Whyman, sales director at Zircotec Ltd started his career in the medical devices sector and worked on a number of coating technologies for orthopaedic devices.
Peter has been involved with specialised plasma-sprayed technologies for more than 10 years and was part of the Zircotec Ltd management buyout in January 2009.
Today he leads the firm’s sales and marketing activities, primarily focussed on OE automotive and motorsport sectors.
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