F1 Turbocharger Materials

[loukayne]

Does anybody know any information on the materials used in the 2014-present F1 turbochargers (compressor housing/wheel, turbine housing/wheel, etc..)?

Thanks

[F1NAC]

From Honeywell

The use of high-grade materials – including titanium and magnesium – and thin-wall geometry has significantly reduced turbo mass while improving core strength. As a result, by optimizing packaging and minimizing mass, Honeywell racing turbos provide race teams more leeway in overall weight distribution, leading to lower center of gravity and thus improving vehicle dynamics or handling.

[R_Redding]

....

[trinidefender]

http://i897.photobucket.com/albums/ac18 ... jwfnhj.jpg

Does turbine wheel materials fall under 5.18.1? I hope not.

Borg Warner EFR turbocharger turbines are made from Gamma TiAl (one of the variants of titanium aluminide). As far as I'm aware these are considered some of the best aftermarket turbochargers available, one of the reasons being the very light weight of the turbine wheel. General Electric will also be using it in the turbine blades of the low pressure section of some of its GEnx engines.

[noname]

Does turbine wheel materials fall under 5.18.1? I hope not.

Yes, it does. And those turbines are running too hot for TiAL.

Turbine wheels of F1 turbochargers are made of materials originating from aerospace, although they are on the heavy side.

[Edax]

I think this picture sums it up nicely.


The whole architecture seems to be posed at keeping the gas as hot as possible so that would make temperature the determining factor. The high melting alloys like Ta, Nb, Re and W based cannot be used in oxidizing environments. For the wheel my guess would be that they use a single crystal gen IV superalloy. These nickle based crystals are widely used in the high pressure core of aircraft turbines and are also used for high performance car turbines.
https://www.mhi-global.com/products/det ... pment.html

For F1 most of the exhaust system is made of alloys like inconel 718 for the tubing, insulation sleeves etc.


http://www.novitecgroup.com/rosso/en/45 ... atalog.php

The turbine housing, in a normal car that is a relatively simple casting, but that would not suffice for the temperatures F1 is running. Below is a nice video from Koeningsegg. In this case it is printed so It will most likely be a TiAlV. But For F1 it also might be an superalloy.



Also consider that the parts likely are coated (Thermal barrier coatings). F1 traditionally is big on coatings since the rules only prescribe construction materials. Back in the nineties the company I worked for was already laying down very exotic coatings on F1 engine parts for one of the current suppliers and I guess that hasn't changed.

[gruntguru]

F1 turbine temperatures are unlikely to be at the extreme end for two reasons:

1. Thermal efficiency. The focus on thermal efficiency demands the highest possible extraction of energy by the piston engine from the combustion process. This will result in minimum possible heat rejection to the cooling system and the exhaust.

2. AFR. The engines run lean - with at least 20% excess air. This dilutes the exhaust gas and reduces exhaust temperature.

[riff_raff]

"The turbine housing, in a normal car that is a relatively simple casting, but that would not suffice for the temperatures F1 is running."

Not true. The turbocharger turbine housing used for commercial vehicles requires some very close tolerance machining to minimize leakage past the turbine blade tips, and the housing must have sufficient structural strength to contain the explosive failure of a turbine wheel.

[Facts Only]

Compressor end is generally 2000 series aluminium 2014/2618/2040 but Magnesium compressor hosuings are now allowed. the centre housing are largely standard Titanium as it has such a low thermal conductivity which helps insulate the turbine side from the comrpessor side.

[Edax]

"The turbine housing, in a normal car that is a relatively simple casting, but that would not suffice for the temperatures F1 is running."

Not true. The turbocharger turbine housing used for commercial vehicles requires some very close tolerance machining to minimize leakage past the turbine blade tips, and the housing must have sufficient structural strength to contain the explosive failure of a turbine wheel.

I work in an environment where 316L is the lowest acceptable standard and anything else is presumed to be forged on open fires in caves, so please accept my apologies for showing insufficient appreciation for the fine mechanics of these parts.

But yes your right it does require some machining for the flanges, bearings, wastegate lever attachment and seat, and if present the mechanism for a variable turbo. But tolerances are not that strict for an average engine. Some of those are done by press fit inserts anyway so the placement accuracy will dominate tolerances.

[Brian Coat]

I know this does not address what is known to be currently in use but does it seem reasonable to suggest/dream that ceramic materials (legal?) could offer benefits:

Low mass
Lower inertia - less joules of spin-up work by MGU-H
Lower thermal expansion (clearance control, especially with ceramic housing!) increases turbo efficiency
High temperature capability
Low conductivity

Edit: This last one does not apply to all ceramic solutions, as pointed out below by "Edax".

[Edax]

I know this does not address what is known to be currently in use but does it seem reasonable to suggest/dream that ceramic materials (legal?) could offer benefits:

Low mass
Lower inertia - less joules of spin-up work by MGU-H
Lower thermal expansion (clearance control, especially with ceramic housing!) increases turbo efficiency
High temperature capability
Low conductivity

I'm not sure about your last requirement, the ceramic which has been researched the most for rotors is silicon nitride which actually has a quite good thermal conductivity.

On paper ceramics look very good but they have a few issues.

- They are almost impossible to make net shape and reworking (polishing, drilling etc) is expensive.
- They are very intolerant to defects. In order to guarantee lifetime you need to either proof test or check 100% of your production (expensive) or keep a large design margin. If you use for instance a safety factor of 10 on the strength then you're sure to be OK, but you're underutilizing the material.
- They are hard to combine with other materials at high temperatures. They have a very low coefficient of thermal expansion compared to metals. So when you make a connection with metal it will have a tendency to either loosen up or start squeezing at temperature. Getting a stress free connection over a large temperature range is not impossible but difficult.
- High end ceramics are not that cheap. Standard powders are in the order of several euros per kg, but when you need to go to really top grade materials you pay well over a 100 euro per kg. Add to that the manufacturing which is expensive and the relatively high production loss( and zero scap value).

I would guess that the cost of production would make these materials unattractive for mainstream applications. For the high end applications I think reliability requirements would turn the balance towards single crystal metals.

There is a small niche in between. I have seen some ceramic rotors being used for small gas turbines so the idea works.

[trinidefender]

Some of the commercial (power generation) gas turbines use steam cooled blades, how about that for an idea.

I can't remember correctly but on avaiaton based gas turbines isn't the most common solution for the high pressure section single crystal alloys with a coating (maybe ceramic coating)? Going to break out of a few of the aviation gas turbine design books I have lying around, probably not the most up to date material though.

I know these days ceramics are heavily used in the combustion chamber of gas turbines, one place they are definitely worth it!

[riff_raff]

I'm not sure about your last requirement, the ceramic which has been researched the most for rotors is silicon nitride which actually has a quite good thermal conductivity.
On paper ceramics look very good but they have a few issues.
- They are almost impossible to make net shape and reworking (polishing, drilling etc) is expensive.
- They are very intolerant to defects. In order to guarantee lifetime you need to either proof test or check 100% of your production (expensive) or keep a large design margin. If you use for instance a safety factor of 10 on the strength then you're sure to be OK, but you're underutilizing the material.
- They are hard to combine with other materials at high temperatures. They have a very low coefficient of thermal expansion compared to metals. So when you make a connection with metal it will have a tendency to either loosen up or start squeezing at temperature. Getting a stress free connection over a large temperature range is not impossible but difficult.
- High end ceramics are not that cheap. Standard powders are in the order of several euros per kg, but when you need to go to really top grade materials you pay well over a 100 euro per kg. Add to that the manufacturing which is expensive and the relatively high production loss( and zero scap value).
I would guess that the cost of production would make these materials unattractive for mainstream applications. For the high end applications I think reliability requirements would turn the balance towards single crystal metals.
There is a small niche in between. I have seen some ceramic rotors being used for small gas turbines so the idea works.

There have been a few limited production auto that used ceramic turbo components. I believe the Nissan GTR used silicon nitride for turbo bearing balls and the turbine wheel. I believe the SiN turbine wheel was brazed to an alloy steel shaft.

As noted SiN is very costly to fabricate, but it does provide a significant reduction in inertia of the rotating parts. One drawback with using SiN for the turbine wheel is that it has poor fracture characteristics. Even a small piece of debris in the exhaust flow impacting the turbine blade at high velocity can cause a catastrophic failure. Ceramic materials don't have the same ability as metals to bend/deform a bit before breaking.

[Brian Coat]

Thanks for the comments/ideas/corrections about ceramics turbo components.

I doubt it is worth the cost but impact resistance has been overcome using matrix composite techniques eg SiC/SiC? And I think techniques for achieving the desired geometry exist but again very costly.