Bonding Carbon Fibre to Titanium castings

[Scarbs]

Bonding Carbon Fibre (CF) to Titanium (Ti) castings.

I've noticed the Ferrari gearcase has been using a novel method of construction since last year. the case has been cast Ti for some time and has had Cf reinforcement added to it. But last year the Casting had a skeletal design, where the was no wall or skin in the larger open sections. Instead these areas had Cf skins bonded to them. this seems to be a halfway house between a full Cf case and a Ti case.

What sort of gain in weight or stiffness would this bring..?

What issues are there in bonding CF to TI..?

Would this be easier to fabricate\assemble than a full Cf case?

Scarbs...

[fcevolini]

Hello Scarbs,

The Ferrari solution is very similar to what also other Teams are making now and have made in the past (Ferrari included). The only difference is that the other Teams are using integrally Ti machined bulkheads inside their carbon gearbox, instead of using a cast Ti skeleton. The use of a rapid casting
Ti skeleton is a clever solution that CRP studied in 2001 for Arrows F1 Team and that was stopped because of the financial problems of the English Team. The main advantage, with this solution, is, more or less, the non shape limits that the gearbox engineer can exploit when he designs the Ti skeleton. In few words, he can better focus on the loads directions and optimize the design.
Please consider that all CF F1 gearbox (as you call it) have, inside and outside in the suspensions pickup points, metal inserts and bulkheads, and this solution is quite expensive.
There are not big problems bonding Titanium and CF, you have just to use the right epoxy resin (that are all derivated from Aerospace industry) and this because the Titanium alloys have a very low CTE linear and so there aren't problem of detachment during the thermal expansion in use. Furthermore the Ti substrate is less sensitive to galvanic corrosion issues when coupled with CF, compared to other alloys such as Alluminium alloys.
It is difficult to say if a Ti+CF gearbox is stiffer and lighter than a Ti cast gearbox, because I have not these data available. In my opinion, the choice is just related much more to the production capability... It is not so simple the production of Ti cast F1 gearbox, considering the F1 needs that are very binding and maybe Ferrari decided to follow a intermediary road.

Ciao,
fcevolini.