GST From United Kingdom, joined Jun 2008, 930 posts, RR: 0 Reply 2, posted (2 years 11 months 3 weeks 4 days 17 hours ago) and read 5351 times:
Corrosion at a join between composite materials (more specifically usually the bonding resin and the metal) and metals is nothing new, usually the metal can be treated with a hard wearing coating material being painted on or dipped in to. I wonder why it hasn't worked here.
flagon From France, joined May 2007, 145 posts, RR: 0 Reply 4, posted (2 years 11 months 3 weeks 3 days 13 hours ago) and read 4883 times:
Quoting GST (Reply 2): Corrosion at a join between composite materials (more specifically usually the bonding resin and the metal) and metals is nothing new, usually the metal can be treated with a hard wearing coating material being painted on or dipped in to. I wonder why it hasn't worked here.
I am assuming you are talking about galvanic corrosion between the carbon contained in typical composite materials and aluminum, anyway unless I missed something the report does not mention composite material in any way, it mentions stealth materials, stealth materials are not necessarily composite materials...
connies4ever From Canada, joined Feb 2006, 4066 posts, RR: 13 Reply 5, posted (2 years 11 months 3 weeks 3 days 2 hours ago) and read 4712 times:
Quoting Shmertspionem (Reply 3): 30 team hours. it involved, removing and replacing parts, new adhesives and panels (don't know if that was the corroded parts - or if this is an altogether new problem)
I wonder what that number implies for ever operating the Raptor from austere fields ? Air dominance is not an issue in Afghanistan, for sure, but let's suppose it was. Could you fly the Raptor from Kandahar and have the a/c retain its' stealthiness ?
Ferpe From France, joined Nov 2010, 2659 posts, RR: 58 Reply 7, posted (2 years 11 months 3 weeks 2 days 6 hours ago) and read 4432 times:
As far as I understand the problem it is more complicated then the CFRP carbon interacting with aluminium.
If I understand stealth technology right you need to make sure you have a wing/body/tail etc without any join gaps as seen by the radar wave otherwise every electromagnetic gap will work as a radar reflector (small cavities full of corners and angels, compare with the radar reflector you put on the top of the mast of a sailboat).
In other words you need to make a electromagnetically totally smooth surface for every surface of the aircraft, i.e. you need to fill every join at least the ones facing forwards.
So you need a material to put in all the joints. I understand it to be some filling material with even silver flakes or alike mixed in to make it electromagnetically conductive at the wavelengths in question (X-band fighter radars). Pair this with the need to have something in the CFRP that makes contact with this conductive material to make it one continous smooth surface (could be the carbon or some conductive mesh in the CFRP) and you have very easily an "electrical battery" setup between the two materials leading to electrochemical corrosion.
So you basically have corrosion in every join on the airframe. Though it might not be structurally dangerous rust does not make great electrical contact, suddenly you have a F22 that gets gradually more visible on the enemy radar!
So your 200m$ aircraft is as good as a 50m$ F15 after a while, not to good