Agreee with ame. Our particular tie-rods can probably be coated from the physical aspects, but it's still probably not a good idea like ame was saying.
1. You would not want to sand blast the ends and would need to seal them off so no grit gets into the socket.
2. Any residual grease already in the socket can come out or at least off-gas under the high heat and ruin the powder coating process at least in that local area, if not further out.
3. I don't think any of ours have teflon liners in the socket, but some sort of anti-wear material like teflon is still a possibility. They do it in a lot of car applications, but not sure they would do it in the heavier truck applications due to premature wear under heavy use. If anything other than metal is in there, it's not going to like the high heat any more than the grease would.
At roughly 400° curing heat for 20-40 minutes, any of those things can rear their ugly heads and ruin your nice coating job. Or your parts!
So I would agree, just scuff, clean and paint.
Besides, it's easier to touch up that way too. The tie-rod takes a real beating when driving sometimes.
If you're sure there is no lining, and you've got a guy willing to experiment with your stuff for free, then there's nothing lost if it does not come out perfectly and you can sand it down and touch it up. Just seems like a lot of work, and a lot of expense if you don't have a cheap method.
I'm pretty sure others have coated theirs, but I'd still say all of those warnings above are valid.
Paul