Titanium Frames and anti seize

[11.4]

There are three common kinds of anti seize -- copper, aluminum, and nickel -- plus some exotic ones like platinum and cobalt for specific exotic applications like nuclear reactors and certain nerve gas production. Nickel is mostly for heat, which is why it's found in aircraft turbines. It isn't needed or recommended in bikes. Aluminum is used for most applications except where it is protecting against certain galvanic reactions. Copper is common and works well around a wide range of metals, though aluminum isn't one of those. I've raced large aluminum sailboats that got overhauled and the next spring had hundreds of pinhole leaks in the bilges -- electricians let their shards of stranded copper wire fall into the bilges and they ate right through a quarter inch of high grade aluminum. Presto, a few hundred eighth-inch holes you had to plug with a mig welder.

The metal is only one part of the equation. You can get anti seize compounds with a lot of metal in them or very little (cheaper ones, and most of those sold for cycling have much less) and you can also get anti seize compounds made with cheap clay lubricants or expensive synthetics. Cycling doesn't deal with pressures or temperatures that need expensive ones, but the lubricant in an anti seize can deteriorate with exposure to air and water and grit and cause you to need to replace it very frequently. Hey, it's still just grease and it gets crappy whether it's got copper flakes floating in it or not.

So frankly for many purposes grease alone is plenty. If you want something more, just buy good grease. If you want to be quite conservative, get high grade copper anti seize and you'll be happy with ti or carbon frames. There is indeed a bit of aluminum in some titanium tubing alloys, but that doesn't mean your anti seize is going to react with it. The chemistry doesn't work that way.

And there are two things going on here. First, galling. This is where metals assume some properties of a liquid and reshape under pressure and/or heat. It takes a lot to make metal actually gall. Otherwise every bolt would get galled. Galling happens regardless of what kind of anti seize you use. For purposes of cycling, just use good grease.

The other thing is corrosion. The point of anti seize is to provide a sacrificial metal so corrosion doesn't happen. However, that means you eat up the sacrificial metal, which means in turn you don't leave it in forever. It does need servicing. Also, it has to be the right metal. Steel and aluminum can create a nice galvanic current. What happens then is that as it corrodes, the oxides are much bulkier than the original metals and it literally jams up the threaded junction. That's why bottom brackets in BSA shells would jam to the point of never coming out. Or alloy seat posts would get frozen in steel frames. Some anti seize can help, but most important is regular service and using a high quality anti seize in the first place. Go to industrial supplies, read the labels, and buy a good product.

Now those alloy flakes do serve a purpose in galling as well. They act like primitive bearings so when one metal surface moves under pressure against another, the two surfaces don't gall and fuse. For something like a seat post sliding into a frame or a bottom bracket in a shell, it's just an in-and-out one-time motion and you really aren't doing enough to create galling. When you cut out such a product after it's frozen, you'll see the white powder of corrosion and know what happened. But galling is not an overwhelming matter because it takes a lot more pressure to gall metal than most bikes will ever see. Take care of corrosion with good grease, good anti seize, draining water, and regular service, and you've kept your frame safe.

[Kontact]

For the purposes of a thread about titanium with aluminum or steel components, electrical reactivity is not at issue. You could stick an unlubricated aluminum plug in a titanium block and soak it in oxygenated salt water and nothing would happen to the titanium. It is not an anode because it doesn't react to corrosives.

[Matthew]

I've only ever used grease on my Moots and other Ti bikes. Have used plumbers tape on the BB. Never had one issue, but mine is a "good" weather Moots! Except for the occasional stray rain shower.

[semdoug]

I too have only used grease with no problems during annual service.

[zank]

The aluminum would be the anode.

[Kontact]

Originally Posted by zank

The aluminum would be the anode.

But the Ti would not be the cathode.

[zank]

Why not? It has a lower potential.

[zank]

It's the same as needing an insulator when bonding aluminum to carbon. Carbon and titanium have similar anodic potentials. If either is in contact with aluminum with an electrolyte present, there will be galvanic corrosion. The aluminum is the sacrificial lamb. Aluminum and steel have simar potentials. As Lane noted above, that's why either can seize in a ti frame.

[Kontact]

Originally Posted by zank

Why not? It has a lower potential.

Unless I'm completely misunderstanding, it has effectively no potential. When it is used in that way in industry they coat it with platinum. Otherwise, the titanium dioxide surface moves electrons about as easily as fired clay.


Aluminum doesn't galvanically seize in titanium - it galls, which makes it seize mechanically because the chips wedge in the pits.

[zank]

It does both.

[Butch]

From what I have seen another major contributor of issues with titanium is dirt/grit. I feel the debates about whether anti seize or grease works better isn't as important as when any parts are installed there is no grit, especially Ti seatposts into a Ti seat tube (not an alloy or carbon sleeve) and threads.

3/2.5 and especially CP Ti do not have good abrasion resistance so it is easy to gouge. Once the two pieces are not fitting properly they can then gall. If grit is in the threads it will muck them up same with a Ti post. Ti bolts should be 6/4 and many of the pieces (H2O bosses, stem parts etc are often CP) making the bolt a lot harder than the parts they are being installed into.

I think there are fewer issues with alloy BB's rotting in any BB shell that has a drain hole, but again doing regular maintenance is the key to longevity.

[AngryScientist]

galvanic corrosion between titanium and aluminum alloys is definitely a thing.


http://blackmtncycles.com/grease-is-noble/

[11.4]

Originally Posted by Kontact

Unless I'm completely misunderstanding, it has effectively no potential. When it is used in that way in industry they coat it with platinum. Otherwise, the titanium dioxide surface moves electrons about as easily as fired clay.


Aluminum doesn't galvanically seize in titanium - it galls, which makes it seize mechanically because the chips wedge in the pits.

Galling isn't a process of chips wedging. The metal has to be under such pressure or heat that it flows -- it literally welds. What does happen sometimes is that the metal distribution is uneven and you get too much metal and not enough grease. At that point it's just like metal filings in the oil in your Toyota. It jams threads, but isn't a true case of galling. Not good.

And anyone who has ever had an aluminum bottom bracket freeze in a titanium BSA bottom bracket shell has seen aluminum corrode. There can still be corrosion without an immediately opposing metal. Even greases and anti seizes can create slight electrical potentials and it takes next to nothing to start corroding an alloy bottom bracket or seat post. Simple weathering is enough to cause a bottom bracket or seat post to seize.

Molybdenum disulfide is an anti seize compound and allows for smooth movement. I've been using it more and enjoying it as a universal solution that doesn't have the downsides of copper or aluminum anti seizes. Not molybdenum lubricants, which have very little metal, but the anti seize. For about $40 you get a lifetime worth of top anti seize that works in all kinds of applications. I also like using this stuff in stainless frames.

Do not use copper anti seize with stainless frames; it can cause intercrystalline corrosion that's quite severe.

Do not use aluminum anti seize with regular steel frames; it'll accelerate corrosion.

Just don't use nickel anti seizes. They have been linked to a number of carcinogenic complications and are prohibited in many applications where they aren't absolutely necessary.

Here's an article that discusses anti seizes from a more technical perspective:

https://www.impomag.com/article/2013...lue-anti-seize

I tend to prefer the following product line, partly because they define the contents so well. Look at the food grade ones if you like to eat while wrenching, or if you want to lick your stem bolts in a tough triathlon. Seriously, they are pretty good in frames because they don't provoke corrosion on their own. They actually use a graphic that's a crankset, though in a nonsensical layout -- so much for relevant art.

https://www.all-spec.com/loctite-anti-seize

I've also used these, and they have some interesting variants I've experimented with for cross, for endurance, and other uses. Also, remember that if you have an older (or sometimes Asian import) carbon frame, you can have extreme reactivity with any resin that hasn't been isolated properly. Pick your anti seizes very carefully in that case. I had an early BMC carbon frame with alloy lugs that corroded right through the lugs and that ate right through a Dura Ace alloy bottom bracket until it literally fell apart. I'm always learning more issues about things as simple as grease and anti seize.

[HenryA]

I’ve used anti seize for assembly and then periodically apply a drop or two of Boeshield to the joint. The Boeshield will wick in and leave a wax coating that helps seal the joint. I’ve done steel and titanium bikes this way for decades and unless the bike is heavily ridden in the rain I have not seen any problem at dissembly.

More than galvanic effects, I think galling is the big problem. My preference is copper carrying antiseize, but anything is better than nothing. High pressure wheel bearing grease is not bad. But I really believe in the dribbling of Boeshield on the joints as a regular thing. This applies to all the joints on the bike, every screw too. It’s the post assembly version of “white grease at assembly” that has been a standard of good bike mechanics forever.

This does not include fastners and joints that require loctite. Obviously, no white grease there. Locktite both locks and seals to some extent. At assembly those joint need threadlocker. Afterwards the Boeshield gets done because it won’t hurt the joint but will serve to seal the joint against intrusion of things that might cause problems.

Anytime you use anything on a threaded fastner you need to take into account the effect of the goo you put in the joint when you set the torque on the fastner. Dry is the usual default, anything else applied to the joint needs to be accounted for in tightening. Usually when the instructions say “apply XXXX. and tighten to Xnm” The manufacturer has taken the application of the goo into account. We can hope. If you are doing it your way, do a little research on what the effect may be on tightening with whatever goo you choose.

[Jcgill]

Thanks for the input everyone, I learned alot from all of your posts!