Alternative to Aluminum Wire

[jdew1920]

Due to the hazards in using Al, we'd like to move away from using it as much as possibile. We will be repairing exterior surfaces on aluminum housings using TWA. Is there an alternative to using Al wire that would give a similar appearance and corrosion protection while minimizing the hazards?

[Stuart Milton]

Can you give a bit more info about your application. What is most important to you - appearance or corrosion protection?

What is the environment that the product is in?

The most obvious alternative is zinc but this is likely to require a thicker coating and will be a different colour (more of a dull grey than aluminium). As a protection for steel, in a splash zone environment for instance, sealed sprayed zinc would be specified as 250 microns as opposed to 150 microns of sealed sprayed aluminium. Zinc/aluminium alloy is also another option that maintains a bit of aluminium. The wire is supplied as standard as Zn/Al 85/15.

[jdew1920]

They are blowers for engines primarily for off-highway vehicles. They are not painted so need to maintain corrosion resistance. As long as not drastically different appearance is less of an issue, but still a concern.

[Gordon]

Hi jdew1920

If your "blowers" get much warmer than ~ 50*C during service, I would stick with aluminium.

As far as "hazards in using Al" I assume you refer to fire and explosion hazards, yes there probably is a little less risk with zinc, but most thermal spray over spray particulates are hazardous in this manner (to greater or lesser degree) and a good thermal spray installation should be design to cope with the majority of materials sprayed including aluminium.

[jdew1920]

Gordon - why do you recommend staying with Al based on the temp? And yes they would see temps higher than 50C.

The dust collection itself isn't an issue, it's just the added expense of a second set of ducts and dust collector that is recommended to us because we spray a significant amount of Al.

Thanks

[Gordon]

Hi Jdew1920

Gordon - why do you recommend staying with Al based on the temp? And yes they would see temps higher than 50C.

Zinc is strange stuff, above 50*C it becomes relatively poor at what does so well below 50*C (due to some reversal of polarity in a corrosion cell). Aluminium is very good with the elevated temperature work and does not suffer the same problems as zinc. Not sure where ZnAl stands in this situation.

The dust collection itself isn't an issue, it's just the added expense of a second set of ducts and dust collector that is recommended to us because we spray a significant amount of Al.

Understood. My only point is that, I heard of ducting fires where zinc was mainly sprayed, so aluminium is not totally alone with this problem. I'm hoping Stuart may be able to advise further, as I'm sure Metallisation would have much knowledge and expertise in this area.

[Stuart Milton]

Hi both and all,

It's not quite as simple as suggested re 50 degrees C. The environment plays a big part. As a general rule, it has to be wet with relatively pure water to reverse polarity. It will reverse back at around 75 degrees too in most cases. This situation was discovered in galvanised hot water tanks but does not occur in other applications with different environmental conditions. Zinc/Al will not react in this way to my knowledge.

Agreed re ducting fires with zinc so as mentioned, aluminium is not alone with this problem. I suggest that you speak with the guys that have been in contact with you and take their advice. It's quite a complex issue that you have and worth addressing in person rather than via the forum.