flame spraying

Paul,

Don't know the guns you mention above, but for my Metco gun the key (pun intended) is to get a good physical key on the work by sand/grit blasting, and metal spraying imediately afterwards before the surface is contaminated.

Mine uses oxygen and acetylene and compressed air to drive the turbine that draws the zinc wire into the flame. The oxy/acetylene tip needs to occasionally be replaced but only like any other cutting torch tip. It is a relatively slow process to ensure nothing is missed and you lay down an even coating.

Andrew Mawson Bromley, Kent, UK

contaminated.

Are the zinc fumes nasty? What type of breathing equipment do you use?

>

Probably, but I'm still alive! I only use it very occasionally - non commercial - though I've not atually been aware of any problems. If the feed rate is adjusted properly, the zinc is just melted and tiny microscopic globules splat onto the work and interlink as they solidify hooking into the nice coarse surface that you prepared earlier with your sand blaster.

I suppose if you slowed down the turbine so the zinc feed was very slow and increased the volume of oxygen and acetylene, then it is possible that you may vaporise the zinc, but that is not what you are aiming for - the zinc should be just barely molten as it hits the work. I've never been aware of the yellow zinc oxide colours around the work that I would associate with zinc vapour, and certainly if I am casting a zinc rich alloy in my foundry and over heat the crucible then I certainly see them then !

Andrew Mawson

I have a gravity-fed flame sprayer that I've used to spray bronze onto steel, but it's also designed to spray stainless steel and other alloys.

My set uses a VERY fine powder which drops right in front of the flame and uses an exothermic reaction (the metal continues to heat up as it move away from the sprayer) so it bonds with the steel.

It works off of a regular oxy-acetylene setup.... Propane doesn't get hot enough to do the job.

I'm not sure what "quite cheaply" means in your world, but this flamesprayer ran me around $1,100 U.S.

James, Seattle, Washington, USA, Earth

I've also been interested in this process, although I've never tried it. About all I know about it is that at a plant maintenance job years ago, large wire drawing capstans were sent out to be resurfaced. They were badly worn and had a lot of surface defects. They looked great when they were sent back.

Found this site with general info about the processes used

A couple of years ago, I found a nice old used Mogul Turbo-Jet sprayer with a couple of good sets of tips, that has an air motor in the gun to feed the wire into the flame. I've not gotten around to trying it out, but someone had mentioned that a set of 2-stage gas regulators were required. The gas fittings are the tiny (BB, I think) connectors, and the pass-thru ports are relatively small (just over 1/8" IIRC).

Numerous other links can be found by searching "flame spray" (with quotes).

WB ................