Triumphrat

ed_h

Rob--

Actually, I was quoting a source on what the efficiency of the chloride bath is. Some others set it higher--as high as 95%.

I haven't measured it, but it would be pretty easy. Just weigh a piece before and after plating, and compare the weight gain with the theoretical of 1.4 grams per amp-hour. I might do that next time I fire up the process.

OTOH, other than the cost of electricity, high efficiency of the bath isn't all that important. Lower efficiency may even imply better ability to reach into recesses ("throwing power").

__________________
For only a little more, you can do it yourself!

Acebars

Just noticed my Honda (Burn it burn it! ) has stainless steel fasteners all over it on aluminium

I've read however that a lot of motorcycle builders do do this and simply put on anti-seize in between the the stainless fastener and the aluminium.

Is this not a way to get around the galvanic corrosion and if not is it possible to do zinc electrolysis on stainless bolts?

Here's where I read a little http://forums.sohc4.net/index.php?topic=81763.0

I'm trying to find some zinc anti-seize grease in the UK for this very purpose!

Snakeoil

Someone on this forum with a metalurgical background, and it may have been ed_h, mentioned in another thread that if you can seal out the moisture and air, the issue with stainless fasteners on aluminum cases is pretty much eliminated. I seem to remember the same person mentioning thread lock products like Loctite. But I could see a healthy coating of anti-sieze or even grease accomplishing the same sealing properties that are desired.

There are tons of bikes out there with stainess fasteners installed on aluminum cases. People still do it and companies still sell fastener kits for that very purpose. I've used them myself, but always with anti-seize or Loctite.

regards,
Rob

ed_h

I'm not a metallurgist, and I'd yield to anyone who is, but I was a chemistry major for a few years before switching to Engineering.

There are normally several things that have to be in place before you get "galvanic" corrosion. First, you need two different metals. Then there has to be a conductive medium (usually a liquid) present--impure water works fine for this. Last, the two metals need to be electrically connected--this is usually the case if the metals are in contact.

To determine which metal corrodes, you have to refer to the "galvanic series" list. The metal higher on the list will corrode (oxidize), and the rate of corrosion will roughly be determined by how far apart the two metals are on the list.

Aluminum and stainless are fairly far apart on the list (farther than mild steel and aluminum), and this is why people warn about corrosion with this combination. The best prevention is to keep the joint from getting wet or staying wet. Some people recommend grease or an anti-sieze compound for this.

Galvanic corrosion is a pretty slow process, so there usually isn't a need to panic if you get caught in a rain storm.

__________________
For only a little more, you can do it yourself!

Acebars

Snakeoil thanks for this clarification, its going to save me a lot of time with all those bolts, I've got some copper anti-seize grease, is that enough or should I fork out for zinc anit-seize circa £40?

I'll still be doing the plating on other parts eventually and will let you know how I get on.

Snakeoil

I'm no expert. Just parrotting what I've heard here an other places where folks have given their credentials along with their recommendations, info etc. So I bow to the experts on your question.

I know the anti-sieze you are talking about. I think a common brand is Felpro C-100. We use it on turbine bolting due to it's high temp capabilities. I have a big can of Permatex anti-sieze that I believe is moly based.

regards,
Rob

Acebars

Hey snakeoil, I was wondering whether or not baking powder can be substituted for the epsom salt (wild suggestion ).

I'm going to be stripping rust via electrolysis I'm thinking of buying baking powder as suggested for this, then cleaning with white spirit and finally zinc plating. Perhaps the epsom salt can substitute the baking powder so I'll just buy a tub of epsom salt.

On another note I have a battery charger that has a trickle charge setting and also 6V/12V settings. Should a trickle charge setting at 6V provide a low enough amperage for the right results?

Likewise I'll be trying out zinc coating on the stainless steel parts. Would be wonderful if it works.

henryanthony

Washing Soda works well for electrolytic rust removal. I stripped a lot of parts this way. It was surprising to see how much rust was hiding behind the paint.

Acebars

I've done a little reading I think that Epsom salts can be substituted successfully also. Saves me having to buy both, I can just buy a tub of Epsom salts.

Acebars

I'll be about ready to finally start electrolysis this week, with many thanks going to Snakeoil.

Only thing I'm missing is some zinc. I have two sources a roofing supplier and a yacht anode supplier.

Is it that important that the anodes are flat like plate, or would it be ok if I just had 4 rods spaced 90 degrees around the tub.

Reason I ask is because I'm able to buy 4 16mm 250mm rods at 1.5 kilo total for the same as 700g of zinc plate.

Likewise I've been thinking of substituting the magnesium sulphate and vinegar for zinc chloride and/or zinc sulphate which can be bought very cheaply and are actually used in industrial zinc electroplating, anyone know anything about this?