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Re: passivate
Re: passivate -- KOEHLER	Post Reply	Top of thread	Forum

Posted by: kelly_bramble ® Administrator, Administrator 10/10/2005, 14:17:45 Author Profile Mail author Edit

In genral I would have to say yes, passivation is a surface cleaning process to remove impurities or other contaminant which may cause corrosion.

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Re: passivate
Re: Re: passivate -- kelly_bramble	Post Reply	Top of thread	Forum

Posted by: KOEHLER ® 10/11/2005, 09:59:20 Author Profile Mail author Edit

Some people here believe it should only be pasivated if it is subject to water. Why spend time passivating a stainless steel bracket that just supports something is the mentality here. I tend to agee with you. Are there any rules about passivating stainless steel?

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Re: passivate
Re: Re: passivate -- KOEHLER	Post Reply	Top of thread	Forum

Posted by: jjg1975 ® 10/17/2005, 09:47:19 Author Profile Mail author Edit

Passivation is basically a process that removes free iron from the surface. Free iron can be transferred to the material in a number of different ways. There are ways to eliminate the need for passivation, but most often it is safer and not too costly to just passivate.

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Re: passivate
Re: Re: passivate -- jjg1975	Post Reply	Top of thread	Forum

Posted by: magnum2point0 ® 10/28/2005, 16:28:27 Author Profile Mail author Edit

I have had humidity problems in my department. We went on vacation last July, came back, and most of our gages and tools were starting to generate rust. Even our stainless steel tools were effected. It was a very expensive vacation. We had to buy new tools. I tested for humidity and found out that the RH was approximately 50%. This is 50% when the air conditioner is on. I can imagine what it was when the place was shut down in mid-July. Anyway, I did some experimenting. I sent some gages to the platers for Clear Passivation (MIL-P-35). Within 2 months the gages started turning black. Not rust per say, looks more like carbon build up. The gages I sent were steel, but not stainless. I was wondering if passivate effects the carbon content of steel under high levels of humidity? Also, does anyone know how to stay rust free under high humitity levels without a ton of oil, passivate, or dehumidifier? A cheap inexpensive way? I think I tried everything. I don't like the oil because it is messy, the passivate I think effects the steels carbon content, those silicone baggies do not work, and a large dehumidifier is too expensive. Any thoughts?

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Re: passivate
Re: Re: passivate -- magnum2point0	Post Reply	Top of thread	Forum

Posted by: magnum2point0 ® 10/28/2005, 16:52:22 Author Profile Mail author Edit

How about Iridite? Will iridite prevent rust without effecting the mechanical properties to within .00005"?

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Re: passivate
Re: Re: passivate -- magnum2point0	Post Reply	Top of thread	Forum

Posted by: kelly_bramble ® 10/28/2005, 17:12:07 Author Profile Mail author Edit

Also, see the following page regading corrosion; /corrosion.shtml

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Re: passivate
Re: Re: passivate -- magnum2point0	Post Reply	Top of thread	Forum

Posted by: kelly_bramble ® Administrator 10/28/2005, 17:09:12 Author Profile Mail author Edit

Iridite, or Chromate Conversion coating is a surface chemical treatment which can only be used on Aluminum. Check out the following /iridite.htm. As far as your stainless steel gages and tools oxidizing, if they where only exposed to 50% relative humidity, they where not a very good grade of stainless steel. I have tools in my basement which are exposed to 60% year round (twenty years plus), and they don't rust. Most quality tools are Chrome Vanadium plated steel. Chrome, Nickel, Anodize (Black) are pretty good surface plating techniques. See the following for some surface plating options: /finishing.htm.

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Re: passivate
Re: Re: passivate -- kelly_bramble	Post Reply	Top of thread	Forum

Posted by: magnum2point0 ® 10/28/2005, 17:59:32 Author Profile Mail author Edit

That is right iridite is used on Aluminum, forgive me, but Chromate can be used on steel after a Cadmium plating, cold rolled or other wise. I just find this very weird. We buy all our tools and gages certified from companies whom supply Starett, Brown and Sharp and Mitutoyo brands. Our pin gages, which had the most concentration of rust, were Vermont gages, fully certted. Like I said it is approx 50% RH with the AC on, with it off I do not know, for I am not there. Now that winter is coming we probably will have less a problem. You mention Black Anodize, but is that realistic? Wouldn't that effect the true dimensions of the gage? I have never heard of a black anodize coating that would be less than .00005, but if it can be done, it's worth experimenting with. Modified by magnum2point0 at Fri, Oct 28, 2005, 18:06:47

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