Armoloy versus Hard Chrome Plating 1

[MetalGuy10]

What is the difference between Armoloy’s chrome electro plating and standard hard chrome electro plating? I have had an inquiry about switching from hard chrome plating to an Armoloy plating. One of the sister branches of my employer have positive comments regarding Armoloy.
Armoloy has a web site that proclaims their superiority versus standard hard chrome plating, but the details on Armoloy’s chemical composition is proprietary so how can a general comparison be made between the two options? Some coating systems like steel galvanizing have ASTM designations like G60 and G90 that can be used to compare coating weight/thickness. Stainless steels can be classified by a PREN (Pitting Resistance) number that is a factor of Cr, Mo, and N. Does a standard practice exist for rating and classifying hard chrome plating corrosion resistance?
One benefit of hard chrome plating is improved corrosion resistance. The part in question will be placed intermittently into corrosive environments. The current hard chrome plating seems to be effective as long as the part is cleaned after each usage.

 

[unclesyd]

If I recall correctly their Thin Dense Plating doesn't have the normal path to the base metal. This allows their plating to be quite a bit thinner than the normal Industrial Hard Chrome. Evidently the have control over the cracking that one normally sees in off the shelf IHC.

From my experience it has worked as advertised under some pretty adverse conditions of polymer with the addition of TiO2 and/or Kaolin.

 

[blacksmith37]

Hard Cr is primarily for wear; I think the Cu ,Ni layers provide most of the improved corrosion resistance. I would run a salt spray (ASTM G85 ?) or some other objective test to evaluate relative corrosion resistance of coatings/plating.

 

[MetalGuy10]

Thanks for the feed back guys. I called to Armoloy and have made some contact to get their imput. The spec on the part was QQ 320 B, class 2. The spec is an old mill spec.

 

[BLaroux]

We've found regular industrial hard chrome thinner than .002" without undercoating offers little or no corrosion protection for immersion-corrosion. Thicker layers (.005" - .010") work alot better if you can afford it. The micro-cracks present in typical IHC don't go that deep, so it eliminates most direct paths for corrosives to the base material.

Thin dense chrome / armoloy is still a 100% Chromium coating applied by electroplating, but with different parameters. There is no cracking, but it is very thin... 1/10th that of a typical IHC layer. It works well for corrosion as long as it doesn't get scraped/gouged off. (which happens to us all the time) If its a gentle service or you can use a very hard substrate it should do fine.