Which coating to use? 1

I know very little about steel coatings and have been trying to research different types to satisfy a specific application I have.&nbsp;&nbsp;I've found so much information and so many coating choices that it is very difficult for me to choose.&nbsp;&nbsp;My application requirements are below.&nbsp;&nbsp;I would greatly appreciate any suggestions.<br><br>Product: long, narrow C-channel<br>Material: 1010 steel<br>Requirements: coating must offer corrosion protection, wear resistance, and color the channel black.

 

[Waterjetz]

Heather...ordinary paint will give you the color and corrosion protection you want, but won't help you with wear. Might be that by the time you find a suitable and compatible coating system for your 1010 channel, you'd be better off looking at a different material to make your channel out of. Just a thought.

 

[HScribner]

What is the channel going to be used for? What kind of surface prep can you provide? What service life do you want from the coating?

Answer these 3 simple questions and I can give you the perfect coating for the job....

I have been in the corrosion business for a few years. I have worked with coatings and cathodic protection systems. You really must think about the environment you will subject this part too, the surface prep, and the service life you are looking for.

hscribner@henkelsaandmccoy.com Email me directly and we will converse about it.

 

[rembrandt]

Try a Ceramic Filled Two Pack Epoxy , or a Glass Flake reinforced Two Pack Epoxy.
Both have good abrasion resistance and corrosion protection, I reckon that they should be able to be purchased in Black.
Hope this helps.

 

[RichardC]

Depending on the end use and the preparation prior to coating an epoxy powder coating should be ok. They are tough,offer corrosion protection and come in all colours. Most industrial coaters will be able to paint the object.

 

[paintguru]

I'm with HScribner....

More info is definitely necessary to formulate a proper coating system. Actual service condition and intended service life is what I'd really need to proceed with a recommendation. Kevin A. Schweikhart, CSI CDT
Senior Professional
SSPC Protective Coatings Specialist
NACE Certified Coating Inspector
LAW Engineering and Environmental Services, Inc.
Phone813)636-1567
Fax: (813) 289-5474
e-mail: kschweik@lawco.com

 

[civeng]

I had about the same situation at one time, and what we did was galvanize the material, and the painted over the galvanize with an epoxy paint.

 

Heather:

For superior corrosion resistance and durability, try an inorganic zinc primer with epoxy mastic double overcoat. If the metal is blast cleaned to SSPC-SP10, you should be able to keep it coated and protected for many years. The only problem with the zinc is it's affinity to lead, so you really need to be careful with the application process of the primer. Good luck!

 

[paintguru]

Responding to Civeng and retired-chef:

Although both options given may offer the protection you are looking for....

Painting over galvanized steel should be undertaken with care and specific requirements. I've had tremendous success overcoating hot-dip galvanized steel by preparing the zinc surface in accordance with SSPC-SP 1 (cleaning residual oils from quench bath) followed by a SSPC-SP 7 (Brush off blast cleaning using a fine abrasive such as DuPont's StarBlast).

After surface preparation, you could apply a coat of &quot;organic zinc&quot;, followed by two coats of epoxy (epoxy amines achieve a harder film) or if you have exterior exposure substitute the finish coat with an aliphatic polyurethane.

We use the &quot;inorganic&quot; zinc (IOZ) over hot-dipped zinc without topcoat on the East Coast of Florida and achieve long-term service (10 years plus). But you are looking for a finish color. In addition, I'm not a big fan of using IOZ when subsequent multiple coats are used (including long-term maintenance). IOZ's are best suited when they are able to be exposed to the atmosphere to achieve their oxidized &quot;tighter/barrier&quot; film. I also consider the relative difficulty in applying IOZs. They tend to &quot;dry spray&quot; and require higher humidity to fully cure. If they don't cure properly or if dry-sprayed, the subsequent coatings may delaminate. Organic zinc is very applicator friendly. There is a whole other debate about the &quot;galvanic properties&quot; of IOZ and organic zinc (another day).

Zincs (specifically hot-dipped galvanizing is the most abrasion resistant) will give you the best &quot;secondary protection&quot; from mechanical damage and/or abrasive wear. To increase abrasion resistance you could also add &quot;chopped glass&quot; to both the mid-coat and finish coat. But these examples are all &quot;cadillacs&quot; and cost should be investigated prior to finalizing your documents.

Regarding LEAD in zincs - lead is naturally occurring in the zinc raw material, although the amounts are typically (all major suppliers) below the Consumer Product Safety Commission's (CPSC) definition of &quot;lead-free&quot; 0.06-percent by weight. Even DOTs acknowledge the &quot;designed risk&quot; of using zincs but the benefit outweighs the risk (worker exposure during removal) in the industrial world.

Just my two-cents worth.... Kevin A. Schweikhart, CSI CDT
Senior Professional
SSPC Protective Coatings Specialist
NACE Certified Coating Inspector
LAW Engineering and Environmental Services, Inc.
Phone813)636-1567
Fax: (813) 289-5474
e-mail: kschweik@lawco.com

 

[takoot]

I've just posted a thread asking whether dull gray color for the galvanized surface is an indication on problem. If it is, shall we sand blast the surfaces where we have the dull gray color and then apply IOZ (or some other alternative coat)?

 

[premlmw]

hello heatherg,
better you go for hard chrome plating,it will give hardness up to 1000Hv it is good for wear resistance as well as chromium generally increases corrosion resistance.
the problem associated with hardchrome plating is edge built up and uneven thickness but it can be avoided by controlling the parameters especially current density.

try this in a trial sample if it satisfy u then continue.

goodluck
ganesh