Where the
world gathers for metal finishing
Q&As since 1989


-----

High temp and abrasion resistant coating

I am not a coatings expert so I could use some help with a finishing problem (finish opportunity if you are an optimist). We use rotating steel furnaces to melt sand in our manufacturing process. Over time the uncoated interior of the steel furnace develops surface rust and tends to flake due to the heat. This rust can contaminate our material. We would like to coat the furnaces when they are new to prevent the rust - we could also recoat as needed if it were not to frequent.

The furnaces go through about 4-5 heating and cooling cycles in a 24 hour period. There is a high temp. arc in the furnace during processing but due to the insulating properties of the sand the furnace surface itself seldom goes over 100 °F. Occasionally the furnace surface will reach 400 - 500 °For a short period if we encounter processing problems. The furnaces are also exposed to quite a bit of abrasion. Each cycle requires sand to be poured into a rotating furnace - so any coating would have to be very tough as well as temperature resistant.

I'm aware of the stove and automotive type high temp paints but I'm sure they would not hold up in this environment. I just saw a Super Therm coating on the net but I haven't checked into it yet.

We could arrange to sand blast for the coating process if necessary. We could also arrange for spraying if it didn't require too much talent or specialized equipment. Can anyone out there give me any suggestions?

Thanks in advance...

Ron Fleenor
- Rogersville, Tennessee, USA
 

---

Ron:

Your problem sounds very much like the one faced by airfoil or turbine buckets. High abrasion, erosion and temperature. So, you should start to look for the type of coatings applied to those components by spraying that are heat resistant and hard, especially by the method of plasma spraying. They are thicker than plating and hold up very well if properly applied. The equipment is portable and able to coat large, internal and irregular surfaces.

Guillermo Marrufo
Monterrey, NL, Mexico