The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Need a coating to withstand heat and corrosion for cast iron

I am looking for the best coating to use on car rotors that we turn on a daily basis. The kids out there today buy these wheels that are so open that the rotor is exposed for everyone to see. They are wanting to stop corrosion first of all, then they ask for different colors to be applied to the rotor. I was doing a zinc dip without much success, I think because the thickness of the dip was too great. We are open to any ideas anyone may have. What we are fighting at this point are heat, corrosion, life of the coating in this application, different colors, and how to do which ever way is best to achieve all the above.

Many thanks for any help you may have.

J. Chuck Hembree
machine shop - Greer , South Carolina, USA
2003

You may want to try a High Phosphorous Electroless Nickel plating.

Todd Osmolski
- Charlotte, North Carolina, USA
2003

---

I've seen chrome on brake rotors for certain low or zero-use show vehicles.

These rotors have a very nice look, but are absolutely horrible at doing what they are supposed to do - stop the vehicle - as now the friction between the pad material and the rotor has been reduced manifold.

I would also suspect (though I cannot confirm) any type of EN coating would have a similar effect.

In this litigious day and age, I would shy away from any kind of work which would coat a brake rotor, especially on a vehicle intended to be driven on public roads.

That being said, we have rotors cryogenically treated, which imparts all sorts of beneficial effects. However, I cannot say that there is a significant difference in corrosion resistance for a low or limited use vehicle.

S.A. McChesney
motorsports design and fabrication - Nanuet, New York
2003

As a certified gearhead, I have first person experience with this problem. My 2001 Corvette has polished aluminum wheels that are very open and you can see the rusting rotors easily. One of our customers is having us EN plate rotors. They look great and work just as well. I was frankly not in favor of plating them for all the obvious reasons, but inexplicably, it works. The problem is one of cost. You can have them zinc plated and yellow or blue chromated, or cad plated, for a lot less than EN plating costs. We are currently working with our customer on cost reduction techniques that will allow EN to compete with the other coatings.

Dan Weaver
- Toccoa, Georgia
2003

There's nothing sexier that a clean wheel house! Tires, rims, and rotors and brake calibers, beside my wife (of course) but seriously, I have been to a lot of hot rod events in my time and have had the good luck to have built a few show & go vehicles. The one thing that I have found to work is having the hub plated and the rotor itself masked off. Also goes true for the calibers. The piston holes and bleed valve, brake hose inlet....anywhere there is a working mechanics involved. After any part that has to do with stopping has been chemically reprocess as electroplating or pickle (with acids) should be heat treated after the process to relieve embrittlement. There are other coatings out there to think about for example ceramics and porcelain but you will pay for what you get.

Mike Crabtree
electroplating-polishing - Raleigh, North Carolina, U.S.A.
2003