DIY High temp coatings
 

I have some hot piping, manifolds, and turbine housings I want coat myself and I wanted to see what you guys have experience with. I plan on blasting, heating, then spraying the material and letting the exhaust heat cure them for the final round.

I saw Cerakote makes some high temp stuff, I know there gun coatings are awesome. Most seems to be around $70 for 16oz or so.

I’ve just been using the VHT ceramic high temp header coating. Has worked very well for me by following the baking directions on the can. Haven’t had anything flake or come off in the past three years of using it. As far as effectiveness I can’t really debate that. Just make sure you cover any threaded holes or studs or you will be re-tapping them. It’s like powder coat after it’s baked on.

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Nice, how did you clean it?

i sandblast everything prior to coating. The stuff pictured I had already coated once before so I just wiped them down and put another coat on since the manifold and charger are off the truck.

Another vote for the Cerakote "C" Series of coatings. Air dry and sprayed with a normal hvlp gun.

A friend of mine has used some of the cerakote bake on stuff (not sure on which mixture) in some fairly high horsepower gasoline pistons with good results. Makes a nice looking finish. Suppose to help with heat rejection and such.

I can promise you VHT doesn’t take 2000* degree EGTs but 1600 and under it holds well

Cerakote C series air dry can take some serious heat cycles and is fairly easy to spray.

With fabricating the new spinny-thing install on my heap recently, I used the Cerakote products to coat the hot-stuff inside and out. Cerakote provides fairly well detailed instruction for applying the product on their website.

Using said instruction (and supplementing here and there) . . . .

- I put all the parts in the dishwasher with a very strong dose of the dishwasher detergent (most are based on Sodium Hydroxide, AKA: Lye) followed by multiple hot water rinses while still in the machine. This helps ensure any oily residues are removed.

- Without touching the metal goods with my oily booger-hooks, I then placed them in the oven, at 500*f, for an hour (after they've come up to 500*f). This further ensures any oily residues are burned.

- Again, without touching the goods with my booger-hooks, after allowing ample time to cool, I bagged the individual parts in individual, new zip-lock plastic bags. NOTE: Any straight cast Iron parts will have begun to oxide at this point, that's OK cause you're gonna get that next).

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- Now, it's time to blast the goods with the likes of 120grit Aluminum Oxide (RTFM). DO NOT Glass-Bead blast the goods as Glass-Bead media simply dimples the material surface. You want to leave the surface with sharp peaks and valleys for the Cerakote products to properly mechanically bond to the articles. Do not use too coarse of a blast media as you don't want the peaks and valleys too deep as the Cerakote product may simply fill the valleys, leaving the peaks standing proud, uncoated. Again: RTFM! REPLACE/RENEW the blast media often as the media fractures/powders with use.
Before removing the goods from the blast-box, make DAMNED sure to blow any and all residual blast media from any nooks and crannys.

The blasting process will most likely turn the surfaces to a dull, flat textured surface. If it still shines in the least bit, continue blasting.

As an example, Before (raw 304 Stainless steel):

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And after:

http://i169.photobucket.com/albums/u...psvmyrfrzx.jpg

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- Again, don't use your booger-hooks to handle the now blasted goods (Use something like the disposable Nitrile gloves). With that, place the goods in the individual plastic bags till it's time to coat them.


- As I coated both the internal and external surfaces, I had to pay attention to the individual coating instruction. I used the Cerakote C-7900 (glacier Titanium) air-cured product for the exterior surfaces. I used the heat-cured Cerakote W-209 Insulkote product for the interior surfaces.
With that, I coated the interior surfaces first with the W-209, followed by the exterior with the C-7900.
READ AND FOLLOW the product application guide. You want a 1~2 mil SINGLE coating IIRC. DO NOT apply too thick as in too heavy a coat. DO NOT apply more than one coat. (If you screw-up the application, you MUST remove it all and start over. PERIOD). I used the Cerakote recommended gun with dry Nitrogen gas as a propellant.

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I let the C-7900 product air-cure for a week (as per the FM).

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Then placed the goods in the oven at 500*f for two hours to heat-cure the W-209 internal coating:

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NOTE: IIRC, Cerakote wants you to heat-cure the W-209 with a notably higher temperature, but I couldn't find a workable excuse for the wife as to why the cabinets around the oven look toasted. Hence, the two hour cure time of 500*f. READ the product instruction and follow as best as is possible in that regard.

- I recommend one consider your overall build schedule and save the coating of goods for the end of the build. You don't want to risk mechanically damaging or fouling the coating(s) during subsequent disassembly and reassembly.
- Be prepared for anything made of straight cast Iron to begin corroding soon. In the past, I've tried the Jet-Hot applied, Jet-Hot coating, only to have it start showing corrosion in short order. Sent it back under warranty and had it stripped and recoated, only to have it start corroding soon thereafter again. Screw Jet-Hot.
I then had that product stripped off and had the local Cerakote dealer apply their product. It started showing light corrosion a little over a year later.

My application of the stuff this go round is already showing corrosion on the straight cast-Iron secondary exhaust housing. :doh: The 304 Stainless components as well a the high Nickle cast-Iron primary exhaust housings are still pristine.

Your mileage may vary.





Hope this helps. :)

Cheap and easy is Loctite Moly dry film lubricant

Touch up is easy also

Probably doesn't last like a genuine high heat coating, but it goes on a rusty manifold without any prep and holds up decent. Don't know if it will adhere to a nice clean surface.

It doesn't smear off once it's been baked on, didn't notice any burning fumes either

If you want a lot better performance for quite a bit more money, Sermetel is the way to go. Do their aluminized primer on the exterior stuff for salt corrosion, then black ceramic over it.

Cerakote C7300 is pretty great, but be careful with C7600. It builds up and flakes REALLY easily. Adhesion is a big problem.

I have fantastic results with DEI Silicone Hi-Temp Silicone Coating Spray without a baking procedure at all. I've used it over 10 years now on various projects. Works very well on cast as well. Held up on my old setup to 1900* peak for 2 years. I used it again but in black this time and it is looking very good after one year but now only EGT's in the 1200* range.

VHT doesn't hold a candle to this stuff. I've done both and wasn't impressed at all with VHT.