High Temperature Ceramic Coatings

[Munkul]

In my experience this would need to be produced from 321 or other type of stabilised stainless to deal with the repeated heating and cooling in the combustion chamber - not to mention the humidity of a bread oven which introduces steam directly into the chamber. This will then render this uneconomical.

I know what you mean, it's getting close to the service limits of 316L for temperature cycling, and moist steam (possibly salty/acidic) probably would push it to a much lower lifespan. The lifespan would depend a lot on how many times a day it cycles. You'd probably get a few years of life... but it's a risk, I agree.

310 or 321 would probably be perfect, if you could get the material at a good price.

I wouldn't want to coat it with anything super expensive. For one thing, after coating and baking, it may alter the balance due to internal stresses moving around.
I'd rather just coat it with cerakote and see how it performs.

 

[indykid]

Are your boundary conditions based on measured/datalogged data or educated guesses/gut feel?

 

[daleyd]

I used to work for a company that made industrial dryers, and the blown air fans had a max temp of around 350 degrees C - the combustion chamber was usually around 720-800 degrees and they open a damper to regulate the air temp. Never saw any coatings, the fans we used were just plain steel, but they did used to crack on a fairly regular basis, sometimes we found them during an inspection sometimes not…some of the bigger ones had 70-80kW motors so they caused some serious damage if they let go.

I’d agree on replacing the fan if it’s an available item, or a good inspection/clean and put back as is if not, and make it a regular service item? How long is it lasted until now, if it’s a few years then it doesn’t seem worth it to go to much effort to get it coated when, even with a coating itself would need to come out for cleaning at some point in the future?

Putting coatings on (especially in a food environment) seems to be a minefield to me, not so much for the coating itself but if it starts to chip and throws bits into the food process? Or introduces some sort of nasties?

 

[Robotstar5]

.......some of the bigger ones had 70-80kW motors so they caused some serious damage if they let go.

The extractor fans at the foundry were powered by 250hp motors and one went out of balance which bent the 6" shaft it was mounted on and stalled the motor, the first we knew was the building shaking and the ammeter pegged at 4000 amps!, we got a few hours overtime getting it sorted ready for production the next day.

 

[Ross365]

Compared with some of the stuff I've worked on in the past, 300'C is nothing. We had silica coatings on nuclear fuel pins tested to 820'C in carbon dioxide. Some coatings are applied by a gun, but the shape here won't allow that. Some coatings are applied in a vapour or plasma, and again the shape might not suit that. Dipping might work and I see that electroless nickel plate is offered by Poetons. Nickel would easily do 300'C in air; I'm not sure exactly what the atmosphere is here; is that known with any certainty? I'm sure that somebody could do silica by dipping if they can be found.

I suspect that who ever applies any sort of coating might want (insist on?) to do the prep-work themselves

 

[Brad93]

I know what you mean, it's getting close to the service limits of 316L for temperature cycling, and moist steam (possibly salty/acidic) probably would push it to a much lower lifespan. The lifespan would depend a lot on how many times a day it cycles. You'd probably get a few years of life... but it's a risk, I agree.

310 or 321 would probably be perfect, if you could get the material at a good price.

I wouldn't want to coat it with anything super expensive. For one thing, after coating and baking, it may alter the balance due to internal stresses moving around.
I'd rather just coat it with cerakote and see how it performs.

12 hours a day 6 days a week

 

[Hitch]

We've had some fancy coatings put on some valve components recently...

I'll drop you a message with the contact details.