Application
High-temperature corrosion
A film that stays on steel above 400 °C
The situation
Carbon steel ducting, stacks, air preheaters and furnace frames that see 400–600 °C in air, with condensate on shutdown and chlorides in the flue gas. The part is too large to stove, so the coating has to cure either at ambient or with a local heat source.
What fails today
- Organic coatings chalk and lose gloss above 400 °C, then crack as the binder burns out.
- Silicone coatings hold the temperature but stay soft and permeable, so chloride reaches the steel underneath.
- Zinc-rich primers stop protecting once the zinc is consumed, which is a matter of time in a wet flue.
- Re-coating a failed stack usually means scaffolding twice: the first failure is the expensive one.
Grades for this duty
SF-180VP
One bottle, four cure routes, 80–90 % ceramic yield
SF-CB103
A precursor film that cures only in the oven
SF-CB105
1005–6005 cSt: for thick barrier films, not for spraying
SF-NF4401
13–15 % fluorine, the entry grade for release and repellency
SF-NF4402
28–30 % fluorine in the trifluoropropyl chain
SF-NF4403
22–25 % fluorine, already at 105–110°
SF-NF4404
Long-chain fluorinated, 38–40 % fluorine
SF-NF4405
The highest fluorine load we make: 55–60 %
SF-NF4406
48–50 % fluorine, long-chain chemistry
SF-RC004
Lowest viscosity in the range, 50–60 % solids, room-temperature cure
How to apply it
Abrasive blast to Sa 2.5, or St 3 where blasting is impossible; the film does not hide a mill scale surface.
Degrease after blasting; the material reacts with water and with alcohols, so the surface must be dry and free of solvent residue.
Thin coats, not one heavy pass: the film cures by reacting with moisture and a thick layer skins over before the solvent leaves.
Cure as the grade requires, then bring the part up to temperature slowly on first service.
Do not topcoat with an amine-cured epoxy: the amine attacks the film while it is still reactive.
How to qualify it
- Qualify on a coupon cut from the same steel, not on a polished test panel.
- Salt spray to ISO 9227 (GB/T 10125), with and without a scribe.
- Adhesion by cross-cut to ISO 2409 or ASTM D3359 before and after the heat cycle.
- A thermal cycle between service temperature and ambient, then a second adhesion test: a film that survives heat but lifts on cooling has failed.
- Pencil hardness to ISO 15184 (GB/T 6739) on the cured film, with the film thickness recorded.
Bring your substrate and your target; we quote a grade and a cure schedule against it.
Next step