Like many other nickel alloys, Hastelloy* coatings are ductile, easy to spray, and possesses exceptional resistance to stress corrosion cracking in chloride-bearing solutions (a form of degradation to which the austenitic stainless steels are prone).
With its high chromium and molybdenum contents, it can withstand both oxidizing and non-oxidizing acids and exhibits outstanding resistance to pitting and crevice corrosion attack in the presence of chlorides and other halides.
Furthermore, it is very resistant to sulfide stress cracking and stress corrosion cracking in sour oil field environments.
The Corrosion Resistance of HVAF Sprayed Hastelloy Coatings
The need for a metal coating appears when a corrosive attack is combined with elevated temperatures, abrasion or cavitation.
The resistance of thermally sprayed Hastelloy C-type coatings to aggressive factors is highly dependent on the coating’s porosity, bond strength and oxidation levels.
Kermetico HVAF coatings are characterized by significantly lower porosity and oxidation than HVOF coatings due to much lower process temperature, higher particle velocity and less oxygen in our HVAF process.
The Typical Properties of Kermetico HVAF Hastelloy Coatings
Pre-alloyed Hastelloy powder, gas-atomized.
| Nominal composition | wt.% |
| Nickel | base |
| Chromium | 16-17 |
| Molybdenum | 16-17 |
| Iron | max 2.0 |
| Silicon | max 1.0 |
| Manganese | max 1.0 |
| Carbon | max 0.10 |
The Properties of the HVAF Hastelloy Coating
| Apparent metallographic porosity | <1.0% |
| Hardness, HRC | 28-30 |
| Bond strength to carbon steel (@ 500 microns (0.020”) thickness), MPA (PSI) | 80 (12,000+) |
| Maximum coating thickness (as-sprayed), mm (inch) | 2 (0.080) |
- Machinable
- Excellent resistance to corrosion in salt water, reducing acids, hydrogen sulfide and gases containing sulfur oxides
- Good resistance to elevated temperature and dew-point corrosion
The Hastelloy coating is usually applied with our HVAF spray-blast technology and contains 5% aluminum oxide particles. It is very ductile and allows welding in proximity to the coating.
A Micrograph of a Kermetico HVAF Hastelloy C Corrosion Resistant Coating, X100
Typical Applications of High Velocity Air Fuel Hasteloy Coatings
Used for corrosion protection of:
- Waterwalls of waste-to-energy boilers
- Impeller blades and housing of pumps
- Pump sleeves and fittings
- Walls of sulfinol-amine contactors
- Sulfuric acid-handling equipment
- Flue-Gas desulfurization systems
- Pharmaceutical reactor vessels
HVAF Spraying Hastelloy Coating Inside a Vessel
Chevron has specified our HVAF Hastelloy coatings for vessels and reducers of oil refinery sulfur removal plants.
HVAF Equipment to Spray Hastelloy Coatings
Most of Kermetico guns can spray Hastaloy coatings.
- Convertible HVOF and HVAF equipment:
- Multi-purpose HVAF AK systems, with a variety of different spray guns:
- AK7 – a high-power gun for the thermal spray of large parts, maximum spray rate – 22 kg (50 lbs.)/hour
- AK5 – a compact gun to spray smaller parts, thin walls and complex surfaces, maximum spray rate – 8 kg (18 lbs.)/hour
- AK-ID – an 80 mm (3.15”) and larger internal diameter spray gun, maximum spray rate – 3 kg (7lbs.)/hour
- AK-IDR – a rotating ID gun to spray 4” (100 mm) and larger bores, maximum spray rate – 3 kg (7lbs.)/hour
- AK-HH – a handheld gun for on-site coating, maximum spray rate – 8 kg (18 lbs.)/hour.
- Additional equipment:
- An HVAF grit feeder for the grit blast preparation of parts to reduce coating costs
- A Gas Permeability Tester for an instant check of a coating’s through porosity
Kermetico, Inc. – Material Science Excellence, HVAF and HVOF Equipment Manufacturing and Thermal Spray Coating Services Since 2006
We create equipment that helps material scientists, engineers, and business managers achieve their goals.
We have installed more than 60 Kermetico HVAF systems in the USA, Europe, Japan, and China.
Some of the systems are at work in Universities and National Labs, but most of them are used in production thermal spray shops.
We proudly design and produce our HVAF thermal spray equipment in California and install it all over the world.
You can visit our R&D center in Benicia to meet our designers and see our HVAF equipment in action.
We also provide HVAF and HVOF thermal spray coating services for customers in the San Francisco Bay Area in California, USA.
*Hastelloy is a registered trademark of Haynes Inc.
