The independent NACE TM0177 tests has proven the resistance of Hardide coating to sulphide stress cracking and stress corrosion in H2S environments.

The Hardide coating has a volume porosity of <0.05%, which is effectively pore-free, with no through porosity from 1μm of coating thickness. It contains no binder-phase such as cobalt or nickel. This allows the coating to protect substrates against corrosive and aggressive media including HCl, H2SO4, HF, H2S and molten metals.

Sulphide stress corrosion cracking is an issue for downhole tools as the natural gas and crude oil materials being processed often contain considerable amounts of H2S. Equipment that comes in contact with H2S environments can be rated for sour service with adherence to NACE MR0175/ISO 15156 for oil and gas production environments or NACE MR0103/ISO 17945 for oil and gas refining environments.

Hardide coated components perform extremely well in these environments, protecting the substrates of downhole tooling, preventing part failure, extending component life and reducing downtime.


30 Day Test
5% NaCl, 0.5% Acetic Acid, saturated with H2S

NACE-TM0177 Test Samples

The uncoated 17-4PH-H1025 sample (top) with three Hardide coated 17-4PH-H1025 samples below

NACE TM0177 Stress Crack on uncoated sample

Detailed view showing cracking across the full 20mm width of the uncoated sample face

The NACE TM0177 Stress Test cocluded that the uncoated 17-4PH sample failed at an applied strain level of 2000µε as a result of sulphide stress cracking.

The three Hardide coated 17-4PH samples tested at applied stress levels of 1500 µε and 2000 µε did not exhibit any evidence of coating cracking, degradation or de-lamination under the imposed test conditions.

Corrosive and aggressive media Hardide coating property
Hydrochloric Acid Resistant to attack
Sulphuric Acid Resistant to attack
Nitric Acid Resistant to attack
Aqua Regia – cold Resistant to attack
Oxygen to 400 °C Resistant to attack
Water to 600 °C Resistant to attack
Hydrogen Resistant to attack
Ammonia below 700 °C Resistant to attack
CO to 800 °C Resistant to attack
Chlorine Gas to 250 °C Resistant to attack
Molten glass to 1700 °C Resistant to attack