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Coating Integrity Tests and Certificates

When coatings are used for corrosion protection in heavy corrosion media, it is essential to ensure full coating integrity (i.e. that the coating is pinhole free). Tantalum Technologies offer a number of tests and may issue EN10204 / 3.1.B certificates. In addition to certify products coated by us, customer parts may be tested for comparison or other customer validation.

Available tests

	Substrates	Suitable Coatings for test	Advantages	EN10204 / 3.1.B certificate can be issued
Corrosion test Hydrochloric acid 20% - 95°C / 203°F	Steel and alloys, titanium and alloys, Cupper and alloys	Ta, Au, Pt, Ag, PTFE, ceramic, paint etc	Real conditions simulation test	YES
Corrosion test Hydrochloric acid 32%- 75°C / 167°F	Steel and alloys, titanium and alloys, Cupper and alloys	Ta, Au, Pt, Ag, PTFE, ceramic, paint etc.	Real conditions simulation test	YES
Ferricyanide test ASTM B 733	Steel and alloys	Ta, Au, Pt, Ag, PTFE, ceramic, paint etc.	Non-destructive	YES
Layer thickness (mass)	All	Only In-house coatings	Fast and non-destructive	YES
Layer thickness (metallographic)	All	All	Shows material distribution on part	N/A*
Electrochemical test (sulphuric acid)	Steel, Stainless and Cupper	Ta, Au, Pt, Ag, PTFE, Ceramic, paint etc.	Minimum destructive. Pinholes/or failure can be repaired by reprocessing	YES

*) separate report is issued

Prices and lead time

	Test Time	Price 1 part (start-up)	Price pr. extra part (same test run)	Masking of uncoated areas prior to test*	Price for EN10204 / 3.1.B certificate
Corrosion test Hydrochloric acid 20% - 95°C / 203°F	1-10 days	EUR 75 USD 90 GBP 50	EUR 25 USD 30 GBP 20	EUR 50 USD 60 GBP 35	EUR 50 USD 60 GBP 35
Corrosion test Hydrochloric acid 32% - 75°C / 167°F	1-10 days	EUR 75 USD 90 GBP 50	EUR 25 USD 30 GBP 20	EUR 50 USD 60 GBP 35	EUR 50 USD 60 GBP 35
Ferricyanide test ASTM B 733	2 days	EUR 75 USD 90 GBP 50	EUR 25 USD 30 GBP 20	EUR 50 USD 60 GBP 35	EUR 50 USD 60 GBP 35
Layer thickness (by mass)	1 day**	EUR 25 USD 30 GBP 20	EUR 10 USD 15 GBP 10	N/A	EUR 50 USD 60 GBP 35
Layer thickness (metallographic)	5-10 days	From approx. EUR 150 USD 180 GBP 100		N/A	N/A***
Electrochemical test (sulphuric acid)	1 day	EUR 100 USD 120 GBP 70	EUR 50 USD 60 GBP 35	EUR 50 USD 60 GBP 35	EUR 50 USD 60 GBP 35

*) necessary if parts contains uncoated areas
**) test must be initiated prior to coating. Cannot be made on final coated parts alone
***) separate report is issued

Corrosion test in hot hydrochloric acid

Internal procedure: K72.02

Description: Parts are exposed to hot hydrochloric acid (se below) for a specified time (see below). Failure (e.g. pinholes) in the coating will show up as pitting corrosion of the substrate and a weight loss from the parts. Exposure time is chosen dependent on the substrates corrosion rate in the test media (tantalum does not corrode). For fast corroding substrates a 48 h exposure is sufficient for validation of integrity (coating failure may be typical be observed after 6-12 hours) For substrates with very low corrosions rates, the test time may be extended to above 7 days.

Test media: 20% HCl at 95°C / 203°F or 32% HCl at 75°C / 167°F

Test time: Min 48 h, substrate dependent

Suitable test substrates (corrosion rate):

Steel (fast): Carbon steel
Stainless Steel (fast): 304; 304L; 316; 316L
Stainless Steel (slow): 904L; 254SMO; Duplex 25-6-3
Titanium (slow) c.p - grade 1 or 2; Ti6Al4V an other alloys
Nickel base Super Alloys (slow): Alloy 600/650; Mo Super alloy 625/725; Mo Super alloy C276; Mo Super alloy 686; Mo Super alloy C22; Mo Super alloy C20000; Ni-Mo alloy B2 Nickel (200)
CoCrMo alloy (slow)
Niobium (slow)
Zirconium (slow)

Substrates that are not suitable:

Gold
Platinum
Carbon
Ceramics - e.g. Al2O3, Glass

Ferricyanide test - ASTM B 733

Internal procedure: K63.05

Description: Parts are exposed to a solution containing potassium ferricyanide, (K₃Fe(CN)₆) and sodium chloride (NaCl). By the test Fe(II) ions from the corroded substrate (if any) will react with Fe(CN)₆^3- ions in solutions and form strong colored spots (Berlin Blue) at insufficient coated areas (e.g. at pinholes). The ferricyanide test may be performed alone or after another (accelerated) corrosion tests, e.g. hydrochloric acid test or polarization test as an very sensitive indicator for pinholes.

Test media: Solution containing NaCl and K₃Fe(CN)₆

Test time: 16 h

Suitable test substrates: Carbon steel and stainless steel (304 and 316) an other iron containing alloys

Polarization test in sulphuric acid or nitric acid

Internal procedure: K63.06

Description: The part is immersed in a solution of sulphuric acid (H₂SO₄) or nitric acid (HNO₃). The current is measured during anodic polarization. If the coating is fully intact (pinhole free), no current will run. If the coating contains pinholes a corrosion current can be measured.

Test medias: Diluted sulphuric acid (steel and stainless steel); diluted nitric acid (cupper)

Test time: < 1 h

Suitable test substrates carbon steel, stainless steel (304 and 316) and Cupper