You Asked: Trivalent Passivation vs Iridite NCP

In order to comply with environmental standards, Silchrome Plating now offer Electroplated Zinc using Trivalent Passivation. We have had positive feedback about this process and a few of our customers have asked if Trivalent Passivation can be used on its own and how it would differ from Iridite NCP.

The Trivalent Passivate system that we use in conjunction with zinc plating is called Tripass ELV 1500LT. This process is specifically tailored to work in conjunction with zinc electroplating and cannot be used as a process in its own right.There are however a number of alternative passivation processes available which includes Iridte NCP, Surtec 605v and many others. 

These systems were developed as alternatives to traditional passivation techniques which produced hexavalent chromium as a by-product. Hexavalent Chromium is a known carcinogen and bad for the environment and is becoming a much more restricted process. There are a number of different trivalent systems that can be used depending on your application and currently there is not a ‘one size fits all’ trivalent process that can perform the function of traditional passivates.

Iridite NCP is one such branded process. It can only be used on components which are made out of Aluminium Alloys. It provides an excellent level of corrosion resistance and can also act as a base coating for paint and powder applications. Iridite NCP is completely Chrome free as a process and meets ELV, RoHS and WEEE directives.

This does contrast to most other Trivalent Passivates. One key issue with many Trivalent Systems is that they still contain chromium and where RoHS compliance is necessary it is often preferable not to use these systems on the basis that if there’s no chrome it’s easier to prove there is no hex chrome. In terms of performance, Iridite NCP is more thermally stable than Trivalent Passivates (up to around 350 degrees Celsius) and can offer 1000 hours resistance under neutral salt spray tests for many Aluminium alloys.

Where you are looking for a completely chrome free way in which to passivate Aluminium Alloys then Iridite NCP may be the right process, but it’s important to understand that non-chromate aluminium treatments are not automatically interchangeable and your application will very much depend upon the process we’d recommend. No doubt Trivalent Passivates with their variety of manufacturers and brand names may cause some confusion for end users but as far as the Tripass ELV 1500LT that Silchrome uses in conjunction with our Electroplated Zinc,that cannot be used as a standalone process.

Silchrome Plating offer a wide range of metal finishing processes including electroplating, conversion coatings, specialist processes and even paint and powder coatings. We are ISO 9001 and 14001 accredited and all of our processes are carried out in our facility in Leeds,West Yorkshire but we do serve the whole UK.