REACH - Applications for authorisation AFA045-01 Chromium trioxide

Closed 7 Aug 2023

Opened 12 Jun 2023


Public consultation on alternatives

Reference: AFA045-01

Applicant: Indestructible Paint Ltd

Application type: Initial

Substance name: Chromium trioxide

  • EC No: 215-607-8
  • CAS No: 1333-82-0

Proposed use: Use of chromium trioxide in the formulation of mixtures intended for supply to authorised downstream users to use these formulations as part of coatings to protect industrial gas turbines and related industrial equipment and components.

Broad information on use applied for (conditions of use and function):

Indestructible Paint are a formulator and applying for authorisation to cover their formulation activities using chromium trioxide.  Chromium trioxide does not have a specific functionality at the formulation (mixing) stage apart from being incorporated into formulations that are used for downstream uses by authorised downstream users.

The chromium trioxide formulations are typically applied to components by specialist coating companies at several different sites in GB. Chromium trioxide is a key constituent in slurry coatings (sacrificial (otherwise known as metallic ceramic aluminium coatings (MCAC)) and diffusion coatings). At the application and use stage, slurry coating products containing chromium trioxide impart important traits and functionalities required within the industries these components are used.

Key functionality criteria for downstream users include:

  • Corrosion resistance
  • Thermal resistance
  • Resistance to humidity and hot water
  • Chemical resistance
  • Adhesion

These are described in more detail within the downstream user application (AFA045-02 use 2).

Additionally, within the acidic slurry compositions, chromium trioxide acts as a passivator to stabilise the formulation by the formation of a thin layer of chromium oxide (Cr2O3) on the surface of each aluminium particle. This helps to create a more stable product with a longer shelf-life.

Formulation takes place at one GB site. The volume of chromium trioxide used in formulation activities is driven by the demand from the downstream supply chain. In total, annual demand for industrial uses is in the range of 0.2 - 5 tonnes per year for all markets.

List of descriptors: 

  • Environmental release category (ERC): ERC2
  • Name of activity / technique Operators producing liquid mixtures
  • Process category (PROC): PROC 5, PROC 8a, PROC 8b, PROC 9, PROC 15, PROC 28
  • Product category formulated PC 14: Metal surface treatment products
  • Technical Function: N/A for formulation

Annual tonnage used:

  • 0.2 - 5 t/a

Review period requested: 12 years 

How to submit comments

Provide some basic information on possible alternative(s) in the online survey below but more detailed information should be provided in document(s) prepared using the commenting templates in the related section below. A “public version” should always be completed and will be published after the consultation has closed. If you want to include confidential information in your submission, please additionally complete a “confidential version” and submit both versions as attachments.

The consultation lasts for 8 weeks (unless otherwise specified) and closes at 23:59 London time (BST).


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  • Registration, Evaluation, Authorisation & restriction of CHemicals (REACH)