Tag Archive for: Corrosion protection

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AD Chemicals, latest innovations chrome-6 free

AD Chemicals has more than 40 years of experience in developing, manufacturing and worldwide supply of a wide range of metal surface pre-treatment chemicals. Pre-treatment is an essential process on metal products that are coated to provide a durable and attractive finish. AD Chemicals draws knowledge and expertise from across the range of AD International chemical disciplines to provide customers with the best possible advice from a leader in its field. This results in robust and reliable processes that are efficient and cost effective.

AD is known in the market for its innovative and market exceeding chromium(VI)-free conversion coatings that meet or outperform hexavalent based treatments. Products are marketed under the “PreCoat” brandname. Many surface treatment operations desire certification by industry organizations, especially when applied to new and technically driven products. Customers have come to rely on AD Chemicals to assist in or lead the certification process. All products meet or exceed current market standards such as GSB, Qualicoat, Qualisteelcoat and MIL.

Latest innovations:

PreCoat Z31: Cromium(VI)-free multi-metal conversion coating, tailored to the high demands for duplex coating applicators (powder coating over hot-dip galvanized steel). Only European alternative that performs equal to chromium(VI). Meets the Qualisteelcoat and GSB standard. Winner of 2016 Dutch Innovation Award for surface treatments. Also Qualicoat(A-119) approved for aluminium.

PreCoat TVL: Multi-metal (iron, steel, galvanized) passivation to upgrade the iron phosphating process, enables corrosion protection over 1000 hours NSS. Exceeds Qualisteelcoat standard and has a Qualicoat (A-095) approval for aluminum.

PreCoat A34: Based on a high-tech aerospace technology. Chromium(III) based conversion coating that enables bare metal corrosion protection in combination with excellent paint adhesion and corrosion resistance, Qualicoat (A-126) approved.

PreCoat CF: Complete chromium-free conversion coating for aluminium. GSB and Qualicoat (A-021) approved. No rinse system.coversion coating PreCoat chromium-6 free

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Alternative Corrosion Protection Pre-treatments for Aluminium Alloys

Aluminium alloys are extensively used in space programs for both structural and non-structural applications. As well known, the corrosion resistance of these alloys is quite limited and anticorrosion treatment is needed.

The most used treatment currently used for improving the corrosion resistance of aluminium alloys are usually chromate (CrVI-based) conversion coatings (CCC). Due to the high environmental impact of these compounds, the REACH Regulation of the European Union decided to limit/restrict the use of hexavalent chromium. A sunset date of mid-2017 has been already set.

For the time being many chromate-free alternative products are available but they have found to be significantly inferior in terms of corrosion protection performances with respect to the chromate options. In this regard there is a great need to develop high performance hexavalent chromium-free anti-corrosion coatings with low environmental impact and conformity with the EU regulations.

The European Space Agency (ESA) is currently involved in a TRP contract with Instituto de Soldadura e Qualidade (ISQ) that is currently on-going. The objective of this study is to evaluate the anticorrosion behaviour of the different alternative pre-treatments applied to the most used aluminium. The outcome of this activity will be the identification and the optimization of the most promising anticorrosion pre-treatment.

Several commercial Cr(VI) free processes were applied onto aluminium alloys (2024-T3 and 2024-T81) used in the construction of ESA spacecraft, in order to investigate their anticorrosive properties compared with Alodine 1200, a widely used conventional CCC. One of these commercial processes (PreCoat A32) presented good anticorrosion performance, even better than Alodine 1200 and these results are presented in this paper.

Salt spray resistance is included in the testing program as well as metallurgical coating evaluation that include microscopy (SEM) observations before and after testing and electrochemical impedance spectroscopy (EIS), in order to evaluate surface and microstructural modifications due to degradation mechanisms. Further studies must be performed with the this promising alternative, modifying application parameters, in order to achieve improved corrosion protection efficiency.

Key Words: Aluminium alloy, Conversion coating, Anti-corrosion coatings, SEM, EIS

Source: Whitepaper Springer.com,Journal of Coatings Technology and Research, pp 1–14, Alternative corrosion protection pretreatments for aluminum alloys

Interested in PreCoat A32 passivation or the full whitepaper? Contact chemicals@adinternationalbv.com

precoat_a32_bare_corrosion_protection

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Most promising innovation for grit blasting ; Combining blasting and chemical pretreatment

One of the most important factors influencing paint adhesion and corrosion resistance is surface preparation. To ensure optimum performance and long-term environmental resistance, metal substrates must be free of organic and inorganic contaminants. To prepare a surface one can basically choose between 2 options, blasting or chemical pretreatment.

 

  1. Mechanical/Blasting – Abrasive particles (sand, grit or metal oxides) are projected against the surface with a stream of air. The character or quality of the treatment is affected by duration of the blast; shape and size of the blasting media; particle velocity; and the hardness, porosity and other substrate properties. A metal surface treatment of blasting ensures a uniformly cleaned surface and good paint adhesion but lacks corrosion resistance on the substrate.

 

  1. Chemical processes, on the other hand, utilize organic and inorganic chemicals to achieve two reactions: • Dissolve, suspend or eliminate soils and surface contaminants. • Convert metal surfaces from the essentially free metallic state into metallic compounds.New option: Combining the worlds of blasting and chemical processingCurrently, AD Chemicals, a subdivision of the Dutch AD, International launches a revolutionary new product on the global grit/sand blasting market. This product is called PreCoat F31/20 suitable for the treatment of substrate steel and PreCoat Z31/20 for the substrates aluminum and galvanized steel. PreCoat is a chemical treatment applied directly after grit/sand blasting or metallization (also referred to as metal spraying). This product portfolio is the result of an R&D trajectory of more than 8 years. PreCoat F31/20 and Z31/20 significantly improve the quality of sandblasted or metallized products.

It has two main benefits; by applying the product directly after grit/sand blasting, a conversion layer is created that substantially improves the adhesion of the painting system (suitable for wet painting and powder coating) and significantly enhances the corrosion-protection resistance properties of the paint system as a whole. The application procedure of PreCoat is very easy and can be easily integrated in every business processes.

The innovative aspect of these products is that it combines the worlds of grit/sand blasting and chemical pre-treatment.

PreCoat F31/20 and Z31/20 are based on PreCoat Z31, a product that won the Dutch Innovation Award for surface treatment, ION Borghardt Award 2016.

AD Chemicals is introducing this product on the worldwide market. The first user responses are very promising. A large blasting company in the Netherlands stated: “With this product I am able to improve to overall quality of my products and therefore offer my customers more value. It is a tool to distinguish myself in a competitive market place”

Besides that the responses from our agents in Spain and the UK are very promising.

As products are better protected against corrosion, the product lifetime increases and thereby lowers the ecological footprint. See below the pictures after 500 hours salt spray testing where the difference is demonstrated between the regular automated grit blasting process and the grit blasting process with PreCoat treatment.

precoat blasting powdercoating chemical pretreatment test results

Want to know more about this innovation? E-mail to chemicals@adinternatonalbv.com

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