ADVANCED CORROSION RESISTANCE TREATMENT

CONTACT: Jane Luht, Head of Technology Transfer, Phone: +372 737 4804, E-mail: jane.luht@ut.ee


For metallurgical applications where superior mechanical and corrosion resistance is desired, the University of Tartu offers a solution. Our team at the Laboratory of Thin Film Technology proposes a novel surface sealing layer that is resistant to both mechanical and chemical damage. The method is suitable for most metals and covers any surface geometry with a high-quality layer with uniform density.


BACKGROUND

Metals used in challenging environments from airplane or automotive parts to medical implants usually need surface passivation in order to make them resistant to the corrosive effects of the environments where they are used. The most common method for creating that passivation layer, besides painting, is via anodization.

Chemical vapor deposition (CVD) and its related method, atomic layer deposition (ALD) also cover surfaces completely, including the inner sides of any open pores, sealing the surface with completely uniform, chemically very homogenous and durable layers. The method creates the surface film one atomic layer at a time, permitting a laminate of different nanolayers. The downside is that the process of laying down one atomic layer at a time is slow. Also, often these nanolayers have problems adhering to the substrate. 

So far, a suitable method of combining the benefits of anodization and atomic layer deposition has eluded practitioners.


THE SOLUTION

The team at UT’s Laboratory of Thin Film Technology has developed a method that combines an advanced anodizing method with atomic layer deposition. The unique properties of the subsequent ALD step, ensure uniform growth of an oxide layer on top of the treated surface, sealing all pores left after anodizing.

The method includes preparation of the object surface, anodizing it in a novel tri-electrode bath and then sealing it using atomic layer deposition. The anodizing step gives the surface the thickness required for mechanical durability and the second layer fills the pores left, giving the surface exceptional durability in extreme environments. Also, the surface layer is thin and strong enough to move with the underlying material as it deforms under mechanical and thermal stresses, without cracking. The method is protected under an US patent application no. US14804533 and European and Japanese patent applications.


THE OFFER

We offer a license for the use of the developed method and to engage in co-operation to develop and adjust the method to suit the specific needs of your application.

The adaption process would take into account the composition and geometry of the object to be treated, along with any constraints set by the production process or client’s requirements. This means after preliminary lab work, the method would be finalized on-site with the client, ensuring the highest possible quality and fit in the production process. All steps of the process shall be validated with top-of the range analysis methods, including electron and scanning probe microscopy, electron spectrometry, voltammetry etc.

A pore in anodized alumina successfully coated with an ALD laminated top-coating, electron microscope image.

THE TEAM

The team at the Laboratory of Thin Film Technology comprises leading scientists in the field of surface treatments, such as Professor Väino Sammelselg, Lauri Aarik, PhD and Maido Merisalu. The team has a good base knowledge and experience in the field together with the flexibility to participate in applied research and development projects.