FemtoSurf

Laser focus on surface structures

Lasers are an important tool in industrial materials processing, enabling scientists to modify the surfaces of materials and tailor their properties. Researchers in the FemtoSurf project are developing a new system to treat large curved surface areas of metals, work which holds interest to several areas of industry, as Femtika CEO Vidmantas Sakalys explains.

A large number of lasers with pulse durations in the nanosecond (10-9 of a second) range have been developed over recent years, but researchers are continuing to push the boundaries of technology and strive for further improvements. As Project Leader of the EU-funded FemtoSurf project, Vidmantas Sakalys is now leading a team of worldclass scientists and engineers to develop a femtosecond (10-15 of a second) laser based surface modification machine. “One of the project targets is to create a very powerful - about 2 kilowatts - femtosecond laser,” he explains. This work could be relevant to a wide range of industrial sectors. “Our main targets in the project are shipbuilding, healthcare, aerospace, and heavy industry,” says V. Sakalys. “For example, with shipbuilding, we can use surface structuring to make the propellers anti-fouling.”

This could have a significant impact on the performance of a vessel and greatly improve efficiency. A ship’s propellers are often rapidly clogged up after a period out on the water as a result of fouling, which V. Sakalys says has a detrimental impact on its overall performance. “Fouling usually causes about a 5 percent increase in fuel consumption, and the ship has to be taken in for cleaning on a regular basis,” he outlines. By modifying the surface of the structure, researchers aim to improve performance and reduce maintenance costs. “If we can make it easier to clean the ship’s propellers, then it would really drastically reduce the costs of using it,” points out V. Sakalys. “The surface of a metal can also be structured in such a way to reduce friction and corrosion.”

Surface structures

The idea in the project is to develop a laser based micro-fabrication machine to structure relatively big and curvy surfaces, with dimensions in the order of several square metres, all within a reasonable and cost effective timeframe. Applying a laser beam with a femtosecond pulse to the surface of a metal can change its behaviour. “Some nanoripples and micro-patterns are formed on the surface of a metal,” explains V. Sakalys. Researchers in the project are working to develop a system to structure the surface of a metal, which V. Sakalys says represents a route to introducing certain interesting properties. “We can make the surface hydrophobic for example, so that it repels water, or hydrophilic, the opposite. It’s also possible to make surfaces anti-microbial,” he says.

A major challenge at the moment is the insufficient power of femtosecond lasers, an issue that V. Sakalys and his colleagues are

Different surface micro-textures resulting in different properties and contact angles between water drop and the surface.

Water drops on the textured water-repellent surface.

working to address in the project. Currently, in order to increase the throughput of a laser, it’s necessary to either increase the spot size of the focused laser beam, or to operate with multiple beams. “This is where the optical chain comes into play,” says V. Sakalys. The optical chain essentially directs light from the laser source to the surface, and it needs to deal with the huge power of the laser in order to structure quite big surfaces in one go. “We are addressing the problem of handling the power of a 2kw

femtosecond laser,” continues V. Sakalys. “A further problem that we are addressing is the surface structuring of big, curved surfaces.”

This is a more complex challenge than structuring the surface of a square metal sheet. Dealing with the curved surface of propellers is extremely tricky for example, as they are extremely heavy and need to be rotated under a laser beam, all while maintaining very high standards. “You need to do this at a great level of precision, within about 1 micron (10-6 of a metre),” outlines V. Sakalys.

This research is primarily about the surface structuring of metals, although V. Sakalys says there are some further possibilities beyond this. “There are also some interesting ideas about covering the surface with nanoparticles, which will create some interesting possibilities, like anti-microbial surfaces for example,” he explains.

The 2 kw laser itself is currently in development, and so currently researchers are working with a 400 watt laser. With a lot of preparatory work done, V. Sakalys and his colleagues hope to hit the ground running when the new, more powerful laser is ready. “We already have the laser parameters, on how surfaces are structured when we have less power at our disposal. We will then look to adapt these parameters to this more powerful laser in future,” he says. Once this new laser has been shown to be effective, the target is to find industrial and commercial applications. “We are working with endusers in the project from several different industries,” continues V. Sakalys. “We can see, for example, that there is a lot of potential for the commercialisation of this research in the medical devices industry.”

Fouling usually causes about a 5 percent increase in

fuel consumption, and the ship has to be taken in for cleaning on a regular basis. If we can make it easier to clean the ship’s propellers, then it would drastically reduce the costs.

Industrial applications

A number of other applications have been identified, including in the automotive sector, where structuring the surface of certain components could improve fuel efficiency. A surface that is not totally flat will have much less friction between the surfaces. “This could be useful for the automotive industry. For example, if we can make a surface hydrophobic then it will require less oiling,” says V. Sakalys. The project’s research holds wider importance in terms of the ‘green’ economy, and the general goal of reducing our use of certain resources. “The adhesion of paint can be improved by structuring the surface of a material so that you need less paint. That means that we can reduce the amount of toxic paints that are released into the environment,” explains V. Sakalys.

The project consortium itself includes nine different partners from across Europe, testament to the level of interest in this research and its wider potential. The ultimate goal is to bring this technology to the market, and to bring metal surface patterning to a wider range of industries. “We are working with end-users in the project, from several different industries,” says V. Sakalys.

Femtosecond laser 3D surface microstructuring for industry applications Project Objectives

The main objective of FemtoSurf project is to develop, test and demonstrate industrial-grade solidstate 2-3 kW-level fs laser with parameters suitable for metal surface patterning of arbitrary shaped metal components with sizes exceeding several meters while retaining micrometer level precision, applicable in industrial settings.

Project Funding

The FemtoSurf Project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 825512. This project is funded by one of the call under the Photonics Public Private Partnership (PPP) (www.photonics21.org)

Project Partners

• https://www.femtosurf.eu/project-partners/

Contact Details

Giedrė Grigalevičiūtė Research & Marketing Sauletekio al. 15, 10224 Vilnius, Lithuania E: info@femtika.lt W: https://www.femtosurf.eu : https://www.linkedin.com/ showcase/67103966/

Vidmantas Sakalys

Vidmantas is the CEO of Femtika, a toplevel business manager with business experience in commercialization of advanced technologies for over 25 years. In 1992 he acquired Bachelor’s degree in Computer Engineering at the Kaunas University of Technology. From 1992 till 2013 he worked in number of companies as IT manager as well as director/business developer. From 2013 after establishment of the company Femtika Vidmantas is working as the CEO of the company.