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High-speed laser deposition process wins award

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Researchers from the Fraunhofer Institute for Laser Technology ILT in Aachen and RWTH Aachen University have been awarded €50,000 for an ultra-high-speed laser material deposition process called EHLA.

Dr Gasser, Thomas Schopphoven and Gerhard Maria Backes received the Joseph von Fraunhofer prize in recognition of their work at the Fraunhofer General Assembly Meeting, held on 30 May in Dresden, Germany.

EHLA offers companies an economical alternative to standard coating processes, such as hard chrome plating, thermal spraying and deposition welding.

The China Academy of Machinery Science and Technology’s (CAMTC) Advanced Manufacture Technology Centre in Beijing will take delivery of the first EHLA system, which is being supplied by the Dutch company Hornet Laser Cladding in cooperation with ACunity, a spin-off of the Fraunhofer ILT.

One of the most common processes for the application of corrosion and wear protective coatings is hard chrome plating. However, this consumes a lot of energy and, from September 2017, companies using chromium(VI) need authorisation because the material is toxic to the environment.

EHLA is a chemical-free application. The resulting layer is metallurgically bonded to the base material and, unlike hard chrome layers, does not delaminate. While hard chrome plating layers have pores and cracks, layers produced using EHLA are non-porous and, thus, offer more efficient long-term protection.

Dr Andres Gasser, group manager at Fraunhofer ILT, explained: ‘We can now use EHLA to apply thin layers in the range of a tenth of a millimetre over large surfaces within a short time, while being resource-efficient and economical.’

EHLA also uses about 90 per cent less material than thermal spraying, while at the same time coating 100 to 250 times faster than conventional laser material deposition.

Dr Gasser explained a key element of the new process: ‘With EHLA, the laser melts the powder particles while they are above the melt pool.’ Since this means that drops of liquid material fall into the weld pool instead of solid powder particles, the layer becomes more homogenous. In addition, less base material needs to be melted: instead of up to a millimetre, now only a few micrometres suffice.

EHLA is also suitable for coating heat-sensitive components, and can be used for completely new material combinations such as coatings on aluminium base alloy or cast iron.