Ultrafast laser welding method joins glass to metal

The laser welding method provides picosecond pulses of infrared light in tracks along the materials to fuse them together.

A team of scientists at Heriot-Watt University (Edinburgh, Scotland) has welded glass and metal together using an ultrafast laser system. The process could have uses in the aerospace, defense, optical technology, and healthcare manufacturing industries.

Using the ultrafast laser welding method, the researchers could join various optical materials such as quartz, borosilicate glass, and sapphire to metals including aluminium, titanium, and stainless steel. The method provides very short, picosecond pulses of infrared light in tracks along the materials to fuse them together.

"Traditionally, it has been very difficult to weld together dissimilar materials like glass and metal due to their different thermal properties—the high temperatures and highly different thermal expansions involved cause the glass to shatter," explains Duncan Hand, a professor and the director of the five-university EPSRC Centre for Innovative Manufacturing in Laser-based Production Processes based at Heriot-Watt University.

"At the moment, equipment and products that involve glass and metal are often held together by adhesives, which are messy to apply and parts can gradually creep, or move," Hand continues. "Outgassing is also an issue—organic chemicals from the adhesive can be gradually released and can lead to reduced product lifetime."

The parts to be welded are placed in close contact, Hand says, and the laser is focused through the optical material to provide a very small and highly intense spot at the interface between the two materials. In doing so, the research team achieved megawatt peak power over an area measuring a few microns across, creating a microplasma inside the material surrounded by a highly confined melt region. The team tested the welds at -50° to 90°C and they remained intact, showing that they are robust enough to withstand extreme conditions.

Hand and his team are working with a consortium led by Oxford Lasers, Coherent Scotland, Leonardo, and Gooch & Housego to develop a prototype for the laser processing system and take it closer to market. Glass Technology Services and the Centre for Process Innovation provide additional routes to commercialization, including in packaging of OLED devices.

For more information, please visit hw.ac.uk.

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