In a breakthrough that has major implications for the manufacturing industry, scientists at Heriot-Watt University (www.hw.ac.uk) in Glasgow have welded glass and metal together, using an ultra-fast laser system.

Various optical materials such as quartz, borosilicate glass and sapphire were successfully welded to metals like aluminium, titanium and stainless steel using the Heriot-Watt laser system, which provides pico-second pulses of infra-red light in tracks along the materials to fuse them together.

Being able to weld glass and metals together could transform manufacturing, with applications in the aerospace, defence, optical technology and health-care sectors.

Duncan Hand, director of the five-university EPSRC Centre for Innovative Manufacturing in Laser-based Production Processes (based at Heriot-Watt), said: “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 very different thermal expansions involved cause the glass to shatter.

“Being able to weld glass and metals together will be a huge step forward in manufacturing and design flexibility.

“At the moment, equipment and products that involve glass and metal are often held together by adhesives, which are messy to apply and the parts can gradually creep.

“Out-gassing from the organic chemicals in the adhesive is also a problem.

“The new process relies on incredibly short pulses from the laser, lasting only a few pico-seconds — a picosecond to a second is like a second compared to 30,000 years.

“The parts to be welded are placed in close contact, 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 — just a few microns across.

“This creates a microplasma — like a tiny ball of lightning — inside the material, surrounded by a highly confined melt region.

“We tested the welds at temperatures from -50 to +90°C, and they remained intact, so we know they are robust enough to cope with extreme conditions.”