Welding breakthrough could transform manufacturing

An innovative technique for the industrial sector has been achieved by Heriot-Watt University scientists who have fused metal and glass together with an ultrafast laser system.

Using the Heriot-Watt laser system, which delivers very short, picosecond pulses of infrared light in tracks along the materials to fuse them together, a variety of optical materials, including quartz, borosilicate glass, and even sapphire, have been successfully welded to metals, including titanium, aluminum, and stainless steel.

The new method has immediate applications in the sectors of optical technology, aerospace, defense, and even healthcare, and it has the potential to completely change the manufacturing industry.

Director of the five-university EPSRC Centre for Innovative Manufacturing in Laser-based Production Processes at Heriot-Watt, Professor Duncan Hand, stated: "Due to their dissimilar thermal properties, it has historically been very difficult to weld together dissimilar materials like glass and metal—the high temperatures and highly different thermal expansions involved cause the glass to shatter.

The ability to fuse metal and glass together will greatly increase production and design flexibility.

Currently, adhesives are frequently used to hold together machinery and items using glass and metal. These adhesives can be messy to apply and cause pieces to progressively creep or shift. Another concern is outgassing, which can cause a product's lifespan to be shortened by the adhesive's organic compounds gradually releasing.

The extremely brief laser pulses are essential to the procedure. These pulses endure only a few picoseconds; in comparison, 30,000 years is equivalent to a second to a picosecond.

We obtained megawatt peak power across an area of a few microns wide by placing the components to be welded in close proximity to one another and focusing the laser through the optical material to generate a very small and extremely intense spot at the interface between the two materials.

As a result, a highly constrained melt area encircles a microplasma—like a little ball of lightning—that forms inside the material.

"We know the welds are robust enough to handle extreme conditions because we tested them at -50C to 90C and the welds remained intact."