Lasers to weld ceramic

Optical transmission through a transparent ceramic (left) vs a traditional opaque ceramic (right).

A TEAM of engineers led by the University of California San Diego has developed a new ceramic welding technology using lasers that could help make smart phones that do not scratch or break, metal-free pacemakers and electronics for space and other harsh environments. This has been published recently in “Science”.

The technique uses an ultrafast pulsed laser to melt ceramic materials along the interface and fuse them together. The process can be carried out in ambient conditions and uses less than 50 watts of laser power. Javier E. Garay, a professor at UC San Diego who led the work, explains that ceramics are challenging to weld together because they need extremely high temperatures to melt.

Ceramic materials are of great interest because they are biocompatible, extremely hard and shatter-resistant, making them ideal for biomedical implants and protective casings for electronics. “Right now there is no way to encase or seal electronic components inside ceramics because you would have to put the entire assembly in a furnace, which would end up burning the electronics,” Garay said. To get around the problem, Garay, Guillermo Aguilar of University of California Riverside, and colleagues used “ultrafast pulsed laser welding” where a series of short laser pulses is aimed along the interface between two ceramic parts so that heat builds up only at the interface and causes localised melting.

To achieve this, the researchers had to optimise the laser parameters (exposure time, number of laser pulses, and duration of pulses) and the transparency of the ceramic material. With the right combination, the laser energy was found to couple strongly to the ceramic, allowing welds to be made at room temperature. “By focusing the energy where we want it, we avoid setting up temperature gradients throughout the ceramic, so we can encase temperature-sensitive materials without damaging them,” Garay said.