Weld done. A new way with ceramics
Clever use of lasers means no furnace required.
US engineers have developed a new welding technology for ceramics that could open up a range of new applications for the material.
A team from the University of California successfully used an ultrafast pulsed laser to melt ceramic materials along the interface and fuse them together.
This not only works in ambient conditions and uses less than 50 watts of laser power, they say, but it is also more practical than current methods that require heating the parts in a furnace.
Ceramic materials are biocompatible, extremely hard and shatter resistant, making them ideal for biomedical implants and protective casings for electronics. But there’s a problem.
"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," says senior author Javier Garay.
Ceramics are also challenging to weld together, he adds, because they need very high temperatures to melt, exposing them to extreme temperature gradients that can cause cracking.
The team’s solution was to aim a series of short laser pulses along the interface between two ceramic parts so that heat built up only at the interface and caused localised melting.
To make it work, they had to take account of the transparency of the material, as well as a number of laser parameters – exposure time, and number and duration of laser pulses.
The sweet spot maximised the melt diameter, minimised material ablation, and timed cooling just right for the best weld possible.
"By focusing the energy right where we want it, we avoid setting up temperature gradients throughout the ceramic, so we can encase temperature-sensitive materials without damaging them," Garay says.
As a proof of concept, the researchers welded a transparent cylindrical cap to the inside of a ceramic tube. Tests showed that the welds are strong enough to hold vacuum.
"The vacuum tests we used on our welds are the same tests that are used in industry to validate seals on electronic and optoelectronic devices," says first author Elias Penilla.
The process has so far only been used to weld ceramic parts less than two centimetres in size. The plan now is to scale things up, as well as account for different types of materials and geometries.
The research is published in the journal Science.