New ceramics welding technology does not require heating parts in a furnace
Engineers used an ultra-fast, low-power pulsed laser to melt ceramic parts along the joint and their welding in ambient conditions.
Ceramic materials are of great interest because they are biocompatible, hard and durable. However, current methods for welding ceramics are complex and require high temperatures that can cause cracking. It also prevents electronic components from being placed and sealed inside the protective ceramic shrouds, as the entire assembly will eventually have to be placed in an oven, destroying the filling..
A group of engineers and materials scientists from the universities of California at San Diego and Riverside decided to send a series of short laser pulses to the surface along the interface between the two ceramic elements so that heat only accumulates at their junction and causes local melting. The new method has been called ultrafast pulsed laser welding.
Optimization of laser parameters (exposure time, number and duration of pulses) and transparency of the ceramic material became an important factor of success. With the correct setting, the radiation interacts well with ceramics, allowing quality welds to be made using a low-power laser (less than 50 W) at room temperature.
Laser system for checking and measuring the transparency of ceramic materials.
Studies have shown that 2 ps duration at 1 MHz is optimal for pulses, together with a moderate total number. This setting maximizes the melt diameter, minimizes material ablation and synchronizes cooling to achieve the best weld.
According to the team, the concentration of energy on specific area prevents temperature gradients throughout the ceramics, which allows temperature-sensitive materials to be enclosed inside without damaging them.
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To prove the concept, the researchers welded a transparent cylindrical cap to the inside of a ceramic tube. Tests have shown that the welds are strong enough to hold vacuum. In the future, engineers will deal with improvement of technology for its application on a larger scale, as well as for materials of various types and shapes.
Previously, a similar system was proposed by Scottish technologists for durable glass-to-metal welding..
text: Ilya Bauer, photo: University of California – San Diego