Welding Ceramics With a Laser
(Inside Science) -- Humans have been using ceramics since antiquity. Although commonly known as the stuff of chipped coffee mugs and tableware, ceramics are a large family of materials that can be extremely durable depending on the composition and production process. Engineers use them in a broad range of modern applications from biomedical implants to body armors and even nose cones for nuclear missiles.
The process of making ceramics puts limitations on their use. Currently, ceramics are made by firing up a kiln and hardening them at temperatures up to a couple of thousand degrees Fahrenheit. Let’s say that you want to encase a biomedical device in a ceramic capsule for implantation in a patient's body -- the temperature during the baking process would cook the electronics to a crisp.
Now, researchers have developed a way to weld ceramics together using tightly focused, ultrafast laser pulses. Melting pieces of ceramics together is no easy task. The lasers target the seam of the material only, creating a sharp temperature gradient that can cause the ceramic to crack and shatter, like pouring hot water into a cold mug.
Using modern lasers that can fire millions of pulses a second, each pulse lasting a few trillionths, the researchers learned how to find the sweet spot for welding ceramics. Too hot, too fast or too frequent, and the ceramic would shatter. Not hot, fast or frequent enough, and the weld wouldn’t hold. After running tests with different combinations of power, pulse duration and frequency, they successfully created a weld between a ceramic cap and a ceramic tube that is secure enough to hold a vacuum.
Looking forward, the researchers hope this method can help find the welding sweet spot for other ceramic materials, which can lead to biocompatible and durable packaging for devices such as electronics and for implantable biomedical devices. Their findings were detailed in a paper published in the journal Science.