We live in a ceramic world. Ceramics are everywhere even in the world of engineering. The most important and general property of ceramics is that they are refractory. What does this mean? They are “rough-and-tumble” materials that will take large amounts of abuse in a wide range of situations. Don’t believe us?
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Ceramic tiles are used for space shuttles. The composite is able to withstand tremendous temperatures and was even used to protect areas of the space shuttle that would rise above 1,260°C. Ceramics have high melting points, great hardness and strength, tremendous durability, and great chemical inertness. So why not use them all the time?
The process of welding ceramics together has traditionally been difficult because they need high temperatures to melt which in turn can expose them to “extreme temperature gradients that cause cracking”. However, researchers from the University of California San Diego and the University of California Riverside have come out with a solution to this problem.
Using lasers on ceramics
Published in a study found in the scientific journal, Science, engineers from both teams have developed an ultrafast pulsed laser that can be used to melt ceramic materials together, fusing them together. What makes this so special? Aside from not even needing a furnace, the new laser process works in ambient conditions and uses less than 50 watts of laser power.
As mentioned above, ceramics are of great interest and have a host of applications. In the study, researchers discuss using ceramics for biomedical implants and as protective casings in electronics. In short, you could create scratch-resistant smart mobile devices, metal-free pacemakers, and electronics for space travel.
"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,” said Javier E. Garay, a professor of mechanical engineering and materials science and engineering at UC San Diego.
How does the laser work?
The ultrafast pulsed laser welding process was created out of the vision to create a series of short laser pulses along the interface of two ceramic parts. This laser heat builds up only at the interface and causes localized melting. To create this system researchers worked on optimizing two aspects of their experiment.
First, they focused their attention on the laser parameters which included exposure time, number of laser pulses, and duration of the pulse. Next, they worked on the transparency of the ceramic material.
"The sweet spot of ultrafast pulses was two picoseconds at the high repetition rate of one megahertz, along with a moderate total number of pulses. This maximized the melt diameter, minimized material ablation, and timed cooling just right for the best weld possible," said mechanical engineering Guillermo Aguilar.
Right now the process is just being used on small ceramic parts no bigger than two centimeters in size. The engineers eventually hope to optimize it for different types of materials and geometries.