Compression sealing means that the expansion coefficient of the selected metal material is greater than that of glass. When the sealing is cooled, the metal shrinkage is greater than the glass shrinkage, which causes the metal to produce a compressive stress on the glass (using glass to withstand compressive strength is much greater than the resistance The characteristics of tensile capacity), in order to achieve the purpose of sealing.

Traditionally, welding is limited to materials with similar characteristics, so it is difficult to weld aluminum and steel together.

Current technology cannot weld metal and glass together well.

The key to this process is an infrared laser that can emit pulses in the range of a few picoseconds.

Using ultrafast laser welding methods, researchers can incorporate various optical materials (such as quartz, borosilicate glass, and sapphire) into metals including aluminum, titanium, and stainless steel. This method produces very short picosecond infrared light pulses during material fusion.

Because the melting points of metals and glass are different, adhesives are generally used to weld these two materials together.

In addition to ensuring that the expansion coefficient of the glass during the curing process is basically the same as that of the metal, the pre-oxidation of the metal, the change in the viscosity of the glass liquid, and the secondary crystallization and cooling of the glass must be fully considered. Current equipment and products involving glass and metal are usually glued together by adhesives, which are cumbersome to apply and the parts will gradually loosen or move.

The technology mentioned here is ultra-fast laser pulses (which emit pulses in the range of a few picoseconds), and the ability to weld glass and metal together will be a major step forward in manufacturing and design flexibility. The glass and the material to be welded are in close contact, and the laser is focused through the optical material to provide a very small and high-intensity light spot at the interface between the two materials of glass and metal, which can achieve megawatts on an area of ​​a few microns Peak power. This will form a micro plasma like a tiny lightning ball inside the material, surrounded by a highly enclosed melting area.

The team tested the welds at temperatures from -50 ° to 90 ° C, and the results showed that they were strong enough to withstand extreme conditions.