Newly Invented 'Metal Glue' Has Some Advantage over Welding and Soldering

Often, if you want to join 2 metal objects together, you either weld or solder them, subject to how big they are. Both processes, however, involve the application of heat. This can do harm to the items (in case of electronics), even cause explosions (in case of things like gas pipes). That’s why scientists from Northeastern University (Boston) create MesoGlue. This glue can work for just about all kinds of solids - polymers, ceramics, metals, and any composites. And it sets at room temperature. 

Often, if you want to join 2 metal objects together, you either weld or solder them, subject to how big they are. Both processes, however, involve the application of heat. This can do harm to the items (in case of electronics), even cause explosions (in case of things like gas pipes). That’s why scientists from Northeastern University (Boston) created MesoGlue. This glue can work for just about all kinds of solids - polymers, ceramics, metals, and any composites. And it sets at room temperature. 

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What it is and how it works

Designed by a team whose leader is Prof. Hanchen Huang, this metal glue is made up of microscopic nanorods that have a metallic core. Some of them are coated with indium, and some with gallium. 

First, the facing surfaces of 2 objects-to-be-joined are treated with these nanorods. A layer of the indium-coated rods goes on one surface, while a layer of the gallium-coated rods is applied to the other. In both cases, the rods stand up from the surface, kinda like the bristles of hairbrush. 

As explained by co-inventor Paul Elliott, “when you mash the head of brushes together, all the little bristles push past each other so the two brushes are basically stuck together. The interlacing process is fairly similar to our glue. The bristles are spaced well enough so they can slide or be pressed in between each other.”

The diagram illustrates how the the comb teeth-like metallic core  nanorods interlace and then create a liquid that is subsequently solidified. (Photo credit: Huang/Northeastern University)

The coated rods are arranged along a substrate (a). Then the teeth are interlaced (b). When the indium and gallium on the rods come into contact, they form a liquid (c). The metal cores of rods then react with the liquid, making it harden into a cohesive solid. This leads to a bond which reportedly matches the strength of traditional weld or solder.  

Generally, as the nanorods grows on the solid surface through physical vapor deposition processes, they create chemical bonds  with the surface. For some solid surfaces, the direct chemical bonds may be weak (when it is ‘non-wetting’), and a buffer layer is used to strengthen the bonding. 

Its outstanding characteristics 

Unlike ones formed by regular polymer based glues, bonds created by MesoGlue are thermally and electrically conductive. They are not adversely impacted by heat; they are highly resistant to moisture/ air leaks; they require little pressure when being created. 

Also, the glue is mechanically strong. As tested by the team, the glue is just broken with about 1500 psi (or 10 MPa) shear load. And it can work for just about all kinds of solids — polymers, ceramics, metals, and any composites.

Where it is applied 

According to Huang, “the metallic glue has multiple applications, many of them in the electronics industry. As a heat conductor, it may replace the thermal grease currently being used, and as an electrical conductor, it may replace today’s solders. Particular products include solar cells, pipe fittings, and components for computers and mobile devices."

Applications of metal glue: a) A CPU on printed circuit board connected to a heat sink. b) A surface mount device attached to a printed circuit board. c) A press fit pipe fitting for environments that welding is dangerous or impossible. d) a glass plate attached to metal with a different thermal expansion coefficient for covering a cavity with hermetic seal. (Photo credit: Huang/Northeastern University)

This metal glue is now being commercially developed by a spin-off company. 

Comments around this invention

xs400: “Better invest in Indium and Gallium, this is going to change the electronics and welding world and many other industries IF it is economically viable, especially for DIYers. Hope it'll be cheap enough for laymen to buy and use.”

HensleyBeuronGarlington: “That's pretty awesome. Lots of benefits to this method where traditional soldering and welding maybe found lacking for certain applications. To me its like a metal velcro that melts together when linked up.”

physics314: “Indium is one of the rarest metals on Earth. I wouldn't hold my breath for it to be used as glue.”

Martin Hone: “The obvious question here is, how does the initial layer get applied to the surface, and how reliable is it ? Ok, two questions, but critical...”

Douglas Rogers: “This might be applied to fibers to reduce pullout length and create a much stronger composite.”

(Source: gizmag.com)

Art Shepherd: “What a boon it would be for automotive applications I would think. Exhaust? Bondo? I wonder how expensive it is to produce and when it might be available to the public?”

Jack Herer: “what if it gets stuck to their fingers or skin how do they get it off?”

(Source: upi.com)

How about your thoughts about this invention?