Materials

Etching tech bonds metal to metal – or anything else

Etching tech bonds metal to metal – or anything else
A microscope image of the surface of aluminum, treated using the new technology
A microscope image of the surface of aluminum, treated using the new technology
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A strip of aluminum – the surface of which has been treated – is permanently bonded with thermoplastic
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A strip of aluminum – the surface of which has been treated  – is permanently bonded with thermoplastic
A microscope image of the surface of aluminum, treated using the new technology
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A microscope image of the surface of aluminum, treated using the new technology

As any good metallurgist will tell you, you can't just take any two types of metal and weld them together. You may instead be able to just join them together with glue, however, thanks to research being carried out at Germany's Kiel University. Scientists there have developed an electro-chemical etching process that not only allows different metals to be strongly bonded to one another, but that also lets metal be bonded to almost any other material.

The "nanoscale-sculpturing" process only affects the very outer surface the metal – a layer that's about one quarter the thickness of the width of a human hair. The structure and stability of the metal beneath that layer remains unaltered.

Once treated, that outer layer takes on a dull matte appearance that's visible to the human eye. Viewed under a microscope, however, it's actually a three-dimensional landscape composed of tiny hooks. When two of these nano-sculptured surfaces are pressed together, with a bonding polymer applied between them, their hooks interlock with one another in three dimensions. From there, once the polymer sets, that bond reportedly becomes virtually unbreakable.

A strip of aluminum – the surface of which has been treated – is permanently bonded with thermoplastic
A strip of aluminum – the surface of which has been treated  – is permanently bonded with thermoplastic

Even the presence of contaminants such as fingerprint oil or gearbox oil apparently don't affect the strength of the connection. As a side benefit, the etching process makes metal surfaces water-repellant.

Additionally, the treatment can be used to remove less chemically-stable particles from metal surfaces. Medical implants, for instance, are often made from titanium with added aluminum – unfortunately, aluminum can cause adverse reactions in the body. Using the nanoscale-sculpturing process, however, most of the aluminum can be removed from the outer surface of the implant, lessening the likelihood of such complications.

A paper on the research was recently published in the journal Nanoscale Horizons. For another take on bonding metals together, check out the MesoGlue that was developed at Northeastern University.

Source: Kiel University

3 comments
3 comments
Grunchy
Friction welding is the process used with the greatest success to weld dissimilar metals.
f8lee
I thought cold plasma treatments have been doing this for decades - changing the surface molecular structure of materials so they can accept paints or adhesives. I once saw a same of two short rods of teflon glued together with Elmer's glue to make a point about how that technology can affect materials.
Bob Siegel
So what is the process to do this 'etching' , and how can we do this ourselves?