The best of both worlds: A new take on metal-plastic hybrid 3D printing


Date:
October 5, 2020
Source:
Waseda University
Summary:
Current 3D printers employ either plastic or metal only, and the
conventional method to coat 3D plastic structures with metal is
not environment-friendly and yields poor results. Now, scientists
have developed a metal-plastic hybrid 3D printing technique that
produces plastic structures with a highly adhesive metal coating
on desired areas.

This approach extends the use of 3D printers to 3D electronics
for future robotics and Internet-of-Things applications.



FULL STORY ========================================================================== Three-dimensional (3D) printing technology has evolved tremendously over
the last decade to the point where it is now viable for mass production in industrial settings. Also known as "additive manufacturing," 3D printing
allows one to create arbitrarily complex 3D objects directly from their
raw materials.

In fused filament fabrication, the most popular 3D printing process,
a plastic or metal is melted and extruded through a small nozzle by a
printer head and then immediately solidifies and fuses with the rest of
the piece. However, because the melting points of plastics and metals
are very different, this technology has been limited to creating objects
of either metal or plastic only -- until now.


==========================================================================
In a recent study published in Additive Manufacturing, scientists from
Waseda University, Japan, developed a new hybrid technique that can
produce 3D objects made of both metal and plastic. Professor Shinjiro
Umezu, who led the study, explains their motivation: "Even though 3D
printers let us create 3D structures from metal and plastic, most of the objects we see around us are a combination of both, including electronic devices. Thus, we thought we'd be able to expand the applications of conventional 3D printers if we managed to use them to create 3D objects
made of both metal and plastic." Their method is actually a major
improvement over the conventional metallization process used to coat 3D
plastic structures with metal. In the conventional approach, the plastic
object is 3D-printed and then submerged in a solution containing palladium (Pd), which adheres to the object's surface.

Afterwards, the piece is submerged in an electroless plating bath that,
using the deposited Pd as a catalyst, causes dissolved metal ions to
stick to the object. While technically sound, the conventional approach produces a metallic coating that is non-uniform and adheres poorly to
the plastic structure.

In contrast, in the new hybrid method, a printer with a dual nozzle
is used; one nozzle extrudes standard melted plastic (acrylonitrile
butadiene styrene, or ABS) whereas the other extrudes ABS loaded with
PdCl2. By selectively printing layers using one nozzle or the other,
specific areas of the 3D object are loaded with Pd. Then, through
electroless plating, one finally obtains a plastic structure with a
metallic coating over selected areas only.

The scientists found the adhesion of the metal coating to be much higher
when using their approach. What's more, because Pd is loaded in the raw material, their technique does not require any type of roughening or
etching of the ABS structure to promote the deposition of the catalyst,
unlike the conventional method. This is especially important when
considering that these extra steps cause damage not only to the 3D
object itself, but to the environment as well, owing to the use of
toxic chemicals like chromic acid. Lastly, their approach is entirely compatible with existing fused filament fabrication 3D printers.

Umezu believes that metal-plastic hybrid 3D printing could become
very relevant in the near future considering its potential use in 3D electronics, which is the focus of upcoming Internet-of-Things and
artificial intelligence applications. In this regard, he adds: "Our
hybrid 3D printing method has opened up the possibility of fabricating 3D electronics so that devices and robots used in healthcare and nursing care could become significantly better than what we have today." This study hopefully paves the way for hybrid 3D printing technology that will
enable us to get the best of both worlds -- metal and plastic combined.


========================================================================== Story Source: Materials provided by Waseda_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Jing Zhan, Takayuki Tamura, Xiaotong Li, Zhenghao Ma, Michinari
Sone,
Masahiro Yoshino, Shinjiro Umezu, Hirotaka Sato. Metal-plastic
hybrid 3D printing using catalyst-loaded filament and electroless
plating. Additive Manufacturing, 2020; 36: 101556 DOI:
10.1016/j.addma.2020.101556 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201005101542.htm

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