February 21, 2024

Different types of metals have different qualities, so combining them can produce items superior to any metal made one Metal. Now, a new technology allows this blending to be performed by a 3D printer, faster and easier than ever.

Currently, one of the most common ways to 3D print objects out of a variety of metals is through a technique called wire-arc additive manufacturing.

In a nutshell, this involves using a welding head to create an arc that melts the wire. The molten metal is deposited in successive layers, gradually forming the desired item. Whenever a print job requires a different metal, the process must be paused to swap out a filament made of one metal for a filament made of another.

To simplify the process, a WSU team led by Professor Amit Bandyopadhyay developed a new technique that combines two commercially available welding heads, each loaded with welding wire made of a different metal.

A head first deposits a metal in a circular pattern, forming a ring. Then another head plunges in, depositing another metal inside the ring, providing a solid core for the structure. As the two metals continue to cool, the outer ring shrinks faster than the inner core. This creates pressure at the interface between the two metals, bonding them together.

This process is repeated, layer by layer, and finally a “bimetallic” column is formed.

So far, scientists have created bimetallic structures, such as columns containing a stainless steel core within a mild steel shell, that are 33 to 42 percent stronger than equivalent structures made of either metal alone.

It is hoped that the technology could eventually be used to make products such as torque-resistant shafts, spacecraft components with cooling cores surrounded by heat-resistant casings, and even artificial hip implants with therapeutic cores encased in durable titanium.

And these items don’t necessarily have to be in the form of rods or columns.

“The example we show in this work is a radial structure where two materials are placed radially,” Bandyopadhyay told us. “(But) we should be able to make any design that can be 3D printed.”

A paper on the research was recently published in the journal natural communication. The following video demonstrates the bimetallic printing process.

LE7 Radial Bimetal Demo

source: washington state university