Refractory Metal Powders Such As Tungsten And Titanium Are Expected To Become Raw Materials For 3D Printing Technology

Jul 20, 2020

3D printing technology is also known as additive manufacturing. The manufacturing of metal devices using this technology is somewhat similar to the current powder gold treatment process, which is based on metal powders, such as ceramic powders and metal powders. The difference is that the powder is not connected by sintering, but by the nozzle, which USES a special adhesive to "print" sections of the parts onto the powder.

One of the current difficulties with 3D printing is using refractory metals, especially those with high melting points such as tungsten, chromium and rhenium, not to mention nanoscale powder particles. Over the years, scientists around the world have been working on new processes that can be cost-effective and meet desirable performance requirements.

Recently, foreign scientists have developed a new technology that USES 3D printing to create complex nanoscale metal structures. The technology could be used for a variety of applications, from creating 3D logic circuits on tiny computer chips to manufacturing components for engineered ultralights, which could create a variety of new nanomaterials with different properties.

In 3D printing, objects are built layer by layer, allowing the creation of products that do not require conventional reduction methods such as etching or milling. Materials scientists at the California Institute of Technology have designed an ultra-thin THREE-DIMENSIONAL structure in a 3D printing unit called an additive manufacturing machine. The beam is nanoscale, too small to be seen with the naked eye.

The new 3-D group prints the structure of a variety of materials, from ceramics to organic compounds. Scientists are also working hard to break out of 3D printing on refractory metals like tungsten and titanium, especially when trying to make tiny powders that are less than 50 microns in size, or about half the width of a hair

The scientists bonded nickel to organic molecules to form a liquid that looked a lot like cough syrup. They used computer software to design a structure and then built it by switching the liquid with a two-photon laser. The laser creates stronger chemical bonds between organic molecules, hardening them into structural building blocks. Since these molecules also bind to nickel, nickel will bind to the structure. In this way, the team was able to print a three-dimensional structure that started out as a mixture of metal ions and nonmetallic organic molecules.

The structure is then placed in an oven and slowly heated to 1000 ° C in a vacuum chamber. This temperature is well below the melting point of nickel (1455℃), but is hot enough to vaporize the organic material in the structure, leaving only the metal. A heating process called pyrolysis also fuses metal particles together.

In addition, because the process evaporates a large amount of structural material, its size is reduced by 80%, but its shape and proportion remain. The resulting shrinkage is an important factor in making the structure so small. The diameter of the printed metal beam in the constructed nanostructure is about 1/1000 of the size of the needle tip.

Scientists are still refining their technique, starting with nickel, but are interested in extending it to other metals commonly used in industry, such as tungsten and titanium. Scientists also hope to use the process to print other materials, including ceramics, semiconductors, piezoelectric materials and other exotic materials.