Three-dimensional Structure 3D Printing Technology Has Been Able to Use Nano Metal Powder Printing

Three-dimensional printing technology is also known as augmentation manufacturing. Using this technology to manufacture metal devices is somewhat the same as our current powder metallurgy process. It is based on metal powder, such as ceramic powder and nano metal powder. The difference is that the material powder is not joined by sintering, but by sprinkler, the section of the part is "printed" on the material powder with special adhesive.

At present, one of the difficulties of 3D printing technology is the use of refractory metals for printing, especially metals with high melting points such as tungsten, chromium and rhenium, let alone nano-sized powder particles. For many years, scientists from all over the world have devoted themselves to the study of new technologies that can achieve both cost-effective and ideal performance requirements.

A few days ago, foreign scientists developed a new technology that could use 3D printing technology to create complex nanoscale metal structures. This technology can be used in a variety of applications, such as creating 3-D logic circuits on tiny computer chips, and manufacturing engineering ultralight aircraft components. This technology can create new nanomaterials with different characteristics.

In 3D printing, objects are built layer by layer, allowing the creation of products that do not require conventional subtraction methods such as etching or milling. Julia Greer, a material scientist at California Institute of Technology, and her team have designed an ultra-thin three-dimensional structure in a 3D printer that is nano-sized and too small to be visible to the naked eye.

The new 3-D group prints out the structures of various materials, from ceramics to organic compounds. In addition, scientists are working hard to break through refractory metals such as tungsten and titanium in 3D printing, especially when trying to make tiny powders smaller than 50 microns or about half the width of hair.

More specifically: Scientists bond nickel with organic molecules to form a liquid that looks like cough syrup. They designed a structure using computer software, and then built it by switching liquids using a two-photon laser. Laser produces stronger chemical bonds between organic molecules and hardens them into structural building blocks. Because these molecules also bind to nickel atoms, nickel binds to the structure. In this way, the team was able to print three-dimensional structures, initially a mixture of metal ions and nonmetallic organic molecules.

The structure is then placed in an oven and slowly heated to 1000 degrees Celsius (about 1800 degrees Fahrenheit) in a vacuum chamber. The temperature is much lower than the melting point of nickel (1455 degrees Celsius or about 2650 degrees Fahrenheit), but it is hot enough to evaporate organic materials in the structure, leaving only metals. The heating process known as pyrolysis also fuses metal particles together.

In addition, due to the evaporation of a large number of structural materials, the size of the process is reduced by 80%, but its shape and proportion are still maintained. The ultimate shrinkage is an important reason for making the structure so small. In this nanostructure, the diameter of the metal beam in the printed part is about 1/1000 of the size of the tip of the sewing needle.

Greer and her team are still refining their technology, and although they start with nickel, they are interested in expanding to other metals commonly used in industry, such as tungsten and titanium. Scientists also hope to use this process to print other materials, including ceramics, semiconductors, piezoelectric materials and other heterogeneous materials.

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