A brand new 3D printing technique could allow scientists to print glass which incorporates different ‘refractive indices’ in a single printed piece of transparent glass. This could make finishing glass products cheaper and easier.
The team, working out of Lawrence Livermore, successfully demonstrated the creation of transparent glass through 3D printing. This development that could lead to altering the design and structure of lasers and other devices that incorporate optics.
The Lab is always looking for different ways to create new materials for optical applications [..] We’re not going to replace the optical materials made through traditional means, but we’re trying to impart new functionality using additive manufacturing. This is the first step to being able to print compositionally graded glass optics.Project lead Rebecca project lead Rebecca Dylla-Spears
Up to now other research institutions have demonstrated that 3D printing of glass is possible, but this has always involved ‘extruding molten glass filaments’ through a heated print-head or using lasers to selectively melt and fuse glass powders.
The problem with these types of methods are that powders and filaments don’t fully meld together in the short times they are heated during the printing process. This means that while the material looks like glass they are often porous or have non-uniform structures making them unsuitable for optical applications.
How it works – the new method for printing transparent glass
The new approach does not rely on printing molten glass.
Instead the team created custom inks that are formed from concentrated suspensions of glass particles. These inks were designed to can be printed at room temperature.
Once printed, the components then under undergo a carefully designed thermal treatment which removes evidence of the printing process.
Last of all – the parts given an optical quality polish.
These steps combined means that the finished product has a much higher chance of achieving optical uniformity.
Materials engineer Du Nguyen, who contributed to the paper explained that “for printing high-quality optics, you shouldn’t be able to see any pores and lines, they have to be transparent… Once we got a general formulation to work, we were able to tweak it so the material could merge during the printing process. Most other groups that have printed glass melt the glass first and cool it down later, which has the potential for residual stress and cracking. Because we print at room temperature, that’s less of an issue.”
What the research means for the 3D printing of glass
This new method mightallow scientists to print glass that incorporates different refractive indices in a single flat optic.
Up to now special shapes that are required for constant composition glasses to achieve similar lensing characteristics.
As someone using the new method would be able to program the composition the final components should end up being both easier and cheaper to finish.
The aim is not replace traditional optics but to create new applications with composition gradients that don’t exist today
The next steps for 3d printing of glass
Now that the team has proved printing transparent glass is possible they will be focusing their attention on creating actual high-quality optics and gradient index lenses using the technique.
Silica inks are developed, which may be 3D printed and thermally processed to produce optically transparent glass structures with sub-millimeter features in forms ranging from scaffolds to monoliths. The inks are composed of silica powder suspended in a liquid and are printed using direct ink writing. The printed structures are then dried and sintered at temperatures well below the silica melting point to form amorphous, solid, transparent glass structures. This technique enables the mold-free formation of transparent glass structures previously inaccessible using conventional glass fabrication processes.Article Abstract