3D Printed Optical Quality Silica and Silica–Titania Glasses from Sol–Gel Feedstocks

Abstract

We report a method for fabricating optical quality silica and silica-titania glasses by additive manufacturing, or 3D printing. Key to this success was the combination of sol-gel derived silica and silica-titania colloidal feedstocks, 3D direct ink writing (DIW) technology, and conventional glass thermal processing methods. Printable silica and silica-titania sol inks were prepared directly from molecular precursors by a simple one-pot method, which was optimized to yield viscous, shear-thinning colloidal suspensions with tuned rheology ideal for DIW. After printing, the parts were dried and sintered under optimized thermal conditions to ensure complete organic removal and uniform densification without crystallization.Characterizations of the 3D-printed pure silica and silica-titania glasses show that they are This article is protected by copyright. All rights reserved. 2 equivalent to commercial optical fused silica (Corning ® 7980) and silica-titania glasses (Corning ULE ® 7972). More specifically, they exhibit comparable chemical composition, SiO 2 network structure, refractive index, dispersion, optical transmission, and coefficient of thermal expansion. 3D printed silica and silica-titania glasses also exhibited comparable polished surface roughness and meet refractive index homogeneity standards within range of commercial optical grade glasses. This method establishes 3D printing as a viable tool to create optical glasses with compositional and geometric configurations that are inaccessible by conventional optical fabrication methods. † denotes value determined by LA-ICP-MS; a-SiO 2 used to represent amorphous SiO 2

Direct Ink Writing Glass: A Preliminary Step for Optical Application

“…As 3D printing is a readily accessible shaping method and has been utilized in many kinds of materials, it may be still a good candidate for shaping glass as well. Recent reports have brought excellent examples and gained confidence in both the glass and 3D printing community by various methods such as depositing and annealing the molten filaments, laser aided filament-fed process, direct ink writing, stereolithography, and digital light processing [12,13,[16][17][18][19]. Among them, the first two require a high energy source such as heating or laser assisted printing, with the glass being prepared in one step, while at least two steps are required for the other methods, that is to say, green glass samples were printed with an extra follow-up sintering process.…”

“…[9,17] Here, we report a preliminary experiment on printing borosilicate glass by direct ink writing. Unlike the previous reports in [12,16], the micron-sized borosilicate glass particles are utilized instead of the nanoparticles or liquid molecular precursors (sol-gel) of silica or silica-based compositions. The first challenge is to form colloidal stable inks as the borosilicate glass used in this study undergoes hydrolysis, which, as mentioned before, makes suspension rheologically unpredictable.…”

Freeform Microfluidic Networks Encapsulated in Laser‐Printed 3D Macroscale Glass Objects

“…However, fabrication of freeform 3D hollow microchannels in fused silica is still difficult for current 2D fabrication techniques in terms of complex and tedious fabrication procedures, additional costs for aligning, stacking, and bonding steps. [27] Meanwhile, 3D printing of glass materials emerging in recent years brings some new opportunities for scalable fabrication of freeform glass structures by either additive manufacturing strategies [28][29][30][31][32][33] or laser subtractive processing methods. [15][16][17][18][19][20] A suspended hollow microchannel structure with a 3D controllable configuration can be fabricated in a way of either laser-assisted selective wet etching [21][22][23] or liquid-assisted laser ablation.…”

High‐Performance Materials for 3D Printing in Chemical Synthesis Applications

“…In addition, both are direct glass printing processes and perform the printing process at elevated temperatures requiring special expensive printing equipment. [36][37][38] Both processes allow printing fused silica glass with resolutions of a few hundred micrometers. The first indirect printing process was developed by our group using silica nanocomposites that can be cured by light and turned into transparent high-quality fused silica glass via thermal debinding and sintering.…”