The effect of laser sintering on the microstructure, relative density, and cracking of sol‐gel–derived silica thin films

Abstract

Combining sol‐gel processing and laser sintering is a promising way for fabricating functional ceramic deposition with high dimensional resolution. In this work, crack‐free silica tracks on a silica substrate with a thickness from ~360 nm to ~950 nm, have been obtained by direct exposure to a CO2 laser beam. At a fixed scanning speed, the density and microstructures of the silica deposition can be precisely controlled by varying the laser output power. The porosity of the laser‐sintered silica tracks ranged from close to 0% to ~60%. When the thickness of the silica deposition exceeded the critical thickness (eg, ~2.2 µm before firing), cracks occurred in both laser‐sintered and furnace‐sintered samples. Cracks propagated along the edge of the laser‐sintered track, resulting in the crack‐free track. However, for the furnace heat‐treated counterpart, the cracks spread randomly. To understand the laser sintering effect, we established a finite element model (FEM) to calculate the temperature profile of the substrate during laser scanning, which agreed well with the one‐dimensional analytical model. The FEM model confirmed that laser sintering was the main thermal effect and the calculated temperature profile can be used to predict the microstructure of the laser‐sintered tracks. Combining these results, we were able to fabricate, predesigned patterned (Clemson tiger paw) silica films with high density using a galvo scanner.

Ultra‐fast, selective, non‐melting, laser sintering of alumina with anisotropic and size‐suppressed grains

“…In this paper, we demonstrate and analyze a localized laser consolidate process that is truly solid‐state sintering. We have also demonstrated that laser sintering can obtain dense ceramic traces, without melting, with small areas at precise positions 28,29 …”

“…We have also demonstrated that laser sintering can obtain dense ceramic traces, without melting, with small areas at precise positions. 28,29 Although laser sintering of ceramics has been studied over decades, the sintering duration was typically a few minutes to about twenty minutes. [30][31][32] The reported laser sintering durations are comparable to the FAST and microwave sintering.…”

One‐Step Fabrication of Nanocrystalline Nanonetwork SnO2 Gas Sensors by Integrated Multilaser Processing

“…[30][31][32] And CO 2 laser heating has been demonstrated for material properties control with high flexibility and short processing time. [33][34][35][36] These laser processing technologies are promising to further improve the fabrication of nanocrystalline metal oxide gas sensors.…”

Information integrated glass module fabricated by integrated additive and subtractive manufacturing

“…During each printing layer, glass pastes [16] are extruded following a line trace through an extruder (eco-Pen300, Preeflow). And CO 2 laser irradiation (with wavelength of 10.6 μm, ti100W, Synrad) is conducted with optimized output power, scanning speed and spot size, for paste melting both in printing layer and between adjacent layers [5,[16][17][18]. The glass 3D printing assisted with CO 2 laser direct melting procedure was described in details in our previous publications [5,16].…”

“…The comparatively larger α CTE of 3D printed glass should be related to the porous structure due to the smaller laser irradiation power and the possible composite difference between the commercial glass/glass fiber and 3D printed glass [16]. The porosity of glass can be flexibly tuned by controlling thickness of top covering paste layers and precise laser processing parameter settings [17,18]. The linear and repeatable temperature responses indicate good bonding between 3D printed glass and silica fiber was realized and the information integrated all-glass module is functional and suitable for high temperature measurements.…”