Analysis of the fume produced during laser-material interactions

Bridgwater, A. E.

Abstract

The purpose of this research was to improve knowledge of the by-products of laser processing; namely the composition of particles, gases and vapours that are evolved during laser-material interactions. For IR sources, photothermal processes occur and thermal degradation products result, whereas UV lasers may additionally induce photochemical effects. The material investigated was an ITO ink (indium tin oxide nanoparticles in a photo-curable binder and organic solvent) spin-coated onto glass substrates. Thermogravimetric analysis showed that even for temperatures below the upper working limit of the glass substrate, gas-phase products are produced. Laser heating of the binder, 3-methacryloxypropyl-trimethoxysilane (MPTS), in a closed chamber showed that infrared irradiation generates butyl methacrylate. In order to collect a sample representative of the fume entrained in a local exhaust ventilation (LEV) system, an isokinetic arrangement was de- veloped. This balances the volumetric flow rates of the main extraction flow and a sampling tube so that both experience the same flow velocity. Gases were collected with this system into a Tedlar bag and then adsorbed onto a solid phase microextraction (SPME) fibre followed by GC-MS analysis. However, contami- nation from polymers in the sampling system was detected and so a glass/metal construction was utilized in the final version. The gas phase data were inconclusive as no peaks above the detection limits of the equipment could be attributed to laser interactions. The cause of this has been tentatively attributed to excessive dilution of the analytes. Through SEM and EDXA measurements, particulates captured following 130mJ/cm2 XeCl laser irradiation were successfully identified as 40nm ITO particle clusters. It is concluded that the use of a three-stage LEV system is advisable with pre-filter, HEPA filter, and activated charcoal. A flow rate of at least 150m3/hr is recommended, and personal monitoring is advised.

Citation

Bridgwater, A. E. (2020). Analysis of the fume produced during laser-material interactions. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4222494

• Thesis Type: Thesis
• Deposit Date: Jun 30, 2020
• Publicly Available Date: Feb 23, 2023
• Keywords: Physics
• Public URL: https://hull-repository.worktribe.com/output/4222494
• Additional Information: Department of Physics, The University of Hull
• Award Date: Apr 1, 2020