COMSOL simulation of microwave plasma polishing on different surfaces

Yadav, Hari Narayan Singh; Kumar, Manjesh; Kumar, Abhinav; Das, Manas

doi:10.1016/j.matpr.2021.01.266

Cited by 11 publications

(5 citation statements)

References 14 publications

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“…Raman microscopy was used for understanding the chemical structure of fused silica. 78, 79 A novel process was introduced to investigate the cracks on the optics’ surface through in situ laser illumination. Fused silica observed an 80% reduction in higher spatial wavelength using power spectral density after plasma polishing.…”

Section: Plasma Polishing Methods Applied To Various Optical Componentsmentioning

confidence: 99%

Plasma polishing processes applied on optical materials: A review

Yadav

Kumar

et al. 2021

Journal of Micromanufacturing

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Nowadays, the surface quality of the material is crucial for industry and science. With the development of micro-electronics and optics, the demand for surface quality has become more and more rigorous, making optical surface polishing more and more critical. Plasma polishing technology is conceived as an essential tool for removing surface and subsurface damages from traditional polishing processes. The plasma processing technology is based on plasma chemical reactions and removes atomic-level materials. Plasma polishing can easily nano-finish hard-brittle materials such as ceramics, glass, crystal, fused silica, quartz, Safire, etc. The optical substrate with micro-level and nano-level surface roughness precision is in demand with the advancement in optics fabrication. The mechanical properties of super-finished optics materials are being used to fulfill the requirement of modern optics. This article discusses the processing of different types of freeform, complex and aspheric optical materials by the plasma polishing process used mainly by the optical industry. The plasma polishing devices developed in the last decade are thoroughly reviewed for their working principles, characteristics and applications. This article also examines the impact of various process parameters such as discharge power, rate of gas flow, mixed gas flow ratio and pressure on the plasma polishing process.

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Section: Plasma Polishing Methods Applied To Various Optical Componentsmentioning

confidence: 99%

Plasma polishing processes applied on optical materials: A review

Yadav

Kumar

et al. 2021

Journal of Micromanufacturing

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“…A free tetrahedral mesh was defined, with physicscontrolled meshing used to generate the element sizes, in a similar way to Yadav et al [24]. This gave substrate maximum and minimum element sizes of 2.8 mm and 350 μm, respectively, and wire element size limits of 400 μm and 3 μm.…”

Section: Assumptions Werementioning

confidence: 99%

Simulated and experimental analysis of laser beam energy profiles to improve efficiency in wire-fed laser deposition

Goffin

Tyrer

Jones

et al. 2021

Int J Adv Manuf Technol

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Laser cladding is a well-established technique, with the majority of prior numerical modelling work focused on delivery and melt pool behaviour of powder-based processes. This research presents new investigations into optimised laser beam shaping for the unique characteristics of wire-based processes, where direct substrate heating, as well as heat transfer between the wire and substrate, is important. The value of this subject is the improved deposition rates and dense metallic structures that can be achieved by wire-based deposition processes compared to powder-based material delivery. The within-wire temperature distribution (AISI 316 stainless steel), the heat transfer and direct heating of the substrate (mild steel) are modelled via heat transfer simulations, with three laser beam irradiance distributions. This analysis identified the removal of localised high-temperature regions typically associated to standard Gaussian distributions, and the improved substrate heating that a uniform square beam profile can provide. Experiments using pre-placed wire and a 1.2 kW CO2 laser were analysed using cross-sectional optical microscopy to provide model validation and evidence of improved wire-substrate wetting, while maintaining favourable austenitic metallurgy in the clad material. A key finding of this work is a reduction, from 480 to 190 W/mm2, in the required irradiance for effective melt pool formation when changing from a Gaussian distribution to a uniform square distribution. This also provided a 50% reduction in total energy. The potential improvements to energy efficiency, cost reductions and sustainability improvements are recognised and discussed.

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“…This technique can fabricate large optical components having excellent optical performance and long operational products [21]. Yadav et al [22] revealed the distribution of electron density, temperature, and potential in the plasma chamber for two separate substrates of fused silica using multiphysics simulation.…”

Section: Introductionmentioning

confidence: 99%

Parametric optimisation of plasma polishing process using response surface methodology

Yadav

Das

2023

Surface Engineering

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The plasma polishing process is one of the non-conventional techniques used to remove material at the atomic level from the substrate. During the polishing of the fused silica substrate, the process parameters, namely radio-frequency (RF) power, pressure ratio (SF 6 / O 2 ), and total pressure of the plasma chamber, are investigated and optimised for material removal rate (MRR) and % change in surface roughness (% ΔR a ) using response surface methodology. The optimum values obtained for MRR and % ΔR a are 0.012 mm 3 /min and 3.59, at RF power of 60 W, pressure ratio of 3, and total pressure of 14.3 mbar. The experimental results reveal that surface roughness slightly increases from 0.344 to 0.356 μm after plasma processing at optimised process conditions. Moreover, the plasma-processed fused silica substrate is characterised using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, which depict the presence of silicon, oxygen, and fluorine on the processed substrate.

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COMSOL simulation of microwave plasma polishing on different surfaces

Cited by 11 publications

References 14 publications

Plasma polishing processes applied on optical materials: A review

Plasma polishing processes applied on optical materials: A review

Simulated and experimental analysis of laser beam energy profiles to improve efficiency in wire-fed laser deposition

Parametric optimisation of plasma polishing process using response surface methodology

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