نتایج جستجو برای: laser melting
تعداد نتایج: 207729 فیلتر نتایج به سال:
This article studies the particle temperature distribution depending on the laser radiation power and the particle’s trajectory and velocity. The uneven heating of particles moving in the laser radiation field is identified. The regimes of laser heating without melting, with partial melting, and with complete particle melting are considered.
Objective: The aim of this study was to evaluate and compare the effect of dental surface treatment with Er:YAG , Nd:YAG ,CO2 lasers and sodium ascorbate to recently laser bleached enamel by scanning electron microscope (SEM). Methods: 15caries-free extracted human third molars were selected for this study. The samples were bleached by Heydent JW power activated by diode laser 810 nm. After 7 d...
Selective laser melting (SLM) and laser cladding are laser additive manufacturing methods that have been developed for application to the near-net-shape process and 3D printing. The temperature distributions and track profiles of SLM and clad layers require additional in-depth investigation to optimize manufacturing processes. This research involved developing a tailored laser heat source model...
Hydrodynamic multi-phase model for simulation of laser-induced non-equilibrium phase transformations
A hydrodynamic model based on transport equations and semi-empirical multiphase equations-of-state for metals is developed and applied to simulation of short pulse laser melting and resolidification. New computational algorithms are developed for modeling of two-phase zones of solid-liquid and liquid-gas coexistence, as well as for explicit tracking of interfaces between the phases. The model a...
Two melting mechanisms are reproduced and quantified for superheating and melting of Al nanolayer irradiated by picoand femtosecond laser using the advanced phase-field approach coupled with mechanics and a two-temperature model. At heating rates Q 79:04 K/ps induced by picosecond laser, two-sided barrierless surface melting forms two solid-melt interfaces, which meet near the center of a sampl...
The kinetics and microscopic mechanisms of laser melting of a thin metal film are investigated in a computational study that combines molecular dynamics simulations with a continuum description of the laser excitation and subsequent relaxation of the conduction band electrons. Two competing melting mechanisms, homogeneous nucleation of liquid regions inside the crystalline material and propagat...
The vapor-liquid equilibria of three recently proposed water models have been computed using Gibbs-Duhem simulations. These models are TIP4P/Ew, TIP4P/2005, and TIP4P/ice and can be considered as modified versions of the TIP4P model. By design TIP4P reproduces the vaporization enthalpy of water at room temperature, whereas TIP4P/Ew and TIP4P/2005 match the temperature of maximum density and TIP...
Combined atomistic-continuum modeling of short-pulse laser melting and disintegration of metal films
The kinetics and microscopic mechanisms of laser melting and disintegration of thin Ni and Au films irradiated by a short, from 200 fs to 150 ps, laser pulse are investigated in a coupled atomistic-continuum computational model. The model provides a detailed atomic-level description of fast nonequilibrium processes of laser melting and film disintegration and, at the same time, ensures an adequ...
objective: the aim of this study was to evaluate and compare the effect of dental surface treatment with er:yag , nd:yag ,co2 lasers and sodium ascorbate to recently laser bleached enamel by scanning electron microscope (sem). methods: 15caries-free extracted human third molars were selected for this study. the samples were bleached by heydent jw power activated by diode laser 810 nm. after 7 d...
The melting duration and molten depth are key information for Laser-Assisted Direct Imprinting, which raises the issue of the melting & solidification induced by excimer-pulse-laser shining through unilaterally transparent binary materials. Based on the matured laser-annealing analysis, the thermal-contact resistance is taken into account to simulate and predict the melting behavior for this pr...
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