Multicomponent Gas-Particle Flow and Heat/Mass Transfer Induced by a Localized Laser Irradiation on a Urethane-Coated Stainless Steel Substrate

TL;DR

This study uses 3D numerical simulations to analyze heat, mass transfer, and chemical reactions during laser irradiation of urethane-coated stainless steel, revealing decomposition and ejection of pigment particles at specific temperatures.

Contribution

It introduces a detailed finite volume method simulation of laser-induced chemical reactions and particle ejection in a urethane-coated steel system, highlighting temperature-dependent behaviors.

Findings

Polyurethane decomposes at 560 K, producing combustion gases.

Chromium oxide pigment is ejected as solid parcels during laser heating.

Laser power influences temperature, flow, and reaction dynamics.

Abstract

A three-dimensional numerical simulation is conducted for a complex process in a laser-material system, which involves heat and mass transfer in a compressible gaseous phase and chemical reaction during laser irradiation on a urethane paint coated on a stainless steel substrate. A finite volume method (FVM) with a co-located grid mesh that discretizes the entire computational domain is employed to simulate the heating process. The results show that when the top surface of the paint reaches a threshold temperature of 560 K, the polyurethane starts to decompose through chemical reaction. As a result, combustion products CO2, H2O and NO2 are produced and chromium (III) oxide, which serves as pigment in the paint, is ejected as solid parcels from the paint into the gaseous domain. Variations of temperature, density and velocity at the center of the laser irradiation spot, and the concentrations of reaction reactant/products in the gaseous phase are presented and discussed, by comparing six scenarios with different laser powers ranging from 2.5 kW to 15 kW with an increment of 2.5 kW.