Ablation of materials subjected to laser radiation and high-speed gas flows

Abstract

This paper presents results of investigations of the steady-state ablation that takes place when materials are irradiated by high-intensity laser radiation in high-speed gas flows. Materials investigated were stainless steels 304 and 310, carbon steel 1020, titanium 6Al-4V alloy, commercially pure titanium, and a glass fiber reinforced polyester. Four gases were used: air, a mixture of 40% oxygen and 60% nitrogen, argon, and nitrogen. Target samples were subjected to continuous-wave irradiation by a carbon-dioxide laser, and to tangential subsonic gas flows at a static pressure of 1 atm. The quantities measured included the ablation rates and surface temperatures. Analysis of the data for the metals yields values for the surface absorptances at 10.6 μm and values for the net contribution to the heat input provided by combustion and cooling. Information is also provided on the mechanism of melt removal and on the surface oxidation processes. For the nonmetal, the enthalpy required for ablation was obtained. These results, which are applicable to the upstream regions of irradiated areas, may be used to predict ablation characteristics for the gas-assisted laser cutting of plates, and the production of large holes in plates.

Optimized laser processing of calibration blocks for grinding burn detection with Barkhausen noise

“…The absorptance that refers to the fraction of incident laser light absorbed by a surface is dependent on multiple factors. studied the effect of the absorptance of two different wavelength lasers at various temperatures on metal surfaces and noticed that a laser beam with a wavelength of 1.07 m was absorbed better by polished metal surfaces than a laser beam with a wavelength of 10.6 m. further concluded that the increase in surface temperature increased the absorptance values for polished stainless steel samples, however, only at elevated temperatures above 700 • C. In addition, Crane et al (1980) reported that surfaceoxidized metal surfaces have higher absorptance values. Pantsar (2005) concluded that similar results were obtained because oxide layers may produce multiple reflections to laser light.…”

Laser‐induced ignition in solid‐state combustion

“…However, this temperature is still very high and the resulting temperature profiles are similar to those in Figures 11 and 12. Absorption of laser radiation leads to material removal from the heated surface (Ready, 1964;Beiko et al, 1967;Crane et al, 1980;Klein and Berry, 1987;Rycalin and Uglov, 1982) due to product sublimation and particle ejection. The location of the moving front surface due to material removal is found either by estimating a sublimation rate based on the latent heat of sublimation or by using an effective mate- rial removal rate estimated from the experimental data.…”

High-power laser resistance of filled sandwich panel with truss core: An experimental study

“…Tangential airflow increases ablative rate by removing melted materials and reducing burn through time [22][23][24][25][26]. This airflow also eliminates the oxide produced by the oxidation of material and supplies extra oxygen.…”