Carbon detection in solid and liquid steel samples using ultraviolet long-short double pulse laser-induced breakdown spectroscopy

An ultraviolet long-short double pulse laser-induced breakdown spectroscopy (UV LS-DP-LIBS) system is employed to detect the carbon element in solid and liquid steel samples. The important issues for the industrial application of LIBS are investigated in this work, which include the carbon excitation in steel, the influences of CO₂, the quantitative analysis and the escape phenomenon of carbon. It is found that the CO₂ in air can also be involved to the plasma generation and emits the carbon specific spectral lines. The strong emission line at C I 193.091 nm can be observed when the sample is placed in the gas atmosphere with CO₂. It is also found that the carbon signal generated from liquid steel is continuously decreasing after the sample is molten. The experimental investigation demonstrates that the influences of O₂ cause the carbon escape phenomenon in liquid steel, which should be fully considered for the industrial application of LIBS.