quantitative analysis of steel using laser induced

IntroductionThe J200 LIBS (Laser Induced Breakdown Spectroscopy) Instrument from Applied Spectra, Inc. provides simple but powerful elemental analysis for a wide range of sample matrices. LIBS provides great elemental coverage from H – Pu, including elements that are difficult or impossible by popular elemental techniques, such as XRF, including non-metals (e.g. C, H, N, S, and O) and halogens (e.g. F). LIBS is a straightforward technique where most measurements are performed in an atmospheric environment without the need for a high vacuum, and LIBS can measure organic elements such as H, N, and O in a purged gas environment with Argon or Helium.

For steel analysis, LIBS is ideal for rapid QC (quantitative analysis and detection of contaminants) for raw ma-terials in production, and to check the elemental composition of finished products. LIBS also offers the ability to analyze slag samples that can lead to the recovery of precious metals lost in the steel production process.

The complex emission lines in LIBS spectra correlate with elements in the steel samples. These can be eas-ily and accurately identified and labeled with Applied Spectra's TruLIBSTM Database. Additionally, using ASI’s advanced calibration software, the user can easily make calibration curves for quantitative analysis.

Quantitative Analysis of Steel Using Laser Induced Breakdown Spectroscopy (LIBS)

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Quantitative Analysis of Steel

Using Laser Induced Breakdown Spectroscopy (LIBS)

Operating ParametersApplied Spectra Inc.’s J200 LIBS Instrument

• 1064 nm Nd:YAG laser

• FlexTM sample chamber with gas flow

• Sample: Bureau of Analysed Samples Ltd. Steel Standards

• LIBS data analyzed using Applied Spectra Data Analysis Software package

Applied Spectra Inc.’s J200 LIBS Instrument

Figure 1. Example LIBS spectrum from BAS CRM 404/2.

Sample AnalysisThe J200 LIBS Instrument was used to analyze a set of stainless steel samples from the Bureau of Analysed Samples Ltd. (10 standards: SS-CRM 401/2 – 410/2). These standards were used to evaluate the ability for LIBS to detect and quantify specific elements of interest (Figure 1). These elements include, but are not limited to C, P, Cu, Mn, and Mo.



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The BAS CRMs were analyzed using the J200 LIBS Instrument equipped with a broadband CCD detector that gives spectral coverage from 190 to 1040 nm. Figure 1 shows a few zoomed-in spectral regions from the full spectrum of the 404/2 BAS CRM’s. Using ASI’s data analysis package provides an advanced calibration algorithm that uses the entire LIBS spectra for performing the quantitative analysis of unknown steel samples. The advanced calibration model was built using 9 of the steel standards, while SRM BAS 404/2 was used as a test sample to determine the accuracy and precision of the model. Figure 2 displays the calibration curves obtained for C, Si, P, and Mo.

Figure 2. Calibration curves for C, Si, P, and Mo created using ASI’s advanced calibration model.

Table 1 displays the results of using BAS 404/2 as sample to test the advanced calibration model. The accu-racy of the method was good (< 10 %BIAS) and ranged from -5.7 to 7.6 %BIAS. The precision of the method was 1.9 – 9.4 %RSD. The reference data from these BAS CRMs were determined using combustion, gravi-metric, ICP-OES, titration, and FAAS methods.

0.0

0.5

1.0

1.5

0.0 0.5 1.0 1.5

Mea

sure

d Va

lue

(wt.

%)

Reference Values (wt. %)

Carbon

0.0

0.5

1.0

1.5

0.0 0.5 1.0 1.5

Mea

sure

d Va

lue

(wt.

%)


Silicon

0.00

0.03

0.06

0.09

0.00 0.03 0.06 0.09

Mea

sure

d Va

lue

(wt.

%)


Phosphorous

0.0

0.4

0.8

1.2

0.0 0.4 0.8 1.2

Mea

sure

d Va

lue

(wt.

%)


Molybdenum



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BAS 404 C Si P Cr Mn Ni Cu Mo

Reference Values (wt. %) 0.696 1.12 0.0479 0.774 0.532 0.393 0.427 0.307

Detected Value (wt. %) 0.702 1.16 0.0502 0.741 0.573 0.375 0.447 0.290

± SD 0.093 0.08 0.0036 0.033 0.033 0.035 0.032 0.050

% RSD 4.5 7.3 7.2 4.5 5.8 9.4 7.1 1.9

% Bias 0.8 3.3 4.8 -4.3 7.6 -4.6 4.7 -5.7

Table 1. Accuracy and precision of the multivariate calibration method tested using the BAS 404 steel CRM.

Conclusion

ASI’s J200 LIBS Instrument provides a simple and elegant solution for simultaneous measurement of impor-tant elements in the steel samples that are sometimes difficult for more traditional methods such as XRF and Arc/Spark OES. Applied Spectra, Inc.’s data analysis software package makes data processing simple for all skill levels of analysts. The accuracy displayed by this experiment is within 3-sigma of the reference values reported by Bureau of Analysed Samples Ltd.

quantitative analysis of steel using laser induced

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